encoders.texi 71 KB
Newer Older
1 2 3
@chapter Encoders
@c man begin ENCODERS

4
Encoders are configured elements in FFmpeg which allow the encoding of
5 6
multimedia streams.

7
When you configure your FFmpeg build, all the supported native encoders
8 9 10 11 12 13 14 15 16
are enabled by default. Encoders requiring an external library must be enabled
manually via the corresponding @code{--enable-lib} option. You can list all
available encoders using the configure option @code{--list-encoders}.

You can disable all the encoders with the configure option
@code{--disable-encoders} and selectively enable / disable single encoders
with the options @code{--enable-encoder=@var{ENCODER}} /
@code{--disable-encoder=@var{ENCODER}}.

17
The option @code{-encoders} of the ff* tools will display the list of
18 19
enabled encoders.

20 21 22 23
@c man end ENCODERS

@chapter Audio Encoders
@c man begin AUDIO ENCODERS
24

25 26
A description of some of the currently available audio encoders
follows.
27

28 29 30 31 32
@anchor{aacenc}
@section aac

Advanced Audio Coding (AAC) encoder.

33 34 35 36 37
This encoder is the default AAC encoder, natively implemented into FFmpeg. Its
quality is on par or better than libfdk_aac at the default bitrate of 128kbps.
This encoder also implements more options, profiles and samplerates than
other encoders (with only the AAC-HE profile pending to be implemented) so this
encoder has become the default and is the recommended choice.
38 39 40 41 42 43

@subsection Options

@table @option
@item b
Set bit rate in bits/s. Setting this automatically activates constant bit rate
44
(CBR) mode. If this option is unspecified it is set to 128kbps.
45 46 47 48 49 50

@item q
Set quality for variable bit rate (VBR) mode. This option is valid only using
the @command{ffmpeg} command-line tool. For library interface users, use
@option{global_quality}.

51 52 53
@item cutoff
Set cutoff frequency. If unspecified will allow the encoder to dynamically
adjust the cutoff to improve clarity on low bitrates.
54 55 56 57 58 59 60 61 62 63

@item aac_coder
Set AAC encoder coding method. Possible values:

@table @samp
@item twoloop
Two loop searching (TLS) method.

This method first sets quantizers depending on band thresholds and then tries
to find an optimal combination by adding or subtracting a specific value from
64 65 66
all quantizers and adjusting some individual quantizer a little.  Will tune
itself based on whether @option{aac_is}, @option{aac_ms} and @option{aac_pns}
are enabled.
67
This is the default choice for a coder.
68

69 70 71 72 73 74 75
@item anmr
Average noise to mask ratio (ANMR) trellis-based solution.

This is an experimental coder which currently produces a lower quality, is more
unstable and is slower than the default twoloop coder but has potential.
Currently has no support for the @option{aac_is} or @option{aac_pns} options.
Not currently recommended.
76 77 78 79 80

@item fast
Constant quantizer method.

This method sets a constant quantizer for all bands. This is the fastest of all
81 82 83
the methods and has no rate control or support for @option{aac_is} or
@option{aac_pns}.
Not recommended.
84 85 86

@end table

87
@item aac_ms
88
Sets mid/side coding mode. The default value of "auto" will automatically use
89
M/S with bands which will benefit from such coding. Can be forced for all bands
90 91
using the value "enable", which is mainly useful for debugging or disabled using
"disable".
92 93 94 95

@item aac_is
Sets intensity stereo coding tool usage. By default, it's enabled and will
automatically toggle IS for similar pairs of stereo bands if it's benefitial.
96
Can be disabled for debugging by setting the value to "disable".
97 98 99 100

@item aac_pns
Uses perceptual noise substitution to replace low entropy high frequency bands
with imperceivable white noise during the decoding process. By default, it's
101
enabled, but can be disabled for debugging purposes by using "disable".
102 103 104 105 106 107 108

@item aac_tns
Enables the use of a multitap FIR filter which spans through the high frequency
bands to hide quantization noise during the encoding process and is reverted
by the decoder. As well as decreasing unpleasant artifacts in the high range
this also reduces the entropy in the high bands and allows for more bits to
be used by the mid-low bands. By default it's enabled but can be disabled for
109
debugging by setting the option to "disable".
110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133

@item aac_ltp
Enables the use of the long term prediction extension which increases coding
efficiency in very low bandwidth situations such as encoding of voice or
solo piano music by extending constant harmonic peaks in bands throughout
frames. This option is implied by profile:a aac_low and is incompatible with
aac_pred. Use in conjunction with @option{-ar} to decrease the samplerate.

@item aac_pred
Enables the use of a more traditional style of prediction where the spectral
coefficients transmitted are replaced by the difference of the current
coefficients minus the previous "predicted" coefficients. In theory and sometimes
in practice this can improve quality for low to mid bitrate audio.
This option implies the aac_main profile and is incompatible with aac_ltp.

@item profile
Sets the encoding profile, possible values:

@table @samp
@item aac_low
The default, AAC "Low-complexity" profile. Is the most compatible and produces
decent quality.

@item mpeg2_aac_low
134 135
Equivalent to @code{-profile:a aac_low -aac_pns 0}. PNS was introduced with the
MPEG4 specifications.
136 137

@item aac_ltp
138 139
Long term prediction profile, is enabled by and will enable the @option{aac_ltp}
option. Introduced in MPEG4.
140

141
@item aac_main
142 143
Main-type prediction profile, is enabled by and will enable the @option{aac_pred}
option. Introduced in MPEG2.
144 145

@end table
146
If this option is unspecified it is set to @samp{aac_low}.
147 148
@end table

149
@section ac3 and ac3_fixed
150 151 152 153 154 155 156 157 158 159 160 161 162 163

AC-3 audio encoders.

These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as
the undocumented RealAudio 3 (a.k.a. dnet).

The @var{ac3} encoder uses floating-point math, while the @var{ac3_fixed}
encoder only uses fixed-point integer math. This does not mean that one is
always faster, just that one or the other may be better suited to a
particular system. The floating-point encoder will generally produce better
quality audio for a given bitrate. The @var{ac3_fixed} encoder is not the
default codec for any of the output formats, so it must be specified explicitly
using the option @code{-acodec ac3_fixed} in order to use it.

164
@subsection AC-3 Metadata
165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182

The AC-3 metadata options are used to set parameters that describe the audio,
but in most cases do not affect the audio encoding itself. Some of the options
do directly affect or influence the decoding and playback of the resulting
bitstream, while others are just for informational purposes. A few of the
options will add bits to the output stream that could otherwise be used for
audio data, and will thus affect the quality of the output. Those will be
indicated accordingly with a note in the option list below.

These parameters are described in detail in several publicly-available
documents.
@itemize
@item @uref{http://www.atsc.org/cms/standards/a_52-2010.pdf,A/52:2010 - Digital Audio Compression (AC-3) (E-AC-3) Standard}
@item @uref{http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf,A/54 - Guide to the Use of the ATSC Digital Television Standard}
@item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf,Dolby Metadata Guide}
@item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf,Dolby Digital Professional Encoding Guidelines}
@end itemize

183
@subsubsection Metadata Control Options
184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199

@table @option

@item -per_frame_metadata @var{boolean}
Allow Per-Frame Metadata. Specifies if the encoder should check for changing
metadata for each frame.
@table @option
@item 0
The metadata values set at initialization will be used for every frame in the
stream. (default)
@item 1
Metadata values can be changed before encoding each frame.
@end table

@end table

200
@subsubsection Downmix Levels
201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233

@table @option

@item -center_mixlev @var{level}
Center Mix Level. The amount of gain the decoder should apply to the center
channel when downmixing to stereo. This field will only be written to the
bitstream if a center channel is present. The value is specified as a scale
factor. There are 3 valid values:
@table @option
@item 0.707
Apply -3dB gain
@item 0.595
Apply -4.5dB gain (default)
@item 0.500
Apply -6dB gain
@end table

@item -surround_mixlev @var{level}
Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo. This field will only be written to the
bitstream if one or more surround channels are present. The value is specified
as a scale factor.  There are 3 valid values:
@table @option
@item 0.707
Apply -3dB gain
@item 0.500
Apply -6dB gain (default)
@item 0.000
Silence Surround Channel(s)
@end table

@end table

234
@subsubsection Audio Production Information
235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267
Audio Production Information is optional information describing the mixing
environment.  Either none or both of the fields are written to the bitstream.

@table @option

@item -mixing_level @var{number}
Mixing Level. Specifies peak sound pressure level (SPL) in the production
environment when the mix was mastered. Valid values are 80 to 111, or -1 for
unknown or not indicated. The default value is -1, but that value cannot be
used if the Audio Production Information is written to the bitstream. Therefore,
if the @code{room_type} option is not the default value, the @code{mixing_level}
option must not be -1.

@item -room_type @var{type}
Room Type. Describes the equalization used during the final mixing session at
the studio or on the dubbing stage. A large room is a dubbing stage with the
industry standard X-curve equalization; a small room has flat equalization.
This field will not be written to the bitstream if both the @code{mixing_level}
option and the @code{room_type} option have the default values.
@table @option
@item 0
@itemx notindicated
Not Indicated (default)
@item 1
@itemx large
Large Room
@item 2
@itemx small
Small Room
@end table

@end table

268
@subsubsection Other Metadata Options
269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322

@table @option

@item -copyright @var{boolean}
Copyright Indicator. Specifies whether a copyright exists for this audio.
@table @option
@item 0
@itemx off
No Copyright Exists (default)
@item 1
@itemx on
Copyright Exists
@end table

@item -dialnorm @var{value}
Dialogue Normalization. Indicates how far the average dialogue level of the
program is below digital 100% full scale (0 dBFS). This parameter determines a
level shift during audio reproduction that sets the average volume of the
dialogue to a preset level. The goal is to match volume level between program
sources. A value of -31dB will result in no volume level change, relative to
the source volume, during audio reproduction. Valid values are whole numbers in
the range -31 to -1, with -31 being the default.

@item -dsur_mode @var{mode}
Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround
(Pro Logic). This field will only be written to the bitstream if the audio
stream is stereo. Using this option does @b{NOT} mean the encoder will actually
apply Dolby Surround processing.
@table @option
@item 0
@itemx notindicated
Not Indicated (default)
@item 1
@itemx off
Not Dolby Surround Encoded
@item 2
@itemx on
Dolby Surround Encoded
@end table

@item -original @var{boolean}
Original Bit Stream Indicator. Specifies whether this audio is from the
original source and not a copy.
@table @option
@item 0
@itemx off
Not Original Source
@item 1
@itemx on
Original Source (default)
@end table

@end table

323
@subsection Extended Bitstream Information
324 325 326 327 328 329 330 331 332
The extended bitstream options are part of the Alternate Bit Stream Syntax as
specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts.
If any one parameter in a group is specified, all values in that group will be
written to the bitstream.  Default values are used for those that are written
but have not been specified.  If the mixing levels are written, the decoder
will use these values instead of the ones specified in the @code{center_mixlev}
and @code{surround_mixlev} options if it supports the Alternate Bit Stream
Syntax.

333
@subsubsection Extended Bitstream Information - Part 1
334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429

@table @option

@item -dmix_mode @var{mode}
Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt
(Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode.
@table @option
@item 0
@itemx notindicated
Not Indicated (default)
@item 1
@itemx ltrt
Lt/Rt Downmix Preferred
@item 2
@itemx loro
Lo/Ro Downmix Preferred
@end table

@item -ltrt_cmixlev @var{level}
Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the
center channel when downmixing to stereo in Lt/Rt mode.
@table @option
@item 1.414
Apply +3dB gain
@item 1.189
Apply +1.5dB gain
@item 1.000
Apply 0dB gain
@item 0.841
Apply -1.5dB gain
@item 0.707
Apply -3.0dB gain
@item 0.595
Apply -4.5dB gain (default)
@item 0.500
Apply -6.0dB gain
@item 0.000
Silence Center Channel
@end table

@item -ltrt_surmixlev @var{level}
Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the
surround channel(s) when downmixing to stereo in Lt/Rt mode.
@table @option
@item 0.841
Apply -1.5dB gain
@item 0.707
Apply -3.0dB gain
@item 0.595
Apply -4.5dB gain
@item 0.500
Apply -6.0dB gain (default)
@item 0.000
Silence Surround Channel(s)
@end table

@item -loro_cmixlev @var{level}
Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the
center channel when downmixing to stereo in Lo/Ro mode.
@table @option
@item 1.414
Apply +3dB gain
@item 1.189
Apply +1.5dB gain
@item 1.000
Apply 0dB gain
@item 0.841
Apply -1.5dB gain
@item 0.707
Apply -3.0dB gain
@item 0.595
Apply -4.5dB gain (default)
@item 0.500
Apply -6.0dB gain
@item 0.000
Silence Center Channel
@end table

@item -loro_surmixlev @var{level}
Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the
surround channel(s) when downmixing to stereo in Lo/Ro mode.
@table @option
@item 0.841
Apply -1.5dB gain
@item 0.707
Apply -3.0dB gain
@item 0.595
Apply -4.5dB gain
@item 0.500
Apply -6.0dB gain (default)
@item 0.000
Silence Surround Channel(s)
@end table

@end table

430
@subsubsection Extended Bitstream Information - Part 2
431 432 433 434 435 436 437 438 439 440 441 442 443

@table @option

@item -dsurex_mode @var{mode}
Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX
(7.1 matrixed to 5.1). Using this option does @b{NOT} mean the encoder will actually
apply Dolby Surround EX processing.
@table @option
@item 0
@itemx notindicated
Not Indicated (default)
@item 1
@itemx on
444
Dolby Surround EX Off
445 446
@item 2
@itemx off
447
Dolby Surround EX On
448 449 450 451 452 453 454 455 456 457 458 459 460
@end table

@item -dheadphone_mode @var{mode}
Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone
encoding (multi-channel matrixed to 2.0 for use with headphones). Using this
option does @b{NOT} mean the encoder will actually apply Dolby Headphone
processing.
@table @option
@item 0
@itemx notindicated
Not Indicated (default)
@item 1
@itemx on
461
Dolby Headphone Off
462 463
@item 2
@itemx off
464
Dolby Headphone On
465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480
@end table

@item -ad_conv_type @var{type}
A/D Converter Type. Indicates whether the audio has passed through HDCD A/D
conversion.
@table @option
@item 0
@itemx standard
Standard A/D Converter (default)
@item 1
@itemx hdcd
HDCD A/D Converter
@end table

@end table

481
@subsection Other AC-3 Encoding Options
482 483 484 485 486 487 488 489 490 491 492

@table @option

@item -stereo_rematrixing @var{boolean}
Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This
is an optional AC-3 feature that increases quality by selectively encoding
the left/right channels as mid/side. This option is enabled by default, and it
is highly recommended that it be left as enabled except for testing purposes.

@end table

493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535
@subsection Floating-Point-Only AC-3 Encoding Options

These options are only valid for the floating-point encoder and do not exist
for the fixed-point encoder due to the corresponding features not being
implemented in fixed-point.

@table @option

@item -channel_coupling @var{boolean}
Enables/Disables use of channel coupling, which is an optional AC-3 feature
that increases quality by combining high frequency information from multiple
channels into a single channel. The per-channel high frequency information is
sent with less accuracy in both the frequency and time domains. This allows
more bits to be used for lower frequencies while preserving enough information
to reconstruct the high frequencies. This option is enabled by default for the
floating-point encoder and should generally be left as enabled except for
testing purposes or to increase encoding speed.
@table @option
@item -1
@itemx auto
Selected by Encoder (default)
@item 0
@itemx off
Disable Channel Coupling
@item 1
@itemx on
Enable Channel Coupling
@end table

@item -cpl_start_band @var{number}
Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a
value higher than the bandwidth is used, it will be reduced to 1 less than the
coupling end band. If @var{auto} is used, the start band will be determined by
the encoder based on the bit rate, sample rate, and channel layout. This option
has no effect if channel coupling is disabled.
@table @option
@item -1
@itemx auto
Selected by Encoder (default)
@end table

@end table

536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614
@anchor{flac}
@section flac

FLAC (Free Lossless Audio Codec) Encoder

@subsection Options

The following options are supported by FFmpeg's flac encoder.

@table @option
@item compression_level
Sets the compression level, which chooses defaults for many other options
if they are not set explicitly.

@item frame_size
Sets the size of the frames in samples per channel.

@item lpc_coeff_precision
Sets the LPC coefficient precision, valid values are from 1 to 15, 15 is the
default.

@item lpc_type
Sets the first stage LPC algorithm
@table @samp
@item none
LPC is not used

@item fixed
fixed LPC coefficients

@item levinson

@item cholesky
@end table

@item lpc_passes
Number of passes to use for Cholesky factorization during LPC analysis

@item min_partition_order
The minimum partition order

@item max_partition_order
The maximum partition order

@item prediction_order_method
@table @samp
@item estimation
@item 2level
@item 4level
@item 8level
@item search
Bruteforce search
@item log
@end table

@item ch_mode
Channel mode
@table @samp
@item auto
The mode is chosen automatically for each frame
@item indep
Chanels are independently coded
@item left_side
@item right_side
@item mid_side
@end table

@item exact_rice_parameters
Chooses if rice parameters are calculated exactly or approximately.
if set to 1 then they are chosen exactly, which slows the code down slightly and
improves compression slightly.

@item multi_dim_quant
Multi Dimensional Quantization. If set to 1 then a 2nd stage LPC algorithm is
applied after the first stage to finetune the coefficients. This is quite slow
and slightly improves compression.

@end table

615 616 617 618 619 620 621 622 623 624 625 626 627 628
@anchor{libfdk-aac-enc}
@section libfdk_aac

libfdk-aac AAC (Advanced Audio Coding) encoder wrapper.

The libfdk-aac library is based on the Fraunhofer FDK AAC code from
the Android project.

Requires the presence of the libfdk-aac headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libfdk-aac}. The library is also incompatible with GPL,
so if you allow the use of GPL, you should configure with
@code{--enable-gpl --enable-nonfree --enable-libfdk-aac}.

629 630 631 632
This encoder is considered to produce output on par or worse at 128kbps to the
@ref{aacenc,,the native FFmpeg AAC encoder} but can often produce better
sounding audio at identical or lower bitrates and has support for the
AAC-HE profiles.
633

634 635 636 637
VBR encoding, enabled through the @option{vbr} or @option{flags
+qscale} options, is experimental and only works with some
combinations of parameters.

638 639 640
Support for encoding 7.1 audio is only available with libfdk-aac 0.1.3 or
higher.

641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663
For more information see the fdk-aac project at
@url{http://sourceforge.net/p/opencore-amr/fdk-aac/}.

@subsection Options

The following options are mapped on the shared FFmpeg codec options.

@table @option
@item b
Set bit rate in bits/s. If the bitrate is not explicitly specified, it
is automatically set to a suitable value depending on the selected
profile.

In case VBR mode is enabled the option is ignored.

@item ar
Set audio sampling rate (in Hz).

@item channels
Set the number of audio channels.

@item flags +qscale
Enable fixed quality, VBR (Variable Bit Rate) mode.
664
Note that VBR is implicitly enabled when the @option{vbr} value is
665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746
positive.

@item cutoff
Set cutoff frequency. If not specified (or explicitly set to 0) it
will use a value automatically computed by the library. Default value
is 0.

@item profile
Set audio profile.

The following profiles are recognized:
@table @samp
@item aac_low
Low Complexity AAC (LC)

@item aac_he
High Efficiency AAC (HE-AAC)

@item aac_he_v2
High Efficiency AAC version 2 (HE-AACv2)

@item aac_ld
Low Delay AAC (LD)

@item aac_eld
Enhanced Low Delay AAC (ELD)
@end table

If not specified it is set to @samp{aac_low}.
@end table

The following are private options of the libfdk_aac encoder.

@table @option
@item afterburner
Enable afterburner feature if set to 1, disabled if set to 0. This
improves the quality but also the required processing power.

Default value is 1.

@item eld_sbr
Enable SBR (Spectral Band Replication) for ELD if set to 1, disabled
if set to 0.

Default value is 0.

@item signaling
Set SBR/PS signaling style.

It can assume one of the following values:
@table @samp
@item default
choose signaling implicitly (explicit hierarchical by default,
implicit if global header is disabled)

@item implicit
implicit backwards compatible signaling

@item explicit_sbr
explicit SBR, implicit PS signaling

@item explicit_hierarchical
explicit hierarchical signaling
@end table

Default value is @samp{default}.

@item latm
Output LATM/LOAS encapsulated data if set to 1, disabled if set to 0.

Default value is 0.

@item header_period
Set StreamMuxConfig and PCE repetition period (in frames) for sending
in-band configuration buffers within LATM/LOAS transport layer.

Must be a 16-bits non-negative integer.

Default value is 0.

@item vbr
Set VBR mode, from 1 to 5. 1 is lowest quality (though still pretty
747 748
good) and 5 is highest quality. A value of 0 will disable VBR, and CBR
(Constant Bit Rate) is enabled.
749

750
Currently only the @samp{aac_low} profile supports VBR encoding.
751

752
VBR modes 1-5 correspond to roughly the following average bit rates:
753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769

@table @samp
@item 1
32 kbps/channel
@item 2
40 kbps/channel
@item 3
48-56 kbps/channel
@item 4
64 kbps/channel
@item 5
about 80-96 kbps/channel
@end table

Default value is 0.
@end table

770
@subsection Examples
771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787

@itemize
@item
Use @command{ffmpeg} to convert an audio file to VBR AAC in an M4A (MP4)
container:
@example
ffmpeg -i input.wav -codec:a libfdk_aac -vbr 3 output.m4a
@end example

@item
Use @command{ffmpeg} to convert an audio file to CBR 64k kbps AAC, using the
High-Efficiency AAC profile:
@example
ffmpeg -i input.wav -c:a libfdk_aac -profile:a aac_he -b:a 64k output.m4a
@end example
@end itemize

788
@anchor{libmp3lame}
789 790
@section libmp3lame

791
LAME (Lame Ain't an MP3 Encoder) MP3 encoder wrapper.
792 793 794 795 796

Requires the presence of the libmp3lame headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libmp3lame}.

797 798
See @ref{libshine} for a fixed-point MP3 encoder, although with a
lower quality.
799

800 801 802 803 804 805 806
@subsection Options

The following options are supported by the libmp3lame wrapper. The
@command{lame}-equivalent of the options are listed in parentheses.

@table @option
@item b (@emph{-b})
807
Set bitrate expressed in bits/s for CBR or ABR. LAME @code{bitrate} is
808 809 810 811 812 813 814 815 816 817 818 819 820 821
expressed in kilobits/s.

@item q (@emph{-V})
Set constant quality setting for VBR. This option is valid only
using the @command{ffmpeg} command-line tool. For library interface
users, use @option{global_quality}.

@item compression_level (@emph{-q})
Set algorithm quality. Valid arguments are integers in the 0-9 range,
with 0 meaning highest quality but slowest, and 9 meaning fastest
while producing the worst quality.

@item reservoir
Enable use of bit reservoir when set to 1. Default value is 1. LAME
822
has this enabled by default, but can be overridden by use
823 824 825
@option{--nores} option.

@item joint_stereo (@emph{-m j})
826
Enable the encoder to use (on a frame by frame basis) either L/R
827 828
stereo or mid/side stereo. Default value is 1.

829 830 831 832 833
@item abr (@emph{--abr})
Enable the encoder to use ABR when set to 1. The @command{lame}
@option{--abr} sets the target bitrate, while this options only
tells FFmpeg to use ABR still relies on @option{b} to set bitrate.

834
@end table
835

836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872
@section libopencore-amrnb

OpenCORE Adaptive Multi-Rate Narrowband encoder.

Requires the presence of the libopencore-amrnb headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libopencore-amrnb --enable-version3}.

This is a mono-only encoder. Officially it only supports 8000Hz sample rate,
but you can override it by setting @option{strict} to @samp{unofficial} or
lower.

@subsection Options

@table @option

@item b
Set bitrate in bits per second. Only the following bitrates are supported,
otherwise libavcodec will round to the nearest valid bitrate.

@table @option
@item 4750
@item 5150
@item 5900
@item 6700
@item 7400
@item 7950
@item 10200
@item 12200
@end table

@item dtx
Allow discontinuous transmission (generate comfort noise) when set to 1. The
default value is 0 (disabled).

@end table

873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908
@anchor{libshine}
@section libshine

Shine Fixed-Point MP3 encoder wrapper.

Shine is a fixed-point MP3 encoder. It has a far better performance on
platforms without an FPU, e.g. armel CPUs, and some phones and tablets.
However, as it is more targeted on performance than quality, it is not on par
with LAME and other production-grade encoders quality-wise. Also, according to
the project's homepage, this encoder may not be free of bugs as the code was
written a long time ago and the project was dead for at least 5 years.

This encoder only supports stereo and mono input. This is also CBR-only.

The original project (last updated in early 2007) is at
@url{http://sourceforge.net/projects/libshine-fxp/}. We only support the
updated fork by the Savonet/Liquidsoap project at @url{https://github.com/savonet/shine}.

Requires the presence of the libshine headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libshine}.

See also @ref{libmp3lame}.

@subsection Options

The following options are supported by the libshine wrapper. The
@command{shineenc}-equivalent of the options are listed in parentheses.

@table @option
@item b (@emph{-b})
Set bitrate expressed in bits/s for CBR. @command{shineenc} @option{-b} option
is expressed in kilobits/s.

@end table

909 910
@section libtwolame

911
TwoLAME MP2 encoder wrapper.
912 913 914 915 916

Requires the presence of the libtwolame headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libtwolame}.

917
@subsection Options
918 919

The following options are supported by the libtwolame wrapper. The
920
@command{twolame}-equivalent options follow the FFmpeg ones and are in
921 922 923
parentheses.

@table @option
924 925 926
@item b (@emph{-b})
Set bitrate expressed in bits/s for CBR. @command{twolame} @option{b}
option is expressed in kilobits/s. Default value is 128k.
927

928 929 930 931 932 933
@item q (@emph{-V})
Set quality for experimental VBR support. Maximum value range is
from -50 to 50, useful range is from -10 to 10. The higher the
value, the better the quality. This option is valid only using the
@command{ffmpeg} command-line tool. For library interface users,
use @option{global_quality}.
934

935 936
@item mode (@emph{--mode})
Set the mode of the resulting audio. Possible values:
937 938 939 940 941 942 943 944 945 946 947 948 949 950

@table @samp
@item auto
Choose mode automatically based on the input. This is the default.
@item stereo
Stereo
@item joint_stereo
Joint stereo
@item dual_channel
Dual channel
@item mono
Mono
@end table

951 952 953 954
@item psymodel (@emph{--psyc-mode})
Set psychoacoustic model to use in encoding. The argument must be
an integer between -1 and 4, inclusive. The higher the value, the
better the quality. The default value is 3.
955

956 957 958
@item energy_levels (@emph{--energy})
Enable energy levels extensions when set to 1. The default value is
0 (disabled).
959

960 961 962
@item error_protection (@emph{--protect})
Enable CRC error protection when set to 1. The default value is 0
(disabled).
963

964 965 966
@item copyright (@emph{--copyright})
Set MPEG audio copyright flag when set to 1. The default value is 0
(disabled).
967

968 969 970
@item original (@emph{--original})
Set MPEG audio original flag when set to 1. The default value is 0
(disabled).
971 972 973

@end table

974 975
@section libvo-amrwbenc

976
VisualOn Adaptive Multi-Rate Wideband encoder.
977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011

Requires the presence of the libvo-amrwbenc headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libvo-amrwbenc --enable-version3}.

This is a mono-only encoder. Officially it only supports 16000Hz sample
rate, but you can override it by setting @option{strict} to
@samp{unofficial} or lower.

@subsection Options

@table @option

@item b
Set bitrate in bits/s. Only the following bitrates are supported, otherwise
libavcodec will round to the nearest valid bitrate.

@table @samp
@item 6600
@item 8850
@item 12650
@item 14250
@item 15850
@item 18250
@item 19850
@item 23050
@item 23850
@end table

@item dtx
Allow discontinuous transmission (generate comfort noise) when set to 1. The
default value is 0 (disabled).

@end table

1012 1013 1014 1015 1016 1017 1018 1019 1020 1021
@section libopus

libopus Opus Interactive Audio Codec encoder wrapper.

Requires the presence of the libopus headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libopus}.

@subsection Option Mapping

1022
Most libopus options are modelled after the @command{opusenc} utility from
1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035
opus-tools. The following is an option mapping chart describing options
supported by the libopus wrapper, and their @command{opusenc}-equivalent
in parentheses.

@table @option

@item b (@emph{bitrate})
Set the bit rate in bits/s.  FFmpeg's @option{b} option is
expressed in bits/s, while @command{opusenc}'s @option{bitrate} in
kilobits/s.

@item vbr (@emph{vbr}, @emph{hard-cbr}, and @emph{cvbr})
Set VBR mode. The FFmpeg @option{vbr} option has the following
1036
valid arguments, with the @command{opusenc} equivalent options
1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059
in parentheses:

@table @samp
@item off (@emph{hard-cbr})
Use constant bit rate encoding.

@item on (@emph{vbr})
Use variable bit rate encoding (the default).

@item constrained (@emph{cvbr})
Use constrained variable bit rate encoding.
@end table

@item compression_level (@emph{comp})
Set encoding algorithm complexity. Valid options are integers in
the 0-10 range. 0 gives the fastest encodes but lower quality, while 10
gives the highest quality but slowest encoding. The default is 10.

@item frame_duration (@emph{framesize})
Set maximum frame size, or duration of a frame in milliseconds. The
argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller
frame sizes achieve lower latency but less quality at a given bitrate.
Sizes greater than 20ms are only interesting at fairly low bitrates.
1060
The default is 20ms.
1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082

@item packet_loss (@emph{expect-loss})
Set expected packet loss percentage. The default is 0.

@item application (N.A.)
Set intended application type. Valid options are listed below:

@table @samp
@item voip
Favor improved speech intelligibility.
@item audio
Favor faithfulness to the input (the default).
@item lowdelay
Restrict to only the lowest delay modes.
@end table

@item cutoff (N.A.)
Set cutoff bandwidth in Hz. The argument must be exactly one of the
following: 4000, 6000, 8000, 12000, or 20000, corresponding to
narrowband, mediumband, wideband, super wideband, and fullband
respectively. The default is 0 (cutoff disabled).

1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093
@item mapping_family (@emph{mapping_family})
Set channel mapping family to be used by the encoder. The default value of -1
uses mapping family 0 for mono and stereo inputs, and mapping family 1
otherwise. The default also disables the surround masking and LFE bandwidth
optimzations in libopus, and requires that the input contains 8 channels or
fewer.

Other values include 0 for mono and stereo, 1 for surround sound with masking
and LFE bandwidth optimizations, and 255 for independent streams with an
unspecified channel layout.

1094 1095
@end table

1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147
@section libvorbis

libvorbis encoder wrapper.

Requires the presence of the libvorbisenc headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libvorbis}.

@subsection Options

The following options are supported by the libvorbis wrapper. The
@command{oggenc}-equivalent of the options are listed in parentheses.

To get a more accurate and extensive documentation of the libvorbis
options, consult the libvorbisenc's and @command{oggenc}'s documentations.
See @url{http://xiph.org/vorbis/},
@url{http://wiki.xiph.org/Vorbis-tools}, and oggenc(1).

@table @option
@item b (@emph{-b})
Set bitrate expressed in bits/s for ABR. @command{oggenc} @option{-b} is
expressed in kilobits/s.

@item q (@emph{-q})
Set constant quality setting for VBR. The value should be a float
number in the range of -1.0 to 10.0. The higher the value, the better
the quality. The default value is @samp{3.0}.

This option is valid only using the @command{ffmpeg} command-line tool.
For library interface users, use @option{global_quality}.

@item cutoff (@emph{--advanced-encode-option lowpass_frequency=N})
Set cutoff bandwidth in Hz, a value of 0 disables cutoff. @command{oggenc}'s
related option is expressed in kHz. The default value is @samp{0} (cutoff
disabled).

@item minrate (@emph{-m})
Set minimum bitrate expressed in bits/s. @command{oggenc} @option{-m} is
expressed in kilobits/s.

@item maxrate (@emph{-M})
Set maximum bitrate expressed in bits/s. @command{oggenc} @option{-M} is
expressed in kilobits/s. This only has effect on ABR mode.

@item iblock (@emph{--advanced-encode-option impulse_noisetune=N})
Set noise floor bias for impulse blocks. The value is a float number from
-15.0 to 0.0. A negative bias instructs the encoder to pay special attention
to the crispness of transients in the encoded audio. The tradeoff for better
transient response is a higher bitrate.

@end table

1148
@anchor{libwavpack}
1149
@section libwavpack
1150

1151
A wrapper providing WavPack encoding through libwavpack.
1152

1153
Only lossless mode using 32-bit integer samples is supported currently.
1154 1155 1156 1157 1158 1159

Requires the presence of the libwavpack headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libwavpack}.

Note that a libavcodec-native encoder for the WavPack codec exists so users can
1160
encode audios with this codec without using this encoder. See @ref{wavpackenc}.
1161 1162 1163 1164 1165

@subsection Options

@command{wavpack} command line utility's corresponding options are listed in
parentheses, if any.
1166

1167
@table @option
1168 1169
@item frame_size (@emph{--blocksize})
Default is 32768.
1170

1171 1172 1173 1174 1175 1176
@item compression_level
Set speed vs. compression tradeoff. Acceptable arguments are listed below:

@table @samp
@item 0 (@emph{-f})
Fast mode.
1177

1178 1179
@item 1
Normal (default) settings.
1180

1181 1182
@item 2 (@emph{-h})
High quality.
1183

1184 1185 1186 1187 1188
@item 3 (@emph{-hh})
Very high quality.

@item 4-8 (@emph{-hh -x}@var{EXTRAPROC})
Same as @samp{3}, but with extra processing enabled.
1189

1190
@samp{4} is the same as @option{-x2} and @samp{8} is the same as @option{-x6}.
1191

1192
@end table
1193 1194
@end table

1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255
@anchor{wavpackenc}
@section wavpack

WavPack lossless audio encoder.

This is a libavcodec-native WavPack encoder. There is also an encoder based on
libwavpack, but there is virtually no reason to use that encoder.

See also @ref{libwavpack}.

@subsection Options

The equivalent options for @command{wavpack} command line utility are listed in
parentheses.

@subsubsection Shared options

The following shared options are effective for this encoder. Only special notes
about this particular encoder will be documented here. For the general meaning
of the options, see @ref{codec-options,,the Codec Options chapter}.

@table @option
@item frame_size (@emph{--blocksize})
For this encoder, the range for this option is between 128 and 131072. Default
is automatically decided based on sample rate and number of channel.

For the complete formula of calculating default, see
@file{libavcodec/wavpackenc.c}.

@item compression_level (@emph{-f}, @emph{-h}, @emph{-hh}, and @emph{-x})
This option's syntax is consistent with @ref{libwavpack}'s.
@end table

@subsubsection Private options

@table @option
@item joint_stereo (@emph{-j})
Set whether to enable joint stereo. Valid values are:

@table @samp
@item on (@emph{1})
Force mid/side audio encoding.
@item off (@emph{0})
Force left/right audio encoding.
@item auto
Let the encoder decide automatically.
@end table

@item optimize_mono
Set whether to enable optimization for mono. This option is only effective for
non-mono streams. Available values:

@table @samp
@item on
enabled
@item off
disabled
@end table

@end table

1256
@c man end AUDIO ENCODERS
1257 1258 1259 1260 1261 1262 1263

@chapter Video Encoders
@c man begin VIDEO ENCODERS

A description of some of the currently available video encoders
follows.

1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299
@section libopenh264

Cisco libopenh264 H.264/MPEG-4 AVC encoder wrapper.

This encoder requires the presence of the libopenh264 headers and
library during configuration. You need to explicitly configure the
build with @code{--enable-libopenh264}. The library is detected using
@command{pkg-config}.

For more information about the library see
@url{http://www.openh264.org}.

@subsection Options

The following FFmpeg global options affect the configurations of the
libopenh264 encoder.

@table @option
@item b
Set the bitrate (as a number of bits per second).

@item g
Set the GOP size.

@item maxrate
Set the max bitrate (as a number of bits per second).

@item flags +global_header
Set global header in the bitstream.

@item slices
Set the number of slices, used in parallelized encoding. Default value
is 0. This is only used when @option{slice_mode} is set to
@samp{fixed}.

@item slice_mode
1300
Set slice mode. Can assume one of the following possible values:
1301 1302 1303 1304 1305 1306 1307

@table @samp
@item fixed
a fixed number of slices
@item rowmb
one slice per row of macroblocks
@item auto
1308 1309 1310
automatic number of slices according to number of threads
@item dyn
dynamic slicing
1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321
@end table

Default value is @samp{auto}.

@item loopfilter
Enable loop filter, if set to 1 (automatically enabled). To disable
set a value of 0.

@item profile
Set profile restrictions. If set to the value of @samp{main} enable
CABAC (set the @code{SEncParamExt.iEntropyCodingModeFlag} flag to 1).
1322 1323 1324 1325 1326 1327

@item max_nal_size
Set maximum NAL size in bytes.

@item allow_skip_frames
Allow skipping frames to hit the target bitrate if set to 1.
1328 1329
@end table

1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340
@section jpeg2000

The native jpeg 2000 encoder is lossy by default, the @code{-q:v}
option can be used to set the encoding quality. Lossless encoding
can be selected with @code{-pred 1}.

@subsection Options

@table @option
@item format
Can be set to either @code{j2k} or @code{jp2} (the default) that
1341
makes it possible to store non-rgb pix_fmts.
1342 1343 1344

@end table

1345 1346 1347 1348 1349 1350 1351 1352 1353
@section snow

@subsection Options

@table @option
@item iterative_dia_size
dia size for the iterative motion estimation
@end table

1354 1355
@section libtheora

1356
libtheora Theora encoder wrapper.
1357 1358 1359 1360 1361

Requires the presence of the libtheora headers and library during
configuration. You need to explicitly configure the build with
@code{--enable-libtheora}.

1362
For more information about the libtheora project see
1363 1364
@url{http://www.theora.org/}.

1365 1366 1367 1368 1369 1370 1371
@subsection Options

The following global options are mapped to internal libtheora options
which affect the quality and the bitrate of the encoded stream.

@table @option
@item b
1372 1373
Set the video bitrate in bit/s for CBR (Constant Bit Rate) mode.  In
case VBR (Variable Bit Rate) mode is enabled this option is ignored.
1374 1375

@item flags
1376
Used to enable constant quality mode (VBR) encoding through the
1377 1378 1379 1380 1381 1382 1383
@option{qscale} flag, and to enable the @code{pass1} and @code{pass2}
modes.

@item g
Set the GOP size.

@item global_quality
1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407
Set the global quality as an integer in lambda units.

Only relevant when VBR mode is enabled with @code{flags +qscale}. The
value is converted to QP units by dividing it by @code{FF_QP2LAMBDA},
clipped in the [0 - 10] range, and then multiplied by 6.3 to get a
value in the native libtheora range [0-63]. A higher value corresponds
to a higher quality.

@item q
Enable VBR mode when set to a non-negative value, and set constant
quality value as a double floating point value in QP units.

The value is clipped in the [0-10] range, and then multiplied by 6.3
to get a value in the native libtheora range [0-63].

This option is valid only using the @command{ffmpeg} command-line
tool. For library interface users, use @option{global_quality}.
@end table

@subsection Examples

@itemize
@item
Set maximum constant quality (VBR) encoding with @command{ffmpeg}:
1408
@example
1409
ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg
1410
@end example
1411 1412 1413 1414 1415 1416 1417

@item
Use @command{ffmpeg} to convert a CBR 1000 kbps Theora video stream:
@example
ffmpeg -i INPUT -codec:v libtheora -b:v 1000k OUTPUT.ogg
@end example
@end itemize
1418

1419 1420
@section libvpx

1421
VP8/VP9 format supported through libvpx.
1422 1423 1424 1425 1426 1427

Requires the presence of the libvpx headers and library during configuration.
You need to explicitly configure the build with @code{--enable-libvpx}.

@subsection Options

1428 1429 1430
The following options are supported by the libvpx wrapper. The
@command{vpxenc}-equivalent options or values are listed in parentheses
for easy migration.
1431

1432 1433 1434 1435
To reduce the duplication of documentation, only the private options
and some others requiring special attention are documented here. For
the documentation of the undocumented generic options, see
@ref{codec-options,,the Codec Options chapter}.
1436

1437 1438 1439 1440
To get more documentation of the libvpx options, invoke the command
@command{ffmpeg -h encoder=libvpx}, @command{ffmpeg -h encoder=libvpx-vp9} or
@command{vpxenc --help}. Further information is available in the libvpx API
documentation.
1441

1442
@table @option
1443

1444 1445 1446 1447
@item b (@emph{target-bitrate})
Set bitrate in bits/s. Note that FFmpeg's @option{b} option is
expressed in bits/s, while @command{vpxenc}'s @option{target-bitrate} is in
kilobits/s.
1448

1449
@item g (@emph{kf-max-dist})
1450

1451
@item keyint_min (@emph{kf-min-dist})
1452

1453
@item qmin (@emph{min-q})
1454

1455
@item qmax (@emph{max-q})
1456

1457 1458 1459 1460 1461
@item bufsize (@emph{buf-sz}, @emph{buf-optimal-sz})
Set ratecontrol buffer size (in bits). Note @command{vpxenc}'s options are
specified in milliseconds, the libvpx wrapper converts this value as follows:
@code{buf-sz = bufsize * 1000 / bitrate},
@code{buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6}.
1462

1463 1464 1465 1466 1467
@item rc_init_occupancy (@emph{buf-initial-sz})
Set number of bits which should be loaded into the rc buffer before decoding
starts. Note @command{vpxenc}'s option is specified in milliseconds, the libvpx
wrapper converts this value as follows:
@code{rc_init_occupancy * 1000 / bitrate}.
1468

1469 1470
@item undershoot-pct
Set datarate undershoot (min) percentage of the target bitrate.
1471

1472 1473
@item overshoot-pct
Set datarate overshoot (max) percentage of the target bitrate.
1474

1475
@item skip_threshold (@emph{drop-frame})
1476

1477
@item qcomp (@emph{bias-pct})
1478

1479 1480 1481 1482
@item maxrate (@emph{maxsection-pct})
Set GOP max bitrate in bits/s. Note @command{vpxenc}'s option is specified as a
percentage of the target bitrate, the libvpx wrapper converts this value as
follows: @code{(maxrate * 100 / bitrate)}.
1483

1484 1485 1486 1487
@item minrate (@emph{minsection-pct})
Set GOP min bitrate in bits/s. Note @command{vpxenc}'s option is specified as a
percentage of the target bitrate, the libvpx wrapper converts this value as
follows: @code{(minrate * 100 / bitrate)}.
1488

1489 1490
@item minrate, maxrate, b @emph{end-usage=cbr}
@code{(minrate == maxrate == bitrate)}.
1491

1492
@item crf (@emph{end-usage=cq}, @emph{cq-level})
1493

1494 1495 1496 1497 1498 1499
@item tune (@emph{tune})
@table @samp
@item psnr (@emph{psnr})
@item ssim (@emph{ssim})
@end table

1500 1501 1502 1503 1504 1505 1506 1507 1508 1509
@item quality, deadline (@emph{deadline})
@table @samp
@item best
Use best quality deadline. Poorly named and quite slow, this option should be
avoided as it may give worse quality output than good.
@item good
Use good quality deadline. This is a good trade-off between speed and quality
when used with the @option{cpu-used} option.
@item realtime
Use realtime quality deadline.
1510 1511
@end table

1512 1513 1514
@item speed, cpu-used (@emph{cpu-used})
Set quality/speed ratio modifier. Higher values speed up the encode at the cost
of quality.
1515

1516
@item nr (@emph{noise-sensitivity})
1517

1518 1519 1520
@item static-thresh
Set a change threshold on blocks below which they will be skipped by the
encoder.
1521

1522 1523 1524 1525
@item slices (@emph{token-parts})
Note that FFmpeg's @option{slices} option gives the total number of partitions,
while @command{vpxenc}'s @option{token-parts} is given as
@code{log2(partitions)}.
1526

1527
@item max-intra-rate
1528 1529
Set maximum I-frame bitrate as a percentage of the target bitrate. A value of 0
means unlimited.
1530 1531 1532 1533

@item force_key_frames
@code{VPX_EFLAG_FORCE_KF}

1534 1535
@item Alternate reference frame related
@table @option
1536 1537 1538 1539 1540 1541 1542 1543 1544 1545
@item auto-alt-ref
Enable use of alternate reference frames (2-pass only).
@item arnr-max-frames
Set altref noise reduction max frame count.
@item arnr-type
Set altref noise reduction filter type: backward, forward, centered.
@item arnr-strength
Set altref noise reduction filter strength.
@item rc-lookahead, lag-in-frames (@emph{lag-in-frames})
Set number of frames to look ahead for frametype and ratecontrol.
1546 1547
@end table

1548 1549
@item error-resilient
Enable error resiliency features.
1550

1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567
@item VP9-specific options
@table @option
@item lossless
Enable lossless mode.
@item tile-columns
Set number of tile columns to use. Note this is given as
@code{log2(tile_columns)}. For example, 8 tile columns would be requested by
setting the @option{tile-columns} option to 3.
@item tile-rows
Set number of tile rows to use. Note this is given as @code{log2(tile_rows)}.
For example, 4 tile rows would be requested by setting the @option{tile-rows}
option to 2.
@item frame-parallel
Enable frame parallel decodability features.
@item aq-mode
Set adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3:
cyclic refresh).
1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579
@item colorspace @emph{color-space}
Set input color space. The VP9 bitstream supports signaling the following
colorspaces:
@table @option
@item @samp{rgb} @emph{sRGB}
@item @samp{bt709} @emph{bt709}
@item @samp{unspecified} @emph{unknown}
@item @samp{bt470bg} @emph{bt601}
@item @samp{smpte170m} @emph{smpte170}
@item @samp{smpte240m} @emph{smpte240}
@item @samp{bt2020_ncl} @emph{bt2020}
@end table
1580
@end table
1581

1582 1583 1584 1585 1586
@end table

For more information about libvpx see:
@url{http://www.webmproject.org/}

1587

Justin Ruggles's avatar
Justin Ruggles committed
1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648
@section libwebp

libwebp WebP Image encoder wrapper

libwebp is Google's official encoder for WebP images. It can encode in either
lossy or lossless mode. Lossy images are essentially a wrapper around a VP8
frame. Lossless images are a separate codec developed by Google.

@subsection Pixel Format

Currently, libwebp only supports YUV420 for lossy and RGB for lossless due
to limitations of the format and libwebp. Alpha is supported for either mode.
Because of API limitations, if RGB is passed in when encoding lossy or YUV is
passed in for encoding lossless, the pixel format will automatically be
converted using functions from libwebp. This is not ideal and is done only for
convenience.

@subsection Options

@table @option

@item -lossless @var{boolean}
Enables/Disables use of lossless mode. Default is 0.

@item -compression_level @var{integer}
For lossy, this is a quality/speed tradeoff. Higher values give better quality
for a given size at the cost of increased encoding time. For lossless, this is
a size/speed tradeoff. Higher values give smaller size at the cost of increased
encoding time. More specifically, it controls the number of extra algorithms
and compression tools used, and varies the combination of these tools. This
maps to the @var{method} option in libwebp. The valid range is 0 to 6.
Default is 4.

@item -qscale @var{float}
For lossy encoding, this controls image quality, 0 to 100. For lossless
encoding, this controls the effort and time spent at compressing more. The
default value is 75. Note that for usage via libavcodec, this option is called
@var{global_quality} and must be multiplied by @var{FF_QP2LAMBDA}.

@item -preset @var{type}
Configuration preset. This does some automatic settings based on the general
type of the image.
@table @option
@item none
Do not use a preset.
@item default
Use the encoder default.
@item picture
Digital picture, like portrait, inner shot
@item photo
Outdoor photograph, with natural lighting
@item drawing
Hand or line drawing, with high-contrast details
@item icon
Small-sized colorful images
@item text
Text-like
@end table

@end table

1649
@section libx264, libx264rgb
1650

1651
x264 H.264/MPEG-4 AVC encoder wrapper.
1652

1653 1654
This encoder requires the presence of the libx264 headers and library
during configuration. You need to explicitly configure the build with
1655 1656
@code{--enable-libx264}.

1657 1658 1659 1660
libx264 supports an impressive number of features, including 8x8 and
4x4 adaptive spatial transform, adaptive B-frame placement, CAVLC/CABAC
entropy coding, interlacing (MBAFF), lossless mode, psy optimizations
for detail retention (adaptive quantization, psy-RD, psy-trellis).
1661

1662 1663 1664
Many libx264 encoder options are mapped to FFmpeg global codec
options, while unique encoder options are provided through private
options. Additionally the @option{x264opts} and @option{x264-params}
1665
private options allows one to pass a list of key=value tuples as accepted
1666
by the libx264 @code{x264_param_parse} function.
1667

1668 1669 1670
The x264 project website is at
@url{http://www.videolan.org/developers/x264.html}.

1671 1672 1673 1674 1675 1676 1677 1678 1679 1680
The libx264rgb encoder is the same as libx264, except it accepts packed RGB
pixel formats as input instead of YUV.

@subsection Supported Pixel Formats

x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at
x264's configure time. FFmpeg only supports one bit depth in one particular
build. In other words, it is not possible to build one FFmpeg with multiple
versions of x264 with different bit depths.

1681
@subsection Options
1682

1683 1684 1685
The following options are supported by the libx264 wrapper. The
@command{x264}-equivalent options or values are listed in parentheses
for easy migration.
1686

1687 1688 1689
To reduce the duplication of documentation, only the private options
and some others requiring special attention are documented here. For
the documentation of the undocumented generic options, see
1690
@ref{codec-options,,the Codec Options chapter}.
1691 1692 1693 1694

To get a more accurate and extensive documentation of the libx264
options, invoke the command @command{x264 --full-help} or consult
the libx264 documentation.
1695

1696
@table @option
1697 1698 1699 1700 1701 1702 1703 1704 1705 1706
@item b (@emph{bitrate})
Set bitrate in bits/s. Note that FFmpeg's @option{b} option is
expressed in bits/s, while @command{x264}'s @option{bitrate} is in
kilobits/s.

@item bf (@emph{bframes})

@item g (@emph{keyint})

@item qmin (@emph{qpmin})
1707 1708 1709 1710
Minimum quantizer scale.

@item qmax (@emph{qpmax})
Maximum quantizer scale.
1711 1712

@item qdiff (@emph{qpstep})
1713
Maximum difference between quantizer scales.
1714 1715

@item qblur (@emph{qblur})
1716
Quantizer curve blur
1717 1718

@item qcomp (@emph{qcomp})
1719
Quantizer curve compression factor
1720 1721

@item refs (@emph{ref})
1722
Number of reference frames each P-frame can use. The range is from @var{0-16}.
1723 1724

@item sc_threshold (@emph{scenecut})
1725
Sets the threshold for the scene change detection.
1726 1727

@item trellis (@emph{trellis})
1728
Performs Trellis quantization to increase efficiency. Enabled by default.
1729 1730 1731 1732

@item nr  (@emph{nr})

@item me_range (@emph{merange})
1733
Maximum range of the motion search in pixels.
1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754

@item me_method (@emph{me})
Set motion estimation method. Possible values in the decreasing order
of speed:

@table @samp
@item dia (@emph{dia})
@item epzs (@emph{dia})
Diamond search with radius 1 (fastest). @samp{epzs} is an alias for
@samp{dia}.
@item hex (@emph{hex})
Hexagonal search with radius 2.
@item umh (@emph{umh})
Uneven multi-hexagon search.
@item esa (@emph{esa})
Exhaustive search.
@item tesa (@emph{tesa})
Hadamard exhaustive search (slowest).
@end table

@item subq (@emph{subme})
1755
Sub-pixel motion estimation method.
1756 1757

@item b_strategy (@emph{b-adapt})
1758
Adaptive B-frame placement decision algorithm. Use only on first-pass.
1759 1760

@item keyint_min (@emph{min-keyint})
1761
Minimum GOP size.
1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787

@item coder
Set entropy encoder. Possible values:

@table @samp
@item ac
Enable CABAC.

@item vlc
Enable CAVLC and disable CABAC. It generates the same effect as
@command{x264}'s @option{--no-cabac} option.
@end table

@item cmp
Set full pixel motion estimation comparation algorithm. Possible values:

@table @samp
@item chroma
Enable chroma in motion estimation.

@item sad
Ignore chroma in motion estimation. It generates the same effect as
@command{x264}'s @option{--no-chroma-me} option.
@end table

@item threads (@emph{threads})
1788
Number of encoding threads.
1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825

@item thread_type
Set multithreading technique. Possible values:

@table @samp
@item slice
Slice-based multithreading. It generates the same effect as
@command{x264}'s @option{--sliced-threads} option.
@item frame
Frame-based multithreading.
@end table

@item flags
Set encoding flags. It can be used to disable closed GOP and enable
open GOP by setting it to @code{-cgop}. The result is similar to
the behavior of @command{x264}'s @option{--open-gop} option.

@item rc_init_occupancy (@emph{vbv-init})

@item preset (@emph{preset})
Set the encoding preset.

@item tune (@emph{tune})
Set tuning of the encoding params.

@item profile (@emph{profile})
Set profile restrictions.

@item fastfirstpass
Enable fast settings when encoding first pass, when set to 1. When set
to 0, it has the same effect of @command{x264}'s
@option{--slow-firstpass} option.

@item crf (@emph{crf})
Set the quality for constant quality mode.

@item crf_max (@emph{crf-max})
1826 1827
In CRF mode, prevents VBV from lowering quality beyond this point.

1828 1829 1830 1831 1832 1833
@item qp (@emph{qp})
Set constant quantization rate control method parameter.

@item aq-mode (@emph{aq-mode})
Set AQ method. Possible values:

1834
@table @samp
1835 1836
@item none (@emph{0})
Disabled.
1837

1838
@item variance (@emph{1})
1839
Variance AQ (complexity mask).
1840 1841

@item autovariance (@emph{2})
1842 1843 1844
Auto-variance AQ (experimental).
@end table

1845 1846
@item aq-strength (@emph{aq-strength})
Set AQ strength, reduce blocking and blurring in flat and textured areas.
1847

1848 1849 1850
@item psy
Use psychovisual optimizations when set to 1. When set to 0, it has the
same effect as @command{x264}'s @option{--no-psy} option.
1851

1852 1853 1854
@item psy-rd  (@emph{psy-rd})
Set strength of psychovisual optimization, in
@var{psy-rd}:@var{psy-trellis} format.
1855

1856 1857 1858 1859 1860 1861 1862 1863 1864
@item rc-lookahead (@emph{rc-lookahead})
Set number of frames to look ahead for frametype and ratecontrol.

@item weightb
Enable weighted prediction for B-frames when set to 1. When set to 0,
it has the same effect as @command{x264}'s @option{--no-weightb} option.

@item weightp (@emph{weightp})
Set weighted prediction method for P-frames. Possible values:
1865 1866

@table @samp
1867 1868 1869 1870 1871 1872 1873
@item none (@emph{0})
Disabled
@item simple (@emph{1})
Enable only weighted refs
@item smart (@emph{2})
Enable both weighted refs and duplicates
@end table
1874

1875 1876 1877 1878 1879 1880 1881
@item ssim (@emph{ssim})
Enable calculation and printing SSIM stats after the encoding.

@item intra-refresh (@emph{intra-refresh})
Enable the use of Periodic Intra Refresh instead of IDR frames when set
to 1.

1882 1883 1884 1885
@item avcintra-class (@emph{class})
Configure the encoder to generate AVC-Intra.
Valid values are 50,100 and 200

1886
@item bluray-compat (@emph{bluray-compat})
1887 1888
Configure the encoder to be compatible with the bluray standard.
It is a shorthand for setting "bluray-compat=1 force-cfr=1".
1889

1890 1891 1892 1893 1894 1895 1896 1897 1898 1899
@item b-bias (@emph{b-bias})
Set the influence on how often B-frames are used.

@item b-pyramid (@emph{b-pyramid})
Set method for keeping of some B-frames as references. Possible values:

@table @samp
@item none (@emph{none})
Disabled.
@item strict (@emph{strict})
1900
Strictly hierarchical pyramid.
1901
@item normal (@emph{normal})
1902 1903 1904
Non-strict (not Blu-ray compatible).
@end table

1905 1906 1907 1908
@item mixed-refs
Enable the use of one reference per partition, as opposed to one
reference per macroblock when set to 1. When set to 0, it has the
same effect as @command{x264}'s @option{--no-mixed-refs} option.
1909

1910 1911 1912 1913
@item 8x8dct
Enable adaptive spatial transform (high profile 8x8 transform)
when set to 1. When set to 0, it has the same effect as
@command{x264}'s @option{--no-8x8dct} option.
1914

1915 1916 1917 1918
@item fast-pskip
Enable early SKIP detection on P-frames when set to 1. When set
to 0, it has the same effect as @command{x264}'s
@option{--no-fast-pskip} option.
1919

1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932
@item aud (@emph{aud})
Enable use of access unit delimiters when set to 1.

@item mbtree
Enable use macroblock tree ratecontrol when set to 1. When set
to 0, it has the same effect as @command{x264}'s
@option{--no-mbtree} option.

@item deblock (@emph{deblock})
Set loop filter parameters, in @var{alpha}:@var{beta} form.

@item cplxblur (@emph{cplxblur})
Set fluctuations reduction in QP (before curve compression).
1933

1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955
@item partitions (@emph{partitions})
Set partitions to consider as a comma-separated list of. Possible
values in the list:

@table @samp
@item p8x8
8x8 P-frame partition.
@item p4x4
4x4 P-frame partition.
@item b8x8
4x4 B-frame partition.
@item i8x8
8x8 I-frame partition.
@item i4x4
4x4 I-frame partition.
(Enabling @samp{p4x4} requires @samp{p8x8} to be enabled. Enabling
@samp{i8x8} requires adaptive spatial transform (@option{8x8dct}
option) to be enabled.)
@item none (@emph{none})
Do not consider any partitions.
@item all (@emph{all})
Consider every partition.
1956
@end table
1957

1958 1959 1960
@item direct-pred (@emph{direct})
Set direct MV prediction mode. Possible values:

1961
@table @samp
1962 1963 1964 1965 1966 1967 1968 1969 1970
@item none (@emph{none})
Disable MV prediction.
@item spatial (@emph{spatial})
Enable spatial predicting.
@item temporal (@emph{temporal})
Enable temporal predicting.
@item auto (@emph{auto})
Automatically decided.
@end table
1971

1972 1973 1974
@item slice-max-size (@emph{slice-max-size})
Set the limit of the size of each slice in bytes. If not specified
but RTP payload size (@option{ps}) is specified, that is used.
1975

1976 1977
@item stats (@emph{stats})
Set the file name for multi-pass stats.
1978

1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989
@item nal-hrd (@emph{nal-hrd})
Set signal HRD information (requires @option{vbv-bufsize} to be set).
Possible values:

@table @samp
@item none (@emph{none})
Disable HRD information signaling.
@item vbr (@emph{vbr})
Variable bit rate.
@item cbr (@emph{cbr})
Constant bit rate (not allowed in MP4 container).
1990
@end table
1991

1992 1993
@item x264opts (N.A.)
Set any x264 option, see @command{x264 --fullhelp} for a list.
1994

1995
Argument is a list of @var{key}=@var{value} couples separated by
1996 1997 1998
":". In @var{filter} and @var{psy-rd} options that use ":" as a separator
themselves, use "," instead. They accept it as well since long ago but this
is kept undocumented for some reason.
1999

2000
For example to specify libx264 encoding options with @command{ffmpeg}:
2001 2002 2003 2004
@example
ffmpeg -i foo.mpg -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv
@end example

2005 2006 2007 2008
@item a53cc @var{boolean}
Import closed captions (which must be ATSC compatible format) into output.
Only the mpeg2 and h264 decoders provide these. Default is 0 (off).

2009 2010 2011
@item x264-params (N.A.)
Override the x264 configuration using a :-separated list of key=value
parameters.
2012

2013
This option is functionally the same as the @option{x264opts}, but is
2014
duplicated for compatibility with the Libav fork.
2015 2016

For example to specify libx264 encoding options with @command{ffmpeg}:
2017
@example
2018 2019 2020
ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\
cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\
no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT
2021 2022 2023
@end example
@end table

2024 2025
Encoding ffpresets for common usages are provided so they can be used with the
general presets system (e.g. passing the @option{pre} option).
2026

2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054
@section libx265

x265 H.265/HEVC encoder wrapper.

This encoder requires the presence of the libx265 headers and library
during configuration. You need to explicitly configure the build with
@option{--enable-libx265}.

@subsection Options

@table @option
@item preset
Set the x265 preset.

@item tune
Set the x265 tune parameter.

@item x265-params
Set x265 options using a list of @var{key}=@var{value} couples separated
by ":". See @command{x265 --help} for a list of options.

For example to specify libx265 encoding options with @option{-x265-params}:

@example
ffmpeg -i input -c:v libx265 -x265-params crf=26:psy-rd=1 output.mp4
@end example
@end table

2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165
@section libxvid

Xvid MPEG-4 Part 2 encoder wrapper.

This encoder requires the presence of the libxvidcore headers and library
during configuration. You need to explicitly configure the build with
@code{--enable-libxvid --enable-gpl}.

The native @code{mpeg4} encoder supports the MPEG-4 Part 2 format, so
users can encode to this format without this library.

@subsection Options

The following options are supported by the libxvid wrapper. Some of
the following options are listed but are not documented, and
correspond to shared codec options. See @ref{codec-options,,the Codec
Options chapter} for their documentation. The other shared options
which are not listed have no effect for the libxvid encoder.

@table @option
@item b

@item g

@item qmin

@item qmax

@item mpeg_quant

@item threads

@item bf

@item b_qfactor

@item b_qoffset

@item flags
Set specific encoding flags. Possible values:

@table @samp

@item mv4
Use four motion vector by macroblock.

@item aic
Enable high quality AC prediction.

@item gray
Only encode grayscale.

@item gmc
Enable the use of global motion compensation (GMC).

@item qpel
Enable quarter-pixel motion compensation.

@item cgop
Enable closed GOP.

@item global_header
Place global headers in extradata instead of every keyframe.

@end table

@item trellis

@item me_method
Set motion estimation method. Possible values in decreasing order of
speed and increasing order of quality:

@table @samp
@item zero
Use no motion estimation (default).

@item phods
@item x1
@item log
Enable advanced diamond zonal search for 16x16 blocks and half-pixel
refinement for 16x16 blocks. @samp{x1} and @samp{log} are aliases for
@samp{phods}.

@item epzs
Enable all of the things described above, plus advanced diamond zonal
search for 8x8 blocks, half-pixel refinement for 8x8 blocks, and motion
estimation on chroma planes.

@item full
Enable all of the things described above, plus extended 16x16 and 8x8
blocks search.
@end table

@item mbd
Set macroblock decision algorithm. Possible values in the increasing
order of quality:

@table @samp
@item simple
Use macroblock comparing function algorithm (default).

@item bits
Enable rate distortion-based half pixel and quarter pixel refinement for
16x16 blocks.

@item rd
Enable all of the things described above, plus rate distortion-based
half pixel and quarter pixel refinement for 8x8 blocks, and rate
distortion-based search using square pattern.
@end table

2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178
@item lumi_aq
Enable lumi masking adaptive quantization when set to 1. Default is 0
(disabled).

@item variance_aq
Enable variance adaptive quantization when set to 1. Default is 0
(disabled).

When combined with @option{lumi_aq}, the resulting quality will not
be better than any of the two specified individually. In other
words, the resulting quality will be the worse one of the two
effects.

2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215
@item ssim
Set structural similarity (SSIM) displaying method. Possible values:

@table @samp
@item off
Disable displaying of SSIM information.

@item avg
Output average SSIM at the end of encoding to stdout. The format of
showing the average SSIM is:

@example
Average SSIM: %f
@end example

For users who are not familiar with C, %f means a float number, or
a decimal (e.g. 0.939232).

@item frame
Output both per-frame SSIM data during encoding and average SSIM at
the end of encoding to stdout. The format of per-frame information
is:

@example
       SSIM: avg: %1.3f min: %1.3f max: %1.3f
@end example

For users who are not familiar with C, %1.3f means a float number
rounded to 3 digits after the dot (e.g. 0.932).

@end table

@item ssim_acc
Set SSIM accuracy. Valid options are integers within the range of
0-4, while 0 gives the most accurate result and 4 computes the
fastest.

2216 2217
@end table

2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241
@section mpeg2

MPEG-2 video encoder.

@subsection Options

@table @option
@item seq_disp_ext @var{integer}
Specifies if the encoder should write a sequence_display_extension to the
output.
@table @option
@item -1
@itemx auto
Decide automatically to write it or not (this is the default) by checking if
the data to be written is different from the default or unspecified values.
@item 0
@itemx never
Never write it.
@item 1
@itemx always
Always write it.
@end table
@end table

2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254
@section png

PNG image encoder.

@subsection Private options

@table @option
@item dpi @var{integer}
Set physical density of pixels, in dots per inch, unset by default
@item dpm @var{integer}
Set physical density of pixels, in dots per meter, unset by default
@end table

2255 2256 2257 2258
@section ProRes

Apple ProRes encoder.

2259
FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder.
2260
The used encoder can be chosen with the @code{-vcodec} option.
2261 2262

@subsection Private Options for prores-ks
2263 2264 2265 2266 2267 2268 2269 2270 2271

@table @option
@item profile @var{integer}
Select the ProRes profile to encode
@table @samp
@item proxy
@item lt
@item standard
@item hq
2272
@item 4444
2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301
@end table

@item quant_mat @var{integer}
Select quantization matrix.
@table @samp
@item auto
@item default
@item proxy
@item lt
@item standard
@item hq
@end table
If set to @var{auto}, the matrix matching the profile will be picked.
If not set, the matrix providing the highest quality, @var{default}, will be
picked.

@item bits_per_mb @var{integer}
How many bits to allot for coding one macroblock. Different profiles use
between 200 and 2400 bits per macroblock, the maximum is 8000.

@item mbs_per_slice @var{integer}
Number of macroblocks in each slice (1-8); the default value (8)
should be good in almost all situations.

@item vendor @var{string}
Override the 4-byte vendor ID.
A custom vendor ID like @var{apl0} would claim the stream was produced by
the Apple encoder.

2302 2303 2304 2305 2306
@item alpha_bits @var{integer}
Specify number of bits for alpha component.
Possible values are @var{0}, @var{8} and @var{16}.
Use @var{0} to disable alpha plane coding.

2307 2308 2309 2310 2311
@end table

@subsection Speed considerations

In the default mode of operation the encoder has to honor frame constraints
Lou Logan's avatar
Lou Logan committed
2312
(i.e. not produce frames with size bigger than requested) while still making
2313 2314 2315 2316 2317 2318 2319 2320 2321
output picture as good as possible.
A frame containing a lot of small details is harder to compress and the encoder
would spend more time searching for appropriate quantizers for each slice.

Setting a higher @option{bits_per_mb} limit will improve the speed.

For the fastest encoding speed set the @option{qscale} parameter (4 is the
recommended value) and do not set a size constraint.

2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342
@section libkvazaar

Kvazaar H.265/HEVC encoder.

Requires the presence of the libkvazaar headers and library during
configuration. You need to explicitly configure the build with
@option{--enable-libkvazaar}.

@subsection Options

@table @option

@item b
Set target video bitrate in bit/s and enable rate control.

@item kvazaar-params
Set kvazaar parameters as a list of @var{name}=@var{value} pairs separated
by commas (,). See kvazaar documentation for a list of options.

@end table

2343 2344 2345
@section QSV encoders

The family of Intel QuickSync Video encoders (MPEG-2, H.264 and HEVC)
2346 2347 2348 2349 2350 2351 2352 2353 2354 2355

The ratecontrol method is selected as follows:

@itemize @bullet
@item
When @option{global_quality} is specified, a quality-based mode is used.
Specifically this means either
@itemize @minus
@item
@var{CQP} - constant quantizer scale, when the @option{qscale} codec flag is
2356
also set (the @option{-qscale} ffmpeg option).
2357 2358 2359

@item
@var{LA_ICQ} - intelligent constant quality with lookahead, when the
2360
@option{look_ahead} option is also set.
2361 2362 2363 2364 2365 2366 2367 2368 2369 2370

@item
@var{ICQ} -- intelligent constant quality otherwise.
@end itemize

@item
Otherwise, a bitrate-based mode is used. For all of those, you should specify at
least the desired average bitrate with the @option{b} option.
@itemize @minus
@item
2371
@var{LA} - VBR with lookahead, when the @option{look_ahead} option is specified.
2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430

@item
@var{VCM} - video conferencing mode, when the @option{vcm} option is set.

@item
@var{CBR} - constant bitrate, when @option{maxrate} is specified and equal to
the average bitrate.

@item
@var{VBR} - variable bitrate, when @option{maxrate} is specified, but is higher
than the average bitrate.

@item
@var{AVBR} - average VBR mode, when @option{maxrate} is not specified. This mode
is further configured by the @option{avbr_accuracy} and
@option{avbr_convergence} options.
@end itemize
@end itemize

Note that depending on your system, a different mode than the one you specified
may be selected by the encoder. Set the verbosity level to @var{verbose} or
higher to see the actual settings used by the QSV runtime.

Additional libavcodec global options are mapped to MSDK options as follows:

@itemize
@item
@option{g/gop_size} -> @option{GopPicSize}

@item
@option{bf/max_b_frames}+1 -> @option{GopRefDist}

@item
@option{rc_init_occupancy/rc_initial_buffer_occupancy} ->
@option{InitialDelayInKB}

@item
@option{slices} -> @option{NumSlice}

@item
@option{refs} -> @option{NumRefFrame}

@item
@option{b_strategy/b_frame_strategy} -> @option{BRefType}

@item
@option{cgop/CLOSED_GOP} codec flag -> @option{GopOptFlag}

@item
For the @var{CQP} mode, the @option{i_qfactor/i_qoffset} and
@option{b_qfactor/b_qoffset} set the difference between @var{QPP} and @var{QPI},
and @var{QPP} and @var{QPB} respectively.

@item
Setting the @option{coder} option to the value @var{vlc} will make the H.264
encoder use CAVLC instead of CABAC.

@end itemize

2431 2432 2433 2434 2435
@section vc2

SMPTE VC-2 (previously BBC Dirac Pro). This codec was primarily aimed at
professional broadcasting but since it supports yuv420, yuv422 and yuv444 at
8 (limited range or full range), 10 or 12 bits, this makes it suitable for
2436
other tasks which require low overhead and low compression (like screen
2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490
recording).

@subsection Options

@table @option

@item b
Sets target video bitrate. Usually that's around 1:6 of the uncompressed
video bitrate (e.g. for 1920x1080 50fps yuv422p10 that's around 400Mbps). Higher
values (close to the uncompressed bitrate) turn on lossless compression mode.

@item field_order
Enables field coding when set (e.g. to tt - top field first) for interlaced
inputs. Should increase compression with interlaced content as it splits the
fields and encodes each separately.

@item wavelet_depth
Sets the total amount of wavelet transforms to apply, between 1 and 5 (default).
Lower values reduce compression and quality. Less capable decoders may not be
able to handle values of @option{wavelet_depth} over 3.

@item wavelet_type
Sets the transform type. Currently only @var{5_3} (LeGall) and @var{9_7}
(Deslauriers-Dubuc)
are implemented, with 9_7 being the one with better compression and thus
is the default.

@item slice_width
@item slice_height
Sets the slice size for each slice. Larger values result in better compression.
For compatibility with other more limited decoders use @option{slice_width} of
32 and @option{slice_height} of 8.

@item tolerance
Sets the undershoot tolerance of the rate control system in percent. This is
to prevent an expensive search from being run.

@item qm
Sets the quantization matrix preset to use by default or when @option{wavelet_depth}
is set to 5
@itemize @minus
@item
@var{default}
Uses the default quantization matrix from the specifications, extended with
values for the fifth level. This provides a good balance between keeping detail
and omitting artifacts.

@item
@var{flat}
Use a completely zeroed out quantization matrix. This increases PSNR but might
reduce perception. Use in bogus benchmarks.

@item
@var{color}
2491
Reduces detail but attempts to preserve color at extremely low bitrates.
2492 2493 2494 2495
@end itemize

@end table

2496
@c man end VIDEO ENCODERS
2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520

@chapter Subtitles Encoders
@c man begin SUBTITLES ENCODERS

@section dvdsub

This codec encodes the bitmap subtitle format that is used in DVDs.
Typically they are stored in VOBSUB file pairs (*.idx + *.sub),
and they can also be used in Matroska files.

@subsection Options

@table @option
@item even_rows_fix
When set to 1, enable a work-around that makes the number of pixel rows
even in all subtitles.  This fixes a problem with some players that
cut off the bottom row if the number is odd.  The work-around just adds
a fully transparent row if needed.  The overhead is low, typically
one byte per subtitle on average.

By default, this work-around is disabled.
@end table

@c man end SUBTITLES ENCODERS