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Linshizhi
ffmpeg.wasm-core
Commits
43af18ef
Commit
43af18ef
authored
Dec 09, 2012
by
Stefano Sabatini
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ffmpeg: implement -force_key_frames expression evalution
parent
2b14344a
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3 changed files
with
112 additions
and
5 deletions
+112
-5
ffmpeg.texi
doc/ffmpeg.texi
+38
-0
ffmpeg.c
ffmpeg.c
+60
-5
ffmpeg.h
ffmpeg.h
+14
-0
No files found.
doc/ffmpeg.texi
View file @
43af18ef
...
...
@@ -552,9 +552,16 @@ Force video tag/fourcc. This is an alias for @code{-tag:v}.
Show QP histogram
@item -vbsf @var
{
bitstream
_
filter
}
Deprecated see -bsf
@item -force
_
key
_
frames[:@var
{
stream
_
specifier
}
] @var
{
time
}
[,@var
{
time
}
...] (@emph
{
output,per-stream
}
)
@item -force
_
key
_
frames[:@var
{
stream
_
specifier
}
] expr:@var
{
expr
}
(@emph
{
output,per-stream
}
)
Force key frames at the specified timestamps, more precisely at the first
frames after each specified time.
If the argument is prefixed with @code
{
expr:
}
, the string @var
{
expr
}
is interpreted like an expression and is evaluated for each frame. A
key frame is forced in case the evaluation is non-zero.
If one of the times is "@code
{
chapters
}
[@var
{
delta
}
]", it is expanded into
the time of the beginning of all chapters in the file, shifted by
@var
{
delta
}
, expressed as a time in seconds.
...
...
@@ -567,6 +574,37 @@ before the beginning of every chapter:
-force
_
key
_
frames 0:05:00,chapters-0.1
@end example
The expression in @var
{
expr
}
can contain the following constants:
@table @option
@item n
the number of current processed frame, starting from 0
@item n
_
forced
the number of forced frames
@item prev
_
forced
_
n
the number of the previous forced frame, it is @code
{
NAN
}
when no
keyframe was forced yet
@item prev
_
forced
_
t
the time of the previous forced frame, it is @code
{
NAN
}
when no
keyframe was forced yet
@item t
the time of the current processed frame
@end table
For example to force a key frame every 5 seconds, you can specify:
@example
-force
_
key
_
frames expr:gte(t,n
_
forced*5)
@end example
To force a key frame 5 seconds after the time of the last forced one,
starting from second 13:
@example
-force
_
key
_
frames expr:if(isnan(prev
_
forced
_
t),gte(t,13),gte(t,prev
_
forced
_
t+5))
@end example
Note that forcing too many keyframes is very harmful for the lookahead
algorithms of certain encoders: using fixed-GOP options or similar
would be more efficient.
@item -copyinkf[:@var
{
stream
_
specifier
}
] (@emph
{
output,per-stream
}
)
When doing stream copy, copy also non-key frames found at the
beginning.
...
...
ffmpeg.c
View file @
43af18ef
...
...
@@ -109,6 +109,15 @@ const int program_birth_year = 2000;
static
FILE
*
vstats_file
;
const
char
*
const
forced_keyframes_const_names
[]
=
{
"n"
,
"n_forced"
,
"prev_forced_n"
,
"prev_forced_t"
,
"t"
,
NULL
};
static
void
do_video_stats
(
OutputStream
*
ost
,
int
frame_size
);
static
int64_t
getutime
(
void
);
...
...
@@ -437,6 +446,7 @@ static void exit_program(void)
avcodec_free_frame
(
&
output_streams
[
i
]
->
filtered_frame
);
av_freep
(
&
output_streams
[
i
]
->
forced_keyframes
);
av_expr_free
(
output_streams
[
i
]
->
forced_keyframes_pexpr
);
av_freep
(
&
output_streams
[
i
]
->
avfilter
);
av_freep
(
&
output_streams
[
i
]
->
logfile_prefix
);
av_freep
(
&
output_streams
[
i
]);
...
...
@@ -873,8 +883,9 @@ static void do_video_out(AVFormatContext *s,
video_size
+=
pkt
.
size
;
write_frame
(
s
,
&
pkt
,
ost
);
}
else
{
int
got_packet
;
int
got_packet
,
forced_keyframe
=
0
;
AVFrame
big_picture
;
double
pts_time
;
big_picture
=
*
in_picture
;
/* better than nothing: use input picture interlaced
...
...
@@ -898,11 +909,41 @@ static void do_video_out(AVFormatContext *s,
big_picture
.
quality
=
ost
->
st
->
codec
->
global_quality
;
if
(
!
enc
->
me_threshold
)
big_picture
.
pict_type
=
0
;
pts_time
=
big_picture
.
pts
!=
AV_NOPTS_VALUE
?
big_picture
.
pts
*
av_q2d
(
enc
->
time_base
)
:
NAN
;
if
(
ost
->
forced_kf_index
<
ost
->
forced_kf_count
&&
big_picture
.
pts
>=
ost
->
forced_kf_pts
[
ost
->
forced_kf_index
])
{
big_picture
.
pict_type
=
AV_PICTURE_TYPE_I
;
ost
->
forced_kf_index
++
;
forced_keyframe
=
1
;
}
else
if
(
ost
->
forced_keyframes_pexpr
)
{
double
res
;
ost
->
forced_keyframes_expr_const_values
[
FKF_T
]
=
pts_time
;
res
=
av_expr_eval
(
ost
->
forced_keyframes_pexpr
,
ost
->
forced_keyframes_expr_const_values
,
NULL
);
av_dlog
(
NULL
,
"force_key_frame: n:%f n_forced:%f prev_forced_n:%f t:%f prev_forced_t:%f -> res:%f
\n
"
,
ost
->
forced_keyframes_expr_const_values
[
FKF_N
],
ost
->
forced_keyframes_expr_const_values
[
FKF_N_FORCED
],
ost
->
forced_keyframes_expr_const_values
[
FKF_PREV_FORCED_N
],
ost
->
forced_keyframes_expr_const_values
[
FKF_T
],
ost
->
forced_keyframes_expr_const_values
[
FKF_PREV_FORCED_T
],
res
);
if
(
res
)
{
forced_keyframe
=
1
;
ost
->
forced_keyframes_expr_const_values
[
FKF_PREV_FORCED_N
]
=
ost
->
forced_keyframes_expr_const_values
[
FKF_N
];
ost
->
forced_keyframes_expr_const_values
[
FKF_PREV_FORCED_T
]
=
ost
->
forced_keyframes_expr_const_values
[
FKF_T
];
ost
->
forced_keyframes_expr_const_values
[
FKF_N_FORCED
]
+=
1
;
}
ost
->
forced_keyframes_expr_const_values
[
FKF_N
]
+=
1
;
}
if
(
forced_keyframe
)
{
big_picture
.
pict_type
=
AV_PICTURE_TYPE_I
;
av_log
(
NULL
,
AV_LOG_DEBUG
,
"Forced keyframe at time %f
\n
"
,
pts_time
);
}
update_benchmark
(
NULL
);
ret
=
avcodec_encode_video2
(
enc
,
&
pkt
,
&
big_picture
,
&
got_packet
);
update_benchmark
(
"encode_video %d.%d"
,
ost
->
file_index
,
ost
->
index
);
...
...
@@ -2272,9 +2313,23 @@ static int transcode_init(void)
codec
->
bits_per_raw_sample
=
frame_bits_per_raw_sample
;
}
if
(
ost
->
forced_keyframes
)
parse_forced_key_frames
(
ost
->
forced_keyframes
,
ost
,
ost
->
st
->
codec
);
if
(
ost
->
forced_keyframes
)
{
if
(
!
strncmp
(
ost
->
forced_keyframes
,
"expr:"
,
5
))
{
ret
=
av_expr_parse
(
&
ost
->
forced_keyframes_pexpr
,
ost
->
forced_keyframes
+
5
,
forced_keyframes_const_names
,
NULL
,
NULL
,
NULL
,
NULL
,
0
,
NULL
);
if
(
ret
<
0
)
{
av_log
(
NULL
,
AV_LOG_ERROR
,
"Invalid force_key_frames expression '%s'
\n
"
,
ost
->
forced_keyframes
+
5
);
return
ret
;
}
ost
->
forced_keyframes_expr_const_values
[
FKF_N
]
=
0
;
ost
->
forced_keyframes_expr_const_values
[
FKF_N_FORCED
]
=
0
;
ost
->
forced_keyframes_expr_const_values
[
FKF_PREV_FORCED_N
]
=
NAN
;
ost
->
forced_keyframes_expr_const_values
[
FKF_PREV_FORCED_T
]
=
NAN
;
}
else
{
parse_forced_key_frames
(
ost
->
forced_keyframes
,
ost
,
ost
->
st
->
codec
);
}
}
break
;
case
AVMEDIA_TYPE_SUBTITLE
:
codec
->
time_base
=
(
AVRational
){
1
,
1000
};
...
...
ffmpeg.h
View file @
43af18ef
...
...
@@ -41,6 +41,7 @@
#include "libavutil/avutil.h"
#include "libavutil/dict.h"
#include "libavutil/eval.h"
#include "libavutil/fifo.h"
#include "libavutil/pixfmt.h"
#include "libavutil/rational.h"
...
...
@@ -289,6 +290,17 @@ typedef struct InputFile {
#endif
}
InputFile
;
enum
forced_keyframes_const
{
FKF_N
,
FKF_N_FORCED
,
FKF_PREV_FORCED_N
,
FKF_PREV_FORCED_T
,
FKF_T
,
FKF_NB
};
extern
const
char
*
const
forced_keyframes_const_names
[];
typedef
struct
OutputStream
{
int
file_index
;
/* file index */
int
index
;
/* stream index in the output file */
...
...
@@ -320,6 +332,8 @@ typedef struct OutputStream {
int
forced_kf_count
;
int
forced_kf_index
;
char
*
forced_keyframes
;
AVExpr
*
forced_keyframes_pexpr
;
double
forced_keyframes_expr_const_values
[
FKF_NB
];
/* audio only */
int
audio_channels_map
[
SWR_CH_MAX
];
/* list of the channels id to pick from the source stream */
...
...
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