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Linshizhi
ffmpeg.wasm-core
Commits
708060d7
Commit
708060d7
authored
Dec 10, 2011
by
Luca Barbato
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doc: update to refer to avconv
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doc/faq.texi
View file @
708060d7
...
...
@@ -24,10 +24,10 @@ No. Windows DLLs are not portable, bloated and often slow.
Moreover Libav strives to support all codecs natively.
A DLL loader is not conducive to that goal.
@section I cannot read this file although this format seems to be supported by
ffmpeg
.
@section I cannot read this file although this format seems to be supported by
avconv
.
Even if
ffmpeg
can read the container format, it may not support all its
codecs. Please consult the supported codec list in the
ffmpeg
Even if
avconv
can read the container format, it may not support all its
codecs. Please consult the supported codec list in the
avconv
documentation.
@section Which codecs are supported by Windows?
...
...
@@ -81,12 +81,6 @@ problem and an NP-hard problem...
@chapter Usage
@section ffmpeg does not work; what is wrong?
Try a @code
{
make distclean
}
in the ffmpeg source directory before the build.
If this does not help see our
@uref
{
http://libav.org/bugreports.html, bug reporting guidelines
}
.
@section How do I encode single pictures into movies?
First, rename your pictures to follow a numerical sequence.
...
...
@@ -94,7 +88,7 @@ For example, img1.jpg, img2.jpg, img3.jpg,...
Then you may run:
@example
ffmpeg
-f image2 -i img
%d.jpg /tmp/a.mpg
avconv
-f image2 -i img
%d.jpg /tmp/a.mpg
@end example
Notice that @samp
{
%d} is replaced by the image number.
...
...
@@ -117,17 +111,17 @@ If you want to sequence them by oldest modified first, substitute
Then run:
@example
ffmpeg
-f image2 -i /tmp/img
%03d.jpg /tmp/a.mpg
avconv
-f image2 -i /tmp/img
%03d.jpg /tmp/a.mpg
@end example
The same logic is used for any image format that
ffmpeg
reads.
The same logic is used for any image format that
avconv
reads.
@section How do I encode movie to single pictures?
Use:
@example
ffmpeg
-i movie.mpg movie
%d.jpg
avconv
-i movie.mpg movie
%d.jpg
@end example
The @file
{
movie.mpg
}
used as input will be converted to
...
...
@@ -135,15 +129,15 @@ The @file{movie.mpg} used as input will be converted to
Instead of relying on file format self-recognition, you may also use
@table @option
@item -
vcodec
ppm
@item -
vcodec
png
@item -
vcodec
mjpeg
@item -
c:v
ppm
@item -
c:v
png
@item -
c:v
mjpeg
@end table
to force the encoding.
Applying that to the previous example:
@example
ffmpeg -i movie.mpg -f image2 -vcodec
mjpeg menu
%d.jpg
avconv -i movie.mpg -f image2 -c:v
mjpeg menu
%d.jpg
@end example
Beware that there is no "jpeg" codec. Use "mjpeg" instead.
...
...
@@ -165,13 +159,13 @@ Try '-f image2 test%d.jpg'.
@section Why can I not change the framerate?
Some codecs, like MPEG-1/2, only allow a small number of fixed framerates.
Choose a different codec with the -
vcodec
command line option.
Choose a different codec with the -
c:v
command line option.
@section How do I encode Xvid or DivX video with
ffmpeg
?
@section How do I encode Xvid or DivX video with
avconv
?
Both Xvid and DivX (version 4+) are implementations of the ISO MPEG-4
standard (note that there are many other coding formats that use this
same standard). Thus, use '-
vcodec
mpeg4' to encode in these formats. The
same standard). Thus, use '-
c:v
mpeg4' to encode in these formats. The
default fourcc stored in an MPEG-4-coded file will be 'FMP4'. If you want
a different fourcc, use the '-vtag' option. E.g., '-vtag xvid' will
force the fourcc 'xvid' to be stored as the video fourcc rather than the
...
...
@@ -188,7 +182,7 @@ things to try: '-bf 2', '-flags qprd', '-flags mv0', '-flags skiprd'.
but beware the '-g 100' might cause problems with some decoders.
Things to try: '-bf 2', '-flags qprd', '-flags mv0', '-flags skiprd.
@section Interlaced video looks very bad when encoded with
ffmpeg
, what is wrong?
@section Interlaced video looks very bad when encoded with
avconv
, what is wrong?
You should use '-flags +ilme+ildct' and maybe '-flags +alt' for interlaced
material, and try '-top 0/1' if the result looks really messed-up.
...
...
@@ -203,9 +197,9 @@ Just create an "input.avs" text file with this single line ...
@example
DirectShowSource("C:
\path
to your file
\yourfile
.asf")
@end example
... and then feed that text file to
ffmpeg
:
... and then feed that text file to
avconv
:
@example
ffmpeg
-i input.avs
avconv
-i input.avs
@end example
For ANY other help on Avisynth, please visit the
...
...
@@ -222,13 +216,13 @@ equally humble @code{copy} under Windows), and finally transcoding back to your
format of choice.
@example
ffmpeg -i input1.avi -sameq
intermediate1.mpg
ffmpeg -i input2.avi -sameq
intermediate2.mpg
avconv -i input1.avi -same
_
quant
intermediate1.mpg
avconv -i input2.avi -same
_
quant
intermediate2.mpg
cat intermediate1.mpg intermediate2.mpg > intermediate
_
all.mpg
ffmpeg -i intermediate
_
all.mpg -sameq
output.avi
avconv -i intermediate
_
all.mpg -same
_
quant
output.avi
@end example
Notice that you should either use @code
{
-same
q
}
or set a reasonably high
Notice that you should either use @code
{
-same
_
quant
}
or set a reasonably high
bitrate for your intermediate and output files, if you want to preserve
video quality.
...
...
@@ -238,10 +232,10 @@ of named pipes, should your platform support it:
@example
mkfifo intermediate1.mpg
mkfifo intermediate2.mpg
ffmpeg -i input1.avi -sameq
-y intermediate1.mpg < /dev/null
&
ffmpeg -i input2.avi -sameq
-y intermediate2.mpg < /dev/null
&
avconv -i input1.avi -same
_
quant
-y intermediate1.mpg < /dev/null
&
avconv -i input2.avi -same
_
quant
-y intermediate2.mpg < /dev/null
&
cat intermediate1.mpg intermediate2.mpg |
\
ffmpeg -f mpeg -i - -sameq -vcodec
mpeg4 -acodec libmp3lame output.avi
avconv -f mpeg -i - -same
_
quant -c:v
mpeg4 -acodec libmp3lame output.avi
@end example
Similarly, the yuv4mpegpipe format, and the raw video, raw audio codecs also
...
...
@@ -260,15 +254,15 @@ mkfifo temp2.a
mkfifo temp2.v
mkfifo all.a
mkfifo all.v
ffmpeg
-i input1.flv -vn -f u16le -acodec pcm
_
s16le -ac 2 -ar 44100 - > temp1.a < /dev/null
&
ffmpeg
-i input2.flv -vn -f u16le -acodec pcm
_
s16le -ac 2 -ar 44100 - > temp2.a < /dev/null
&
ffmpeg
-i input1.flv -an -f yuv4mpegpipe - > temp1.v < /dev/null
&
@
{
ffmpeg
-i input2.flv -an -f yuv4mpegpipe - < /dev/null | tail -n +2 > temp2.v ; @
}
&
avconv
-i input1.flv -vn -f u16le -acodec pcm
_
s16le -ac 2 -ar 44100 - > temp1.a < /dev/null
&
avconv
-i input2.flv -vn -f u16le -acodec pcm
_
s16le -ac 2 -ar 44100 - > temp2.a < /dev/null
&
avconv
-i input1.flv -an -f yuv4mpegpipe - > temp1.v < /dev/null
&
@
{
avconv
-i input2.flv -an -f yuv4mpegpipe - < /dev/null | tail -n +2 > temp2.v ; @
}
&
cat temp1.a temp2.a > all.a
&
cat temp1.v temp2.v > all.v
&
ffmpeg
-f u16le -acodec pcm
_
s16le -ac 2 -ar 44100 -i all.a
\
avconv
-f u16le -acodec pcm
_
s16le -ac 2 -ar 44100 -i all.a
\
-f yuv4mpegpipe -i all.v
\
-same
q
-y output.flv
-same
_
quant
-y output.flv
rm temp[12].[av] all.[av]
@end example
...
...
@@ -304,7 +298,7 @@ the silver bullet that solves this problem, feel free to shoot it at us.
We strongly recommend you to move over from MSVC++ to MinGW tools.
@section Can I use Libav
or libavcodec
under Windows?
@section Can I use Libav under Windows?
Yes, but the Cygwin or MinGW tools @emph
{
must
}
be used to compile Libav.
Read the @emph
{
Windows
}
section in the Libav documentation to find more
...
...
@@ -314,7 +308,7 @@ information.
No. These tools are too bloated and they complicate the build.
@section Why not rewrite
ffmpeg
in object-oriented C++?
@section Why not rewrite
Libav
in object-oriented C++?
Libav is already organized in a highly modular manner and does not need to
be rewritten in a formal object language. Further, many of the developers
...
...
@@ -327,7 +321,7 @@ Yes, as long as the code is optional and can easily and cleanly be placed
under #if CONFIG
_
GPL without breaking anything. So for example a new codec
or filter would be OK under GPL while a bug fix to LGPL code would not.
@section I'm using
libavcodec
from within my C++ application but the linker complains about missing symbols which seem to be available.
@section I'm using
Libav
from within my C++ application but the linker complains about missing symbols which seem to be available.
Libav is a pure C project, so to use the libraries within your C++ application
you need to explicitly state that you are using a C library. You can do this by
...
...
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