2002-11-04 18:50:04 +00:00
|
|
|
\input texinfo @c -*- texinfo -*-
|
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
@settitle FFmpeg FAQ
|
2002-11-04 18:50:04 +00:00
|
|
|
@titlepage
|
2011-03-17 15:55:58 +00:00
|
|
|
@center @titlefont{FFmpeg FAQ}
|
2002-11-04 18:50:04 +00:00
|
|
|
@end titlepage
|
|
|
|
|
2011-01-29 12:24:13 +00:00
|
|
|
@top
|
|
|
|
|
|
|
|
@contents
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2008-01-26 12:18:28 +00:00
|
|
|
@chapter General Questions
|
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
@section Why doesn't FFmpeg support feature [xyz]?
|
2008-01-26 12:18:28 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
Because no one has taken on that task yet. FFmpeg development is
|
2008-01-26 12:18:28 +00:00
|
|
|
driven by the tasks that are important to the individual developers.
|
|
|
|
If there is a feature that is important to you, the best way to get
|
2008-01-26 12:23:24 +00:00
|
|
|
it implemented is to undertake the task yourself or sponsor a developer.
|
2008-01-26 12:18:28 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
@section FFmpeg does not support codec XXX. Can you include a Windows DLL loader to support it?
|
2008-01-26 12:18:28 +00:00
|
|
|
|
2008-01-26 12:23:24 +00:00
|
|
|
No. Windows DLLs are not portable, bloated and often slow.
|
2011-03-17 15:55:58 +00:00
|
|
|
Moreover FFmpeg strives to support all codecs natively.
|
2008-01-26 12:23:24 +00:00
|
|
|
A DLL loader is not conducive to that goal.
|
2008-01-26 12:18:28 +00:00
|
|
|
|
2004-10-01 02:35:21 +00:00
|
|
|
@section I cannot read this file although this format seems to be supported by ffmpeg.
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2008-01-26 12:23:24 +00:00
|
|
|
Even if ffmpeg can read the container format, it may not support all its
|
2002-11-04 18:50:04 +00:00
|
|
|
codecs. Please consult the supported codec list in the ffmpeg
|
|
|
|
documentation.
|
|
|
|
|
2008-01-26 12:18:28 +00:00
|
|
|
@section Which codecs are supported by Windows?
|
|
|
|
|
|
|
|
Windows does not support standard formats like MPEG very well, unless you
|
2008-06-06 07:51:36 +00:00
|
|
|
install some additional codecs.
|
2008-01-26 12:18:28 +00:00
|
|
|
|
|
|
|
The following list of video codecs should work on most Windows systems:
|
|
|
|
@table @option
|
|
|
|
@item msmpeg4v2
|
|
|
|
.avi/.asf
|
|
|
|
@item msmpeg4
|
|
|
|
.asf only
|
|
|
|
@item wmv1
|
|
|
|
.asf only
|
|
|
|
@item wmv2
|
|
|
|
.asf only
|
|
|
|
@item mpeg4
|
2008-06-06 07:51:36 +00:00
|
|
|
Only if you have some MPEG-4 codec like ffdshow or Xvid installed.
|
2011-04-07 22:26:49 +00:00
|
|
|
@item mpeg1video
|
2008-01-26 12:18:28 +00:00
|
|
|
.mpg only
|
|
|
|
@end table
|
|
|
|
Note, ASF files often have .wmv or .wma extensions in Windows. It should also
|
|
|
|
be mentioned that Microsoft claims a patent on the ASF format, and may sue
|
|
|
|
or threaten users who create ASF files with non-Microsoft software. It is
|
|
|
|
strongly advised to avoid ASF where possible.
|
|
|
|
|
|
|
|
The following list of audio codecs should work on most Windows systems:
|
|
|
|
@table @option
|
|
|
|
@item adpcm_ima_wav
|
|
|
|
@item adpcm_ms
|
2011-04-07 22:26:49 +00:00
|
|
|
@item pcm_s16le
|
2008-06-06 07:51:36 +00:00
|
|
|
always
|
2011-04-07 22:26:49 +00:00
|
|
|
@item libmp3lame
|
2008-06-06 07:51:36 +00:00
|
|
|
If some MP3 codec like LAME is installed.
|
2008-01-26 12:18:28 +00:00
|
|
|
@end table
|
|
|
|
|
|
|
|
|
2008-05-28 16:12:40 +00:00
|
|
|
@chapter Compilation
|
|
|
|
|
|
|
|
@section @code{error: can't find a register in class 'GENERAL_REGS' while reloading 'asm'}
|
|
|
|
|
|
|
|
This is a bug in gcc. Do not report it to us. Instead, please report it to
|
|
|
|
the gcc developers. Note that we will not add workarounds for gcc bugs.
|
|
|
|
|
2008-07-29 07:55:51 +00:00
|
|
|
Also note that (some of) the gcc developers believe this is not a bug or
|
|
|
|
not a bug they should fix:
|
|
|
|
@url{http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11203}.
|
|
|
|
Then again, some of them do not know the difference between an undecidable
|
|
|
|
problem and an NP-hard problem...
|
2008-05-28 16:12:40 +00:00
|
|
|
|
2008-01-26 12:18:28 +00:00
|
|
|
@chapter Usage
|
|
|
|
|
2008-06-06 07:51:36 +00:00
|
|
|
@section ffmpeg does not work; what is wrong?
|
2008-01-26 12:18:28 +00:00
|
|
|
|
2011-07-08 13:33:17 +00:00
|
|
|
Try a @code{make distclean} in the ffmpeg source directory before the build.
|
2011-07-12 22:42:11 +00:00
|
|
|
If this does not help see
|
2008-01-26 12:18:28 +00:00
|
|
|
(@url{http://ffmpeg.org/bugreports.html}).
|
|
|
|
|
2008-06-06 07:51:36 +00:00
|
|
|
@section How do I encode single pictures into movies?
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2007-06-01 12:03:33 +00:00
|
|
|
First, rename your pictures to follow a numerical sequence.
|
|
|
|
For example, img1.jpg, img2.jpg, img3.jpg,...
|
|
|
|
Then you may run:
|
2002-11-04 18:50:04 +00:00
|
|
|
|
|
|
|
@example
|
2006-08-24 14:03:08 +00:00
|
|
|
ffmpeg -f image2 -i img%d.jpg /tmp/a.mpg
|
2002-11-04 18:50:04 +00:00
|
|
|
@end example
|
|
|
|
|
2007-06-01 12:03:33 +00:00
|
|
|
Notice that @samp{%d} is replaced by the image number.
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2007-06-01 12:03:33 +00:00
|
|
|
@file{img%03d.jpg} means the sequence @file{img001.jpg}, @file{img002.jpg}, etc...
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2010-01-19 22:05:02 +00:00
|
|
|
If you have large number of pictures to rename, you can use the
|
|
|
|
following command to ease the burden. The command, using the bourne
|
|
|
|
shell syntax, symbolically links all files in the current directory
|
|
|
|
that match @code{*jpg} to the @file{/tmp} directory in the sequence of
|
|
|
|
@file{img001.jpg}, @file{img002.jpg} and so on.
|
|
|
|
|
|
|
|
@example
|
2011-02-12 09:12:41 +00:00
|
|
|
x=1; for i in *jpg; do counter=$(printf %03d $x); ln -s "$i" /tmp/img"$counter".jpg; x=$(($x+1)); done
|
2010-01-19 22:05:02 +00:00
|
|
|
@end example
|
|
|
|
|
|
|
|
If you want to sequence them by oldest modified first, substitute
|
|
|
|
@code{$(ls -r -t *jpg)} in place of @code{*jpg}.
|
|
|
|
|
|
|
|
Then run:
|
|
|
|
|
|
|
|
@example
|
|
|
|
ffmpeg -f image2 -i /tmp/img%03d.jpg /tmp/a.mpg
|
|
|
|
@end example
|
|
|
|
|
2007-06-01 12:03:33 +00:00
|
|
|
The same logic is used for any image format that ffmpeg reads.
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2007-06-21 05:14:00 +00:00
|
|
|
@section How do I encode movie to single pictures?
|
2006-08-24 14:03:08 +00:00
|
|
|
|
2006-11-05 13:31:57 +00:00
|
|
|
Use:
|
2006-07-25 11:42:13 +00:00
|
|
|
|
|
|
|
@example
|
2006-11-05 13:31:57 +00:00
|
|
|
ffmpeg -i movie.mpg movie%d.jpg
|
2006-07-25 11:42:13 +00:00
|
|
|
@end example
|
|
|
|
|
2006-11-05 13:31:57 +00:00
|
|
|
The @file{movie.mpg} used as input will be converted to
|
|
|
|
@file{movie1.jpg}, @file{movie2.jpg}, etc...
|
2006-07-25 11:42:13 +00:00
|
|
|
|
|
|
|
Instead of relying on file format self-recognition, you may also use
|
|
|
|
@table @option
|
2011-12-10 00:58:04 +00:00
|
|
|
@item -c:v ppm
|
|
|
|
@item -c:v png
|
|
|
|
@item -c:v mjpeg
|
2006-07-25 11:42:13 +00:00
|
|
|
@end table
|
|
|
|
to force the encoding.
|
|
|
|
|
|
|
|
Applying that to the previous example:
|
|
|
|
@example
|
2011-12-10 23:40:09 +00:00
|
|
|
ffmpeg -i movie.mpg -f image2 -c:v mjpeg menu%d.jpg
|
2006-07-25 11:42:13 +00:00
|
|
|
@end example
|
|
|
|
|
|
|
|
Beware that there is no "jpeg" codec. Use "mjpeg" instead.
|
|
|
|
|
2007-06-21 05:14:00 +00:00
|
|
|
@section Why do I see a slight quality degradation with multithreaded MPEG* encoding?
|
2004-08-23 19:48:41 +00:00
|
|
|
|
|
|
|
For multithreaded MPEG* encoding, the encoded slices must be independent,
|
2004-10-01 02:35:21 +00:00
|
|
|
otherwise thread n would practically have to wait for n-1 to finish, so it's
|
|
|
|
quite logical that there is a small reduction of quality. This is not a bug.
|
2004-08-23 19:48:41 +00:00
|
|
|
|
2007-06-21 05:14:00 +00:00
|
|
|
@section How can I read from the standard input or write to the standard output?
|
2002-11-19 19:16:26 +00:00
|
|
|
|
2008-06-06 07:51:36 +00:00
|
|
|
Use @file{-} as file name.
|
2002-11-19 19:16:26 +00:00
|
|
|
|
2005-06-09 19:54:58 +00:00
|
|
|
@section -f jpeg doesn't work.
|
2004-07-09 20:11:52 +00:00
|
|
|
|
2006-08-24 14:03:08 +00:00
|
|
|
Try '-f image2 test%d.jpg'.
|
2004-07-09 20:11:52 +00:00
|
|
|
|
2011-11-29 16:50:25 +00:00
|
|
|
@section Why can I not change the frame rate?
|
2004-09-12 16:46:15 +00:00
|
|
|
|
2011-11-29 16:50:25 +00:00
|
|
|
Some codecs, like MPEG-1/2, only allow a small number of fixed frame rates.
|
2011-12-10 00:58:04 +00:00
|
|
|
Choose a different codec with the -c:v command line option.
|
2004-09-12 16:46:15 +00:00
|
|
|
|
2008-05-27 12:32:59 +00:00
|
|
|
@section How do I encode Xvid or DivX video with ffmpeg?
|
2004-10-16 16:47:42 +00:00
|
|
|
|
2008-05-27 12:32:59 +00:00
|
|
|
Both Xvid and DivX (version 4+) are implementations of the ISO MPEG-4
|
2004-10-16 16:47:42 +00:00
|
|
|
standard (note that there are many other coding formats that use this
|
2011-12-10 00:58:04 +00:00
|
|
|
same standard). Thus, use '-c:v mpeg4' to encode in these formats. The
|
2005-06-09 17:55:36 +00:00
|
|
|
default fourcc stored in an MPEG-4-coded file will be 'FMP4'. If you want
|
2005-12-17 18:14:38 +00:00
|
|
|
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
|
2004-10-16 16:47:42 +00:00
|
|
|
default.
|
|
|
|
|
2007-01-15 05:46:42 +00:00
|
|
|
@section Which are good parameters for encoding high quality MPEG-4?
|
2007-01-02 01:19:58 +00:00
|
|
|
|
2010-10-03 17:15:18 +00:00
|
|
|
'-mbd rd -flags +mv4+aic -trellis 2 -cmp 2 -subcmp 2 -g 300 -pass 1/2',
|
2007-01-15 05:46:42 +00:00
|
|
|
things to try: '-bf 2', '-flags qprd', '-flags mv0', '-flags skiprd'.
|
2007-01-02 01:19:58 +00:00
|
|
|
|
2007-01-15 05:46:42 +00:00
|
|
|
@section Which are good parameters for encoding high quality MPEG-1/MPEG-2?
|
2007-01-02 01:19:58 +00:00
|
|
|
|
2008-11-29 13:58:41 +00:00
|
|
|
'-mbd rd -trellis 2 -cmp 2 -subcmp 2 -g 100 -pass 1/2'
|
2007-01-15 05:46:42 +00:00
|
|
|
but beware the '-g 100' might cause problems with some decoders.
|
|
|
|
Things to try: '-bf 2', '-flags qprd', '-flags mv0', '-flags skiprd.
|
2007-01-02 01:19:58 +00:00
|
|
|
|
2008-07-27 12:36:58 +00:00
|
|
|
@section Interlaced video looks very bad when encoded with ffmpeg, what is wrong?
|
2007-01-02 01:19:58 +00:00
|
|
|
|
2007-01-15 05:46:42 +00:00
|
|
|
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.
|
2007-01-02 01:19:58 +00:00
|
|
|
|
2006-09-17 07:34:54 +00:00
|
|
|
@section How can I read DirectShow files?
|
2006-09-16 12:40:18 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
If you have built FFmpeg with @code{./configure --enable-avisynth}
|
2006-09-17 07:34:54 +00:00
|
|
|
(only possible on MinGW/Cygwin platforms),
|
|
|
|
then you may use any file that DirectShow can read as input.
|
2006-09-16 12:40:18 +00:00
|
|
|
|
|
|
|
Just create an "input.avs" text file with this single line ...
|
|
|
|
@example
|
|
|
|
DirectShowSource("C:\path to your file\yourfile.asf")
|
|
|
|
@end example
|
2011-04-23 14:40:01 +00:00
|
|
|
... and then feed that text file to ffmpeg:
|
2006-09-16 12:40:18 +00:00
|
|
|
@example
|
|
|
|
ffmpeg -i input.avs
|
|
|
|
@end example
|
|
|
|
|
2011-07-08 13:33:17 +00:00
|
|
|
For ANY other help on Avisynth, please visit the
|
|
|
|
@uref{http://www.avisynth.org/, Avisynth homepage}.
|
2006-09-16 12:40:18 +00:00
|
|
|
|
2007-06-02 21:50:45 +00:00
|
|
|
@section How can I join video files?
|
|
|
|
|
2007-06-04 21:09:38 +00:00
|
|
|
A few multimedia containers (MPEG-1, MPEG-2 PS, DV) allow to join video files by
|
2007-06-02 21:50:45 +00:00
|
|
|
merely concatenating them.
|
|
|
|
|
|
|
|
Hence you may concatenate your multimedia files by first transcoding them to
|
|
|
|
these privileged formats, then using the humble @code{cat} command (or the
|
2007-06-04 21:09:38 +00:00
|
|
|
equally humble @code{copy} under Windows), and finally transcoding back to your
|
2007-06-02 21:50:45 +00:00
|
|
|
format of choice.
|
|
|
|
|
|
|
|
@example
|
2011-12-10 23:40:09 +00:00
|
|
|
ffmpeg -i input1.avi -same_quant intermediate1.mpg
|
|
|
|
ffmpeg -i input2.avi -same_quant intermediate2.mpg
|
2007-06-02 21:50:45 +00:00
|
|
|
cat intermediate1.mpg intermediate2.mpg > intermediate_all.mpg
|
2011-12-10 23:40:09 +00:00
|
|
|
ffmpeg -i intermediate_all.mpg -same_quant output.avi
|
2007-06-02 21:50:45 +00:00
|
|
|
@end example
|
|
|
|
|
2011-12-10 00:58:04 +00:00
|
|
|
Notice that you should either use @code{-same_quant} or set a reasonably high
|
2007-06-02 21:50:45 +00:00
|
|
|
bitrate for your intermediate and output files, if you want to preserve
|
|
|
|
video quality.
|
|
|
|
|
2007-06-04 21:09:38 +00:00
|
|
|
Also notice that you may avoid the huge intermediate files by taking advantage
|
2007-06-02 21:50:45 +00:00
|
|
|
of named pipes, should your platform support it:
|
|
|
|
|
|
|
|
@example
|
|
|
|
mkfifo intermediate1.mpg
|
|
|
|
mkfifo intermediate2.mpg
|
2011-12-10 23:40:09 +00:00
|
|
|
ffmpeg -i input1.avi -same_quant -y intermediate1.mpg < /dev/null &
|
|
|
|
ffmpeg -i input2.avi -same_quant -y intermediate2.mpg < /dev/null &
|
2007-06-02 21:50:45 +00:00
|
|
|
cat intermediate1.mpg intermediate2.mpg |\
|
2011-12-10 23:40:09 +00:00
|
|
|
ffmpeg -f mpeg -i - -same_quant -c:v mpeg4 -acodec libmp3lame output.avi
|
2007-06-02 21:50:45 +00:00
|
|
|
@end example
|
|
|
|
|
|
|
|
Similarly, the yuv4mpegpipe format, and the raw video, raw audio codecs also
|
|
|
|
allow concatenation, and the transcoding step is almost lossless.
|
2010-01-06 13:49:31 +00:00
|
|
|
When using multiple yuv4mpegpipe(s), the first line needs to be discarded
|
|
|
|
from all but the first stream. This can be accomplished by piping through
|
|
|
|
@code{tail} as seen below. Note that when piping through @code{tail} you
|
|
|
|
must use command grouping, @code{@{ ;@}}, to background properly.
|
|
|
|
|
2007-06-02 21:50:45 +00:00
|
|
|
For example, let's say we want to join two FLV files into an output.flv file:
|
|
|
|
|
|
|
|
@example
|
|
|
|
mkfifo temp1.a
|
|
|
|
mkfifo temp1.v
|
|
|
|
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 &
|
2010-01-06 13:49:31 +00:00
|
|
|
@{ ffmpeg -i input2.flv -an -f yuv4mpegpipe - < /dev/null | tail -n +2 > temp2.v ; @} &
|
2007-06-02 21:50:45 +00:00
|
|
|
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 \
|
|
|
|
-f yuv4mpegpipe -i all.v \
|
2011-12-10 00:58:04 +00:00
|
|
|
-same_quant -y output.flv
|
2007-06-02 21:50:45 +00:00
|
|
|
rm temp[12].[av] all.[av]
|
|
|
|
@end example
|
|
|
|
|
2002-11-04 18:50:04 +00:00
|
|
|
@chapter Development
|
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
@section Are there examples illustrating how to use the FFmpeg libraries, particularly libavcodec and libavformat?
|
2003-07-22 13:08:52 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
Yes. Read the Developers Guide of the FFmpeg documentation. Alternatively,
|
2005-12-17 18:14:38 +00:00
|
|
|
examine the source code for one of the many open source projects that
|
2011-03-17 15:55:58 +00:00
|
|
|
already incorporate FFmpeg at (@url{projects.html}).
|
2003-07-22 13:08:52 +00:00
|
|
|
|
2007-06-21 05:14:00 +00:00
|
|
|
@section Can you support my C compiler XXX?
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2007-01-25 17:34:08 +00:00
|
|
|
It depends. If your compiler is C99-compliant, then patches to support
|
|
|
|
it are likely to be welcome if they do not pollute the source code
|
|
|
|
with @code{#ifdef}s related to the compiler.
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2007-11-09 14:05:43 +00:00
|
|
|
@section Is Microsoft Visual C++ supported?
|
2007-02-05 16:38:47 +00:00
|
|
|
|
2007-11-09 14:05:43 +00:00
|
|
|
No. Microsoft Visual C++ is not compliant to the C99 standard and does
|
2011-03-17 15:55:58 +00:00
|
|
|
not - among other things - support the inline assembly used in FFmpeg.
|
2007-11-10 13:23:22 +00:00
|
|
|
If you wish to use MSVC++ for your
|
2007-10-24 03:26:10 +00:00
|
|
|
project then you can link the MSVC++ code with libav* as long as
|
2007-02-05 16:38:47 +00:00
|
|
|
you compile the latter with a working C compiler. For more information, see
|
2011-03-17 15:55:58 +00:00
|
|
|
the @emph{Microsoft Visual C++ compatibility} section in the FFmpeg
|
2007-10-24 03:26:10 +00:00
|
|
|
documentation.
|
2007-02-05 16:38:47 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
There have been efforts to make FFmpeg compatible with MSVC++ in the
|
2007-02-05 16:38:47 +00:00
|
|
|
past. However, they have all been rejected as too intrusive, especially
|
2007-11-09 14:05:43 +00:00
|
|
|
since MinGW does the job adequately. None of the core developers
|
2007-10-24 03:26:10 +00:00
|
|
|
work with MSVC++ and thus this item is low priority. Should you find
|
2007-02-05 16:38:47 +00:00
|
|
|
the silver bullet that solves this problem, feel free to shoot it at us.
|
|
|
|
|
2007-11-10 13:23:22 +00:00
|
|
|
We strongly recommend you to move over from MSVC++ to MinGW tools.
|
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
@section Can I use FFmpeg or libavcodec under Windows?
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
Yes, but the Cygwin or MinGW tools @emph{must} be used to compile FFmpeg.
|
|
|
|
Read the @emph{Windows} section in the FFmpeg documentation to find more
|
2007-10-24 03:26:10 +00:00
|
|
|
information.
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
To get help and instructions for building FFmpeg under Windows, check out
|
2007-02-05 16:45:36 +00:00
|
|
|
the FFmpeg Windows Help Forum at
|
2008-09-13 18:50:53 +00:00
|
|
|
@url{http://ffmpeg.arrozcru.org/}.
|
2007-02-05 16:45:36 +00:00
|
|
|
|
2007-06-21 05:14:00 +00:00
|
|
|
@section Can you add automake, libtool or autoconf support?
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2007-01-25 17:34:08 +00:00
|
|
|
No. These tools are too bloated and they complicate the build.
|
2002-11-04 18:50:04 +00:00
|
|
|
|
2011-12-10 23:40:09 +00:00
|
|
|
@section Why not rewrite FFmpeg in object-oriented C++?
|
2004-07-15 21:28:18 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
FFmpeg is already organized in a highly modular manner and does not need to
|
2005-12-17 18:14:38 +00:00
|
|
|
be rewritten in a formal object language. Further, many of the developers
|
2004-10-01 02:35:21 +00:00
|
|
|
favor straight C; it works for them. For more arguments on this matter,
|
2011-07-08 13:33:17 +00:00
|
|
|
read @uref{http://www.tux.org/lkml/#s15, "Programming Religion"}.
|
2004-10-01 02:35:21 +00:00
|
|
|
|
2007-06-21 05:14:00 +00:00
|
|
|
@section Why are the ffmpeg programs devoid of debugging symbols?
|
2004-10-01 02:35:21 +00:00
|
|
|
|
|
|
|
The build process creates ffmpeg_g, ffplay_g, etc. which contain full debug
|
2008-06-06 07:51:36 +00:00
|
|
|
information. Those binaries are stripped to create ffmpeg, ffplay, etc. If
|
2011-02-14 13:29:43 +00:00
|
|
|
you need the debug information, use the *_g versions.
|
2004-07-15 21:28:18 +00:00
|
|
|
|
2007-06-21 05:14:00 +00:00
|
|
|
@section I do not like the LGPL, can I contribute code under the GPL instead?
|
2005-09-11 16:39:47 +00:00
|
|
|
|
2005-09-12 15:51:29 +00:00
|
|
|
Yes, as long as the code is optional and can easily and cleanly be placed
|
2011-11-29 16:50:25 +00:00
|
|
|
under #if CONFIG_GPL without breaking anything. So, for example, a new codec
|
2008-06-06 07:51:36 +00:00
|
|
|
or filter would be OK under GPL while a bug fix to LGPL code would not.
|
2005-09-11 16:39:47 +00:00
|
|
|
|
2011-12-10 23:40:09 +00:00
|
|
|
@section I'm using FFmpeg from within my C++ application but the linker complains about missing symbols which seem to be available.
|
2007-07-27 13:40:02 +00:00
|
|
|
|
2011-03-17 15:55:58 +00:00
|
|
|
FFmpeg is a pure C project, so to use the libraries within your C++ application
|
2007-07-27 13:40:02 +00:00
|
|
|
you need to explicitly state that you are using a C library. You can do this by
|
2011-03-17 15:55:58 +00:00
|
|
|
encompassing your FFmpeg includes using @code{extern "C"}.
|
2007-07-27 13:40:02 +00:00
|
|
|
|
|
|
|
See @url{http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html#faq-32.3}
|
|
|
|
|
2011-09-10 14:23:50 +00:00
|
|
|
@section I'm using libavutil from within my C++ application but the compiler complains about 'UINT64_C' was not declared in this scope
|
|
|
|
|
2011-12-08 19:07:32 +00:00
|
|
|
FFmpeg is a pure C project using C99 math features, in order to enable C++
|
2011-09-10 14:23:50 +00:00
|
|
|
to use them you have to append -D__STDC_CONSTANT_MACROS to your CXXFLAGS
|
|
|
|
|
2008-03-12 23:58:46 +00:00
|
|
|
@section I have a file in memory / a API different from *open/*read/ libc how do I use it with libavformat?
|
2006-05-18 08:01:47 +00:00
|
|
|
|
2010-07-19 08:34:38 +00:00
|
|
|
You have to implement a URLProtocol, see @file{libavformat/file.c} in
|
2011-03-17 15:55:58 +00:00
|
|
|
FFmpeg and @file{libmpdemux/demux_lavf.c} in MPlayer sources.
|
2006-05-18 08:01:47 +00:00
|
|
|
|
2007-04-04 11:41:13 +00:00
|
|
|
@section Where can I find libav* headers for Pascal/Delphi?
|
2007-03-20 21:09:02 +00:00
|
|
|
|
|
|
|
see @url{http://www.iversenit.dk/dev/ffmpeg-headers/}
|
|
|
|
|
2007-04-04 11:41:13 +00:00
|
|
|
@section Where is the documentation about ffv1, msmpeg4, asv1, 4xm?
|
2007-03-20 21:12:06 +00:00
|
|
|
|
2010-07-18 14:01:33 +00:00
|
|
|
see @url{http://www.ffmpeg.org/~michael/}
|
2007-03-20 21:12:06 +00:00
|
|
|
|
2007-09-13 13:45:49 +00:00
|
|
|
@section How do I feed H.263-RTP (and other codecs in RTP) to libavcodec?
|
2007-07-15 12:17:05 +00:00
|
|
|
|
2007-07-17 14:15:39 +00:00
|
|
|
Even if peculiar since it is network oriented, RTP is a container like any
|
2007-07-17 14:59:29 +00:00
|
|
|
other. You have to @emph{demux} RTP before feeding the payload to libavcodec.
|
|
|
|
In this specific case please look at RFC 4629 to see how it should be done.
|
2007-07-15 12:17:05 +00:00
|
|
|
|
2011-11-29 16:50:25 +00:00
|
|
|
@section AVStream.r_frame_rate is wrong, it is much larger than the frame rate.
|
2007-09-11 10:25:34 +00:00
|
|
|
|
2011-11-29 16:50:25 +00:00
|
|
|
r_frame_rate is NOT the average frame rate, it is the smallest frame rate
|
2007-09-13 13:45:49 +00:00
|
|
|
that can accurately represent all timestamps. So no, it is not
|
|
|
|
wrong if it is larger than the average!
|
|
|
|
For example, if you have mixed 25 and 30 fps content, then r_frame_rate
|
2007-09-11 10:25:34 +00:00
|
|
|
will be 150.
|
|
|
|
|
2002-11-04 18:50:04 +00:00
|
|
|
@bye
|