The audio is AC3 (a.k.a. A/52). AC3 decoding is an optional component in ffmpeg
as the component that handles AC3 decoding (liba52) is currently released under
the GPL. If you have liba52 installed on your system, enable AC3 decoding
-with @code{./configure --enable-a52}. Take care: by
+with @code{./configure --enable-liba52 --enable-gpl}. Take care: by
enabling AC3, you automatically change the license of libavcodec from
LGPL to GPL.
@section Why does the chrominance data seem to be sampled at a different time from the luminance data on bt8x8 captures on Linux?
This is a well-known bug in the bt8x8 driver. For 2.4.26 there is a patch at
-(@url{http://mplayerhq.hu/~michael/bttv-420-2.4.26.patch}). This may also
+(@url{http://svn.mplayerhq.hu/michael/trunk/patches/bttv-420-2.4.26.patch?view=co}). This may also
apply cleanly to other 2.4-series kernels.
@section How do I avoid the ugly aliasing artifacts in bt8x8 captures on Linux?
Pass 'combfilter=1 lumafilter=1' to the bttv driver. Note though that 'combfilter=1'
-will cause somewhat too strong filtering. A fix is to apply (@url{http://mplayerhq.hu/~michael/bttv-comb-2.4.26.patch})
-or (@url{http://mplayerhq.hu/~michael/bttv-comb-2.6.6.patch})
+will cause somewhat too strong filtering. A fix is to apply (@url{http://svn.mplayerhq.hu/michael/trunk/patches/bttv-comb-2.4.26.patch?view=co})
+or (@url{http://svn.mplayerhq.hu/michael/trunk/patches/bttv-comb-2.6.6.patch?view=co})
and pass 'combfilter=2'.
@section I have a problem with an old version of ffmpeg; where should I report it?
@section ffmpeg does not work; What is wrong?
-Try a 'make distclean' in the ffmpeg source directory. If this does not help see
+Try a 'make distclean' in the ffmpeg source directory before the build. If this does not help see
(@url{http://ffmpeg.org/bugreports.php}).
@section How do I encode XviD or DivX video with ffmpeg?
@item non-working stuff
B-frames
@item example command line
-ffmpeg -i input -acodec aac -ab 128 -vcodec mpeg4 -b 1200Kb -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 320x180 -title X output.mp4
+ffmpeg -i input -acodec aac -ab 128kb -vcodec mpeg4 -b 1200kb -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 320x180 -title X output.mp4
@end table
@section How do I encode videos which play on the PSP?
@item non-working stuff
B-frames
@item example command line
-ffmpeg -i input -acodec aac -ab 128 -vcodec mpeg4 -b 1200Kb -ar 24000 -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp output.mp4
+ffmpeg -i input -acodec aac -ab 128kb -vcodec mpeg4 -b 1200kb -ar 24000 -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp output.mp4
@item needed stuff for H.264
-acodec aac -vcodec h264 width*height<=76800 width%16=0? height%16=0? -ar 48000 -coder 1 -r 30000/1001 or 15000/1001 -f psp
@item working stuff for H.264
@item non-working stuff for H.264
CAVLC
@item example command line
-ffmpeg -i input -acodec aac -ab 128 -vcodec h264 -b 1200Kb -ar 48000 -mbd 2 -coder 1 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp -flags loop -trellis 2 -partitions parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 output.mp4
+ffmpeg -i input -acodec aac -ab 128kb -vcodec h264 -b 1200kb -ar 48000 -mbd 2 -coder 1 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp -flags loop -trellis 2 -partitions parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 output.mp4
@end table
+@section Which are good parameters for encoding high quality MPEG-4?
+
+'-mbd rd -flags +4mv+trell+aic -cmp 2 -subcmp 2 -g 300 -pass 1/2',
+things to try: '-bf 2', '-flags qprd', '-flags mv0', '-flags skiprd'.
+
+@section Which are good parameters for encoding high quality MPEG-1/MPEG-2?
+
+'-mbd rd -flags +trell -cmp 2 -subcmp 2 -g 100 -pass 1/2'
+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, whats 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.
+
@section How can I read DirectShow files?
If you have built FFmpeg with @code{./configure --enable-avisynth}
For ANY other help on Avisynth, please visit @url{http://www.avisynth.org/}.
+@section My bugreport/mail to ffmpeg-devel/user has not received any replies.
+
+Likely reasons
+@itemize
+@item We are busy and haven't had time yet to read your report or
+investigate the issue.
+@item You didn't follow bugreports.html.
+@item You didn't use Subversion HEAD.
+@item You reported a segmentation fault without gdb output.
+@item You describe a problem but not how to reproduce it.
+@item It's unclear if you use ffmpeg as command line tool or use
+libav* from another application.
+@item You speak about a video having problems on playback but
+not what you use to play it.
+@item We have no faint clue what you are talking about besides
+that it is related to FFmpeg.
+@end itemize
+
@chapter Development
@section When will the next FFmpeg version be released? / Why are FFmpeg releases so few and far between?
@section Can you support my C compiler XXX ?
-No. Only GCC is supported. GCC is ported to most systems available and there
-is no need to pollute the source code with @code{#ifdef}s
-related to the compiler.
+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.
+
+@section Visual C++ produces many errors.
+
+Visual C++ is not compliant to the C standard and does not support
+the inline assembly used in FFmpeg.
+If you wish - for whatever weird reason - to use Visual C++ for your
+project then you can link the Visual C++ code with libav* as long as
+you compile the latter with a working C compiler. For more information, see
+the @emph{Visual C++ compatibility} section in the FFmpeg documentation.
+
+There have been efforts to make FFmpeg compatible with Visual C++ in the
+past. However, they have all been rejected as too intrusive, especially
+since MinGW does the job perfectly adequately. None of the core developers
+work with Visual C++ and thus this item is low priority. Should you find
+the silver bullet that solves this problem, feel free to shoot it at us.
@section Can I use FFmpeg or libavcodec under Windows ?
@emph{Native Windows Compilation} and @emph{Visual C++ compatibility}
sections in the FFmpeg documentation to find more information.
+To get help and instructions for using FFmpeg under Windows, check out
+the FFmpeg Windows Help Forum at
+@url{http://arrozcru.no-ip.org/ffmpeg/}.
+
@section Can you add automake, libtool or autoconf support ?
-No. These tools are too bloated and they complicate the build. Moreover,
-since only @samp{gcc} is supported they would add little advantages in
-terms of portability.
+No. These tools are too bloated and they complicate the build.
@section Why not rewrite ffmpeg in object-oriented C++ ?
ffmpeg 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
favor straight C; it works for them. For more arguments on this matter,
-read "Programming Religion" at (@url{http://lkml.org/faq/lkmlfaq-15.html}).
+read "Programming Religion" at (@url{http://www.tux.org/lkml/#s15}).
@section Why are the ffmpeg programs devoid of debugging symbols ?
You can also try to hack it and remove more, but if you had problems fixing
the compilation failure then you are probably not qualified for this.
-@section Visual C++ produces many errors.
-
-Visual C++ is not compliant to the C standard and does not support
-the inline assembly used in FFmpeg.
-If you wish - for whatever weird reason - to use Visual C++ for your
-project then you can link the Visual C++ code with libav* as long as
-you compile the latter with a working C compiler. For more information, see
-the @emph{Visual C++ compatibility} section in the FFmpeg documentation.
-
-There have been efforts to make FFmpeg compatible with Visual C++ in the
-past. However, they have all been rejected as too intrusive, especially
-since MinGW does the job perfectly adequately. None of the core developers
-work with Visual C++ and thus this item is low priority. Should you find
-the silver bullet that solves this problem, feel free to shoot it at us.
-
@section I have a file in memory / a API different from *open/*read/ libc how do i use it with libavformat ?
You have to implement a URLProtocol, see libavformat/file.c in FFmpeg
The standard MSys bash (2.04) is broken. You need to install 2.05 or later.
+@section I tried to pass RTP packets into a decoder, but it doesn't work.
+
+Of course not, you MUST strip ALL RTP headers and assemble valid packets
+first, an MP3 decoder decodes MP3 packets not bastardized MP3 packets
+encapsulated in RTP. The same applies to all decoders, this is not specific
+to ffmpeg or libavcodec.
+
+@section Where can I find libav* headers for Pascal/Delphi?
+
+see @url{http://www.iversenit.dk/dev/ffmpeg-headers/}
+
+@section Where is the documentation about ffv1, msmpeg4, asv1, 4xm?
+
+see @url{http://svn.mplayerhq.hu/michael/trunk/docs/}
+
@bye
projects / ffmpeg / blobdiff