@end titlepage
-@chapter General Problems
+@chapter General Questions
+
+@section When will the next FFmpeg version be released? / Why are FFmpeg releases so few and far between?
+
+Like most open source projects FFmpeg suffers from a certain lack of
+manpower. For this reason the developers have to prioritize the work
+they do and putting out releases is not at the top of the list, fixing
+bugs and reviewing patches takes precedence. Please don't complain or
+request more timely and/or frequent releases unless you are willing to
+help out creating them.
+
+@section I have a problem with an old version of FFmpeg; where should I report it?
+Nowhere. Upgrade to the latest release or if there is no recent release upgrade
+to Subversion HEAD. You could also try to report it. Maybe you will get lucky and
+become the first person in history to get an answer different from "upgrade
+to Subversion HEAD".
+
+@section Why doesn't FFmpeg support feature [xyz]?
+
+Because no one has taken on that task yet. FFmpeg development is
+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
+it implemented is to undertake the task yourself or sponsor a developer.
+
+@section FFmpeg does not support codec XXX. Can you include a Windows DLL loader to support it?
+
+No. Windows DLLs are not portable, bloated and often slow.
+Moreover FFmpeg strives to support all codecs natively.
+A DLL loader is not conducive to that goal.
+
+@section My bug report/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
+
+@section Is there a forum for FFmpeg? I do not like mailing lists.
+
+You may view our mailing lists with a more forum-alike look here:
+@url{http://dir.gmane.org/gmane.comp.video.ffmpeg.user},
+but, if you post, please remember that our mailing list rules still apply there.
@section I cannot read this file although this format seems to be supported by ffmpeg.
-Even if ffmpeg can read the file format, it may not support all its
+Even if ffmpeg can read the container format, it may not support all its
codecs. Please consult the supported codec list in the ffmpeg
documentation.
-@section How do I encode single pictures to movies?
+@section Which codecs are supported by Windows?
+
+Windows does not support standard formats like MPEG very well, unless you
+install some additional codecs.
+
+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
+Only if you have some MPEG-4 codec like ffdshow or Xvid installed.
+@item mpeg1
+.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
+@item pcm
+always
+@item mp3
+If some MP3 codec like LAME is installed.
+@end table
+
+
+@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.
+
+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...
+
+@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
+(@url{http://ffmpeg.org/bugreports.html}).
+
+@section How do I encode single pictures into movies?
First, rename your pictures to follow a numerical sequence.
For example, img1.jpg, img2.jpg, img3.jpg,...
Beware that there is no "jpeg" codec. Use "mjpeg" instead.
-@section FFmpeg does not support codec XXX. Can you include a Windows DLL loader to support it?
-
-No. FFmpeg only supports open source codecs. Windows DLLs are not
-portable, bloated and often slow.
-
-@section I get "Unsupported codec (id=86043) for input stream #0.1". What is the problem?
-
-This is the Qcelp codec, FFmpeg has no support for that codec currently. Try mencoder/mplayer it might work.
-
@section Why do I see a slight quality degradation with multithreaded MPEG* encoding?
For multithreaded MPEG* encoding, the encoded slices must be independent,
@section How can I read from the standard input or write to the standard output?
-Use @file{-} as filename.
+Use @file{-} as file name.
-@section Why does ffmpeg not decode audio in VOB files?
+@section Why does FFmpeg not decode audio in VOB files?
-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-liba52 --enable-gpl}. Take care: by
-enabling AC3, you automatically change the license of libavcodec from
+The audio is AC-3 (a.k.a. A/52). AC-3 decoding is an optional component in FFmpeg
+as the component that handles AC-3 decoding is currently released under the GPL.
+Enable AC-3 decoding with @code{./configure --enable-gpl}. Take care: By
+enabling AC-3, you automatically change the license of libavcodec from
LGPL to GPL.
-@section Which codecs are supported by Windows?
-
-Windows does not support standard formats like MPEG very well, unless you
-install some additional codecs
-
-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
-only if you have some MPEG-4 codec installed like ffdshow or XviD
-@item mpeg1
-.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
-@item pcm
-@item mp3
-if some MP3 codec like LAME is installed
-@end table
-
@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://svn.mplayerhq.hu/michael/trunk/patches/bttv-420-2.4.26.patch?view=co}). This may also
+(@url{http://svn.ffmpeg.org/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://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})
+will cause somewhat too strong filtering. A fix is to apply (@url{http://svn.ffmpeg.org/michael/trunk/patches/bttv-comb-2.4.26.patch?view=co})
+or (@url{http://svn.ffmpeg.org/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?
-Nowhere. Upgrade to the latest release or if there is no recent release upgrade
-to Subversion HEAD. You could also try to report it. Maybe you will get lucky and
-become the first person in history to get an answer different from "upgrade
-to Subversion HEAD".
-
@section -f jpeg doesn't work.
Try '-f image2 test%d.jpg'.
Some codecs, like MPEG-1/2, only allow a small number of fixed framerates.
Choose a different codec with the -vcodec command line option.
-@section ffmpeg does not work; What is wrong?
-
-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?
-@section How do I encode XviD or DivX video with ffmpeg?
-
-Both XviD and DivX (version 4+) are implementations of the ISO MPEG-4
+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 these formats. The
+same standard). Thus, use '-vcodec 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
@item non-working stuff
B-frames
@item example command line
-ffmpeg -i input -acodec libfaac -ab 128kb -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 libfaac -ab 128kb -vcodec mpeg4 -b 1200kb -mbd 2 -flags +4mv -trellis 2 -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 libfaac -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
+ffmpeg -i input -acodec libfaac -ab 128kb -vcodec mpeg4 -b 1200kb -ar 24000 -mbd 2 -flags +4mv -trellis 2 -aic 2 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp output.mp4
@item needed stuff for H.264
--acodec libfaac -vcodec h264 width*height<=76800 width%16=0? height%16=0? -ar 48000 -coder 1 -r 30000/1001 or 15000/1001 -f psp
+-acodec libfaac -vcodec libx264 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
title, loop filter
@item non-working stuff for H.264
CAVLC
@item example command line
-ffmpeg -i input -acodec libfaac -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
+ffmpeg -i input -acodec libfaac -ab 128kb -vcodec libx264 -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
+@item higher resolution for newer PSP firmwares, width<=480, height<=272
+-vcodec libx264 -level 21 -coder 1 -f psp
+@item example command line
+ffmpeg -i input -acodec libfaac -ab 128kb -ac 2 -ar 48000 -vcodec libx264 -level 21 -b 640kb -coder 1 -f psp -flags +loop -trellis 2 -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 -g 250 -s 480x272 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',
+'-mbd rd -flags +4mv+aic -trellis 2 -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'
+'-mbd rd -trellis 2 -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?
+@section Interlaced video looks very bad when encoded with ffmpeg, 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.
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
-
@section How can I join video files?
A few multimedia containers (MPEG-1, MPEG-2 PS, DV) allow to join video files by
rm temp[12].[av] all.[av]
@end example
-@section Is there a forum for ffmpeg, i dont like mailinglists?
+@section FFmpeg does not adhere to the -maxrate setting, some frames are bigger than maxrate/fps.
-yes, (@url{http://dir.gmane.org/gmane.comp.video.ffmpeg.user})
+Read the MPEG spec about video buffer verifier.
-@section what is thread hijacking?
+@section I want CBR, but no matter what I do frame sizes differ.
-see (@url{http://en.wikipedia.org/wiki/Thread_hijacking})
+You do not understand what CBR is, please read the MPEG spec.
+Read about video buffer verifier and constant bitrate.
+The one sentence summary is that there is a buffer and the input rate is
+constant, the output can vary as needed.
+@section How do I check if a stream is CBR?
-@chapter Development
+To quote the MPEG-2 spec:
+"There is no way to tell that a bitstream is constant bitrate without
+examining all of the vbv_delay values and making complicated computations."
-@section When will the next FFmpeg version be released? / Why are FFmpeg releases so few and far between?
-
-Like most open source projects FFmpeg suffers from a certain lack of
-manpower. For this reason the developers have to prioritize the work
-they do and putting out releases is not at the top of the list, fixing
-bugs and reviewing patches takes precedence. Please don't complain or
-request more timely and/or frequent releases unless you are willing to
-help out creating them.
-
-@section Why doesn't FFmpeg support feature [xyz]?
-
-Because no one has taken on that task yet. FFmpeg development is
-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
-it implemented is to undertake the task yourself.
+@chapter Development
@section Are there examples illustrating how to use the FFmpeg libraries, particularly libavcodec and libavformat?
Yes. Read the Developers Guide of the FFmpeg documentation. Alternatively,
examine the source code for one of the many open source projects that
-already incorporate ffmpeg at (@url{projects.php}).
+already incorporate FFmpeg at (@url{projects.html}).
@section Can you support my C compiler XXX?
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.
+@section Is Microsoft Visual C++ supported?
-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
+No. Microsoft Visual C++ is not compliant to the C99 standard and does
+not - among other things - support the inline assembly used in FFmpeg.
+If you wish to use MSVC++ for your
+project then you can link the MSVC++ 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.
+the @emph{Microsoft Visual C++ compatibility} section in the FFmpeg
+documentation.
-There have been efforts to make FFmpeg compatible with Visual C++ in the
+There have been efforts to make FFmpeg compatible with MSVC++ 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
+since MinGW does the job adequately. None of the core developers
+work with MSVC++ and thus this item is low priority. Should you find
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 FFmpeg or libavcodec under Windows?
-Yes, but the MinGW tools @emph{must} be used to compile FFmpeg. You
-can link the resulting DLLs with any other Windows program. Read the
-@emph{Native Windows Compilation} and @emph{Visual C++ compatibility}
-sections in the FFmpeg documentation to find more information.
+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
+information.
-To get help and instructions for using FFmpeg under Windows, check out
+To get help and instructions for building FFmpeg under Windows, check out
the FFmpeg Windows Help Forum at
-@url{http://arrozcru.no-ip.org/ffmpeg/}.
+@url{http://ffmpeg.arrozcru.org/}.
@section Can you add automake, libtool or autoconf support?
@section Why not rewrite ffmpeg in object-oriented C++?
-ffmpeg is already organized in a highly modular manner and does not need to
+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://www.tux.org/lkml/#s15}).
@section Why are the ffmpeg programs devoid of debugging symbols?
The build process creates ffmpeg_g, ffplay_g, etc. which contain full debug
-information. Those binaries are strip'd to create ffmpeg, ffplay, etc. If
+information. Those binaries are stripped to create ffmpeg, ffplay, etc. If
you need the debug information, used the *_g versions.
@section I do not like the LGPL, can I contribute code under the GPL instead?
Yes, as long as the code is optional and can easily and cleanly be placed
-under #ifdef CONFIG_GPL without breaking anything. So for example a new codec
-or filter would be OK under GPL while a bugfix to LGPL code would not.
+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 want to compile xyz.c alone but my compiler produced many errors.
See @url{http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html#faq-32.3}
-@section I have a file in memory / a API different from *open/*read/ libc how do i use it with libavformat?
+@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
and libmpdemux/demux_lavf.c in MPlayer sources.
The standard MSys bash (2.04) is broken. You need to install 2.05 or later.
+@section I get "./configure: line <xxx>: pr: command not found" in MSys.
+
+The standard MSys install doesn't come with pr. You need to get it from the coreutils package.
+
@section I tried to pass RTP packets into a decoder, but it doesn't work.
RTP is a container format like any other, you must first depacketize the
@section Where is the documentation about ffv1, msmpeg4, asv1, 4xm?
-see @url{http://svn.mplayerhq.hu/michael/trunk/docs/}
+see @url{http://svn.ffmpeg.org/michael/trunk/docs/}
-@section how do I feed H.263-RTP (and other codecs in RTP) to libavcodec?
+@section How do I feed H.263-RTP (and other codecs in RTP) to libavcodec?
Even if peculiar since it is network oriented, RTP is a container like any
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.
+@section AVStream.r_frame_rate is wrong, it is much larger than the framerate.
+
+r_frame_rate is NOT the average framerate, it is the smallest framerate
+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
+will be 150.
+
@bye
projects / frescor / ffmpeg.git / blobdiff