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diff --git a/ffmpeg1/doc/faq.texi b/ffmpeg1/doc/faq.texi deleted file mode 100644 index ebf21f5..0000000 --- a/ffmpeg1/doc/faq.texi +++ /dev/null @@ -1,558 +0,0 @@ -\input texinfo @c -*- texinfo -*- - -@settitle FFmpeg FAQ -@titlepage -@center @titlefont{FFmpeg FAQ} -@end titlepage - -@top - -@contents - -@chapter General Questions - -@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 I cannot read this file although this format seems to be supported by ffmpeg. - -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 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 mpeg1video -.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_s16le -always -@item libmp3lame -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... - -@section I have installed this library with my distro's package manager. Why does @command{configure} not see it? - -Distributions usually split libraries in several packages. The main package -contains the files necessary to run programs using the library. The -development package contains the files necessary to build programs using the -library. Sometimes, docs and/or data are in a separate package too. - -To build FFmpeg, you need to install the development package. It is usually -called @file{libfoo-dev} or @file{libfoo-devel}. You can remove it after the -build is finished, but be sure to keep the main package. - -@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,... -Then you may run: - -@example - ffmpeg -f image2 -i img%d.jpg /tmp/a.mpg -@end example - -Notice that @samp{%d} is replaced by the image number. - -@file{img%03d.jpg} means the sequence @file{img001.jpg}, @file{img002.jpg}, etc. - -Use the @option{-start_number} option to declare a starting number for -the sequence. This is useful if your sequence does not start with -@file{img001.jpg} but is still in a numerical order. The following -example will start with @file{img100.jpg}: - -@example - ffmpeg -f image2 -start_number 100 -i img%d.jpg /tmp/a.mpg -@end example - -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 - x=1; for i in *jpg; do counter=$(printf %03d $x); ln -s "$i" /tmp/img"$counter".jpg; x=$(($x+1)); done -@end example - -If you want to sequence them by oldest modified first, substitute -@code{$(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 - -The same logic is used for any image format that ffmpeg reads. - -You can also use @command{cat} to pipe images to ffmpeg: - -@example - cat *.jpg | ffmpeg -f image2pipe -c:v mjpeg -i - output.mpg -@end example - -@section How do I encode movie to single pictures? - -Use: - -@example - ffmpeg -i movie.mpg movie%d.jpg -@end example - -The @file{movie.mpg} used as input will be converted to -@file{movie1.jpg}, @file{movie2.jpg}, etc... - -Instead of relying on file format self-recognition, you may also use -@table @option -@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 -c:v mjpeg menu%d.jpg -@end example - -Beware that there is no "jpeg" codec. Use "mjpeg" instead. - -@section Why do I see a slight quality degradation with multithreaded MPEG* encoding? - -For multithreaded MPEG* encoding, the encoded slices must be independent, -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. - -@section How can I read from the standard input or write to the standard output? - -Use @file{-} as file name. - -@section -f jpeg doesn't work. - -Try '-f image2 test%d.jpg'. - -@section Why can I not change the frame rate? - -Some codecs, like MPEG-1/2, only allow a small number of fixed frame rates. -Choose a different codec with the -c:v command line option. - -@section How do I encode Xvid or DivX video with ffmpeg? - -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 '-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 -default. - -@section Which are good parameters for encoding high quality MPEG-4? - -'-mbd rd -flags +mv4+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 -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, 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. - -@section How can I read DirectShow files? - -If you have built FFmpeg with @code{./configure --enable-avisynth} -(only possible on MinGW/Cygwin platforms), -then you may use any file that DirectShow can read as input. - -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: -@example - ffmpeg -i input.avs -@end example - -For ANY other help on Avisynth, please visit the -@uref{http://www.avisynth.org/, Avisynth homepage}. - -@section How can I join video files? - -To "join" video files is quite ambiguous. The following list explains the -different kinds of "joining" and points out how those are addressed in -FFmpeg. To join video files may mean: - -@itemize - -@item -To put them one after the other: this is called to @emph{concatenate} them -(in short: concat) and is addressed -@ref{How can I concatenate video files, in this very faq}. - -@item -To put them together in the same file, to let the user choose between the -different versions (example: different audio languages): this is called to -@emph{multiplex} them together (in short: mux), and is done by simply -invoking ffmpeg with several @option{-i} options. - -@item -For audio, to put all channels together in a single stream (example: two -mono streams into one stereo stream): this is sometimes called to -@emph{merge} them, and can be done using the -@url{http://ffmpeg.org/ffmpeg-filters.html#amerge, @code{amerge}} filter. - -@item -For audio, to play one on top of the other: this is called to @emph{mix} -them, and can be done by first merging them into a single stream and then -using the @url{http://ffmpeg.org/ffmpeg-filters.html#pan, @code{pan}} filter to mix -the channels at will. - -@item -For video, to display both together, side by side or one on top of a part of -the other; it can be done using the -@url{http://ffmpeg.org/ffmpeg-filters.html#overlay, @code{overlay}} video filter. - -@end itemize - -@anchor{How can I concatenate video files} -@section How can I concatenate video files? - -There are several solutions, depending on the exact circumstances. - -@subsection Concatenating using the concat @emph{filter} - -FFmpeg has a @url{http://ffmpeg.org/ffmpeg-filters.html#concat, -@code{concat}} filter designed specifically for that, with examples in the -documentation. This operation is recommended if you need to re-encode. - -@subsection Concatenating using the concat @emph{demuxer} - -FFmpeg has a @url{http://www.ffmpeg.org/ffmpeg-formats.html#concat, -@code{concat}} demuxer which you can use when you want to avoid a re-encode and -your format doesn't support file level concatenation. - -@subsection Concatenating using the concat @emph{protocol} (file level) - -FFmpeg has a @url{http://ffmpeg.org/ffmpeg-protocols.html#concat, -@code{concat}} protocol designed specifically for that, with examples in the -documentation. - -A few multimedia containers (MPEG-1, MPEG-2 PS, DV) allow to concatenate -video by merely concatenating the files containing 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 -equally humble @code{copy} under Windows), and finally transcoding back to your -format of choice. - -@example -ffmpeg -i input1.avi -qscale:v 1 intermediate1.mpg -ffmpeg -i input2.avi -qscale:v 1 intermediate2.mpg -cat intermediate1.mpg intermediate2.mpg > intermediate_all.mpg -ffmpeg -i intermediate_all.mpg -qscale:v 2 output.avi -@end example - -Additionally, you can use the @code{concat} protocol instead of @code{cat} or -@code{copy} which will avoid creation of a potentially huge intermediate file. - -@example -ffmpeg -i input1.avi -qscale:v 1 intermediate1.mpg -ffmpeg -i input2.avi -qscale:v 1 intermediate2.mpg -ffmpeg -i concat:"intermediate1.mpg|intermediate2.mpg" -c copy intermediate_all.mpg -ffmpeg -i intermediate_all.mpg -qscale:v 2 output.avi -@end example - -Note that you may need to escape the character "|" which is special for many -shells. - -Another option is usage of named pipes, should your platform support it: - -@example -mkfifo intermediate1.mpg -mkfifo intermediate2.mpg -ffmpeg -i input1.avi -qscale:v 1 -y intermediate1.mpg < /dev/null & -ffmpeg -i input2.avi -qscale:v 1 -y intermediate2.mpg < /dev/null & -cat intermediate1.mpg intermediate2.mpg |\ -ffmpeg -f mpeg -i - -c:v mpeg4 -acodec libmp3lame output.avi -@end example - -@subsection Concatenating using raw audio and video - -Similarly, the yuv4mpegpipe format, and the raw video, raw audio codecs also -allow concatenation, and the transcoding step is almost lossless. -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. - -For example, let's say we want to concatenate 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 & -@{ ffmpeg -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 \ - -f yuv4mpegpipe -i all.v \ - -y output.flv -rm temp[12].[av] all.[av] -@end example - -@section -profile option fails when encoding H.264 video with AAC audio - -@command{ffmpeg} prints an error like - -@example -Undefined constant or missing '(' in 'baseline' -Unable to parse option value "baseline" -Error setting option profile to value baseline. -@end example - -Short answer: write @option{-profile:v} instead of @option{-profile}. - -Long answer: this happens because the @option{-profile} option can apply to both -video and audio. Specifically the AAC encoder also defines some profiles, none -of which are named @var{baseline}. - -The solution is to apply the @option{-profile} option to the video stream only -by using @url{http://ffmpeg.org/ffmpeg.html#Stream-specifiers-1, Stream specifiers}. -Appending @code{:v} to it will do exactly that. - -@section Using @option{-f lavfi}, audio becomes mono for no apparent reason. - -Use @option{-dumpgraph -} to find out exactly where the channel layout is -lost. - -Most likely, it is through @code{auto-inserted aconvert}. Try to understand -why the converting filter was needed at that place. - -Just before the output is a likely place, as @option{-f lavfi} currently -only support packed S16. - -Then insert the correct @code{aconvert} explicitly in the filter graph, -specifying the exact format. - -@example -aconvert=s16:stereo:packed -@end example - -@section Why does FFmpeg not see the subtitles in my VOB file? - -VOB and a few other formats do not have a global header that describes -everything present in the file. Instead, applications are supposed to scan -the file to see what it contains. Since VOB files are frequently large, only -the beginning is scanned. If the subtitles happen only later in the file, -they will not be initally detected. - -Some applications, including the @code{ffmpeg} command-line tool, can only -work with streams that were detected during the initial scan; streams that -are detected later are ignored. - -The size of the initial scan is controlled by two options: @code{probesize} -(default ~5 Mo) and @code{analyzeduration} (default 5,000,000 µs = 5 s). For -the subtitle stream to be detected, both values must be large enough. - -@section Why was the @command{ffmpeg} @option{-sameq} option removed? What to use instead? - -The @option{-sameq} option meant "same quantizer", and made sense only in a -very limited set of cases. Unfortunately, a lot of people mistook it for -"same quality" and used it in places where it did not make sense: it had -roughly the expected visible effect, but achieved it in a very inefficient -way. - -Each encoder has its own set of options to set the quality-vs-size balance, -use the options for the encoder you are using to set the quality level to a -point acceptable for your tastes. The most common options to do that are -@option{-qscale} and @option{-qmax}, but you should peruse the documentation -of the encoder you chose. - -@chapter Development - -@section Are there examples illustrating how to use the FFmpeg libraries, particularly libavcodec and libavformat? - -Yes. Check the @file{doc/examples} directory in the source -repository, also available online at: -@url{https://github.com/FFmpeg/FFmpeg/tree/master/doc/examples}. - -Examples are also installed by default, usually in -@code{$PREFIX/share/ffmpeg/examples}. - -Also you may 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.html}). - -@section Can you support my C compiler XXX? - -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 Is Microsoft Visual C++ supported? - -Yes. Please see the @uref{platform.html, Microsoft Visual C++} -section in the FFmpeg documentation. - -@section Can you add automake, libtool or autoconf support? - -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 @uref{http://www.tux.org/lkml/#s15, "Programming Religion"}. - -@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 stripped to create ffmpeg, ffplay, etc. If -you need the debug information, use 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 #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 FFmpeg from within my C application but the linker complains about missing symbols from the libraries themselves. - -FFmpeg builds static libraries by default. In static libraries, dependencies -are not handled. That has two consequences. First, you must specify the -libraries in dependency order: @code{-lavdevice} must come before -@code{-lavformat}, @code{-lavutil} must come after everything else, etc. -Second, external libraries that are used in FFmpeg have to be specified too. - -An easy way to get the full list of required libraries in dependency order -is to use @code{pkg-config}. - -@example - c99 -o program program.c $(pkg-config --cflags --libs libavformat libavcodec) -@end example - -See @file{doc/example/Makefile} and @file{doc/example/pc-uninstalled} for -more details. - -@section I'm using FFmpeg from within my C++ application but the linker complains about missing symbols which seem to be available. - -FFmpeg 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 -encompassing your FFmpeg includes using @code{extern "C"}. - -See @url{http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html#faq-32.3} - -@section I'm using libavutil from within my C++ application but the compiler complains about 'UINT64_C' was not declared in this scope - -FFmpeg is a pure C project using C99 math features, in order to enable C++ -to use them you have to append -D__STDC_CONSTANT_MACROS to your CXXFLAGS - -@section I have a file in memory / a API different from *open/*read/ libc how do I use it with libavformat? - -You have to create a custom AVIOContext using @code{avio_alloc_context}, -see @file{libavformat/aviobuf.c} in FFmpeg and @file{libmpdemux/demux_lavf.c} in MPlayer or MPlayer2 sources. - -@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://www.ffmpeg.org/~michael/} - -@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 frame rate. - -r_frame_rate is NOT the average frame rate, it is the smallest frame rate -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. - -@section Why is @code{make fate} not running all tests? - -Make sure you have the fate-suite samples and the @code{SAMPLES} Make variable -or @code{FATE_SAMPLES} environment variable or the @code{--samples} -@command{configure} option is set to the right path. - -@section Why is @code{make fate} not finding the samples? - -Do you happen to have a @code{~} character in the samples path to indicate a -home directory? The value is used in ways where the shell cannot expand it, -causing FATE to not find files. Just replace @code{~} by the full path. - -@bye |