From 0395d37abb304ba9eb5b3aa9aec48a63724b3229 Mon Sep 17 00:00:00 2001 From: Luca Barbato Date: Sat, 10 Dec 2011 01:52:05 +0100 Subject: doc: remove some stale entries from the faq Some entries should be still amended. --- doc/faq.texi | 135 ----------------------------------------------------------- 1 file changed, 135 deletions(-) (limited to 'doc/faq.texi') diff --git a/doc/faq.texi b/doc/faq.texi index affe88b813..91a380e573 100644 --- a/doc/faq.texi +++ b/doc/faq.texi @@ -11,22 +11,6 @@ @chapter General Questions -@section When will the next Libav version be released? / Why are Libav releases so few and far between? - -Like most open source projects Libav 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 Libav; where should I report it? -Nowhere. We do not support old Libav versions in any way, we simply lack -the time, motivation and manpower to do so. If you have a problem with an -old version of Libav, upgrade to the latest git snapshot. If you -still experience the problem, then you can report it according to our -@uref{http://libav.org/bugreports.html, bug reporting guidelines}. - @section Why doesn't Libav support feature [xyz]? Because no one has taken on that task yet. Libav development is @@ -40,31 +24,6 @@ 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 My bug report/mail to libav-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 did not follow our - @uref{http://libav.org/bugreports.html, bug reporting guidelines}. -@item You didn't use git master. -@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 Libav. -@end itemize - -@section Is there a forum for Libav? 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 container format, it may not support all its @@ -218,44 +177,6 @@ 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 How do I encode videos which play on the iPod? - -@table @option -@item needed stuff --acodec libfaac -vcodec mpeg4 width<=320 height<=240 -@item working stuff -mv4, title -@item non-working stuff -B-frames -@item example command line -ffmpeg -i input -acodec libfaac -ab 128k -vcodec mpeg4 -b 1200k -mbd 2 -flags +mv4+aic -trellis 2 -cmp 2 -subcmp 2 -s 320x180 -metadata title=X output.mp4 -@end table - -@section How do I encode videos which play on the PSP? - -@table @option -@item needed stuff --acodec libfaac -vcodec mpeg4 width*height<=76800 width%16=0 height%16=0 -ar 24000 -r 30000/1001 or 15000/1001 -f psp -@item working stuff -mv4, title -@item non-working stuff -B-frames -@item example command line -ffmpeg -i input -acodec libfaac -ab 128k -vcodec mpeg4 -b 1200k -ar 24000 -mbd 2 -flags +mv4+aic -trellis 2 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -metadata title=X -f psp output.mp4 -@item needed stuff for H.264 --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 128k -vcodec libx264 -b 1200k -ar 48000 -mbd 2 -coder 1 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -metadata 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 128k -ac 2 -ar 48000 -vcodec libx264 -level 21 -b 640k -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 +mv4+aic -trellis 2 -cmp 2 -subcmp 2 -g 300 -pass 1/2', @@ -351,24 +272,6 @@ ffmpeg -f u16le -acodec pcm_s16le -ac 2 -ar 44100 -i all.a \ rm temp[12].[av] all.[av] @end example -@section The ffmpeg program does not respect the -maxrate setting, some frames are bigger than maxrate/fps. - -Read the MPEG spec about video buffer verifier. - -@section I want CBR, but no matter what I do frame sizes differ. - -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? - -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." - - @chapter Development @section Are there examples illustrating how to use the Libav libraries, particularly libavcodec and libavformat? @@ -424,14 +327,6 @@ 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 want to compile xyz.c alone but my compiler produced many errors. - -Common code is in its own files in libav* and is used by the individual -codecs. They will not work without the common parts, you have to compile -the whole libav*. If you wish, disable some parts with configure switches. -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 I'm using libavcodec 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 @@ -450,34 +345,4 @@ to use them you have to append -D__STDC_CONSTANT_MACROS to your CXXFLAGS You have to implement a URLProtocol, see @file{libavformat/file.c} in Libav and @file{libmpdemux/demux_lavf.c} in MPlayer sources. -@section I get "No compatible shell script interpreter found." in MSys. - -The standard MSys bash (2.04) is broken. You need to install 2.05 or later. - -@section I get "./configure: line : 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 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 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 -- cgit v1.2.3