mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-22 15:23:11 +00:00
FAQ update; entry on C++
Originally committed as revision 3542 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
parent
669484b49e
commit
cacf7199a1
91
doc/faq.texi
91
doc/faq.texi
@ -10,22 +10,22 @@
|
||||
|
||||
@chapter General Problems
|
||||
|
||||
@section ffserver doesn't not work.
|
||||
@section ffserver does not work.
|
||||
|
||||
ffmpeg development is now concentrated on the codec and format
|
||||
handling. New developments broke ffserver, so don't expect it to work
|
||||
correctly. If you have time and experience, please help us fix it.
|
||||
|
||||
@section I cannot read this file although this format seems to be suppored by ffmpeg.
|
||||
@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
|
||||
codecs. Please consult the supported codec list in the ffmpeg
|
||||
documentation.
|
||||
|
||||
@section I get audio/video synchro problems when grabbing.
|
||||
@section I get audio/video synchronization problems when grabbing.
|
||||
|
||||
Currently, the grabbing stuff does not handle synchronisation
|
||||
correctly. You are free to correct it. It is planned to fix it ASAP.
|
||||
correctly. You are free to correct it. A fix is planned.
|
||||
|
||||
@section How do I encode jpegs to another format ?
|
||||
|
||||
@ -49,17 +49,19 @@ portable, bloated and often slow.
|
||||
@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 its
|
||||
quite logic that there is a small reduction of quality, this is not a bug
|
||||
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 filename.
|
||||
|
||||
@section Why Audio is not decoded in VOB files ?
|
||||
@section Why does ffmpeg not decode audio in VOB files ?
|
||||
|
||||
AC3 decoding is optional as the codec is currently released under the
|
||||
GPL. Enable it with @code{./configure --enable-a52}. Take care: by
|
||||
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
|
||||
enabling AC3, you automatically change the license of libavcodec from
|
||||
LGPL to GPL.
|
||||
|
||||
@ -83,10 +85,10 @@ only if you have some mpeg4 codec installed like ffdshow or xvid
|
||||
@item mpeg1
|
||||
.mpg only
|
||||
@end table
|
||||
note, asf often uses .wmv or .wma extensions in windows, it should also be
|
||||
mentioned that asf is patented, so microsoft may sue or threaten users who
|
||||
use it if they see any reason to do so, it is strongly recommanded to avoid asf
|
||||
for any use
|
||||
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
|
||||
@ -97,49 +99,51 @@ The following list of audio codecs should work on most windows systems
|
||||
if some mp3 codec like lame is installed
|
||||
@end table
|
||||
|
||||
@section The chrominance seems to come from a different time then the luminance on bt8x8 captures on linux?
|
||||
@section Why does the chrominance data seem to be sampled at a different time than the luminance data on bt8x8 captures on Linux?
|
||||
|
||||
well known bug in the bt8x8 driver, for 2.4.26 theres a patch at
|
||||
(@url{http://www.mplayerhq.hu/~michael/bttv-420-2.4.26.patch}), i suspect that
|
||||
this will also apply cleanly to other 2.4 kernels
|
||||
This is a well-known bug in the bt8x8 driver. For 2.4.26 there is a patch at
|
||||
(@url{http://www.mplayerhq.hu/~michael/bttv-420-2.4.26.patch}). This may also
|
||||
apply cleanly to other 2.4-series kernels.
|
||||
|
||||
@section How to avoid the ugly aliassing artefacts in bt8x8 captures on linux?
|
||||
@section How do I avoid the ugly aliassing 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 too apply (@url{http://www.mplayerhq.hu/~michael/bttv-comb-2.4.26.patch})
|
||||
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://www.mplayerhq.hu/~michael/bttv-comb-2.4.26.patch})
|
||||
or (@url{http://www.mplayerhq.hu/~michael/bttv-comb-2.6.6.patch})
|
||||
and pass 'combfilter=2'
|
||||
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 cvs, you could also try to report it, maybe you are lucky and
|
||||
will become the first person in history to get a different awnser from "upgrade
|
||||
@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 cvs. You could also try to report it. Maybe you will get lucky and
|
||||
become the first person in history to get a different answer from "upgrade
|
||||
to cvs".
|
||||
|
||||
@section -f jpeg doesnt work.
|
||||
|
||||
try '-f image -img jpeg test%d.jpg'
|
||||
|
||||
@section i cant change the framerate
|
||||
@section Why can I not change the framerate?
|
||||
|
||||
some codecs, like mpeg1/2 only allow a small number of fixed framerates,
|
||||
choose a different codec with -vcodec
|
||||
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 it doesnt work
|
||||
@section ffmpeg does not work; What is wrong?
|
||||
|
||||
try a 'make distclean' if this doesnt help see
|
||||
(@url{ffmpeg-bugreport.html})
|
||||
Try a 'make distclean' in the ffmpeg source directory. If this does not help see
|
||||
(@url{ffmpeg-bugreport.html}).
|
||||
|
||||
@chapter Development
|
||||
|
||||
@section Are there examples of use of the FFmpeg libraries libavcodec and libavformat ?
|
||||
@section Are there examples illustrating how to use the FFmpeg libraries, particularly libavcodec and libavformat ?
|
||||
|
||||
Yes. Read the Developers Guide of the FFmpeg documentation.
|
||||
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}).
|
||||
|
||||
@section Can you support my C compiler XXX ?
|
||||
|
||||
No. Only GCC is supported. GCC is ported on most systems available and I
|
||||
don't see the need to pollute the source code with @code{#ifdef}s
|
||||
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.
|
||||
|
||||
@section Can I use FFmpeg or libavcodec under Windows ?
|
||||
@ -147,16 +151,25 @@ related to the compiler.
|
||||
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} section in the FFmpeg documentation
|
||||
to have more information.
|
||||
to find more information.
|
||||
|
||||
@section Can you add automake, libtool or autoconf support ?
|
||||
|
||||
No. These tools are too blowted and they complicate the build. Moreover,
|
||||
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.
|
||||
|
||||
@section ffmpeg doesnt contain any debugging symbols ?
|
||||
@section Why not rewrite ffmpeg in object-oriented C++ ?
|
||||
|
||||
try ffmpeg_g, ffplay_g, ...
|
||||
ffmpeg is already organized in a highly modular manner 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}).
|
||||
|
||||
@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
|
||||
you need the debug information, used the *_g versions.
|
||||
|
||||
@bye
|
||||
|
Loading…
Reference in New Issue
Block a user