cf196d91105f1ba50c5b03682cfbf237dde7291f
[libav.git] / doc / faq.texi
1 \input texinfo @c -*- texinfo -*-
2
3 @settitle FFmpeg FAQ
4 @titlepage
5 @sp 7
6 @center @titlefont{FFmpeg FAQ}
7 @sp 3
8 @end titlepage
9
10
11 @chapter General Problems
12
13 @section ffserver doesn't not work.
14
15 ffmpeg development is now concentrated on the codec and format
16 handling. New developments broke ffserver, so don't expect it to work
17 correctly. It is planned to fix it ASAP.
18
19 @section I cannot read this file although this format seems to be suppored by ffmpeg.
20
21 Even if ffmpeg can read the file format, it may not support all its
22 codecs. Please consult the supported codec list in the ffmpeg
23 documentation.
24
25 @section I get audio/video synchro problems when grabbing.
26
27 Currently, the grabbing stuff does not handle synchronisation
28 correctly. You are free to correct it. It is planned to fix it ASAP.
29
30 @section How do I encode jpegs to another format ?
31
32 If the jpegs are named img1.jpg, img2.jpg, img3.jpg,..., use:
33
34 @example
35 ffmpeg -i img%d.jpg /tmp/a.mpg
36 @end example
37
38 @samp{%d} is replaced by the image number.
39
40 @file{img%03d.jpg} generates @file{img001.jpg}, @file{img002.jpg}, etc...
41
42 The same system is used for the other image formats.
43
44 @section FFmpeg does not support codec XXX. Can you include a Windows DLL loader to support it ?
45
46 No. FFmpeg only supports open source codecs. Windows DLLs are not
47 portable, bloated and often slow.
48
49 @section How can I read from the standard input or write to the standard output ?
50
51 Use @file{-} as filename.
52
53 @section Why Audio is not decoded in VOB files ?
54
55 AC3 decoding is optional as the codec is currently released under the
56 GPL. Enable it with @code{./configure --enable-a52}. Take care: by
57 enabling AC3, you automatically change the license of libavcodec from
58 LGPL to GPL.
59
60 @section Which codecs are supported by windows ?
61
62 Windows does not support standard formats like mpeg very well, unless you
63 install some additional codecs
64
65 The following list of video codecs should work on most windows systems
66 @table @option
67 @item msmpeg4v2
68 .avi/.asf
69 @item msmpeg4
70 .asf only
71 @item wmv1
72 .asf only
73 @item wmv2
74 .asf only
75 @item mpeg4
76 only if you have some mpeg4 codec installed like ffdshow or xvid
77 @item mpeg1
78 .mpg only
79 @end table
80 note, asf often uses .wmv or .wma extensions in windows, it should also be
81 mentioned that asf is patented, so microsoft may sue or threaten users who
82 use it if they see any reason to do so, it is strongly recommanded to avoid asf
83 for any use
84
85 The following list of audio codecs should work on most windows systems
86 @table @option
87 @item adpcm_ima_wav
88 @item adpcm_ms
89 @item pcm
90 @item mp3
91 if some mp3 codec like lame is installed
92 @end table
93
94 @section The chrominance seems to come from a different time then the luminance on bt8x8 captures on linux?
95
96 well known bug in the bt8x8 driver, for 2.4.26 theres a patch at
97 (@url{http://www.mplayerhq.hu/~michael/bttv-420-2.4.26.patch}), i suspect that
98 this will also apply cleanly to other 2.4 kernels
99
100 @section How to avoid the ugly aliassing artefacts in bt8x8 captures on linux?
101
102 pass 'combfilter=1 lumafilter=1' to the bttv driver, note though that 'combfilter=1'
103 will cause somewhat too strong filtering, a fix is too apply (@url{http://www.mplayerhq.hu/~michael/bttv-comb-2.4.26.patch})
104 or (@url{http://www.mplayerhq.hu/~michael/bttv-comb-2.6.6.patch})
105 and pass 'combfilter=2'
106
107 @section I have a problem with an old version of ffmpeg, where should i report it?
108 Nowhere, upgrade to the latest release or if there is no recent release upgrade
109 to cvs, you could also try to report it, maybe you are lucky and
110 will become the first person in history to get a different awnser from "upgrade
111 to cvs".
112
113 @section -f jpeg doesnt work.
114
115 try '-f image -img jpeg test%d.jpg'
116
117 @chapter Development
118
119 @section Are there examples of use of the FFmpeg libraries libavcodec and libavformat ?
120
121 Yes. Read the Developers Guide of the FFmpeg documentation.
122
123 @section Can you support my C compiler XXX ?
124
125 No. Only GCC is supported. GCC is ported on most systems available and I
126 don't see the need to pollute the source code with @code{#ifdef}s
127 related to the compiler.
128
129 @section Can I use FFmpeg or libavcodec under Windows ?
130
131 Yes, but the MinGW tools @emph{must} be used to compile FFmpeg. You
132 can link the resulting DLLs with any other Windows program. Read the
133 @emph{Native Windows Compilation} section in the FFmpeg documentation
134 to have more information.
135
136 @section Can you add automake, libtool or autoconf support ?
137
138 No. These tools are too blowted and they complicate the build. Moreover,
139 since only @samp{gcc} is supported they would add little advantages in
140 terms of portability.
141
142 @section ffmpeg doesnt contain any debugging symbols ?
143
144 try ffmpeg_g, ffplay_g, ...
145
146 @bye