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# 1. General Problems

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## 1.1 ffserver doesn't 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. It is planned to fix it ASAP.

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## 1.2 I cannot read this file although this format seems to be suppored 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.

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## 1.3 I get audio/video synchro 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.

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## 1.4 How do I encode jpegs to another format ?

If the jpegs are named img1.jpg, img2.jpg, img3.jpg,..., use:

      ffmpeg -i img%d.jpg /tmp/a.mpg

``%d'` is replaced by the image number.

``img%03d.jpg'` generates ``img001.jpg'`, ``img002.jpg'`, etc...

The same system is used for the other image formats.

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## 1.5 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.

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## 1.6 How can I read from the standard input or write to the standard output ?

Use ``-'` as filename.

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## 1.7 Why Audio is not decoded in VOB files ?

AC3 decoding is optional as the codec is currently released under the GPL. Enable it with `./configure --enable-a52`. Take care: by enabling AC3, you automatically change the license of libavcodec from LGPL to GPL.

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## 1.8 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

``msmpeg4v2'`

  .avi/.asf

``msmpeg4'`

  .asf only

``wmv1'`

  .asf only

``wmv2'`

  .asf only

``mpeg4'`

  only if you have some mpeg4 codec installed like ffdshow or xvid

``mpeg1'`

  .mpg only

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

The following list of audio codecs should work on most windows systems

``adpcm_ima_wav'`
``adpcm_ms'`
``pcm'`
``mp3'`

  if some mp3 codec like lame is installed

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## 1.9 The chrominance seems to come from a different time then the luminance on bt8x8 captures on linux?

well known bug in the bt8x8 driver, for 2.4.26 theres a patch at (http://www.mplayerhq.hu/~michael/bttv-420-2.4.26.patch), i suspect that this will also apply cleanly to other 2.4 kernels

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## 1.10 How to avoid the ugly aliassing artefacts 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 (http://www.mplayerhq.hu/~michael/bttv-comb-2.4.26.patch) or (http://www.mplayerhq.hu/~michael/bttv-comb-2.6.6.patch) and pass 'combfilter=2'

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## 1.11 -f jpeg doesnt work.

try '-f image -img jpeg test%d.jpg'

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# 2. Development

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## 2.1 Are there examples of use of the FFmpeg libraries libavcodec and libavformat ?

Yes. Read the Developers Guide of the FFmpeg documentation.

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## 2.2 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 `#ifdef`s related to the compiler.

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## 2.3 Can I use FFmpeg or libavcodec under Windows ?

Yes, but the MinGW tools must be used to compile FFmpeg. You can link the resulting DLLs with any other Windows program. Read the Native Windows Compilation section in the FFmpeg documentation to have more information.

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## 2.4 Can you add automake, libtool or autoconf support ?

No. These tools are too blowted and they complicate the build. Moreover, since only ``gcc'` is supported they would add little advantages in terms of portability.

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# About This Document

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