# FFmpeg FAQ

# Table of Contents

- 1. General Problems
  - 1.1 ffserver doesn't not work.
  - 1.2 I cannot read this file although this format seems to be suppored by ffmpeg.
  - 1.3 I get audio/video synchro problems when grabbing.
  - 1.4 How do I encode jpegs to another format ?
  - 1.5 FFmpeg does not support codec XXX. Can you include a Windows DLL loader to support it ?
  - 1.6 How can I read from the standard input or write to the standard output ?
  - 1.7 Why Audio is not decoded in VOB files ?
- 2. Development
  - 2.1 Are there examples of use of the FFmpeg libraries libavcodec and libavformat ?
  - 2.2 Can you support my C compiler XXX ?
  - 2.3 Can I use FFmpeg or libavcodec under Windows ?
  - 2.4 Can you add automake, libtool or autoconf support ?

FFmpeg FAQ

# 1. General Problems

## 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.

## 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.

## 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.

## 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.

## 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.

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

Use ``-'` as filename.

## 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.

# 2. Development

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

Yes. Read the Developers Guide of the FFmpeg documentation.

## 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.

## 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.

## 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.

This document was generated on 16 September 2003 using texi2html 1.56k.