[FFmpeg-user] AC3 encoding problem - wrong audio tag?

[Carl Eugen Hoyos]

Stefan Gofferje <ffmpeg-user <at> home.gofferje.net> writes:

> RIFF (little-endian) data, AVI, 624 x 352, 23.98 fps, video: XviD,
> audio: (6 channels, 48000 Hz)
          ^

> If I check older files that work on the Showcenter, the output of file is:
> 
> RIFF (little-endian) data, AVI, 624 x 352, 23.98 fps, video: XviD,
> audio: Dolby AC3 (stereo, 48000 Hz)
                    ^^^^^^

FFmpeg developers believe that the Microsoft specification 
requires an avi muxer to use different headers (WAVEFORMATEX) 
depending on the number of channels (stereo vs 6 channels).
Many playback applications are unable to read the header that is - 
as we believe - required for surround sound.

(Note that stereo files should work fine.)

There are many reports about this, so far nobody could provide 
any indication that FFmpeg developers are wrong in their 
interpretation of the standard.
(The best test would be with a Xbox - if it turns out that the 
Xbox does not read the waveformatextensible header, the code 
will probably be changed, see ticket #253.)

Carl Eugen