avi+aac - AudioSpecificConfig missing

[Kees]

When muxing an avi (video only) and lc aac with ffmpeg:

1) cbSize is set to zero in the WAVEFORMATEX structure.
2) AudioSpecificConfig is missing.

avi: ​http://www.datafilehost.com/d/abf5b1ae
aac: ​http://www.datafilehost.com/d/6ca94fe8

ffmpeg -i h264.avi -i SurroundTest20.aac -c copy SurroundTest20.avi

Since wFormatTag = WAVE_FORMAT_RAW_AAC1, cbSize should be two (and five for SBR?) and AudioSpecificConfig should be filled (with cbSize its size):

​http://msdn.microsoft.com/en-us/library/windows/desktop/dd317599%28v=vs.85%29.aspx

Here is the resulting file:
​http://www.datafilehost.com/d/a7f35def

At the address 0x1168 the WAVEFORMATEX structure starts. I expect something like

FF 0002 0044 AC00 0094 3E00 0000 0610 0002 0012 10 ...

instead of

FF 0002 0044 AC00 0094 3E00 0000 0610 0000 004A 55 ...

version info:
Zeranoe's FFmpeg Builds Home Page: <​http://ffmpeg.zeranoe.com/builds/>
This build was compiled on: Aug 16 2013, at: 20:10:34.

Regards, Wilbert

[Carl Eugen Hoyos]

Did you test if setting the correct values fixes playback with any application?
The output file you uploaded plays fine here with ffplay, MPlayer and vlc.

[Kees]

Fcchandler's AAC ACM codec does some validation on the stream format structure contents. So I can't open the file in Virtualdub and AviSynth with that codec:

​http://forum.doom9.org/showthread.php?p=1639389#post1639389

Accordingly to some other participant in that thread it doesn't play in GOM Media Player either (but i didn't know GOM, so i can't comment on that).

[Carl Eugen Hoyos]

Replying to Wilbert:

Fcchandler's AAC ACM codec does some validation on the stream format structure contents. So I can't open the file in Virtualdub and AviSynth with that codec

Were you able to test if setting cbSize and/or adding AudioSpecificConfig fixes decoding?

[Kees]

I don't know how to do that properly. If i just replace 00 004A 55 with 02 0012 10, Virtualdub is able to open the file, play it and i hear the sound. But beforehand i get a warning 'AVI: Truncated or invalid compressed audio format detected (18 bytes, should be 20). Attempting to fix.'.

If i use AVIMux to mux the files (which does write AudioSpecificConfig and sets cbSize=2), it plays fine in Virtualdub.