[FFmpeg-devel] [PATCH] AAC: Simple ADTS support

Robert Swain robert.swain
Wed Jan 7 23:03:20 CET 2009

Hello Robert,

2009/1/7 Robert Swain <robert.swain at gmail.com>:
> 2009/1/6 Alex Converse <alex.converse at gmail.com>:
>> This patch adds support for simple (One RDB per ADTS frame, no
>> implicit channel config) AAC ADTS files. It is based on the AC3 parser
>> and a patch by Rob. The first patch moves the error definitions from
>> ac3 to the shared code. The second adds support for ADTS to the AAC
>> decoder including necessary parser refactoring. With these patches
>> applies the al09 family of ADTS reference streams should decode
>> properly.
> I've applied the first patch but while testing the second patch I
> noticed some strange things.
> Using the FAAD CLI or ffaac through ffplay to decode al09_48.adts, the
> result sounds fine. If I configure FFmpeg with --enable-libfaad
> --disable-decoder=aac and try decoding the file, it seems to play at
> half speed.

This issue occurs without the patch as well so it's a separate issue.

> Also, the FAAD CLI thinks the file is stereo whereas FFmpeg with your
> patch thinks it is mono.

FAAD apparently considers many streams that aren't stereo as stereo
for the sake of parametric stereo. (
http://www.hydrogenaudio.org/forums/index.php?showtopic=33719 )

As such, I have no further issues with this patch and it will be
applied shortly. Thanks, Alex, for your effort cleaning up the idea
and making it better.


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