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

Robert Swain robert.swain
Wed Jan 7 20:40:19 CET 2009

Hello Alex,

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.

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

So, I think there may be something wrong with the parsing. I edited
some of the code for the second patch though the changes are purely
cosmetic. Please see attached and work from that for your alterations.
I'll probably talk to you shortly when you're online. :)

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