Demux AAC from CAF

[Thiago Santos]

On 11/09/2014 12:53 PM, Dr. Peter G. Baum wrote:
> Hi,
>
> I'm developing a Core Audio Format (CAF) Demuxer (see 
> https://bugzilla.gnome.org/show_bug.cgi?id=738538).
> Since uncompressed PCM works for me, I'm looking at embedded AAC.
>
> In CAF I have an "ESDS Atom" and "MPEG-4 AAC data".
> Just concatenating both and feeding it to the faad plug-in gives an 
> error: "_gst_audio_decoder_error:<faad0> error: decoding error: 
> Bitstream value not allowed by specification".
> So, does anyone has an idea on what's the correct way to transfer the 
> necessary information to faad?
> Some kind of encapsulation/wrapping?

You usually get those to faad by putting it as a GstBuffer codec_data 
field in the caps.

You can take a look at qtdemux's source code to see how it adds the 
codec_data to caps from ESDS atom.
http://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/gst/isomp4/qtdemux.c 
in handle_esds function

Regards,

>
> Many thanks for your help,
>
> Peter
>
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-- 
Thiago Sousa Santos
Senior Multimedia Engineer, Open Source Group
Samsung Research America - Silicon Valley