Problems with AAC and qtdemux

Neil Jones neiljay at
Tue Mar 20 04:05:14 PDT 2012

Cheers for the replies guys,

the codec_data buffer provided in the caps looks promising ( i just
assumed this was the address of the first buffer ).

This appears to be just an address, can I just dereference this ? are
there any buffer ownership issues I need to be aware of ?



On Mon, Mar 19, 2012 at 6:22 PM, Tim-Philipp Müller <t.i.m at> wrote:
> On Mon, 2012-03-19 at 15:31 +0000, Neil Jones wrote:
>> this is a 48Khz LC-AAC with SBR (ie HE-AAC), looking a this with
>> qtdemux and fakesink gives:
>>  gst-launch -vvv filesrc location=cooper.mp4 ! qtdemux ! fakesink | more
>> ....
>> caps = audio/mpeg, mpegversion=(int)4, framed=(boolean)true,
>> stream-format=(string)raw, codec_data=(buffer)139056e5a0,
>> rate=(int)44100, channels=(int)2
>> ....
>> So as qtdemux gives us raw data (not adts or adif framed) I need to
>> setup my decoder on the info provided by qtdemux, unfortunatley it
>> gives me the wrong sample rate 44.1 instead of 48 and I need to know
>> that the profile has SBR as this effects my decoder setup.
>> How do other AAC decoders deal with this? Do they just parse the raw
>> data, I cant easily do this as my plugin is for a hardware decoder.
> You can get that information from the "codec_data" buffer in the caps,
> which is basically codec setup data. It's the same as the "esds" atom in
> a quicktime/isomp4 container.
>  Cheers
>  -Tim
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