[FFmpeg-devel] [PATCH] LATM Parser & LATM/AAC Decoder

[David Conrad]

On Apr 22, 2009, at 1:34 AM, Paul Kendall wrote:

> On Wednesday 22 April 2009 05:28:40 pm Diego Biurrun wrote:
>> On Wed, Apr 22, 2009 at 04:33:47PM +1200, Paul Kendall wrote:
>>> On Tuesday 21 April 2009 01:46:43 am Robert Swain wrote:
>>>> On 20/4/09 08:11, Paul Kendall wrote:
>>>>> After a long delay and some thinking...
>>>>> The first patch is for a LATM Parser and LATM/AAC Decoder using
>>>>> libfaad2. The second patch is to add support for LATM to mpegts&
>>>>> mpeg.
>>>>>
>>>>> Please comment and I'll endeavor to to get any fixes done ASAP.
>>>>
>>>> - The bitstream parser should not be tied to any one decoder
>>>> implementation. It should at least work (non-hackishly) with both
>>>> libfaad and ffaac.
>>>
>>> Once ffaac can do HE-AAC I'd prefer to remove libfaad support
>>> permanently.
>>
>> ffaac should gain HE-AAC support somewhen this year.  Once this has
>> reasonably stabilized, libfaad support will be removed.
>>
>> But even in the meantime the LATM parser should not be tied to  
>> libfaad.
>>
> Agreed, how do I make it support both codecs? How would a user or an
> application choose which decoder the data should be sent to?

Make an AVBitStreamFilter or AVParser (bitstream filter is probably  
more appropriate) that takes LATM wrapped AAC and extracts a raw AAC  
bitstream, then add a way to get it to automatically use it in the ts  
demuxer. Then the standard mechanisms (-codec for ffmpeg) will allow  
choosing between multiple plain AAC decoders. As an added plus, this  
won't horribly break codec copy.

> This also means that the LATM support needs to be built into the  
> ffmpeg
> AAC decoder.

Why would any AAC decoder need to know anything about LATM?