[FFmpeg-devel] GSoC 2008 qualification task

[Tomasz Żernicki]

Dnia 30 marca 2008 15:42 Kostya <kostya.shishkov at gmail.com> napisa?(a):

> On Sun, Mar 30, 2008 at 01:01:53PM +0200, Tomasz ?ernicki wrote:
> > Dear All,
> > Currently I?m trying to figure out how does the transforms in Nellymoser Asao codec work. 
> > Due to forthcoming deadline of GSoC 2008, I would like to know what are your expectations
> > connected with "AAC-LC Encoder" task? 
> 
> My expectations are that I will do it :)
> 
> And more seriously, here is the list of requirements I think everybody will agree with.
> 
> General requirements:
>  * encoder should be able to write data that AAC decoders can understand and play
>  * sound should be recognizable and preferably not very distorted
>  * encoder should perform fast (comparing with libfaac and other encoders)
> 
> Code requirements:
>  * encoder should be clean and extensible (maybe somebody will want to add SBR or
>    other HE-AAC features)
>  * encoder parameters should be easy to manipulate
> 
> > What does exactly mean "flexible framework for a serious psychoacoustic implementation"?
> 
> Encoder should have some kind of interface to psychoacoustic models
> implementations, so it can be used in this way (as I see it):
> 
> * some option(s) replated to psy model choosing and finetuning
> * encoder init function calls ff_psy_init() and tells what psy model it wants,
>   what kind of data to expect (bands, block size?) etc...
> * encoding calls something like ff_psy_twiddle() to manipulate frequencies in
>   desired way, then encodes modified data.
> 
> So it is not hardcorded into encoder ("let's throw away all high frequencies")
> but can be tuned independently and reused in other encoders.
> 

So, if I understand, the task is to implement full AAC-LC encoder, am I right? 
What about using code from faac encoder which is under LGPL license? 
Is it possible to use a part of the faac code in a new implementation of AAC encoder?

Greetings
Tomasz ?ernicki