[FFmpeg-soc] AAC Encoding - Where we stand, what's left

[Justin Ruggles]

Michael Niedermayer wrote:
> On Wed, Jul 08, 2009 at 02:55:54PM -0700, Baptiste Coudurier wrote:
>> On 07/08/2009 02:06 PM, Michael Niedermayer wrote:
>>> On Wed, Jul 08, 2009 at 01:41:52PM -0700, Baptiste Coudurier wrote:
>>>> Hi Michael,
>>>>
>>>> On 07/08/2009 12:28 PM, Michael Niedermayer wrote:
>>>>> On Wed, Jul 08, 2009 at 01:12:20AM -0400, Alex Converse wrote:
>>>>>
>>>>> [...]
>>>>>
>>>>> Also if you need (per codec) options as you said, tell me which, ill add
>>>>> them
>>>> Do you have a per codec option system ready ? :)
>>> no, i need a list of requirements/goals/use cases first
>>> once i know what the system should do that AVCodecContext fields cannot,
>>> iam sure it shouldnt be that hard ...
>> What's needed:
>>
>> is custom options for encoders/decoders/muxers/demuxers which are only 
>> needed for one element.
>>
>> The idea of using AVCodecContext/AVFormatContext doesn't please some devs 
>> it seems (including Justin, Alex, and me).
>>
>> Of course global values used by all must be put in the global context.
>>
>> I think _devs_ would like to be able to have custom options not fitting 
>> everywhere else without poluting global context. This would also permit to 
>> have x264 and lame mapped commandlines options.
>>
>> Can this request be considered ?
> 
> yes, i just need to understand what people really want and why.
> Heres a try, thats different from what we do now and also is similar to it
> 
> give each codec/(de)muxer a foobar_opts.h file that lists its custom options
> and then put
> 
> #include "foobar_opts.h" inside AVCodecContext from avcodec.h
> 
> At a binary level its exactly the same, it also makes moving between custom
> and global options very easy, and it adds more seperation to the astronomic
> AVCodecContext.

Could we move current global options that are only used by 1 codec into
custom options at the next major version bump?

I understand about adding fields to AVCodecContext with #include, but I
don't quite get how AVOption would fit in?  Would there be a custom
AVOption array added to AVCodec?  Or would they all have to go under the
global options[]?

Would there be a way for ffmpeg -h to indicate custom options in some
way or say what AVCodec they belong to?  Or would that have to be
appended to the AVOption help text?

> Does that look better to (Justin, Alex, and you) ?
> If not please all 3 of you be as elaborate as possible about what is good
> and bad on it

One minor downside could be name conflicts between codecs for custom
options that do different things.  But that would just have to be
avoided with careful and specific naming.

It also does not seem to allow for the case where a global option would
be appropriate because of shared functionality, but where different
codecs need to have different default/min/max values or help text.

-Justin