[FFmpeg-devel] [GSoC] [RFC] Abstract AVFilterFormats to AVRefCountedList for reuse

[Mina Nagy Zaki]

On Thursday 02 June 2011 06:46:57 Michael Niedermayer wrote:
> On Wed, Jun 01, 2011 at 09:32:49AM +0300, Mina Nagy wrote:
> > ----- Original message -----
> > 
> > > On Mon, May 30, 2011 at 11:36:22PM +0200, Stefano Sabatini wrote:
> > > > On date Monday 2011-05-30 12:00:01 +0300, Mina Nagy Zaki encoded:
> > > > > AVRefCountedList will be used for lists of supported formats and
> > > > > channel   layouts. There is a problem currently with chlayouts,
> > > > > they are int64 while   formats are int32. I could not determine
> > > > > why chlayouts are 64 bit, but trying   to change them will break
> > > > > API/ABI. This means AVRefCountedList will have to   support both.
> > > > > After discussion with Stefano I think simply having a
> > > > > avfilter_refcounted_list_make32() will do. Video filters will have
> > > > > to use that   since they will store PixelFormat lists, which are
> > > > > enums and hence 32bit.
> > > > 
> > > > Or alternatively use int64_t and convert the enum pix_fmts[] arrays
> > > > to int64_t arrays.
> > > > 
> > > > 
> > > > Michael, Peter?
> > > 
> > > maybe the functions/fields could be named better but i dont have
> > > specific ideas
> > 
> > Which part needs changing? The namespace (AVFilter* instead of AV*) or
> > the 'refcounted' name itself, or perhaps 'list' ('set' is more apropos),
> > or does it just need to be shortened (av_rclist_make, etc) ?
> 
> nothing needs changing its just that somehow refcounted sounds a
> bit obscure compared to formats.
> maybe its just the best term that exists, i dunno
> this is not an objection to the patch 

It makes a little more sense when you see it in usage as a set of 
formats/layouts... but I'm actually starting to doubt the whole idea. Are 
there situations/filters that will actually benefit from layout negotiation. The 
one example I have (af_earwax) actually *doesn't* benefit, it makes more sense 
for it to simply abort when faced with the wrong channel layout.

Can someone comment on whether or not layout negotiation is going to be useful 
or have I over-engineered this?

-- 
Mina