[FFmpeg-devel] [libav-devel] [RFC] lavfi: audio data packing

Alex Converse alex.converse at gmail.com
Wed Jul 6 08:37:54 CEST 2011

On Tue, Jul 5, 2011 at 7:07 AM, Mina Nagy Zaki <mnzaki at gmail.com> wrote:
> Hello lists,
> I need opinions on whether the lavfi framework should negotiate audio data
> packing between filters or should it just assume all filters will support
> handling both packed and planar data.
> In other words, should we allow filters to just declare that they only support
> handling planar data (or packed data) and have the framework automatically
> convert incoming data to that filter?
> AISI this can cause a lot of inefficiency as it may lead to loads of unnecessary
> conversions. It will probably lead to filter writers just supporting the easier
> option and letting the framework convert for them, when in most cases it is
> probably not too difficult to support both.
> Also, what does ffmpeg/libav do about this internally? In what format is audio
> data passed around?
> Comments appreciated! Thanks!

I think when looking at third party library filters we may run into
the scenario where only one format is supported and we have to
implement this conversion in the wrapper. We may wind up having to do
several of these conversions for multiple filters. We might also waste
a sample format conversion before the filter where this could have
been combined. As far as native filters go, it's pretty easy to only
commit filters that implement both unless the filter has a good reason
not to.


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