[FFmpeg-devel] hwaccel infrastructure in libavcodec

Carl Eugen Hoyos cehoyos
Wed Mar 16 16:06:43 CET 2011

Gregor Riepl <onitake <at> gmail.com> writes:

> > I was under the impression that the "right" API for OSX would be
> > VideoToolBox:
> > http://www.tuaw.com/2011/01/20/xbmc-for-ios-and-atv2-now-available/
> > (It supports more hardware and more features, iiuc.)
> I haven't looked at that so far. But if the comments further down (about
> being a private framework) are true, I don't think it wise to use it.
> Apple can change or deprecate it at any point of time. I know the hell
> of kernel extensions that tap into private part parts of the Mach
> kernel, and the situation with frameworks is only slightly better.

I'll make a note that you are convinced VDA will neither be deprecated nor
changed ;-)
(Don't misunderstand me: It would be great if MPlayer/FFmpeg would support VDA,
I am just surprised that everybody seems to believe the arguments that made XBMC
not support VDA are invalid / weak.)

> > (I can only speak for VDPAU)
> > I am not sure if this is what the users of the players would find helpful.
> > Decoding alone is nice, but - imo - not what makes VDPAU so (very) useful:
> > The De-interlacer is the important part, especially since it is not easy to
> > find a system where decoding with VDPAU is faster than with the CPU.
> > (Disclaimer: I - still - did not test this but I would be surprised if that
> > were wrong.)
> Well, for one, I don't think there is any reason why VDPAU deinterlacing
> should not be offered by ffmpeg.

I do not think this would work (the way you seem to expect it works):

> Suggestion: Add a module to libavfilter that accepts only the
> PIX_FMT_VDPAU_* picture formats as input and outputs the same. Behind
> the scenes, it sets up deinterlacing or whatever filters VDPAU offers
> instead of doing the filtering in software.
> As for VDPAU being better than CPU decoding, there's NVIDIA Ion, which
> is usually paired with a very slow CPU. For example, my Media Player Box
> has a Atom D510 and a Ion2. Playing 1080p material on this CPU would be
> outright impossible. The Ion can handle it nicely, even if it is 60fps,
> has lots of motion and insane bitrates.

(Apart from the fact that I still do not believe that it supports 60fps, but
this doesn't matter atm)
Of course, "playing" 1080 at 30 works fine with Ion, but did you test *decoding*?
(I didn't, so it may well work fine.)

Carl Eugen

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