[FFmpeg-devel] SOC Qualifiction tasks

Michael Niedermayer michaelni
Fri Mar 14 22:29:30 CET 2008

On Fri, Mar 14, 2008 at 03:20:29PM -0400, Alexander Strange wrote:
> On Mar 14, 2008, at 2:54 PM, Uoti Urpala wrote:
> > On Fri, 2008-03-14 at 18:56 +0100, Andreas ?man wrote:
> >> * Asynchronous decoding (I.e. decoding frames even when the caller
> >>   is not currently in 'avcodec_decode_video()').
> >>   Of course this must be fully hidden from the caller POV.
> >
> > You can't hide it from the caller. Normally the caller gives the frame
> > data and expects full results before the call returns. With that API
> > there is nothing to decode when the caller is not currently in
> > avcodec_decode_video(). For asynchronous decoding you need a different
> > API that allows the caller to queue frames in advance.
> We can fit it in the current API by adding more decoder delay - it'll  
> be sort of asynchronous (the first frame can start decoding when you  
> submit it), but if you run into the maximum threads it'll have to  
> block until the first decoding thread finishes.
> I'm not sure what it would do to players that need one-frame-in-one- 
> out; is that important?

It must work with ffplay and it should be reasonable easy to be used in
other players.

Also there are 2 ways to get decoded frames with timestamps
1. by feeding frames with pts into the decoder and have the decoder output
   frames with properly reordered pts
2. by taking the dts of the just input frame as the pts of the just output

1 should just work fine with threading, but 2. does not look like it will
"just work".
The problem here is that some containers (AVI for examples) have no pts
(just dts).

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I count him braver who overcomes his desires than him who conquers his
enemies for the hardest victory is over self. -- Aristotle
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