[vlc-devel] [PATCH] prefetch: reading while paused is valable

Alexandre Janniaux ajanni at videolabs.io
Mon Nov 18 22:27:26 CET 2019


On Mon, Nov 18, 2019 at 10:07:22PM +0200, Rémi Denis-Courmont wrote:
> Le maanantaina 18. marraskuuta 2019, 19.13.03 EET Alexandre Janniaux a écrit :
> > Hi,
> >
> > On Mon, Nov 18, 2019 at 05:56:43PM +0200, Rémi Denis-Courmont wrote:
> > > I don't see how the error message is wrong. It is not permissible to read
> > > from a paused stream, by definition. This patch looks wrong to me.
> > The concept of a playback pipeline being paused is fairly simple
> > considering the user point of view, but from the internal point of
> > view I would have expected that pause is just relative to audio/video
> > playback itself, not everything before which would be paced by the
> > pool of available resources.
> The concept of pause is easy. Data does not flow during pause. There are no
> other reasons why pause was exposed to stream filters and accesses in the first
> place.

Sure, I hear that, it is not really a hint about why though.

I should have phrase my sentence like the following:

If we want data to not flow during pause, it can be achieved
by two effects:
+ we don't process data anymore, the whole pipeline is
+ we don't switch the last frame / don't display audio, the
pipeline process is stalled because paced.

What Thomas is doing is the second one in this patch. I
tested it and it allows seeking while pausing and brings a
better UX.

The two questions then:
+ if we keep doing the first, how pause should be handled to
allow frame by frame ?
+ if we're going for the second, what are the setbacks?

Do you have any hints with regards to these ?

Alexandre Janniaux

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