[MPlayer-dev-eng] Fixes/enhancements to vdpau

[Uoti Urpala]

On Mon, 2009-04-06 at 13:22 +0200, Dan Oscarsson wrote:
> My patches include:

Are these patches visible somewhere? Some comments below based on what
your descriptions tell.

>   - an option to vdpau: max-delay
>     which if set to 0 results in 2 output surfaces and working
>     like current code.
>     if set will drop frames if a frame would be delayed longer
>     then given value.

Drop which frame? Dropping the latest frame before seeing the following
ones is always undesirable as you can't know when or if those next ones
appear - playback may pause and then you'd be stuck showing the wrong
frame.

>                       the number of output surfaces will be adjusted to
>     match.

Adjusted how? How can you map times to numbers of surfaces? Are you
making assumptions about the video having a consistent FPS?

>   - a global option: match-vsync-speed
>     that will change speed of movie to vsync speed (if nearly the same).
>     this allows movies to be shown with less frame dropping.

Change based on what? Are you making assumptions about the video having
an FPS value? Or using some kind of more local logic (what?). And how do
you change the speed?

>   - a global option: card-time-correction
>     that gives correction that is needed to correct that graphics card
>     have a time that have a different speed then system time.

Do you really need this? Can such differences not be corrected for
automatically at runtime?

>   - an option to vdpau: time-corr
>     which measures card time and prints correction value at end of
>     movie. To be used with option: card-time-correction

What does this measure against? If there is no sound then the system
clock is what matters; but in the usual case where there is sound the
system clock has little significance and the important reference is the
audio playback speed.