[SDL] Re: extension for 2D with DRI

Pierre Phaneuf pp at ludusdesign.com
Fri Apr 14 07:55:34 PDT 2000

Mattias Engdegård wrote:

> You are perfectly right; I must have been thinking of two things at the
> same time, thus overtaxing the sponge pretending to be my brain.


> I was concerned about synching for replaying at a fixed video/frame ratio,
> but thinking about it, it is probably not very important since the vertical
> refresh (~80Hz) is far higher than for movies movies (24 frames/s). So
> I guess there is little risk of temporal aliasing artifacts from that,
> and it's better to used fixed timing between frames.


> I wonder if it makes sense to simulate the 50 interlaced half-frames
> per second for TV playback, though. How do people do it? Simply pair them
> together and run them at 25Hz?

You mean, with a TV tuner in your PC? Or on a real TV? On a real TV, you
effectively get a framerate of 25 or 30 Hz (depending on where you
live!) because it takes two cycles to draw a full frame. I guess TV
tuner cards approximate to the next vertical retrace like we'd do
playing an MPEG movie.

Pierre Phaneuf

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