Phoronix: DRI2 Video Support Still Being Planned
Rob Clark of Texas Instruments talked more at XDC2012 about his plans for "DRI2 Video" support...
I understand the main benefit is zero-copy. Tear-free was already possible a decade ago using the video overlay.
Another problem with Linux is the lack of a modern standard API for video presentation. Xv is old, and it shows in many ways. We have VDPAU, but that is not supported on all chipsets.
does that reduce cpu usage in video playback... yesterday I tried because of that wayland in quantal but here (radeon) no pointer did appear
Yep, it reduces CPU usage and latency pretty greatly, by eliminating a couple of huge stalls. In the best case, you can have the overlay scan directly out of the buffer the DSP decoded into, which saves you two copies (in and out of the SHM area). This helps hugely with 1080p especially.
Using overlays rather than GL still helps you a lot because the overlays typically have much higher-quality scaling, filtering and colourspace conversion. They're pretty crucial in mobile because the you expend a great deal more power using the GPU for that.