[MPlayer-dev-eng] alpha compositing over video with gpu acceleration

[Grigori Goronzy]

On 09/02/2010 02:07 AM, Chris Morgan wrote:
> Hello.
> 
> I'm working on a proof of concept for showing an alpha blended osd
> that could be modified at runtime on top of hd video playback. The
> target is an intel atom system, possibly the d510.
>

The vdpau and gl outputs already do this for both normal OSD and EOSD.
It's a bit limited (no RGBA, only A8 bitmaps can be blended, but the
color can be chosen freely), but there is work going on to generalize
the EOSD interface. So far it is only used for the ASS/SSA subtitle
renderer and tightly integrated into it.

gl video output does work fine on Intel IGPs. If you want to play HD
content, you're still better off with an NVidia Ion based system,
although an Atom dualcore should be good enough for 1080p as long as
ffmpeg-mt is used.

> I've considered using a window manager and putting the osd window
> above the video window, this only seems to provide a single alpha
> value for the osd window, so to make a semi-transparent background I'd
> also end up with semi-transparent text.
>

With non-overlay outputs it should be possible to use XRender to
composite pixmaps on top of the video with full alpha, I think.

> I've heard mention of an alternate path for vf_overlay development in
> terms of a different design and location in mplayer. Is this work
> beyond the design phase?
>

Maybe you mean EOSD?

Grigori