The attached patch adds alpha blending support to the video overlay on radeon hardware. It's been tested on my 9200. It adds three new Xv attributes: XV_ALPHA_MODE, XV_GR_ALPHA, and XV_OV_ALPHA.
XV_ALPHA_MODE - (0 or 1) selects the alpha blending mode. right now it only supports key and global modes, per-pixel can be added later. 0 is key mode, 1 is global mode. Key mode blends the overlay or graphics layer with the colorkey. Global mode blends the graphics layer and the overlay.
XV_GR_ALPHA - (0-255) set the alpha level of the graphics layer (everything but the overlay) (applies to either mode)
XV_OV_ALPHA - (0-255) set the alpha level of the overlay (applies to either mode)
The patch is against DRI cvs, but should apply pretty easily to any tree. I'm not 100% clear on the function the first two fields of OV0_KEY_CNTL, perhaps someone out there could explain it to me. see my comments in the code. let me know if you have any comments or questions. Is it worth opening a bug in bugzilla for this?
The patch and binaries also are available here: http://www.botchco.com/alex/radeon/xv_alpha/
Look out for an improved Xv gamma patch soon.
Alex,
while you are at it, does the radeon hardware support chroma-keying? (Chroma keying means the overlay is shown if the _video_ color is within a certain range. Chroma-Keying is extremely useful for creating blue-box like effects, like for example people in front of a blue background, which is being replaced by the graphics at playback time).
If so, you might want to take a look at the sis driver. Besides, the sis driver also has a property named XV_DISABLE_COLORKEY to avoid the problem of the colorkey always drawn. This works more or less by 1) disabling the colorkey in the video code, and 2) by ignoring accelerator fill-commands with the colorkey as foreground color. Of course, this is no bullet-proof method, but perhaps this is helpful for you, too.
Thomas
-- Thomas Winischhofer Vienna/Austria thomas AT winischhofer DOT net *** http://www.winischhofer.net/ twini AT xfree86 DOT org
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