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View Full Version : Part of full YUV MPEG1 shown as CCIR601


FredThompson
31st October 2006, 22:18
I've got a screen capture of a PowerPoint presentation with embedded video. Encoding to MPEG1 with TMPGEnc set for the full YUV range works just fine in that the white "backgrounds" are white and black text is pure black. However, what was embedded video is darkened on playback if hardware acceleration is enabled.

All the source frames, which are screen grabs, have the full range. It loads just fine into VirtualDub and looks fine in the TMPGEnc preview. It also plays with proper luma levels if hardware acceleration is off.

How to prevent this darkening of part of a frame during playback while hardware acceleration is enabled? The goal is a plain MPEG1 file for portability, not a custom playback configuration. I've tried the various matrices of TMPGEnc on a whim, that was no help. :mad:

Does anyone know how to make this "play nice"?

thought: Does hardware acceleration look at the luma range in a block? That would seem odd but maybe that's what is happening. If so, that would mean the video which is embedded MUST be expanded to the full luma range before the screen capture, right?

Arachnotron
31st October 2006, 23:00
How to prevent this darkening of part of a frame during playback while hardware acceleration is enabled? The goal is a plain MPEG1 file for portability, not a custom playback configuration.I'm no expert on this, but AFAIK what constitutes 'hardware acceleration' is a collection of functions off-loaded to the GPU. What they are and how they are implemented will differ from card to card. So how do you know whatever you do will function as you want with all graphic cards out there?

You could of course use a codec that has no hardware acceleration associated with it. Embedded huffyuv anyone? :)

FredThompson
1st November 2006, 01:35
Ugh! I'm shipping files on CDR, not HD... :P

It's really strange. What kind of idiot would change the luma on part of a frame during playback? It's just nuts.

FredThompson
1st November 2006, 05:10
Well, it turns out MPC can be set to use VMR7 (renderless) and the offensive darkening won't happen. Not a perfect solution but getting warmer. Seems this is really a DirectShow issue...

dbloom
1st November 2006, 15:37
Some graphics cards have hardware overlay adjustment controls in their driver's control panel. Be sure to check that out (it's usually in the Display/Settings/Advanced window).