Problem using overlay mode

[frankmcg]

Have things mostly working using VMR9 custom (see my other posts for various problems though!) but tried last night to switch to overlay mode to see if this helped things.

All I switched was purevideo to prefer overlay and selected overlay in the GB-PVR playback tab, now I don't get any picture on the display at all for live tv, only sound. OSD works fine too, just don't get the TV picture.

Any idea what's causing this? Does overlay mode use the same decoders as VMR9?

[stefan]

If you have "default" picked as video decoders, then I don't think it's necessarily true that the same decoders are used in vmr9 and overlay.

[frankmcg]

No I kept it as purevideo rather than system default in both cases. Only thing I can think of is when I applied a registry tweak a while back to purevideo to force it to use the best form of deinterlacing. Could this some how be clashing with my choosing overlay as a renderer?

[stefan]

Could... IIRC, purevideo deinterlacing (with purevideo) only works when using dxva and hardware acceleration, which does not work in overlay mode... but I'm no expert... csy is a user on this forum who seems to know these things pretty well...

[twinfrey]

It could be one other thing. You said that the picture does not show up on your TV, but does it show up on your computer? When I use overlay, I have to specify to my video card which display is the main one. That ends up being the only display that video can be displayed on. So in my settings, I have to specify that the TV is the main display. VMR9 makes it so that your video shows up on both displays.

[frankmcg]

Thanks for the suggestion but I don't think it could be that - I only have the computer connected to the TV so as far as windows is concerned that's the only display.

[Braklet]

Could... IIRC, purevideo deinterlacing (with purevideo) only works when using dxva and hardware acceleration, which does not work in overlay mode...

I had to switch to overlay mode when I added an ATSC receiver, and I am pretty sure that DXVA and hardware acceleration continue to work on my nVidia system. When I disable those functions CPU usage goes up and video quality goes down.

I'm still not sure why Overlay mode got rid of my HD stutter, I've been blaming my 6600-based cards relative lack of memory bandwidth but don't know for sure. I definitely preferred VMR9 Custom rendering function-wise but can live without transparent OSD if it means better video quality.

I'll have to look into whether my vidcard was trying to drive both a primary and secondary display with VMR9, and it just couldn't handle HD. But for now Overlay mode definitely made a big positive difference in HD display.

[stefan]

Yep, it seems I remembered wrong. In http://forums.nextpvr.com/showthread.php?p=130999 csy says

due to a limitation in the way the Purevideo video decoder works, because the registry patch has enabled "Prefer VMR", it has disabled decoder support for overlay mode, meaning this decoder will not be used if GBPVR is configued to Overlay renderer (unless you change the patch to "Prefer Overlay", but that will disable hardware de-interlacing)"

Obviously he is talking about de-interlacing, not about DXVA/hardware acceleration. Sorry for misleading you.

[Braklet]

Sorry for misleading you.

No sweat! I couldn't use that registry patch anyway; hardcoding that information seemed to disable my ability to manipulate audio settings via the PureVideo GUI. I was able to reproduce most of the registry settings in the updated GUI and quality seems fine.

I should also add that I originally pursued PureVideo because of terrible deinterlacing performance with my previous decoders. Even changing to Overlay mode I retain PureVideo's superior deinterlacing capabilities.

IIRC, that thread focused on a previous PureVideo release so maybe nVidia changed something.

[frankmcg]

Notwithstanding the above though, has anyone got any other suggestions on why I get a blank screen when switching to overlay mode?

Could it be that I've hard patched purevideo to VMR9 mode and therefore it doesn't work in overlay mode any more? I'm a bit confused about what csy is saying.