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[InflatableMouse]

The MadVR Guide sparked some overdue tuning I needed to do. I got a day off tomorrow so I'll be playing around some I figured I'd start a new thread for this to allow some discussion and not flood the guide thread.

I'm trying to solve a small issue I'm seeing. Video seems to speed up a little bit for half a second or so. Like it needs to catch up or something. It's very sporadic and sometimes it can play a video without it occuring (or without me noticing), sometimes it happens a few times during a movie. I can't find something in common, like certain videotypes or resolutions, it seems completely random. I've logged some counters like CPU usage and I don't see any spikes from background processes that could interfere or give a lead. Files are stored locally so no network involved. I don't always have the Madvr stats open but the times I did, I saw no framedrops. I asume the stats are always counting even when its not displaying, and when I checked after I saw it happen, I saw nothing out of the ordinary. I have personally never seen the queue counters change. If they do (I asume they do) I expect them to go up once the problem is over. It could be these are changing but because of the short duration of the issue it may be that by the time I'm looking at the correct counters its already back to full. I admit, I don't know exactly how this works so ... .

MadVR scaling settings are all set Lanczos 3 taps + AR. The only thing I just changed is I'm using DXVA2 copy/back mode in LAV as I'm using a Nvidia GT430 and I switched from FSE to FSW mode. FSE doesn't seem to provide much of a benefit in my situation (and the issue I'm having still appears with FSE).

Typically, the stats are:
23.9712Hz
FSW Mode
Clock Deviation: 0,019982%
Movie: 23.976 fps
1 Frame Repeat every ~3 days
Vsync interval: 41.72ms
Movie interval: 41.71ms
Dec Q.:11-12/12
Upl Q.: 7-8/8
Ren Q.: 7-8/8
BbQ.: 2-3/3
Ave Rendering: 11.78ms
Ave Present: 23.14ms

Depending on the material (SD) the rendering times go up a few ms. Everything seems pretty solid to me and I don't really see these fluctuate a lot.

I think I generally understand what these stats are but that's also about all I claim to know about it. The way I interpret it is that the rendering times should be well below the vsync/movie interval times and the queues should generally be nearly full. Clock deviation is never far off because my display supports every refresh rate used for common video types.

A few questions:
Why is Lanczos not advised for chroma upscaling or image downscaling?
Why is it not advised to use lanczos or jinc for image downscaling?
Should I change my settings for chroma upscaling and image downscaling from lanczos 3 taps + AR to bicubic 75 + AR and catmull-rom + AR respectively?

The big question:
Any idea what could be causing the effect I'm seeing? It's not a major issue but it is annoying.

Thanks in advance!

[6233638]

I'm trying to solve a small issue I'm seeing. Video seems to speed up a little bit for half a second or so. Like it needs to catch up or something. It's very sporadic and sometimes it can play a video without it occuring (or without me noticing), sometimes it happens a few times during a movie. I can't find something in common, like certain videotypes or resolutions, it seems completely random. I've logged some counters like CPU usage and I don't see any spikes from background processes that could interfere or give a lead. Files are stored locally so no network involved. I don't always have the Madvr stats open but the times I did, I saw no framedrops. I asume the stats are always counting even when its not displaying, and when I checked after I saw it happen, I saw nothing out of the ordinary. I have personally never seen the queue counters change. If they do (I asume they do) I expect them to go up once the problem is over. It could be these are changing but because of the short duration of the issue it may be that by the time I'm looking at the correct counters its already back to full. I admit, I don't know exactly how this works so ... .

The stats do always keep track of things, even when they aren't being displayed.

Do you have VideoClock enabled? Try enabling it if you don't.

While you aren't seeing any dropped frames, are you seeing any delayed frames or presentation glitches?

Depending on the material (SD) the rendering times go up a few ms. Everything seems pretty solid to me and I don't really see these fluctuate a lot.

The stats look fine to me.

Why is Lanczos not advised for chroma upscaling or image downscaling?

In most cases Bicubic 75 + AR gives virtually identical results to Lanczos for chroma scaling - if I remember correctly it is actually better in some cases.

Why is it not advised to use lanczos or jinc for image downscaling?

Well you can't use Jinc for downscaling, and Lanczos is too sharp in my experience. Catmull-Rom with anti-ringing and linear-light scaling enabled seemed to give the best results in my testing - but it is rare that I have to downscale video, and I haven't had the opportunity to compare the results on a display that actually has a low native resolution. (such as a 1366x768 display)
I have not done nearly as extensive testing with image downscaling as I have with upscaling luma/chroma.

Should I change my settings for chroma upscaling and image downscaling from lanczos 3 taps + AR to bicubic 75 + AR and catmull-rom + AR respectively?

Only if you aren't happy with what you have now. Your rendering times might drop a little if you change the chroma scaling but I wouldn't expect to see much of a difference.

Any idea what could be causing the effect I'm seeing? It's not a major issue but it is annoying.

Unfortunately no. A while back I was seeing problems with certain films freezing for up to 30s and then playing back quickly until it caught up, but I haven't seen it recently, and there was a huge number of dropped frames reported when it happened.

You might want to try increasing the number of backbuffers used or frames presented in advance and see if that helps.

[InflatableMouse]

Do you have VideoClock enabled? Try enabling it if you don't.

Yes, its enabled.

While you aren't seeing any dropped frames, are you seeing any delayed frames or presentation glitches?

No, I meant to mention it, they all remain zero.

Unfortunately no. A while back I was seeing problems with certain films freezing for up to 30s and then playing back quickly until it caught up, but I haven't seen it recently, and there was a huge number of dropped frames reported when it happened.

You might want to try increasing the number of backbuffers used or frames presented in advance and see if that helps.

I can try that, but when I change it to something other than the default (3), it says Madvr didn't accept the modified settings. Nevermind, playback was stopped. I'll test with 6.

Thanks for the help.

[InflatableMouse]

I think I've improved things quite a bit. Turns out when I enable Aero in combination with FSW or FSE mode it improves rendering times by 3 to 5ms and presentation times drop from 23ms to 0.35ms.

With the latest version switching to DXVA-CB mode I reverted from the custom LAV filter to the default again. I also changed Chroma upscaling to bicubic 75 + AR and downscaling to CR + AR/LL (although downscaling should not occur).

I haven't seen the annoying speed ups anymore, but its too soon to say for sure. I did run into another issue but its unrelated to this so I'll open a new topic for that.

Thanks so far!