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Old 06-18-09, 01:25 PM   #13
Stephen Warren
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

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Originally Posted by crisalide View Post
Yes, when xine drops frames, these frames are simply never passed to vo driver, so for the vo, the deint "previous frame" is always the latest displayed frame.
OK. That's definitely a bug, and probably could cause some kind of artifacts. However, our deinterlacing engineer doesn't think it's likely that's the cause of these particular artifacts. One thing he wanted to check: Does xine make 100% sure that it never renders to a video surface (i.e. never starts to call decoder_render to that surface) before any mixer call using it as input or history has returned?

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Atm, i'm using the 9500gt. When i downclock it from 550 to 137Mhz, it gives the same mixer perfs as 8400gs, and of course xine drops frames with temporal_spatial. But i don't see any artefact.
(Also note that with ivtc, even temporal isn't fast enougth.)
So, this seems GPU model specific? Which models does it pass and fail on for you? I guess you mentioned it passes on a 9500GT (G96), fails on an 8400GS (G98), and the original reporter also has has an 8400GS (G98). Did you or the reporter have any other models to test with? Let me see if I can repro that difference, and test with other cards.
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Old 06-18-09, 02:03 PM   #14
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

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1) How were the screenshots grabbed? It seems like when playback is paused, xine displays a non-deinterlaced version of the picture even if deinterlacing is enabled?
I made the screenshots by pausing playback of a recording (made in VDR) and taking a picture of my tv with a digital camera.

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2) When the problem occurs for you, is xine dropping frames, or is playback smooth?
I believe both, but definitely with during smooth playback.

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3) Can you describe the problem a little more; is the purple fringing something constant, or does it appear and disappear? Does the color change? Also, from the screenshots, it looks like deinterlacing is always working (i.e. there aren't any weave/feathering artifacts); the problem is that there are a lot of color artifacts caused by the deinterlacing process?
The purple is fringing is pretty constant. It seems as though it happens less when there's little motion and more when there's a lot of motion. That could be my eyes playing tricks however. It would seem the deinterlacing is causing the problem but you and the xine dev guys would know more about that than I.

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So, this seems GPU model specific? Which models does it pass and fail on for you? I guess you mentioned it passes on a 9500GT (G96), fails on an 8400GS (G98), and the original reporter also has has an 8400GS (G98). Did you or the reporter have any other models to test with? Let me see if I can repro that difference, and test with other cards.
Unfortunately I don't have any other cards to test with. Hopefully there's enough people looking at this problem now that others may be able to try different cards.

Many thanks for looking into this problem! Let me know if there's anything else I can do to help!

Derek
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Old 06-18-09, 02:59 PM   #15
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

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OK. That's definitely a bug, and probably could cause some kind of artifacts.
We are unlikely to change that, it would require a lot of code for something that is not really a big problem, after all, the biggest "visual artifact" is the frame drop itself.

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However, our deinterlacing engineer doesn't think it's likely that's the cause of these particular artifacts.
I agree.

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One thing he wanted to check: Does xine make 100% sure that it never renders to a video surface (i.e. never starts to call decoder_render to that surface) before any mixer call using it as input or history has returned?
Absolutely. Frames are protected by a refcount locking mechanism.

Quote:
So, this seems GPU model specific? Which models does it pass and fail on for you? I guess you mentioned it passes on a 9500GT (G96), fails on an 8400GS (G98), and the original reporter also has has an 8400GS (G98). Did you or the reporter have any other models to test with? Let me see if I can repro that difference, and test with other cards.
No more cards to test
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Old 06-19-09, 01:05 PM   #16
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

crisalide,

To fully investigate this, I need to completely disable any/all frame dropping on both the decode or display side in xine. Can you tell me how to hack the code to do this. I tried modifying xine-engine/video_out.c to force frames_to_skip=0, but that didn't help,
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Old 06-19-09, 05:33 PM   #17
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

It looks like there are multiple bugs here.

The simplest issue, which explains the complete lack of de-interlacing for some displays surfaces, is that xine is sometimes sending VDP_VIDEO_MIXER_PICTURE_STRUCTURE_FRAME to VdpVideoMixerRender. This explicitly requests no de-interlacing (i.e. weaving). I think that when this happens, it's related to frame drops; perhaps the first surface after each drop or something?

I'm still looking into the other issues.
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Old 06-19-09, 08:59 PM   #18
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

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The simplest issue, which explains the complete lack of de-interlacing for some displays surfaces, is that xine is sometimes sending VDP_VIDEO_MIXER_PICTURE_STRUCTURE_FRAME to VdpVideoMixerRender. This explicitly requests no de-interlacing (i.e. weaving). I think that when this happens, it's related to frame drops; perhaps the first surface after each drop or something?
If you want to avoid this for your tests, remove the stream_speed condition in the if statement at line ~1562 in video_out_vdpau.c
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Old 06-19-09, 09:32 PM   #19
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

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To fully investigate this, I need to completely disable any/all frame dropping on both the decode or display side in xine. Can you tell me how to hack the code to do this. I tried modifying xine-engine/video_out.c to force frames_to_skip=0, but that didn't help,
In our case, video_out is the bottleneck, so try to change video_out.c to make sure function "expire_frames" never throws away any frame, e.g. :

Code:
int nodrop=1;
      
    if ( !nodrop && (diff > duration || this->discard_frames) ) {
But I can't guaranty that you won't get any unexpected behaviour
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Old 06-22-09, 02:09 PM   #20
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

We believe we've fixed the ghosting/flashing issue. The fix will be in a forthcoming driver.

Last edited by Stephen Warren; 06-22-09 at 02:09 PM. Reason: Typo
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Old 06-22-09, 02:42 PM   #21
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

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We believe we've fixed the ghosting/flashing issue. The fix will be in a forthcoming driver.
Great, thanx.
Btw, i've noticed a speed improvement of ~10% in vdpau post-processing with 185.18.14 compared to 180.xx. Is it a vdpau only gain or is it a general GL improvement?

@primerib:
But still the best fix is to use a post-processing combination that your hardware can run
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Old 06-22-09, 03:07 PM   #22
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

crisalide, there were a couple of small improvements to a subset of the algorithms in various 185.* releases. However, we didn't mention them in the release notes since I hadn't profiled them to get a good idea how worthwhile they were mentioning.
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Old 06-22-09, 03:08 PM   #23
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Default Re: deinterlace & color problems with 185.18.14 (w/screenshots)

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We believe we've fixed the ghosting/flashing issue. The fix will be in a forthcoming driver.
Great news! Thanks for the quick attention & fix to this problem!

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Originally Posted by crisalide View Post
@primerib:
But still the best fix is to use a post-processing combination that your hardware can run
Yeah but I don't think this was an issue with the gpu being too slow since it happened on all deinterlacers. Glad it's fixed, can't wait til the new driver is released!
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