Live TV works great, MPEG-2 file playback terrible

[Braklet]

[In the following discussion, "uses PureVideo" means the nVidia icon appears in my Taskbar. "Doesn't use PureVideo" means some video shows up without a corresponding nVidia icon.]

After wrestling with some DVD issues, I finally resorted to removing every codec I could find on my system EXCEPT for nVidia PureVideo v1.02-223. (DECCHECK shows only PureVideo, marked as Default.)

I configured GB-PVR to use the NVIDIA PureVideo video and audio decoders wherever possible, and VMR9. I always configure the PureVideo decoder to the same mode as GB-PVR.

Now, LiveTV displays great and properly uses the PureVideo decoder. When DVDs play (I'm still having navigation issues), they use the PureVideo decoder. However, GB-PVR playback of recorded MPEG-2 material including timeshift mode is terrible: it does not use PureVideo, the video information is crowded in the upper left part of the frame with noise through the remaining frame.

I can mitigate the frame fill problems somewhat by switching GB-PVR and PureVideo to Overlay Mode, however when I do so the frame is compressed and it doesn't appear to use the PureVideo decoder. Video quality is worse under Overlay Mode for both LiveTV and MPEG-2 file playback.

Note that the exact same MPEG-2 files that play poorly under GB-PVR play beautifully with Windows Media Player, which also uses PureVideo.

I am mystified as to why any video is shown when the PureVideo decoder is inactive. Where is GB-PVR finding a decoder when DECCHECK says PureVideo is the only one on the system?

My video source is a Hauppauge WinTV-PVR-500 so even LiveTV is an MPEG-2 stream. I understand why the LiveTV display would use PureVideo, but not why timeshifted MPEG-2 does not.

I'm not real sure what to try next, anybody have ideas?

Thanks!

[sub]

It is worth noting that the the default bitrate for live TV is 6000 Kbps (9000 peak), wheras the default for a recording is 3500 Kbps (7200 peak), so this can account for a reasonable difference in quality between live tv and recordings. You can change this of course, but it will mean larger recording files.

Now, LiveTV displays great and properly uses the PureVideo decoder. When DVDs play (I'm still having navigation issues), they use the PureVideo decoder. However, GB-PVR playback of recorded MPEG-2 material including timeshift mode is terrible: it does not use PureVideo

If you've uninstalled the all MPEG2 decoder other than the PureVideo decoder, then it must be using the PureVideo. I can double check for you if you post your gbpvr.exe-native.log after playing one of these recordings.

the video information is crowded in the upper left part of the frame with noise through the remaining frame.

This sounds like the nvidia aspect ratio bug. If you switch from using the VMR9 Custom renderer instead of standard VMR9, does the problem go away?

[Braklet]

It is worth noting that the the default bitrate for live TV is 6000 Kbps (9000 peak), wheras the default for a recording is 3500 Kbps (7200 peak), so this can account for a reasonable difference in quality between live tv and recordings. You can change this of course, but it will mean larger recording files.

Good point, but I don't think the VBR settings have anything to do with my buffered/recorded GB-PVR display weirdness. The MPEG-2 files that GB-PVR produces play beautifully with Windows Media Player.

FWIW I changed my default recording setting to High. Once I settle on a working GB-PVR platform I plan to customize them as I've also done for WinTV2K and my settop recorder.

If you've uninstalled the all MPEG2 decoder other than the PureVideo decoder, then it must be using the PureVideo. I can double check for you if you post your gbpvr.exe-native.log after playing one of these recordings.

I apologize for not attaching logs to these posts; I'm still in the nascent stages of figuring GB-PVR out. I'll run some experiments tonight and get some clean logs to examine.

This sounds like the nvidia aspect ratio bug. If you switch from using the VMR9 Custom renderer instead of standard VMR9, does the problem go away?

I've had problems with all settings but don't know if I've tried VMR9 Custom since wiping all the other codecs off the system. Will try this tonight as well.

I also plan to get a copy of GraphEdit to see if anything changes between Windows Media Player and GB-PVR.

GB-PVR is the nicest, easiest to use combo front/back ends I've tried and I really want to make it work. Thanks for all the help & advice.

[Braklet]

OK, I tried wiping out all the logs, restarting GB-PVR, and playing an MPEG-2 file which displayed the weirdness I described before. The resulting logs are in the attached ZIP archive. Didn't see any obvious errors.

I also tried setting GB-PVR to VMR9 Custom Renderer. This eliminated the "video in upper left frame" problem, but playback quality was still way off, with lots of periodic deinterlacing errors etc. It also played everything in a 16:9 window, even though the source material is 4:3. I could change aspect to Pillar Mode via the F7 key but I think I prefer straight VMR9. Interesting behavior, nonetheless.

I played with Windows Media Player some more. It reports "missing codec" errors on the MPEG-2 files, even though it plays them great and the nVidia icon appears in my taskbar!

GSpot also tells me the system is missing codecs when I analyze MPEG-2 files. However, its system codec/filter lists includes a line for "NVIDIA Video Decoder" under the "MPEG2_VIDEO" format. It has this line highlighted as "Other" rather than a "Decoder," however. I also note that the file codec case is different ("MPEG2_Video") which could be a problem?

I couldn't get GraphEdit to connect to any working processes so that was a bust.

Do you think that the nVidia PureVideo package is actually NOT registering itself as an MPEG-2 decoder? Very, very weird.

GSpot reports the NVIDIA Video Decoder in the system, format "MPEG2_VIDEO"

[sub]

21:34:01.187 VERBOSE Graph contains the following filters:
21:34:01.187 VERBOSE - Video Renderer
21:34:01.187 VERBOSE - SB Audigy Audio [B000]
21:34:01.187 VERBOSE - NVIDIA Video Decoder
21:34:01.187 VERBOSE - NVIDIA Audio Decoder
21:34:01.187 VERBOSE - GB-PVR Flow Status
21:34:01.187 VERBOSE - MPEG-2 Demultiplexer
21:34:01.187 VERBOSE - E:\Video\GB-PVR\Manual Recordings\ Adult Swim Sunday_20060827223000.mpg

Its definitely using the nvidia video decoder.

I couldn't get GraphEdit to connect to any working processes so that was a bust.

You can only connect to working processes that allow you to. In a thread the other day, I gave the details of a registry setting you needed to add to allow graphedit to connect to GB-PVR.

[Braklet]

Upshot: GB-PVR configured to use nVidia PureVideo and VMR9 Custom renderer looks pretty decent and I will shift my focus from playback to IR blasting. Thanks for all the help & advice.

I'll dig through the archives to find the GraphEdit registry tweaks & play with that, too.

Installing ffdshow eliminated my "missing MPEG-2 codec" issue, but I'm still not clear on the interaction between DirectShow filters, codec registration, and multiple codecs.

I had to reinstall the Hauppauge version of the Intervideo codec to enable WinTV2K (I use it as a backup recorder).

Still don't know why PureVideo alone doesn't register the correct MPEG-2 filters to let GSpot know it is there. The nVidia forums are completely blank on the subject.

[sub]

Installing ffdshow eliminated my "missing MPEG-2 codec" issue, but I'm still not clear on the interaction between DirectShow filters, codec registration, and multiple codecs.

I had to reinstall the Hauppauge version of the Intervideo codec to enable WinTV2K (I use it as a backup recorder).

Still don't know why PureVideo alone doesn't register the correct MPEG-2 filters to let GSpot know it is there. The nVidia forums are completely blank on the subject.

It often seems people are using the nvidia decoder when they get quirky behaviour like this. Other decoders fair better on the reliability front (not always better picture quality though)

[Braklet]

It often seems people are using the nvidia decoder when they get quirky behaviour like this. Other decoders fair better on the reliability front (not always better picture quality though)

Judging from the GB-PVR forums and nVidia forums, I believe it.

My HTPC is connected to a big HDTV, and I am running it in parallel with my HDD/DVD recording settop, so video quality is my primary concern. I'm willing to live with lower reliability if I must. It must be at least comparable to the settop for me to completely switch over to the PC.

I will say this: the PureVideo decoder video is miles above the Cyberlink PowerDVD codecs I used before (both v5 and v6). Offloading rendering tasks to the GPU didn't hurt my impressions, either.

At some point I'll sort out the ffdshow vs. PureVideo decoder issues. Hopefully a combination of GSpot and GraphEdit will let me know what different players and different media want to do.

I wonder if it would be possible for me to create my own filters/graphs to maximize video quality? Hmmmm...

[diehard2]

Hi,

I'm having the same problems. The playback on MPEG2 is very choppy and then just stops. The NVIDIA tray icon does not appear on playback, but does appear on Live TV. Any help would be appreciated.

~Steve

[diehard2]

Upon further investigation, it appears that it doesn't matter what decoder I use. I unregistered the mpv/mpa filters that gbpvr was using by default (feature request: please give an option for playback filters ). The file itself appears to be corrupt. I'm able to play other MPEG2 files created by the same tv card in another program and I haven't changed my drivers in awhile. PVR250 Windows XP