Disappointing MPEG2 decoding

[wtg]

I've been using GB-PVR for a couple months now and I'm generally satisfied, though it took a while to get the MPEG playback to a point where it didn't stutter consistently. It turned out I needed to use the "CyberLink Video/SP Decoder (ATI)" decoder and select the Deinterlace filter - why I don't know - but after getting the Deinterlace filter set movies and such have played back well. But now I've run into a problem.

Last week I recorded Band of Brothers off the history channel and these MPEGs are giving me trouble. They were recorded with the High setting (as are all of my recordings) and the video really stutters during scenes of high action, lots of explosions, people running amok and quick camera pans. At first I thought maybe it was just my machine having too little horse power to decode these scenes in realtime, but it's not the case since they play back fine using RealPlayer, Microsoft MediaPlayer or Nero's media player. So what do I do, and why can't GB-PVR do what these other players do?

My decoder options in GB-PVR are the following:

• CyberLink Video/SP Decoder (ATI)
  
• CyberLink Video/SP Decoder
  
• InterVideo NonCSS Video Decoder for Hauppauge
  

The ATI one is the only one that gives decent playback performance (with all the other media besides Band of Brothers to date), but again, only if I chose the Deinterlace filter. One would think the filter would slow it down, but without it chosen, things really stuttered, especially in Live TV.

The machine I'm using isn't very high powered, a 1.2 GHz Celeron, but really, it seems like it should be enough. For the video's I've watched so far it's been more than adequate even with one recording going in the background and comskip running in nice mode. But I'm finding now that a high-action MPEG really seems to be beyond GB-PVR's capabilities even if nothing else is running. But other media players seem to handle them fine.

Does anyone have any suggestions? Will GB-PVR ever support decoding being done through Microsoft Media Player?

Will an option to launch an external media player ever be considered? It might not offer commercial skip integration or OSD, but it would solve my problem and also allow currently un-supported media to be handled without GB-PVR needing to recognize them.

Any thoughts?
Tim

1.2 GHz Celeron, PVR-250, ATI Radeon 9200, 512 RAM, 280 GB disk

[KingArgyle]

I've thought about creating a plugin for GBPVR running on a PC (not for MVP), that will allow you to pick and choose which external player you want to play back your video with. I doubt that it would ever work with LiveTV unless it was timeshifted. I personally like the features of ZoomPlayer for playback, so eventually I may fiddle with this.

[sub]

But I'm finding now that a high-action MPEG really seems to be beyond GB-PVR's capabilities even if nothing else is running. But other media players seem to handle them fine.

GB-PVR doesnt do any playback of video itself. Instead it just asks Microsoft directshow to do the playback (then steps out of the way). This is the same thing used by Windows Media Player, and every other Windows based PVR and media player application.

If you're finding a difference in the playback quality between applications, then its most likely using different MPEG decoder to the other application or different renderer Overlay/VMR7/VMR9. If you end up with the same combination of render and decoders, then the performance will be exactly the same as other applications (because it will the exact same components doing the playback).

Also, given the speed of your CPU, you probably want to make sure your dont have ffdshow or dscaler installed, as you dont have the horse power required for these.

[wtg]

Tipster, I'll give the Omega drivers a try. I've not had any reason to believe my drivers aren't giving decent performance, and outside of GB-PVR I'm not having any problems, but if I can get good playback performance inside of GB-PVR I'm willing to try about anything.

You mention that you use the MainConcept MPEG1/2 Decoder. I don't have this as an option though it is of course listed in Config.xml. I presume it doesn't show up in the configuration dialogs because I don't have it installed. Does this come from the Omega drivers or some other hauppauge installation? Whatever the case it's not an option for me at this point.

My disk space is actually split between two physical drives, 120 GB and 160 GB each. One drive has Windows 2000 and my music, pictures and a video archive that doesn't change much, while the other drive I use for new recordings and live tv buffer. Since I almost never use LiveTV there's little chance of disk thrashing with a recording and live tv going at the same time.

My page file I don't recall exactly, but I think it's probably set to either Windows managed or 1536MB/1536MB.

KingArgyle, the plugin would be nice though you'd want it to work inside of other plugins, like My Videos and whatnot. I don't know if the plugin architecture makes that easy or not. Of course, I personally wouldn't care about the plugin at this point if my playback was good. It does seem like it would be a nice feature though, considering all the media possibilities these days.

Thanks,
Tim

[wtg]

GB-PVR doesnt do any playback of video itself. Instead it just asks Microsoft directshow to do the playback (then steps out of the way). This is the same thing used by Windows Media Player, and every other Windows based PVR and media player application.

If you're finding a difference in the playback quality between applications, then its most likely using different MPEG decoder to the other application or different renderer Overlay/VMR7/VMR9. If you end up with the same combination of render and decoders, then the performance will be exactly the same as other applications (because it will the exact same components doing the playback).

That's kind of what I thought, which is why I'm more confused about the difference in performance between playback inside GB-PVR and playback with Windows Media Player. I have GB-PVR configured to use VMR9. I can't say that I've tried the others because I thought VMR9 was supposed to give the best performance.

Also, given the speed of your CPU, you probably want to make sure your dont have ffdshow or dscaler installed, as you dont have the horse power required for these.

I do have ffdshow and maybe dscaler installed, but I turned off the ffdshow option in the config (it was on) so it's not being used now. I don't recall what the dscalar option is so I can't vouch for it being off from memory, but I did try and turn off anything I could think of. The fact that the files playback fine in Windows Mediaplayer is what really confuses me. Why shouldn't it be the same in gbpvr?

Any other suggestions?

Thanks,
Tim

[sub]

VMR9 does have much higher CPU requirements than the Overlay render (which may be being used by WMP on your machine).

Why shouldn't it be the same in gbpvr?

As I said, the only reason it would be different is if its using different render or decoders than WMP. You should be able to get the exact same performance with the right combination of components.

[j3flight]

This is going to sound like a silly suggestion at first, but it worked for me. I also have an ATI card and I found that some movies would not play well through GB-PVR even though they played great through other media players (Windows Media Player, Media Player Classic, Winamp, etc). I managed to find a solution that was unrelated to codecs or GBPVR.

There is a apparently a bug in DirectX 9.0c that seems to only appear on certain platforms - probably video driver related. Some people experience it, others don't and I happen to be one of the ones who encountered it. Seemed to be ATI cards mostly, but I read some nVidia owners complaining about it as well.

To make a long story short, the bug has to do with quartz.dll, a part of Microsoft's DirectShow implementation. DirectX 9.0b does not exhibit this stuttering problem and so to solve it, you just replace the 9.0c quartz.dll with the 9.0b quartz.dll. I couldn't believe this is it, but it solved my issues 100%. (This is all assuming you have DirectX 9.0c installed.

Read this link (go to the 3rd post):
http://www.dscaler.org/phpBB/viewtopic.p...8ab582d201

On that page is a link to here which gives more of an explanation:
http://forums.snapstream.com/vb/showthre...ge=1&pp=15

I'm not saying this will definitely solve your problem, but it could. If it does not, then you know you have other codec issues and you should probably put the original quartz.dll file back. If it fixes it, feel free to experiment with other codecs. I have found DScaler to be the best for MPEG2 playback, but be your own judge.

If you installed 9.0c, you can probably find the 9.0b file on your hard drive just by searching for all instances of quartz.dll and looking at the properties for the version number. The threads above explain which version is which.

Let us know...

Jason

PS: I recently tried the Omega drivers during my search for the solution to this and found them to be pretty cool. They offer a lot of extra tweaks if you're a gamer, but I didn't see any advantages for what I use my card for. Use whatever you're comfortable with.

I also use sweet little program called "Replacer" to do system file switches like this. Very easy to use.
http://www3.telus.net/_/replacer/

[wtg]

A big thanks to Jason because it was his advice to downgrade to the quartz.dll found directx 9.0b that provided the answer, but I learned a few things in the process too. A lot of it seemed to contradict what sub was saying and common-sense suggested, but in the end I think I figured out why.

Before I downgraded my quartz.dll version I did some more experimenting with decoder settings and made some interesting discoveries. Despite everything seeming to point to the contrary, before replacing my quartz file I got the best playback performance with VMR9, ffdshow post-processing, and Deinterlace enabled. If I switched to Overlay or VMR7 mode, playback and Live TV stuttered significantly more. If I switched off ffdshow post-processing on the playback tab or set Deinterlacing to None (or encoder pass-through or ffdshow), playback of any video or Live TV was much worse - jittery video and audio and video sometimes getting out of synch. I know common sense seems like it should be the other way, but it wasn't.

Next, I took Jason's advice and replaced my directx 9.0c quartz.dll with the file that came from directx 9.0b. It took a while to find it since my machine was rebuilt clean with 9.0c not too long ago, but fortunately I finally found someone that has posted it on the net. The performance and quality improvements were huge.

First, I was able to playback my problem video perfectly. While most videos and live tv were fine before, I have a Band of Brothers episode that stuttered horrible in some real high-action scenes with lots of explosions, etc. With quartz.dll replaced, it played back fine. With it playing during the problem scenes I checked CPU percentage and it was running 65-70 percent. Then a made some other changes.

I was still bothered by the fact that I needed ffdshow and deinterlacing turned on to get good playback, since it would seem these would slow things down instead of improve performance. So I went back in config and turned them off now that I'd was getting good results even with my problem video, and things improved even more. The video playback was fine but now, during the same intensive scene, my CPU percentage was only 15-25 percent!

So, here's what I learned. First, the problems with quartz.dll in directx 9.0c was my real trouble all along. I struggled to get decent playback performance of any video or live tv when I installed gbpvr a couple months ago. Video playback was jerky and Live TV was really bad. I was about ready to throw in the towel but based on someone else's advice here in the forums I finally found that I got acceptable results with ffdshow post-processing and deinterlacing enabled even though that seemed counter-intuitive. From what I've learned now though, I think that must only have worked by somehow making the video playback bypass some function(s) in quartz.dll that make it stutter to begin with. Those settings enabled did improve things and make 95% of my playback fine, but at the expense of a lot of CPU power that wasn't really necessary. I think my Band of Brothers episode was just more than my CPU could muster, unable to produce good results even with ffdshow and deinterlacing enabled.

Downgrading the quartz.dll changed everything. Now acceptable playback of my toughest video is possible with ffdshow and deinterlacing enabled, but disabling both cut the load on my CPU by about 60% and playback is still excellent.

I wonder how many other people are having trouble with Directx 9.0c and just don't know it. My guess is that if I had a higher-end CPU I might have had enough horse-power to power through the video that started all of this. I'd have still been spending much more CPU power on decoding than necessary, but having more to spare I might not have noticed. Also, based on what I found on the net there are a lot of people with directx 9.0c playback issues, many with much beefier processors than I've dedicated to my machine. Certainly there have been a lot of people in these forums complaining about jittery playback. I feel like I was just lucky to find the ffdshow/deinterlacing work-around because if not I'd have given up on gbpvr a long time ago. I wonder how many others are really just have problems due to the 9.0c quartz dll and just don't know it.

Thanks everyone for your help. Tipster, I still may try the Omega drivers later but for now I'm going to let things stay settled a while. You hate to touch things when you finally get them working. Sub, thanks for your suggestions. Maybe my experience here can help some others and you with support. I still don't know why Windows Mediaplayer and Realplayer could play back the videos without stuttering while gbpvr couldn't, but I'm guessing they somehow were bypassing the trouble spots in 9.0c's quartz.dll.

Jason, thanks again for taking to time to make your suggestion. It was spot on!

Tim

[j3flight]

Cool, I'm glad my suggestion worked out!

I think this may be a sticky candidate or something, because I think it would help a fair number of people with playback issues. For a while I was recording stuff with GBPVR and playing it back manually through Media Player Classic because GBPVR's playback was terrible - until this fix. I still don't understand why MPC worked fine and GBPVR did not (and yes, I had the built in mpeg2 codec turned off in MPC, so it should have been using the same DirectShow graph as GBPVR).

I am really surprised that there is no patch from Microsoft for this. With the number of posts just on that snapstream board, it is obviously a common issue. I almost gave up also, but I'm really happy with my setup now after replacing quartz.dll. I wish there were a cleaner way, but now that it works, I don't care.

Jason

[valkokir]

I had a hard time locating it so here's a direct link to the post with quartz.dll from 9.0b (for those of us with a fresh install of windows and no previous versions of directx). I may give this a shot later tonight.

http://forums.snapstream.com/vb/showpost...stcount=26