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whitemank
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Posted: Mon Dec 29, 2003 8:51 pm |
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Joined: Mon Dec 29, 2003 8:40 pm
Posts: 11
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I just built my knoppmyth box and am finally getting close to a working system. The problem I have is that the video and audio within MythTV is very choppy. The video is only running at a few frames a second and the audio cuts in and out. When I pause the tv and then play it again, I get a second or so of decent performance and then it goes back to being choppy. If I record an mpeg to my drive using "cat" from /dev/video0, it records an excellent quality file. Running that file under mplayer it looks great and there is no choppy video or audio. However, any video running within MythTv seems sluggish. What is special about the way MythTv works?
I notice that changing channels seems to take forever, too (2-3 seconds). I assume it is related.
I've verified that my drives are using DMA. I am using a Pentium III 600Mhz with 196Mb of RAM, a PVR-250, a soundblaster live!, and an old nVidia TNT2 video card.
Does anyone have any ideas?
Ken
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Xsecrets
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Posted: Mon Dec 29, 2003 9:04 pm |
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Joined: Mon Oct 06, 2003 10:38 am
Posts: 4978
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Nashville, TN
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well if you are talking about livetv then the difference is that mythtv is recording then imediately playing back at the same time. This is quite a load on an older system. the recording takes almost no cpu, but you have no sort of acceleration for the decode on the output, but I would think those specs should still handle it.
A couple of things to look at make sure you are not using the xvmc support, as the tnt2 does not support it. You may want to make sure you are using xv for playback which may speed things up a bit, I think mplayer uses xv by default.
Also on the 2-3 second channel switch this is the time it takes mythtv to buffer the video from the card and start playing it back. this is normal operation. It improves somewhat in 0.13, but just due to the nature that livetv works it will take a bit of time to change channels.
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whitemank
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Posted: Tue Dec 30, 2003 12:47 pm |
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Joined: Mon Dec 29, 2003 8:40 pm
Posts: 11
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When I use mplayer I get good performance no matter what I do. I've used the live TV pause feature within mplayer, I've played mpg's from my hard drive, and I've played live tv from /dev/video0, all without any problems. That makes me think that it's not a hardware issue. It must be caused by MythTV software or by my MythTV configuration.
Pardon me if I ask a couple of dumb questions. How I find out if mplayer is uses xv and whether I'm using xvmc support? I'm not very familiar with linux. I was hoping that I could make things easy by selecting standard hardware, but so far it hasn't been very smooth sailing. I'm glad I remember some UNIX basics from my college days.
If that doesn't work, does anyone have any other ideas?
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cesman
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Posted: Tue Dec 30, 2003 12:58 pm |
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Joined: Fri Sep 19, 2003 7:05 pm
Posts: 5088
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Fontana, Ca
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If you run mplayer from an xterm, it will give output of what it is doing and using. Did you install the nvidia drivers?
_________________ cesman
When the source is open, the possibilities are endless!
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whitemank
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Posted: Tue Dec 30, 2003 1:23 pm |
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Joined: Mon Dec 29, 2003 8:40 pm
Posts: 11
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No, I didn't install any special drivers for my nVidia card. The fact that both the video and audio are choppy make me think it is more than just the video driver unless it is somehow interfereing with the sound card driver. Also, it seems to work fine with mplayer, so unless MythTv is using some different feature on my video card, I'd be surpised if that is the issue. I'll give that a shot, though. As soon as I get the video working, I plan to upgrade to an MX440 with TV-out. At this point I'm desperate.
Can someone give me an overview of the differences between mplayer and the player used by MythTV? Do they use the same engine? Are there configuration files for each? Are they completely different pieces of software?
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Xsecrets
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Posted: Tue Dec 30, 2003 1:33 pm |
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Joined: Mon Oct 06, 2003 10:38 am
Posts: 4978
Location:
Nashville, TN
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they are completely different pieces of software.
how did you go about pausing livetv in mplayer? It doesn't really supprise me that mplayer has this capability, I've just never heard of it before. And can you rewind?
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whitemank
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Posted: Tue Dec 30, 2003 1:49 pm |
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Joined: Mon Dec 29, 2003 8:40 pm
Posts: 11
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I think it was the 'p' key that got it working. My friend was helping me and he just started pressing keys and managed to find all kinds of goodies, including the pause/play function. I haven't looked for a man page on the player, so I don't know whether the features are documented. I don't recall seeing a ffw or rwd.
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Xsecrets
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Posted: Tue Dec 30, 2003 4:10 pm |
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Joined: Mon Oct 06, 2003 10:38 am
Posts: 4978
Location:
Nashville, TN
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well I knew that you can ffw rew and pause with mplayer when you are viewing a file, but I did not know that they worked when viewing a stream like you get from the tvcard.
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whitemank
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Posted: Sun Jan 04, 2004 2:23 am |
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Joined: Mon Dec 29, 2003 8:40 pm
Posts: 11
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Installing the nVidia drivers fixed the problem. I guess the processor was getting loaded with all the tasks the video card would normally handle. I still occasionally get a small skip a second or two after changing channels, but it doesn't bug me too much. Thanks for your help!
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