Re: [mythtv-users]Tips for fixing prebuffering pause and WriteAudio: buffer underrun
On Mar 31, 2005, at 8:12 PM, Tj wrote: Michael Carland wrote: Still on my list of things to try is use OSS instead of ALSA. Others have suggested ALSA may be the culprit, and Sorry couldn't be much help. :) FWIW, I have no problems with ALSA (I am using 1.0.8).. Had high hopes there for a moment! Thought I was on ALSA 1.0.6, but I really have 1.0.8. Been reading too many posts tonight I guess. Thanks again. -Michael ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users]Tips for fixing prebuffering pause and WriteAudio: buffer underrun
Michael Carland wrote: Still on my list of things to try is use OSS instead of ALSA. Others have suggested ALSA may be the culprit, and they may be right, but I have a feeling it isn't. The problem is usually worse when entering live tv mode, and then smooths out, and then occasionally appears now and then. To me it seems like a borderline bandwidth issue somewhere. I think I'll try bumping down my bitrate. I did order parts from Monarch to build a new backend. I'm hoping to use these parts to try and troubleshoot this. If they ever ship. But thanks for the suggestion. Sorry couldn't be much help. :) FWIW, I have no problems with ALSA (I am using 1.0.8).. Regarrds, Tj ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users]Tips for fixing prebuffering pause and WriteAudio: buffer underrun
On Mar 31, 2005, at 8:04 AM, Tj NG wrote: >I seem to have all of my install mistakes corrected, except for one. > >When I play recorded content all is well. But when I play live TV, I get >many "*prebuffering* *pause*" messages, and an occasional "WriteAudio: buffer >underrun". The video stutters during the *prebuffering* messages. Did u compile with opengl-vsync on? Once that disabled, playback is fine on my machine... Regards. Tj Sadly, no. Always looking for the easy fix. I turned on full logging on the backend and the frontend, but I'll need to do some homework before I can total sense of it. It does look like the audio buffer is constantly low, but until I look into what code is writing what messages, I won't be able to decode what is happening. Thinking about this, I came up with what would be a cool debugging tool. It would be slick if there were dummy sources/sinks, that could be plugged into myth, and could be used to stress test the various parts of the system. So there would be a module that acted like a frontend, and tried to stream data from the backend at a rate that was stepped up until the backend couldn't keep up, and then printed statistics. Or a simplified backend that was capable of sending a simple stream (something like gears) at a high rate and logged stats about the requests from the frontend. Maybe this functionality exists, dunno. I do know if I was smarter, I would write it. I don't know if my problem right now is a slow backend, frontend, or network. I assume it is not the network, I'm using 100Mbps with a switch, and I tried copying files over NFS from the backend to the frontends /dev/null (frontend is diskless, nowhere else to write it that wouldn't interfere with the network), and noted a fairly decent throughput. Still on my list of things to try is use OSS instead of ALSA. Others have suggested ALSA may be the culprit, and they may be right, but I have a feeling it isn't. The problem is usually worse when entering live tv mode, and then smooths out, and then occasionally appears now and then. To me it seems like a borderline bandwidth issue somewhere. I think I'll try bumping down my bitrate. I did order parts from Monarch to build a new backend. I'm hoping to use these parts to try and troubleshoot this. If they ever ship. But thanks for the suggestion. -Michael ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users]Tips for fixing prebuffering pause and WriteAudio: buffer underrun
>I seem to have all of my install mistakes corrected, except for one. > >When I play recorded content all is well. But when I play live TV, I get >many "*prebuffering* *pause*" messages, and an occasional "WriteAudio: buffer >underrun". The video stutters during the *prebuffering* messages. Did u compile with opengl-vsync on? Once that disabled, playback is fine on my machine... Regards. Tj ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] Tips for fixing prebuffering pause and WriteAudio: buffer underrun
On 28/03/2005, at 11:22 PM, Michael Carland wrote: --- Matthew Phillips <[EMAIL PROTECTED]> wrote: On 28/03/2005, at 9:15 AM, Michael Carland wrote: I seem to have all of my install mistakes corrected, except for one. When I play recorded content all is well. But when I play live TV, I get many "prebuffering pause" messages, and an occasional "WriteAudio: buffer underrun". The video stutters during the prebuffering messages. Hi Michael, I had a very similar problem which cropped up after switching to ALSA output. After a long saga of list-trawling, it turned out to be an error with an uninitialised variable in Myth's ALSA audio module (I so wish C++ would regard this sort of thing as an error). After grabbing a patch from CVS and rebuilding, all is fixed. The patch against 0.17 is attached. Since we have the same frontend hw, I could look into making the (RPM) binaries available if there's somewhere to drop them. Matthew. Thanks for the patch. At first, I thought it worked. When I started live tv, 4 pauses and one underrun where logged, but then it was looking good. That lasted about a minute, and then it was back to the stuttering. It's a little confusing, it does not happen recording a program, and it does not happen when playing a recording, so it's not easy to pin on the frontend or backend. That's very odd. My impression is that live TV mode is really the same as watching a recording as it's laid down (with the added feature of the buffer being limited and circular). So the fact that you get the problem only with live TV is unexpected - I was getting it regardless of mode. I also found that FF/RW a few times would re-sync until the next time I hit pause/unpause or a signal glitch threw it off. May I ask what kind of tuner card you are using? I'm using a VisionPlus VisionDTV DVB-T PCI card. Matthew. ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] Tips for fixing prebuffering pause and WriteAudio: buffer underrun
--- Matthew Phillips <[EMAIL PROTECTED]> wrote: > On 28/03/2005, at 9:15 AM, Michael Carland wrote: > > > I seem to have all of my install mistakes corrected, except for one. > > > > When I play recorded content all is well. But when I play live TV, I > > get > > many "prebuffering pause" messages, and an occasional "WriteAudio: > > buffer > > underrun". The video stutters during the prebuffering messages. > > Hi Michael, > > I had a very similar problem which cropped up after switching to ALSA > output. After a long saga of list-trawling, it turned out to be an > error with an uninitialised variable in Myth's ALSA audio module (I so > wish C++ would regard this sort of thing as an error). After grabbing a > patch from CVS and rebuilding, all is fixed. > > The patch against 0.17 is attached. Since we have the same frontend hw, > I could look into making the (RPM) binaries available if there's > somewhere to drop them. > > Matthew. Thanks for the patch. At first, I thought it worked. When I started live tv, 4 pauses and one underrun where logged, but then it was looking good. That lasted about a minute, and then it was back to the stuttering. It's a little confusing, it does not happen recording a program, and it does not happen when playing a recording, so it's not easy to pin on the frontend or backend. May I ask what kind of tuner card you are using? -Michael __ Do you Yahoo!? Yahoo! Mail - Easier than ever with enhanced search. Learn more. http://info.mail.yahoo.com/mail_250 ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
Re: [mythtv-users] Tips for fixing prebuffering pause and WriteAudio: buffer underrun
On 28/03/2005, at 9:15 AM, Michael Carland wrote: I seem to have all of my install mistakes corrected, except for one. When I play recorded content all is well. But when I play live TV, I get many "prebuffering pause" messages, and an occasional "WriteAudio: buffer underrun". The video stutters during the prebuffering messages. I done some googling, and tried a few things, but have not been able to get around this. I am looking for tips on how to find the source of the problem. I have tried vmstat on both the frontend and the backend, and don't see anything that stands out. No swapping, plenty of memory, at least 20% idle cpu on both ends. I have the "Extra audio buffering" checked. I tried the "Aggresive Soundcard Buffering", but it didn't help, so I turned it back off. I am using ALSA on the frontend, and other than the stutters, it sounds fine. Hi Michael, I had a very similar problem which cropped up after switching to ALSA output. After a long saga of list-trawling, it turned out to be an error with an uninitialised variable in Myth's ALSA audio module (I so wish C++ would regard this sort of thing as an error). After grabbing a patch from CVS and rebuilding, all is fixed. The patch against 0.17 is attached. Since we have the same frontend hw, I could look into making the (RPM) binaries available if there's somewhere to drop them. Matthew. mythtv-0.17-mppalsa.patch Description: Binary data ___ mythtv-users mailing list mythtv-users@mythtv.org http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
