[mythtv-users] help with buffer pauses during playback

[James Armstrong]

I used to be able to play hd content with no problems. It seems that
something has changed early on in .19 that caused problems with my
system. I don't know if it is a setting for hardware or software. I am
running an Intel 2.6ghz 64EMT backend with 512megs ram and a Intel P4
3ghz hyperthread frontend with 1gig ram, nvidia 5200 using xv. The cpu
usage looks ok during playback for the backend and frontend. When I
first start watching a recorded show it plays fine for about 10 seconds,
then starts pausing every few seconds. I have played with every setting
I can think of and it still does it. It looks like it is related to the
audio buffer. From what I can gather from the log myth has an audio
buffer that it fills then uses that to fill the audio card buffer when
it can. It looks like the myth audio buffer empties then it pauses the
audio and video until the buffer fills back up before it unpauses
playback. If this is so, why does it not try and fill the myth audio
buffer sooner before it runs out? Just guessing here. Here is a small
part of the log, I am attaching the rest. Also, if the buffer has 731135
free, why does it never fill it up? Does it have to wait for the video?:

2006-04-18 20:22:04.956 _AddSamples bytesa44, used6865, frees1135,
timecode$78400
2006-04-18 20:22:04.963 audio waiting for space on soundcard: have 5296
need 6144
2006-04-18 20:22:04.971 Broadcasting free space avail
2006-04-18 20:22:04.971 WriteAudio: Preparing 6144 bytes (1536 frames)
....

Looks like the buffer gets down to 12289, then 6144 bytes are pulled out
and sent to the sound card twice, leaving the audio buffer empty?

2006-04-18 20:22:05.571 _AddSamples bytesa44, used289, freeu5711,
timecode$78880
2006-04-18 20:22:05.572 audio waiting for space on soundcard: have 5200
need 6144
2006-04-18 20:22:05.589 Broadcasting free space avail
2006-04-18 20:22:05.590 WriteAudio: Preparing 6144 bytes (1536 frames)
2006-04-18 20:22:05.591 audio waiting for space on soundcard: have 2992
need 6144
2006-04-18 20:22:05.600 audio waiting for space on soundcard: have 4648
need 6144
2006-04-18 20:22:05.609 Broadcasting free space avail
2006-04-18 20:22:05.610 WriteAudio: Preparing 6144 bytes (1536 frames)
2006-04-18 20:22:05.610 audio waiting for space on soundcard: have 448
need 6144
2006-04-18 20:22:05.622 audio waiting for space on soundcard: have 2672
need 6144
...
Then it pauses util the buffer fills back up?

2006-04-18 20:22:05.623 NVP: prebuffering pause
2006-04-18 20:22:05.624 NVP: Waiting for prebuffer.. 0
AAAAAAAAAAAuAALAAAULAAAAAAAAAAA
2006-04-18 20:22:05.627 _AddSamples bytesa44, useda45, freev1855,
timecode$78912
2006-04-18 20:22:05.630 OutputAudioLoop: audio paused
2006-04-18 20:22:05.630 4304 bytes free on soundcard
2006-04-18 20:22:05.635 5192 bytes free on soundcard
2006-04-18 20:22:05.640 6148 bytes free on soundcard
2006-04-18 20:22:05.645 7112 bytes free on soundcard
2006-04-18 20:22:05.650 8068 bytes free on soundcard
2006-04-18 20:22:05.655 9028 bytes free on soundcard
2006-04-18 20:22:05.660 9988 bytes free on soundcard
2006-04-18 20:22:05.665 10948 bytes free on soundcard
2006-04-18 20:22:05.669 11716 bytes free on soundcard
2006-04-18 20:22:05.673 12484 bytes free on soundcard
2006-04-18 20:22:05.678 13444 bytes free on soundcard
2006-04-18 20:22:05.679 _AddSamples bytesa44, used289, freeu5711,
timecode$78944
2006-04-18 20:22:05.683 14404 bytes free on soundcard
2006-04-18 20:22:05.687 15176 bytes free on soundcard
2006-04-18 20:22:05.692 16136 bytes free on soundcard
2006-04-18 20:22:05.697 17096 bytes free on soundcard
2006-04-18 20:22:05.702 18052 bytes free on soundcard
2006-04-18 20:22:05.706 18820 bytes free on soundcard
2006-04-18 20:22:05.710 _AddSamples bytesa44, used433, freet9567,
timecode$78976
2006-04-18 20:22:05.711 19780 bytes free on soundcard
2006-04-18 20:22:05.716 20744 bytes free on soundcard
2006-04-18 20:22:05.721 21704 bytes free on soundcard
2006-04-18 20:22:05.726 22676 bytes free on soundcard
2006-04-18 20:22:05.731 23624 bytes free on soundcard
2006-04-18 20:22:05.736 221184 bytes free on soundcard
2006-04-18 20:22:05.736 WriteAudio: Preparing 6144 bytes (1536 frames)
2006-04-18 20:22:05.737 WriteAudio: buffer underrun
2006-04-18 20:22:05.742 18432 bytes free on soundcard
2006-04-18 20:22:05.745 _AddSamples bytesa44, used$577, freet3423,
timecode$79008
2006-04-18 20:22:05.776 NVP: Waiting for prebuffer.. 1
AAAAAAAAAAAUAAuAALUULULAAAAAAAA
2006-04-18 20:22:05.793 _AddSamples bytesa44, used0721, frees7279,
timecode$79040
2006-04-18 20:22:05.820 _AddSamples bytesa44, used6865, frees1135,
timecode$79071
2006-04-18 20:22:05.852 _AddSamples bytesa44, usedC009, freer4991,
timecode$79103
2006-04-18 20:22:05.894 _AddSamples bytesa44, usedI153, freeq8847,
timecode$79136
2006-04-18 20:22:05.922 _AddSamples bytesa44, usedU297, freeq2703,
timecode$79168
2006-04-18 20:22:05.926 NVP: Waiting for prebuffer.. 2
AAAAAAAAAAAUAAUAAUUUuUULUUALLAA
2006-04-18 20:22:05.956 _AddSamples bytesa44, useda441, freep6559,
timecode$79200
2006-04-18 20:22:06.012 _AddSamples bytesa44, usedg585, freep0415,
timecode$79232
2006-04-18 20:22:06.027 OutputAudioLoop: Play Event
2006-04-18 20:22:06.027 Broadcasting free space avail
2006-04-18 20:22:06.027 WriteAudio: Preparing 6144 bytes (1536 frames)

Thanks,
James


-------------- next part --------------
A non-text attachment was scrubbed...
Name: mythlog.zip
Type: application/x-zip-compressed
Size: 4496 bytes
Desc: not available
Url : http://mythtv.org/pipermail/mythtv-users/attachments/20060419/a9a29410/attachment.bin