[mythtv-users] Mythtv 0.24 Acer Revo ALSA WriteAudio buffer underruns

Mon Feb 14 09:37:43 UTC 2011

2011/2/14 Johnny Stenback <mythtv-users at jstenback.com>:
>
> I've been playing around with this for some time now (since you
> recommended it here), and I don't think I can say that things work any
> better in mythavtest playing off of a cifs mounted share than when
> playing with mythfrontend through storage groups. IOW, still see
> occasional pauses. What I did was to run mythavtest -v audio,playback on
> the frontend, and when I notice the pauses I see stuff like this in the
> output:
>
> 2011-02-13 18:04:23.200 Player(0): 1600 interlaced frames seen.
> 'video_output' mean = '33343.91', std. dev. = '4309.38', fps = '29.99'
> 'video_output' mean = '33358.56', std. dev. = '608.63', fps = '29.98'
> 'video_output' mean = '33357.87', std. dev. = '425.53', fps = '29.98'
> 'video_output' mean = '33357.87', std. dev. = '469.70', fps = '29.98'
> 2011-02-13 18:04:36.546 Player(0): 2000 interlaced frames seen.
> 'video_output' mean = '33363.51', std. dev. = '518.59', fps = '29.97'
> 'video_output' mean = '33352.72', std. dev. = '736.49', fps = '29.98'
> 'video_output' mean = '33380.18', std. dev. = '552.62', fps = '29.96'
> 2011-02-13 18:04:46.458 Player(0): Waiting for video buffers...
> 2011-02-13 18:04:46.462 AO: Pause 1
> 2011-02-13 18:04:46.469 AO: OutputAudioLoop: audio paused
> 2011-02-13 18:04:46.573 Player(0): Waited 100ms for video buffers
> AAAAAAAAAAAADdDLL
> 2011-02-13 18:04:46.709 Player(0): Waited 100ms for video buffers
> AAAAAAAAAAAADdDLL
> 2011-02-13 18:04:46.823 Player(0): Waited 100ms for video buffers
> AAAAAAAAAAAADdDLL
> 2011-02-13 18:04:46.846 Player(0): Waited 100ms for video buffers
> AAAAAAAAAAAADdDLL
> 2011-02-13 18:04:46.940 AO: Pause 0
> 2011-02-13 18:04:46.943 AO: OutputAudioLoop: Play Event
> 2011-02-13 18:04:46.973 ALSA, Error: WriteAudio: buffer underrun
> 'video_output' mean = '37709.28', std. dev. = '48871.93', fps = '26.52'
> 2011-02-13 18:04:47.126 Player(0): Waiting for video buffers...
> 2011-02-13 18:04:47.126 AO: Pause 1
> 2011-02-13 18:04:47.144 AO: OutputAudioLoop: audio paused
> 2011-02-13 18:04:47.162 AO: Pause 0
> 2011-02-13 18:04:47.230 AO: OutputAudioLoop: Play Event
> 2011-02-13 18:04:50.416 Player(0): 2400 interlaced frames seen.
> 'video_output' mean = '34233.21', std. dev. = '4730.83', fps = '29.21'
> 'video_output' mean = '33363.96', std. dev. = '337.42', fps = '29.97'
> 'video_output' mean = '33365.04', std. dev. = '456.08', fps = '29.97'
> 'video_output' mean = '33389.13', std. dev. = '469.25', fps = '29.95'
>
> At the same time this happened I was running "vmstat 1" on the frontend
> as well, and here's what it shows during this pause:
>
> procs -system-- ----cpu----
>  r  b   in   cs us sy id wa
>  3  0 7429 1454 13 15 72  0
>  0  0 7714 1383 10 13 77  0
>  3  0 7681 1363 10 14 76  0
>  1  0 7760 1378 14 24 62  0
>  1  0 7901 1151  9 13 78  0
>  0  0 7508 1079  9 13 78  0
>  0  0 7744 1118 10 13 77  0
>  0  0 7734 1099  9 15 76  0
>  2  0 7478 1118 11 15 74  0
>  1  0 7675 2349 31 35 34  0   <---
>  1  0 7622 1687 33 26 41  0
>  0  0 7831 1361  1  3 96  0
>  2  0 7809 1196  1  3 97  0
>  0  0 7030 1170  2  5 93  0
>  1  0 7265  967  5  5 90  0
>  0  0 7349 1077  6 10 84  0
>  0  0 6287  999  8 12 81  0
>  0  0 7192  993  9 14 77  0
>  2  0 7684 1068 10 12 78  0
>  0  0 7706 1307 11 15 73  0
>  0  0 7690 1217 10 16 74  0
>
> (memory and IO info cut out, as there's nothing of interest in those fields)
>
> What seems consistent with the pauses is that the idle value reported by
> vmstat drops from ~70% to 50 or less. When watching the CPU usage of
> various processes (using top) while these pauses are happening there's
> no noticeable change to anything other than mythavtest, which spikes to
> 100% for a short period of time.
>
> I've also been running vmstat 1 on the backend, but I haven't seen any
> consistent changes on the backend while the pauses happen.
>
> If anyone's got other ideas on what to try here, I'll gladly try to
> collect more data here...
>
>>
>> JY

Hello, I read on some post that it works better with TWO memory slots,
on the las line is a comment about it:
http://www.mythtv.org/wiki/VDPAU#User_results

"Needed to install two matched RAM sticks for dual-channel mode, or
GPU memory bandwidth was insufficient. Initially tried with one 2GB
stick; Temporal 2x at 1080i was very jerky, but works perfectly with
two 1GB sticks.
Also, MB is running with nothing but RAM added; PXE boot + NFS root,
with excellent performance. (File access hits 110 - 120MB/sec, limited
only by GigE speeds.) "

May this help, best regards.

-- 
Josu Lazkano