[alsa-devel] Getting XRUN after writei in RUNNING state?
Hi folks,
I've trying to improve the ALSA driver for the Robust Audio Tool (RAT) tool: http://frostie.cs.ucl.ac.uk/nets/mmedia/wiki/RatWiki
Specifically the code I'm talking about is: http://frostie.cs.ucl.ac.uk/nets/mmedia/browser/rat/trunk/auddev_alsa.c
I've added some status dumps in the code that I'm running which aren't in the repository version but basically the code is doing the same thing.
However I'm seeing weird XRUNs (under runs on the playback side) - There's as couple of instances I don't understand: (The pcm device setup is shown at the bottom);
1) RAT is happily writing audio to the playback device for while then the device just seems to go in XRUN state after being in RUNNING state and doing a writei()??:
[+945 auddev_alsa.c] Time since last write: 42734us, Trying to write 640 frames state : RUNNING trigger_time: 1194622844.333930000 tstamp : 0.000000 delay : 121 avail : 1927 avail_max : 2043 [pid/9901 +954 auddev_alsa.c] Wrote 1280 bytes, frames: 640 state : XRUN trigger_time: 1194622844.333930000 tstamp : 0.000000 delay : 758 avail : 1290 avail_max : 2046
2) RAT is writing audio to the playback device for while then the device just seems to go in XRUN state when there's still positive delay in the buffer.
Here's last write that went ok - showing the snd_pcm_status_dump before doing the write and afterwards:
[+945 auddev_alsa.c] Time since last write: 42635us, Trying to write 640 frames state : RUNNING trigger_time: 1194622843.886113000 tstamp : 0.000000 delay : 275 avail : 1773 avail_max : 2041 [+954 auddev_alsa.c] Wrote 1280 bytes, frames: 640 state : RUNNING trigger_time: 1194622843.886113000 tstamp : 0.000000 delay : 907 avail : 1141 avail_max : 2043
The next time the audio write is called the state is checked and found to be in XRUN with 225 delay in the buffer:??? (And yet I've seen other writes find the device still running with alot less delay in the buffer??):
[ +936 auddev_alsa.c] In SND_PCM_STATE_XRUN - preparing audio [pid/9901 +945 auddev_alsa.c] Frames avail to be written=2048, time diff=43182, Trying to write 640 frames, Curr delay 0 state : XRUN trigger_time: 1194622843.886113000 tstamp : 0.000000 delay : 225 avail : 1823 avail_max : 2049 [pid/9901 +954 auddev_alsa.c] Wrote 1280 bytes, frames: 640 state : RUNNING trigger_time: 1194622844.142516000 tstamp : 0.000000 delay : 637 avail : 1411 avail_max : 1708
Currently I'm stumped at to solve these problems.... And basically ALSA sound quality as worse than the OSS driver for RAT as a result.
Any suggestions are to how improve or sort these problems is welcome.
Thanks,
Piers O'Hanlon. University College London
===snd_pcm_dump_setup:=============== stream : PLAYBACK access : RW_INTERLEAVED format : S16_LE subformat : STD channels : 1 rate : 16000 exact rate : 16000 (16000/1) msbits : 16 buffer_size : 2048 period_size : 341 period_time : 21333 tick_time : 0 tstamp_mode : NONE period_step : 1 sleep_min : 0 avail_min : 341 xfer_align : 1 start_threshold : 341 stop_threshold : 2048 silence_threshold: 0 silence_size : 0 boundary : 536870912
On Fri, 9 Nov 2007, Piers O'Hanlon wrote:
===snd_pcm_dump_setup:=============== stream : PLAYBACK access : RW_INTERLEAVED format : S16_LE subformat : STD channels : 1 rate : 16000 exact rate : 16000 (16000/1) msbits : 16 buffer_size : 2048 period_size : 341 period_time : 21333 tick_time : 0 tstamp_mode : NONE period_step : 1 sleep_min : 0 avail_min : 341 xfer_align : 1 start_threshold : 341 stop_threshold : 2048 silence_threshold: 0 silence_size : 0 boundary : 536870912
Could you do whole dump (snd_pcm_dump()) to see all plugins in chain? I judge from period_size that we have another problem with rate plugin. It would be better to do rate resampling in RAT.
Jaroslav
----- Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project
Hi,
Thanks for getting back me.
Jaroslav Kysela wrote:
On Fri, 9 Nov 2007, Piers O'Hanlon wrote: ....
Could you do whole dump (snd_pcm_dump()) to see all plugins in chain? I judge from period_size that we have another problem with rate plugin. It would be better to do rate resampling in RAT.
I set the period size to the match the closest to the expected minimum audio packet size (20ms - 320 bytes in our case) - I wasn't sure the best choice for all parameters. I initially set the buffer size to approx 3 packets - though I tried increasing to twice that. It just wasn't clear which parameters were causing it to go into XRUN (I also set the stop threshold to maximum to make sure it was the stop threshold - though I guess it it overrun the buffer size we'll get audio from the beginning of the ring buffer anyway wthat wouldn't sound too good)
(snd_pcm_dump()) is below:
Plug PCM: Rate conversion PCM (48000, sformat=S16_LE) Its setup is: stream : PLAYBACK access : RW_INTERLEAVED format : S16_LE subformat : STD channels : 1 rate : 16000 exact rate : 16000 (16000/1) msbits : 16 buffer_size : 2048 period_size : 341 period_time : 21333 tick_time : 0 tstamp_mode : NONE period_step : 1 sleep_min : 0 avail_min : 341 xfer_align : 1 start_threshold : 341 stop_threshold : 2048 silence_threshold: 0 silence_size : 0 boundary : 536870912 Slave: Route conversion PCM (sformat=S16_LE) Transformation table: 0 <- 0 1 <- 0 Its setup is: stream : PLAYBACK access : MMAP_INTERLEAVED format : S16_LE subformat : STD channels : 1 rate : 48000 exact rate : 48000 (48000/1) msbits : 16 buffer_size : 6144 period_size : 1024 period_time : 21333 tick_time : 0 tstamp_mode : NONE period_step : 1 sleep_min : 0 avail_min : 1024 xfer_align : 3 start_threshold : 1024 stop_threshold : 6144 silence_threshold: 0 silence_size : 0 boundary : 1610612736 Slave: Direct Stream Mixing PCM Its setup is: stream : PLAYBACK access : MMAP_INTERLEAVED format : S16_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 16 buffer_size : 6144 period_size : 1024 period_time : 21333 tick_time : 0 tstamp_mode : NONE period_step : 1 sleep_min : 0 avail_min : 1024 xfer_align : 3 start_threshold : 1024 stop_threshold : 6144 silence_threshold: 0 silence_size : 0 boundary : 1610612736 Hardware PCM card 0 'AMD AMD8111' device 0 subdevice 0 Its setup is: stream : PLAYBACK access : MMAP_INTERLEAVED format : S16_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 16 buffer_size : 16384 period_size : 1024 period_time : 21333 tick_time : 4000 tstamp_mode : NONE period_step : 1 sleep_min : 0 avail_min : 1024 xfer_align : 1024 start_threshold : 1 stop_threshold : 1073741824 silence_threshold: 0 silence_size : 1073741824 boundary : 1073741824
Jaroslav
Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project
Hi Jaroslav,
Just to let you know I'm running this on Ubuntu 7.10 (alsa-lib-1.0.14), though I've been seeing this underrun problem for a while on a few systems (Ubuntu 7.04/6.10, and Gentoo 2006.1). It hasn't been clear to me what the key parameters are that control underrun behaviour. (It would be great if someone wrote a comprehensive book/article on ALSA....)
BTW you mentioned doing the rate resampling in RAT - which it can do - how does one discover if rate conversion is occurring in ALSA and obtain that 'base' rate? (Though I has assumed that ALSA would do the better job of rate resampling if it was necessary...).
Thanks,
Piers.
On 09/11/2007, Jaroslav Kysela perex@perex.cz wrote:
On Fri, 9 Nov 2007, Piers O'Hanlon wrote:
===snd_pcm_dump_setup:=============== stream : PLAYBACK access : RW_INTERLEAVED format : S16_LE subformat : STD channels : 1 rate : 16000 exact rate : 16000 (16000/1) msbits : 16 buffer_size : 2048 period_size : 341 period_time : 21333 tick_time : 0 tstamp_mode : NONE period_step : 1 sleep_min : 0 avail_min : 341 xfer_align : 1 start_threshold : 341 stop_threshold : 2048 silence_threshold: 0 silence_size : 0 boundary : 536870912
Could you do whole dump (snd_pcm_dump()) to see all plugins in chain? I judge from period_size that we have another problem with rate plugin. It would be better to do rate resampling in RAT.
Jaroslav
Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project
participants (2)
-
Jaroslav Kysela -
Piers O'Hanlon