[pulseaudio-discuss] snd_pcm_avail no reliable

[Raymond Yau]

>
>   below is what the terminate shows when running pcm_avail.c
>
>   uid=0 gid=1007 at nutshell:/ #
alsactl_test
> min_period_size: 8 frames, dir: 0
> Playback hwparams: FIFO size is 8
> Hardware PCM card 0 'rsnd-dai.0-dirana3.0' device 0 subdevice 0
> Its setup is:
>   stream       : PLAYBACK
>   access       : RW_INTERLEAVED
>   format       : S16_LE
>   subformat    : STD
>   channels     : 2
>   rate         : 48000
>   exact rate   : 48000 (48000/1)
>   msbits       : 16
>   buffer_size  : 4096
>   period_size  : 1024
>   period_time  : 21333
>   tstamp_mode  : NONE
>   period_step  : 1
>   avail_min    : 1024
>   period_event : 0
>   start_threshold  : 1024
>   stop_threshold   : 4096
>   silence_threshold: 0
>   silence_size : 0
>   boundary     : 1073741824
>   appl_ptr     : 0
>   hw_ptr       : 0
> Playing silence
> Available: 0, loop iteration: 0
> Available: 1024, loop iteration: 1469
> Available: 2048, loop iteration: 5609
> Available: 3072, loop iteration: 9667
>
>  All I got is just the 4 lines.

If your sound card only increment hw_ptr only at interrupt occur, you need
to increase default_rewind_safeguard from 256 bytes to your selected period
size

This mean that  your sound card won't work with timer scheduling or dynamic
latency, you can only archieve low latency by decrease period size
Why do pulseaudio enable timer scheduling when most sound card use IRQ ?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20150609/830baabd/attachment.html>