[alsa-devel] hw_ptr accuracy with intel8x0 -> PulseAudio issue

[Raymond Yau]

2009/12/10 pl bossart <bossart.nospam at gmail.com>

>
>
> > I: module-alsa-sink.c: Using 2 fragments of size 4096 bytes, buffer time
> is
> > 46.44ms
> > D: alsa-util.c:   buffer_size  : 2048
> > D: alsa-util.c:   period_size  : 1024
>
> With small buffers like this, I don't see the point of the timer-based
> scheduling, you will have one interrupt every 23ms.
>
>
Do you mean that this is a limitation of pulseaudio server timer-based
scheduling  ?

It seem the problem is not related to small buffer since

It work quite well with 2 fragments (8196 bytes) on pulseaudio-0.9.14

D: alsa-util.c: Hardware PCM card 0 'Aureal Vortex au8830' device 0
subdevice 0
D: alsa-util.c: Its setup is:
D: alsa-util.c:   stream       : PLAYBACK
D: alsa-util.c:   access       : MMAP_INTERLEAVED
D: alsa-util.c:   format       : S16_LE
D: alsa-util.c:   subformat    : STD
D: alsa-util.c:   channels     : 2
D: alsa-util.c:   rate         : 44100
D: alsa-util.c:   exact rate   : 44100 (44100/1)
D: alsa-util.c:   msbits       : 16
D: alsa-util.c:   buffer_size  : 2048
D: alsa-util.c:   period_size  : 1024
D: alsa-util.c:   period_time  : 23219
D: alsa-util.c:   tstamp_mode  : NONE
D: alsa-util.c:   period_step  : 1
D: alsa-util.c:   avail_min    : 4661
D: alsa-util.c:   period_event : 0
D: alsa-util.c:   start_threshold  : -1
D: alsa-util.c:   stop_threshold   : -1
D: alsa-util.c:   silence_threshold: 0
D: alsa-util.c:   silence_size : 0
D: alsa-util.c:   boundary     : 1073741824
D: alsa-util.c:   appl_ptr     : 0
D: alsa-util.c:   hw_ptr       : 0


but fail on 16 fragments ( 65536 bytes) on pulseaudio-0.9.19

D: alsa-util.c: Hardware PCM card 1 'Aureal Vortex au8830' device 0
subdevice 0
D: alsa-util.c: Its setup is:
D: alsa-util.c:   stream       : PLAYBACK
D: alsa-util.c:   access       : MMAP_INTERLEAVED
D: alsa-util.c:   format       : S16_LE
D: alsa-util.c:   subformat    : STD
D: alsa-util.c:   channels     : 2
D: alsa-util.c:   rate         : 44100
D: alsa-util.c:   exact rate   : 44100 (44100/1)
D: alsa-util.c:   msbits       : 16
D: alsa-util.c:   buffer_size  : 16384
D: alsa-util.c:   period_size  : 1024
D: alsa-util.c:   period_time  : 23219
D: alsa-util.c:   tstamp_mode  : ENABLE
D: alsa-util.c:   period_step  : 1
D: alsa-util.c:   avail_min    : 15502
D: alsa-util.c:   period_event : 0
D: alsa-util.c:   start_threshold  : -1
D: alsa-util.c:   stop_threshold   : 1073741824
D: alsa-util.c:   silence_threshold: 0
D: alsa-util.c:   silence_size : 0
D: alsa-util.c:   boundary     : 1073741824
D: alsa-util.c:   appl_ptr     : 0
D: alsa-util.c:   hw_ptr       : 0


May be PA server cannot calculate the correct sleeping time when the sound
card use  more than 2 periods ?