[pulseaudio-discuss] snd_pcm_avail no reliable

[golden]

Hi

   "time based scheduling" is enabled by default, my hardware is ARM for 
automotive, maybe it is not suitable for
   the "time based scheduling", I wonder if I smaller the period size 
would make the snd_pcm_avail more reliable.


BR,
Lixin

在 2015年06月09日 13:02, Raymond Yau 写道:
>
>
> >
> >   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 ?
>
>
>
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