On Thu, Aug 25, 2011 at 12:15 AM, Clemens Ladisch
<cladi...@googlemail.com>wrote:
> Raymond Toy wrote:
> > I'm working on an application where I wanted to do double-buffering and
> > tried to set the buffer size to 4096 and the period size to 2048.
> However,
> > the actual period size used by ALSA is 1365. In fact, it seems that
> > whatever I choose for the buffer size, the period size used by ALSA is
> 1/3
> > of the buffer size. Is this a limitation of the audio HW that I'm using?
>
> This is possible. There isn't any particular combination of buffer/
> period parameters that is guaranteed to be supported with all hardware.
>
> If you want to have two periods, call snd_pcm_hw_params_set_periods
> before try to set the other parameters, but this might fail.
>
I think I tried that and it failed, but I will try again to be sure.
> > cat /proc/asound/cards says:
> >
> > 0 [Intel ]: HDA-Intel - HDA Intel
> > HDA Intel at 0xf8000000 irq 21
>
> HDA is quite flexible, but it's possible that you're using plugins that
> introduce additional restrictions. What device name are you using in
> your program? What plugins are shown when you run
> "aplay -D devicename -v something.wav"?
>
>
It says:
Playing WAVE 'M1F1-int16WE-AFsp.wav' : Signed 16 bit Little Endian, Rate
8000 Hz, Stereo
ALSA <-> PulseAudio PCM I/O Plugin
Its setup is:
stream : PLAYBACK
access : RW_INTERLEAVED
format : S16_LE
subformat : STD
channels : 2
rate : 8000
exact rate : 8000 (8000/1)
msbits : 16
buffer_size : 4000
period_size : 1000
period_time : 125000
tstamp_mode : NONE
period_step : 1
avail_min : 1000
period_event : 0
start_threshold : 4000
stop_threshold : 4000
silence_threshold: 0
silence_size : 0
boundary : 9007199254740992000
I have read about PulseAudio potentially being a problem, but getting rid of
it is not so easy. Besides, for the application I'm looking at, I won't
have control over that.
Thanks,
Ray
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