[alsa-devel] new driver: 30mS interval problem

[Takashi Iwai]

At Mon, 25 Feb 2008 15:46:28 +0100,
William Juul wrote:
> 
> Hello
> 
> I am new to ALSA and trying to write a new driver for a DAC connected
> with PCM to an AVR32 on a NGW100 reference card provided by Atmel.
> 
> The sampling rate I am currently using is 11047and the DAC is
> providing 4 channels of 24bit. The HW interface is using DMA to copy
> data to RAM.
> By studying the audio data in hexdump or in Audacity I can verify that
> the sound looks good in intervals of about 30mS, then all channels are
> garbled for 30mS. This pattern repeat itself throughout the audio
> capture.
> 
> I am not confident I have configured all ALSA parameters properly.
> How can I go about fixing/debugging this 30mS intverval problem?

Maybe the period size has to be aligned to some value?

> 
> Below is the command I am using.
> 
> 
> Best regards
> William Juul
> 
> # arecord -r 11047 -c 4 -f S24_LE -s 1 -A 100 -d 5 --buffer-size 16384
> -F 21333 -v > test.wav

Try to change the period size as well.


Takashi


> Recording WAVE 'stdin' : Signed 24 bit Little Endian, Rate 11047 Hz, Channels 4
> Plug PCM: Hardware PCM card 0 'AVR32 NGW100 external DAC' device 0 subdevice 0
> pcm->setup: 1
>   stream       : CAPTURE
>   access       : RW_INTERLEAVED
>   format       : S24_LE
>   subformat    : STD
>   channels     : 4
>   rate         : 11047
>   exact rate   : 11047 (11047/1)
>   msbits       : 32
>   buffer_size  : 16384
>   period_size  : 490
>   period_time  : 44355
>   tick_time    : 4000
>   tstamp_mode  : NONE
>   period_step  : 1
>   sleep_min    : 0
>   avail_min    : 490
>   xfer_align   : 490
>   start_threshold  : 1
>   stop_threshold   : 16384
>   silence_threshold: 0
>   silence_size : 0
>   boundary     : 1073741824
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