On 8/23/07, Liam Girdwood lg@opensource.wolfsonmicro.com wrote:
On Wed, 2007-08-22 at 22:13 +0530, Pharaoh . wrote:
Hi While testing the audio driver using aplay in blocking mode, a periodic murmur is observed, this increases with the audio volume and occurs even when there are no issues like xrun etc.
Aplay was used in normal read/write mode i.e. no mmap. The song can be heard properly i.e. with no noticable gaps
aur
hisses but the clicks are audible.
Clock domain mismatch issues cause periodic ticks that increase in frequency with increasing sample rate. It's possible your clocking the codec and controller in two different clock domains. i.e. I2S controller (bitclk and frame) clocked from CPU and codec clocked from separate crystal.
It's best to make sure that only one clock is clocking both the codec and digital audio interface.
Liam
I tried playing /dev/zero at the same sampling rate as a wav file, but /dev/zero played without any clicks i.e absolutely no sound heard, but while playing a wav file using same parameters clicks occur. I am thinking it is not about clocks mis-match, since I have checked it several times. I was thinking whether junk data is being processed at end of buffer size, but since /dev/zero plays well, I am ruling out that possibility also.
What else could explain the latencies at buffer ending as shown in the log in previous mail.
-Pharaoh.