On 8/23/07, Pharaoh . <pharaoh137@xxxxxxxxx> wrote: > > > > On 8/23/07, Liam Girdwood <lg@xxxxxxxxxxxxxxxxxxxxxxxxxxx > 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. > > > > > > Further debug reveals that the pointer callback is called multiple times at the beginning of buffer . Could it be cause of latency? I am playing the same .wav file with using aplay with 16K buffer size and 4K period size . Here is the log, audio_get_dma_pos is my pointer function. In period 0 it is called 4 times, while in period 1,2 and 3 it is called only once. Does it mean that first time pointer is called it is not getting correct value and it keeps retrying till it gets some sensible value? [ 1013.037107] current period = 0 current offset = c000 [ 1013.044950] audio_get_dma_pos [ 1013.051770] audio_get_dma_pos [ 1013.056944] audio_get_dma_pos [ 1013.063780] audio_get_dma_pos [ 1013.135178] audio_get_dma_pos [ 1013.138445] current period = 1 current offset = 0 [ 1013.236261] audio_get_dma_pos [ 1013.239453] current period = 2 current offset = 4000 [ 1013.337485] audio_get_dma_pos [ 1013.340640] current period = 3 current offset = 8000 [ 1013.438684] audio_get_dma_pos [ 1013.441886] current period = 0 current offset = c000 [ 1013.449263] audio_get_dma_pos [ 1013.454452] audio_get_dma_pos [ 1013.461301] audio_get_dma_pos [ 1013.466879] audio_get_dma_pos [ 1013.539984] audio_get_dma_pos [ 1013.543208] current period = 1 current offset = 0 [ 1013.641070] audio_get_dma_pos [ 1013.644283] current period = 2 current offset = 4000 [ 1013.742383] audio_get_dma_pos [ 1013.745553] current period = 3 current offset = 8000 [ 1013.843631] audio_get_dma_pos [ 1013.846833] current period = 0 current offset = c000 [ 1013.854221] audio_get_dma_pos [ 1013.861027] audio_get_dma_pos [ 1013.866227] audio_get_dma_pos [ 1013.873090] audio_get_dma_pos [ 1013.944925] audio_get_dma_pos [ 1013.948187] current period = 1 current offset = 0 [ 1014.045988] audio_get_dma_pos [ 1014.049177] current period = 2 current offset = 4000 [ 1014.147209] audio_get_dma_pos [ 1014.150370] current period = 3 current offset = 8000 -pharaoh. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
