Hi Daniel,
-----Original Message----- From: Daniel Mack [mailto:daniel@zonque.org] Sent: Tuesday, January 14, 2014 9:42 AM
If this can help in the investigation of your problem, I can experience
crackles and clicks during pcm playback on my small hpmini notebook. I have kinda nailed down the source of the crackles and clicks.
It turns out that when my Wifi card is on but not connected, I have the
crackles and clicks. If I connect to a Wifi network or close the Wifi, the crackles and clicks go away. I have not had the time check the Wifi driver code yet but my explanation of the behavior is that in that specific state, some wifi IRQ handler is taking too much time and stop my sound device irqs to be timely serviced.
My advice, is try to unload as much as possible kernel driver modules that
may interfere with your audio playback and see if your crackles and clicks go away. For reference, here is my HW, in case you have the same Wifi Adapter....
I'm not sure whether you're on the right track here.
Which program are you using for this? How are the buffer sizes configured? Are you seeing XRUNs?
And are you sure the audio distortion doesn't relate to bad USB power? Please check with a different PC as well, and for tests, put a powered(!) USB hub inbetween your PC and the DAC.
Daniel
I experience the audible clicks with VLC but I have reproduced it with aplay as well. The clicks that I hear corresponds to underruns. For the records, this is not happening with a USB device. I have a Intel HDA sound card. I did chime in the discussion to point out that the problem could come from something else than ALSA or the sound card driver. Here is the output of my aplay session. This makes me doubt my hypothesis. I'll check the cpu usage while the Wifi is on but not connected or see if running aplay in real-time prio makes things any better.
Note that the underrun duration printed in the output sound fishy...
underrun!!! (at least 1856093977.967 ms long)
lano1106@hpmini ~/Music $ aplay -v -c1 sine.wav Playing WAVE 'sine.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo Plug PCM: Rate conversion PCM (48000, sformat=S32_LE) Converter: linear-interpolation Protocol version: 10002 Its setup is: stream : PLAYBACK access : RW_INTERLEAVED format : S16_LE subformat : STD channels : 2 rate : 44100 exact rate : 44100 (44100/1) msbits : 16 buffer_size : 15052 period_size : 940 period_time : 21333 tstamp_mode : NONE period_step : 1 avail_min : 940 period_event : 0 start_threshold : 15052 stop_threshold : 15052 silence_threshold: 0 silence_size : 0 boundary : 986447872 Slave: Soft volume PCM Control: PCM Playback Volume min_dB: -51 max_dB: 0 resolution: 256 Its setup is: stream : PLAYBACK access : MMAP_INTERLEAVED format : S32_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 32 buffer_size : 16384 period_size : 1024 period_time : 21333 tstamp_mode : NONE period_step : 1 avail_min : 1024 period_event : 0 start_threshold : 16384 stop_threshold : 16384 silence_threshold: 0 silence_size : 0 boundary : 1073741824 Slave: Direct Stream Mixing PCM Its setup is: stream : PLAYBACK access : MMAP_INTERLEAVED format : S32_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 32 buffer_size : 16384 period_size : 1024 period_time : 21333 tstamp_mode : NONE period_step : 1 avail_min : 1024 period_event : 0 start_threshold : 16384 stop_threshold : 16384 silence_threshold: 0 silence_size : 0 boundary : 1073741824 Hardware PCM card 0 'HDA Intel' device 0 subdevice 0 Its setup is: stream : PLAYBACK access : MMAP_INTERLEAVED format : S32_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 32 buffer_size : 16384 period_size : 1024 period_time : 21333 tstamp_mode : ENABLE period_step : 1 avail_min : 1024 period_event : 0 start_threshold : 1 stop_threshold : 1073741824 silence_threshold: 0 silence_size : 1073741824 boundary : 1073741824 appl_ptr : 0 hw_ptr : 40810501 underrun!!! (at least 1856093977.967 ms long)
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