Hello,
I am using an USB soundcard (ID : 046d:0a24 : Logitech Speaker Lapdesk N550).
During playback, I have frequent messages like these :
delay: estimated 795, actual 662 delay: estimated 133, actual 0 delay: estimated 751, actual 662 delay: estimated 89, actual 0
When those messages appear, I am hearing some "cracks" from the soundcard.
I've tried to make some research on this, I only found some messages that hint about some interrupt problems. I'm not using any closed source driver and I can reproduce the issue with any computer running Linux.
On interesting thing to notice is that it happens only when the CPU is near idle. To workaround the problem, I can just do something like :
nice -n 20 dd if=/dev/zero of=/dev/null bs=1k count=500G
This would keep my CPU busy and I have no more messages nor cracks.
This does not seem to be a recent regression since I've experienced this since I bought the lapdesk in december or so. I am still experiencing this issue with the latest rc (linux-3.4rc3 at the moment)
I tried using different .asoundrc setups, tried to install pulseaudio (usually I'm using bare alsa) and still experience the problem.
Below is some information that might help locating the problem. I can make some test if needed and even code if I have some information on where the problem might me located.
Note: those commands are typed during playback.
$ cat /proc/asound/N550/stream0 Logitech, Inc. Logitech Speaker Lapdesk N550 at usb-0000:00:1d.0-2, full speed : USB Audio
Playback: Status: Running Interface = 1 Altset = 1 URBs = 2 [ 20 20 ] Packet Size = 200 Momentary freq = 44100 Hz (0x2c.199a) Interface 1 Altset 1 Format: S16_LE Channels: 2 Endpoint: 1 OUT (ADAPTIVE) Rates: 44100, 48000
$ cat /proc/asound/N550/pcm0p/info card: 0 device: 0 subdevice: 0 stream: PLAYBACK id: USB Audio name: USB Audio subname: subdevice #0 class: 0 subclass: 0 subdevices_count: 1 subdevices_avail: 0
$ cat /proc/asound/N550/pcm0p/sub0/hw_params access: RW_INTERLEAVED format: S16_LE subformat: STD channels: 2 rate: 44100 (44100/1) period_size: 5513 buffer_size: 22050
$ cat /proc/asound/N550/pcm0p/sub0/info card: 0 device: 0 subdevice: 0 stream: PLAYBACK id: USB Audio name: USB Audio subname: subdevice #0 class: 0 subclass: 0 subdevices_count: 1 subdevices_avail: 0
$ cat /proc/asound/N550/pcm0p/sub0/status state: RUNNING owner_pid : 1210 trigger_time: 3264.436419606 tstamp : 3302.883104696 delay : 20904 avail : 2646 avail_max : 21026 ----- hw_ptr : 1695160 appl_ptr : 1714564
$ cat /proc/asound/N550/pcm0p/sub0/sw_params tstamp_mode: NONE period_step: 1 avail_min: 5513 start_threshold: 16537 stop_threshold: 22050 silence_threshold: 0 silence_size: 0 boundary: 1445068800