* Can't get snd-aloop in sync with another device
@ 2021-07-08 16:24 Mark Hills
0 siblings, 0 replies; only message in thread
From: Mark Hills @ 2021-07-08 16:24 UTC (permalink / raw)
To: alsa-devel; +Cc: Andrew Gabbasov
I use dmix+snd-aloop for all local applications; then forwarded to the
dmix+Layla3G using a custom C program.
Despite asking for clock sync, they slowly drift. Am I doing something
wrong?
$ echo hw:Layla3G,0,0 > /proc/asound/Loopback/timer_source
The forwarder drains its buffer and eventually underruns. Loopback is not
providing enough audio to feed Layla3G -- drifts by about 9 samples/second
at 48kHz.
This _feels_ like a regression; I'm pretty sure this was perfectly in time
before. I'd need to bisect kernel and alsa-lib changes.
Below shows the status during playback/capture.
The timer is definitely connected in some way. It's listed below, and
aloop ticking corresponds to whether Layla3G is open by any application
(not just the forwarder)
--
Mark
$ cat /proc/asound/Loopback/cable#0
Cable 0 substream 0:
inactive
Cable 0 substream 1:
inactive
Cable 0 substream 2:
inactive
Cable 0 substream 3:
valid: 3
running: 3
pause: 0
Playback
buffer_size: 65536
buffer_pos: 12800
silent_size: 0
period_size: 512
bytes_per_sec: 384000
sample_align: 8
rate_shift: 0
sound timer: hw:0,0,0
timer open: playback
Capture
buffer_size: 65536
buffer_pos: 53760
silent_size: 0
period_size: 512
bytes_per_sec: 384000
sample_align: 8
rate_shift: 0
sound timer: hw:0,0,0
timer open: playback
Cable 0 substream 4:
inactive
Cable 0 substream 5:
inactive
Cable 0 substream 6:
inactive
Cable 0 substream 7:
inactive
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2021-07-08 16:24 Can't get snd-aloop in sync with another device Mark Hills
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