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| author | St33v <github@f3rr3t.com> | 2022-01-26 16:06:59 +1100 |
|---|---|---|
| committer | St33v <github@f3rr3t.com> | 2022-01-26 16:06:59 +1100 |
| commit | f8ab5828ae318cb3c2c38bd1bc4a8bcafba10bf4 (patch) | |
| tree | f2b5259ca394a3e1b10124e3809b91a929d84ae0 /speakerWatchdog.sh | |
| parent | 572ab720e51cfa6b0cecb30b4dde4d7261ec54f5 (diff) | |
| parent | b236ba24b168db0720dcf5a2f75c95302ef95a8d (diff) | |
Merge branch 'master' of github.com:F3RR3T/bashups
Diffstat (limited to 'speakerWatchdog.sh')
| -rw-r--r-- | speakerWatchdog.sh | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/speakerWatchdog.sh b/speakerWatchdog.sh index 344955f..d78c40a 100644 --- a/speakerWatchdog.sh +++ b/speakerWatchdog.sh @@ -10,3 +10,56 @@ # st33v@cr4y:~$ grep RUNNING /proc/asound/card*/pcm*/sub*/status # /proc/asound/card2/pcm0p/sub0/status:state: RUNNING +# That is fine, but the status remains as 'RUNNING' even after the speakers have turned themselves off... +# So I'm going down the track of periodically sending a 'sound' to a loopback device +# sudo modprobe snd-aloop +# Now aply -l shows a new 'card' called Loopback. + + +record one second of default stream: + +$ rec -d -n trim 0 1 stat + + rec sox in record mode + -d default input + -n direct output to /dev/null + trim 0 1 duration 1 second + stat + +Output: + +Input File : 'default' (pulseaudio) +Channels : 2 +Sample Rate : 48000 +Precision : 16-bit +Sample Encoding: 16-bit Signed Integer PCM + +In:0.00% 00:00:01.02 [00:00:00.00] Out:48.0k [ | ] Clip:0 +Samples read: 96000 +Length (seconds): 1.000000 +Scaled by: 2147483647.0 +Maximum amplitude: 0.000000 +Minimum amplitude: 0.000000 +Midline amplitude: 0.000000 +Mean norm: 0.000000 +Mean amplitude: 0.000000 +RMS amplitude: 0.000000 +Maximum delta: 0.000000 +Minimum delta: 0.000000 +Mean delta: 0.000000 +RMS delta: 0.000000 +Rough frequency: -2147483648 +Done. + +So if Max amplitude = 0 then we have silence! + +to generate a tone that is not audible: +play -n synth 1 sine 40 fade .2 0 + + play sox alias + -n dummy input file + synth synthesise a sound + sine sine wave [the default, so not strictly necessary] + 40 Hz + fade fade in from zero volume to max volume over 200 msec. + '0' says fade out at end over same period. |