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| -rw-r--r-- | speakerWatchdog.sh | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/speakerWatchdog.sh b/speakerWatchdog.sh index 3d8f9a7..d78c40a 100644 --- a/speakerWatchdog.sh +++ b/speakerWatchdog.sh @@ -16,3 +16,50 @@ # 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. |