PeppyMeter and moOde

[TheOldPresbyope]

@raspiter 

Ok, I think I have a solution, thanks to some hints I found on the InterWeb™. I've tested it briefly with the ALSA Loopback enabled and using the  peppyalsa-client (described in @fdealexa github documentation) which displays a text-based bar graph in real time in the terminal window. This combo works with the Art Blakey M4A tracks I downloaded from Apple iTunes, the other M4A test tracks I had on hand, on the moOde Internet radio stations, and some music tracks with other encodings.

You might give it a try with your full PeppyMeter installlation.

My solution consists of an modification of /etc/alsa/conf.d/_sndaloop.conf to insert a new plugin in the loopback branch which explicitly forces the format in that branch to be S16_SE. I arbitrary named the new plugin peppyprep.

Here's my entire new file

Code:

pi@moode837:/etc/alsa/conf.d $ more _sndaloop.conf
#
# This file provides a default Loopback device by overriding the _audioout device defined in /etc/alsa/conf.d/
#
# The trailing underscores are removed/added by job "alsa_loopback" to effectively turn the override On/Off.
# This job is submitted by snd-config.php and corresponds to the setting "ALSA loopback ON/OFF".
#
# modified by TheOldPresbyope to define and interconnect plugin "peppyprep"
#
pcm.!_audioout {
type plug
slave.pcm {
type multi
slaves {
a { channels 2 pcm "plughw:2,0" }
b { channels 2 pcm "peppyprep" }
}
bindings {
0 { slave a channel 0 }
1 { slave a channel 1 }
2 { slave b channel 0 }
3 { slave b channel 1 }
}
}
ttable [
[ 1 0 1 0 ]   # left  -> a.left,  b.left
[ 0 1 0 1 ]   # right -> a.right, b.right
]
}

pcm.peppyprep {
       type plug
       slave
       {
       pcm "pippopeppy"
       format S16_LE
       }
       }

pcm.pippopeppy {
       type meter
       slave.pcm "hw:Loopback,0"
       scopes.0 peppyalsa
}

pcm_scope.peppyalsa {
       type peppyalsa
       decay_ms 400
       meter "/var/tmp/peppyfifo"
       meter_max 100
       meter_show 0
}

pcm_scope_type.peppyalsa {
       lib /usr/local/lib/libpeppyalsa.so
}

The hint found on the InterWeb™ was that plugin type meter doesn't advise ALSA of its input format requirements so this alteration lets us tell it explicitly.

Let us know how it goes.

Regards,
Kent

PS - It should be possible to use a simplified syntax in the definition of peppyprep but that didn't work for me. I had to use the syntax you see here.