[mh] Network camera audio I/O

[Brian R. <br...@pr...>]

Hi Folks,

A few years ago I did some work to get basic audio I/O functioning with 
a handful of OEM network cameras based on Fitivision designs 
(Airlink101, TRENDnet, IPUX, Techgear, Mayfair, Swann, etc...) and 
wanted to share my findings with the MisterHouse community in the event 
some of you may find them useful.

These cameras typically have a built-in microphone and either built-in 
speakers, or an audio out jack for external speakers. Audio I/O is 
full-duplex, so independent use of the mic, speakers (and camera video) 
are possible.

My earlier work was done by analyzing Wireshark traces, but shortly 
thereafter specifications surfaced for the CGI control commands. I 
placed a copy of these here, as the original source seems to have gone 
missing: 
http://www.praecogito.com/~brudy/setsnest/zoneminder/CGI%20SPEC%20Ver1_0_5_TrendNET-33.pdf

At the time, I wrote some proof of concept Perl scripts for capturing 
audio from the camera's mic, and playing back audio through the camera's 
speakers prior to the specification being released, but recently went 
back and modified them based on the spec:
http://www.praecogito.com/~brudy/setsnest/zoneminder/test-audio-dump.pl
http://www.praecogito.com/~brudy/setsnest/zoneminder/test-audio-push.pl

Last night I did a quick and dirty hack to get Misterhouse Festival 
audio out to one of the cameras. Here is the excerpt from my mh.private.ini:

# Send to the Airlink101 cam audio
festival_init_cmds=(Parameter.set 'Audio_Method 'Audio_Command)
                   (Parameter.set 'Audio_Required_Rate 22000)
                   (Parameter.set 'Audio_Required_Format 'wav)
                   (Parameter.set 'Audio_Command "sox $FILE -r 44100 
$$.wav; sox $$.wav -c 1 -r 8192 -w -t raw $$-2.raw; 
/usr/local/bin/fitivision-audio-push.pl --camip 192.168.1.11 --username 
admin --password admin --upfile $$-2.raw; rm $$.wav; rm $$-2.raw")

I haven't yet had a go at feeding the mic audio through Sphinx, but this 
will likely be the next step.


Have fun!