Silence detection and timestamping
Imagine there is something like civil band radio and you want to run some software overnight and have conversations logged like this:
-rw-r--r-- 1 jenda jenda 183k rec-2012-08-08-18-37-37.ogg -rw-r--r-- 1 jenda jenda 98k rec-2012-08-08-18-41-49.ogg -rw-r--r-- 1 jenda jenda 100k rec-2012-08-08-18-47-35.ogg -rw-r--r-- 1 jenda jenda 200k rec-2012-08-08-18-54-52.ogg
We will use one computer for receiving and another for splitting based on silence detection.
gnuradio-companion sketch is here. It receives narrow-band FM, but changing it for other modulations should be easy.
Create a pipe, run netcat to transmit data over the network and run the gnuradio program.
mkfifo test.wav cat test.wav | nc 192.168.77.226 3333 & ./top_block.py
On the other end (well, you can run everything on one computer just by piping it instead of using netcat) download and compile squelch-cut.c and run it like
nc -l -p 3333 | ./a.out
WAV (they are actually RAW) files should appear in current working directory after the first transmission occurs.
Use oggenc to encode them to some more common format.
oggenc -r -C 1 --raw-endianness 1 rec-*.wav