Music

I talked about Rotter in a previous post. This litte app connect to a Jack plug and record the audio to a file, in mp3, wav or other depending how you compiled it.
This app can also be told to spead files in a tree depending of the date, create a new file every X minutes and remove files older than X hours. Great.
But I had some crashed or unexpected exit. A friend of mine, already using it for a month or two said having no problem with it. But digging in the code let us find what the problem may be :

As we are recording in stereo, we are getting 2 ports from Jack. Then we create one stereo file (in wave).
The process is simple :
Inside a loop, check the jack ring-buffer to see if enough data is here. If yes, write a new chunk of sound. If not, wait for some time and check again.
I first found that the Jack ring-buffer check was made only on the first channel. As we are having 2 channels for stereo, what will happen if the first channel is filled up but not the second ?
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Darkice is a really good free product when talking about live encoding and streaming. It is the best friend of Icecast, which is the deflector module (ie : the link between live stream and customers).

I used to use Darkice directly from ALSA, the Linux sound layer, and encode my live audio from the soundcard to MP3. But for my new radio project I had to use Jack. I already talked about Jack earlier. It is so damn easy you won’t believe it :
Start jack (or have Jack start automaticaly when you start something using jack – see /etc/jackd.conf)
Start your favorite app, let’s say Darkice
Connect your Darkice plug to the soundcard
and you’re done !
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