Richard Jones, Esq.

Transcoding HTTP mp3 streaming proxy in bash

Here’s how to make a proxy for streaming mp3s. It transcodes on-the-fly to 64kpbs MP3 using lame. When transcoding is finished, it calls the ./posthandler.sh script, which can either just delete the file, or potentially archive it so you don’t need to transcode it again.

One interesting limitation seems to be the buffer size of a fifo pipe in linux. Even though the transcoding step is pretty quick, if a client is connected the transcoding only manages to fill the pipe a couple of hundred k ahead of what is being read.

The -i flag to `tee` means it ignores interrupts, and will finish transcoding the file and call the posthandler even if the client disconnects.

Run is like this:

while [ 1 ]; do nc -vlp 8080 -c './transstreamer.sh' ; done

Then hit up a url of your choice using your awesome new proxy:

mpg321 "http://localhost:8080/http://freedownloads.last.fm/download/105468518/Letters%2BFrom%2BThe%2BBoatman.mp3"

Not the most scalable solution, but a mildly amusing quick hack.

Tags: bash, hack, netcat, streaming