ac3jack 0.1.2

ac3jack is a tool for creating an AC-3 (Dolby Digital) multichannel stream from its JACK input ports. Using this tool, an AC-3 stream (up to 5.1 channels) is created in real time and either written to a file or streamed to standard output.

When streamed to stdout and piped through the ALSA tool ac3dec -C, the AC-3 stream can be passed out the SPDIF port on your audio interface for connection to a multichannel surround receiver. In this way, you can achieve full 5.1 surround mixing and monitoring of your JACK applications with a single digital cable, and no need for hardware supporting discrete outputs and inputs.

AC-3 is a compressed audio format, so quality will suffer a little, but it is the price you pay for easy surround sound. After all, if it is good enough for DVD and film soundtracks, it must be OK. The AC-3 encoder used here comes from the FFMPEG project, and I have not done any quality comparisons with commercial encoders.