Personal tools

How do I make Rivendell play Audio from the "Line In" of the Sound Card on the air?

From Rivendell Wiki

Jump to: navigation, search


  1. I want to use the sound card of this computer (delta 66) as a switcher. That is, at certain hours of the day, we want to broadcast the audio (well, in fact the news) from another station (a national one). We use a FM receiver and we want to re-broadcast its output. Is it possible to mute the output of rdairplay and connect an input from the sound card directly to the output by means of rdcatch?
  2. How do I make Rivendell play Audio from the "Line In" of the Sound Card on the air to play audio from a satellite feed?


As an example, this station replays the BBC World service for 8 hours per day received off a satellite dish. Using two macro items in the log, the sound card audio input from the dish can be routed directly to the output and the log paused.

  1. Macro Stream on... (timed event to start satellite Audio)
    1. ST 0 1 1! < -- Switch Take event... connects input 1 to output 1 on matrix 0
    2. LB BBC World Service! < -- Displays Label in rdairplay to tell people in studio what is happening
    3. PS 0! < -- Player Stop --- Stops rdairplay
    4. SP 2000! < -- Wait for 2 seconds
  1. Macro Stream Off... (timed event to return to local program)
    1. LB Radio Station Name! < -- Displays my radio station name in rdairplay
    2. SR 0 1 1! < -- Switch Remove event .... disconnects input 1 to output 1 on matrix 0
    3. PN 0! < -- Player Start --- Start rdairplay
    4. SP 2000! < -- Wait for 2 seconds

The two macros should sleep for a second or two to prevent RDairplay skipping over them. Ensure that 'Execute asynchronously' is not enabled for each cart.

Configure a switcher using the 'local audio' device (rdadmin->manage hosts ->switchers/gpio), then the standard switcher commands can be used to switch to and away from the sat. feed. The best thing to do is probably to use a macro cart to switch and stop the main log at the appropriate time (fire it from rdcatch so you have gpi signals available).

"Local audio device" is Rivendell switcherese for a local soundcard, you configure it to function as a switcher just like an external one, but done in software.

Basically, a standard rivendell soundcard has inputs feeding a routing matrix with the outputs from the matrix summed with the output ports from the playback engine (Either in hardware, with ASI cards or in software within caed), when you define a matrix as being a "Local audio" that routing matrix becomes available as a switcher device to rivendell.

Thus if a given host has say a 4 stereo in/ 4 stereo out card (say a delta 1010LT or something) then you can define it as a local audio adaptor and can route any input to any output in addition to using it to playback and record audio in the normal way.

  • You may have to fuss a bit with a mixer program (e.g. alsamixer) to get the line-in jack routed to RD's input. Specifically, you want the line-in input to be set as the 'record device'. Many sound card drivers default this to the mic input, which is probably not what you want. The specifics vary according to the model of card in use.