Thursday, October 20, 2011

All Digital

As of Wednesday Oct. 12, WSBF's web stream is digital, all the way through the chain.  WSBF's studio A control board is a PR&E Airwave Digital; when I started this project, the auxiliary analog output for our control board's Program 1 was used for web streaming and the digital output was used for our over the air broadcast.  I originally implemented a way to use the digital output from Program 2 for our web stream, but we soon realized that, because our phone module can only output to one Program channel at a time, we wouldn't be able to hear callers over the air and on the web stream at the same time.  I tried to fix this by swapping some Studio Hub cables around to let Program 1 go to both places.  Unfortunately, we figured out that the same Studio Hub cable that brings the digital Program 2 audio into the production studio also brings the production computer audio back into studio A, so my first efforts to implement this solution left a live session silent for a few minutes.  Eventually I came up with a combination of connections that would let Program 1 go to both places and still allow the production studio to work.  At this point, for the first time, WSBF's web stream was post dump and post EAS, but the chain was still not entirely digital.  The digital Program 1 audio was going into the processor that we used for web streaming, but it was going out of the processor to the transcoding computer as analog.  To fix this I found an old audio card, an RME Digi96/8 PST, that supports AES/EBU audio; I looked up some info on Linux support for the card and luckily it works with OSS, which is what our system already used.  I installed the card in the computer and was not the least bit surprised when it didn't work.  After a few hours of reinstalling OSS and tinkering with settings, I go the card to show up as being installed, but I couldn't change any settings for it.  On a hunch, David Cohen installed pulseaudio on the computer and that allowed us to change the settings of the sound card to use the correct input and format.  At that point though, the sound card still wouldn't work, so it was back to a couple more hours of tinkering with OSS settings.  After a lot of research and a few restarts, I launched Darkice, refreshed the listen now page, clicked play, and something wonderful happened; the all digital audio poured out of my speakers.  You can hear for yourself at wsbf.net/listen.

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