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Monitoring PPM for Online Streams
Here's one way to monitor your online PPM signal.
The hardware and software
Finding a suitable rack mountable computer was simple. A quick browse of the storeroom yielded a used 2RU case with a 2.66GHz Pentium 4 and a fresh install of Windows XP Pro. I first tried without success to use two Digigram MixArt audio cards that provide four outputs each, unfortunately their age and tricky wave driver support made them unsuitable. For an alternative I found the M-Audio Delta1010LT that provides four stereo unbalanced outputs is relatively inexpensive and supports my PC's PCI-X bus architecture. I bought two. Total cost: $340.
The software proved to be the hard part. I first checked out the usual suspects: VLC, Winamp, Quicktime, iTunes, Window Media Player. All had issues. You couldn't run more than one instance of the player or you couldn't select the desired audio output - each stream has to be assigned it's own dedicated audio port. Also important is repeatable configuration so that if the system needs to be restarted all of the audio patches remain. Naturally no software designer ever imagined it necessary to connect to more than one stream so I needed to find a way to run six instances of the player application each assigned to its own dedicated audio output.
Following a somewhat exhaustive search I fell upon an obscure player and web stream recorder application by The Best Ware Studio called Radio? Sure! Pro. Thinking the program aptly named I tried it and found it hit all of my bullet points. I could run six instances each pointed to a different output of the two M-Audio Delta LT1010 cards installed in the system. Best of all each instance could be started by way of a simple desktop shortcut. Total cost: $10.
Radio? Sure! Pro reads its configuration at application startup from an XML file located in whatever folder you chose to run the executable from. This makes it possible to install several copies of the program, edit the XML accordingly, and create a shortcut. The XML file is really the key here. If the programmer had chosen to save his settings in the registry, it would not have been possible to create several slightly different setups whereby the audio output and stream URL are unique. Of course editing the XML file is a snap too, compared with attempting to locate and manipulate several cryptic registry entries.
With six streams all playing out simultaneously, I note a minimal 20-30 percent CPU load and very consistent 500MB of RAM memory in use. As I write this, our system has performed without fail or interaction for three solid months and I suspect it will run smoothly well into the future.
Kernen is the chief engineer of WCSX, WRIF and WMGC, Greater Media Detroit.
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