SMPTE 2011: Remote and Mobile Monitoring of On-Air Signals For Centralcasters
October 28, 2011
HOLLYWOOD: Hello. This is NBC calling. We want remote
monitoring of our 10 TV stations and multicasts with discrete, full-resolution
channels, and multiviewers for each channel group, distributed across multiple
“Within 30 Rock, they wanted them on digital and analog baseband
infrastructure, in-house QAM distribution, Internet streamed and to air-check
Michael Wright of TI Broadcast Solutions Group. “And they
wanted to do it with minimum financial outlay.”
Wright’s team brought discrete channels into TI’s Atlanta hub into a
multiviewer via HD-SDI, then encoded them for traffic down the line, he said. Individual
program streams were downcoverted at the hub for the multiplexer. From the
multiplexer, they came out ASI and were put through a transport stream
processor, then moved across the MPLS IP WAN, on to the decoders for the
network. No new network was created for this, he said.
TI used a single 16-input multiviewer and fed it baseband. They had HD
channels, SD encoded downcoverted signals, and HD encoded multiviewer output.
They wanted to keep the signals HD in the multiviewer because they’d be
windowed fairly small, Wright said.
The primaries were HD, but not the dot-twos, which were SD from the start. TI
used an existing IRD, passed them through to the multiplexor and HD encoded them
for the multiviewer.
“The real key to the project came when it was time to remux,” Wright said. “As
we set out to determine the bit rate, we had to consider the WAN bandwidth and
the target distribution methods.”
Again, NBC wanted the signals Internet streamed, distributed on the digital and
analog baseband infrastructure, in-house in QAM, and to air-check recorders. The
challenge was creating a remux of the 10 discrete HD streams of the stations,
and get them back up to New York.
“We came up with a single-threaded approach,” he said. “We used a daisy chain
of 10 encoders to the multiplexor. Each is at 3 Mbps, so you end up with 30
Mbps. We had set our multiviewer at 5 Mbps, meeting the payload limit of 38.8
Mbps. We didn’t have to apply the daisy chain to the SD nonstop channels. All
10 of those were simply fed into the mux. And so, what we wind up with is, two
program streams... going from Atlanta to New York--one for the flagships and
one for the nonstops (SDs). New York then gets NBC HD multiviewer; HD NBC
channels converted to SD; the SD nonstop multiviewer stream, and the SD nonstop