In case you hadn’t been paying attention, the FCC recently concluded a massive spectrum auction that (a) didn’t bring in nearly as much money as the government expected and (b) removed channels 38 through 51 from TV broadcast service.

The problem is that there aren’t quite enough open channels for all the stations that are vacating the UHF spectrum. Some stations opted to sell their channel, turn off the transmitter, and go onto other pursuits. Others brainstormed ways to share a common channel, massaging their video encoders to accommodate two or three different broadcasters – something that, not too long ago, was prohibited by the FCC.

In the Philadelphia TV market, a big game of musical chairs is already underway. UHF channels that were once lit up and are now dark include 8 (WNJB), 23 (WNJS), 25 (WTVE), 27 (WGTW), 29 (WUVP), 35 (WYBE), 38 (WTXF Lehigh Valley), 39 (WLVT), 43 (WNJT), and 46 (WFMZ). The UHF spectrum, once bustling with stations, now looks like a ghost town.

Several stations took the money and ran, while others doubled and tripled up to share a channel and presumably cut operating costs. That’s all fine and dandy, but what does that do to the quality of HD video? Granted, MPEG2 encoders have come a long way since they were first brought to market a quarter-century ago.

But now, we have MPEG streams with two HD and multiple SD video programs, all taxing the adaptive bit rate streaming and statistical multiplexing functions of encoders. The result? HD channels don’t look as bad as I thought, but that depends on the content – you can compress the heck out of a newscast or other talking head content, but live sports present a much bigger challenge.

As for the SD channels, many of them are pretty bad, not to mention being formatted in the older 4:3 aspect ratio. I don’t understand why some of these stations need to offer so many of these low-resolution SD program services, aside from specialized channels like France 24 and NHK. KJWP on channel 2 in Philadelphia broadcasts nothing but old TV shows, just about every one in a 4:3 format.

Here’s what the Philadelphia and Allentown UHF spectrum used to look like a couple of years ago.

And here’s what it looks like now. Only ten RF carriers were detected during my tests of the Channel Master Stream+ Media Player – 2 (KJWP), 6 (WPVI), 9 (WBPH), 12 (WHYY), 17 (WPHL), 26 (KYW), 31 (ION), 32 (WPSG), 34 (WCAU), and 42 (WTXF).

KJWP-2 has five minor channel services, while WPVI-6 offers two HD channels and one SD channel. PBS station WHYY on channel 12 is now sharing its bits with shopping channel WMCN, and WPHL on channel 17 shares bits with the former Univision station in Philly, WUVP. KYW-26 has two channels as before – one HD, and one SD – while WCAU has combined both NBC programming and Telemundo broadcasts. (NBC owns Telemundo.)

Curiously, WPSG on channel 32 continues to provide just one minor channel for HD broadcasts, leading one to wonder if they’ll enter into a channel-sharing agreement in the near future. And Fox O&O WTXF has yet to abandon channel 42, carrying one HD and three SD program services.

KJWP on channel 2 has five standard definition channels in its multiplex.

 

Here’s the “mux” from KYW-26, which is more conventional with one HD and one SD program service. HD picture quality is very high.

 

In contrast, the mux from VHF channel 9 in Bethlehem has no fewer than ten different channels, most of them standard definition. Two HD channels are allocated about 5-6 Mb/s each. Four different TV stations share the channel encoder.

 

But the craziest “mux” has to be VHF channel 9, formerly WBPH in Bethlehem, PA. This channel is now shared by four different stations – WYBE, WBPH, WLVT (PBS), and WFMZ (Ind). There is a total of TEN different minor channels packed into a 19 Mb/s stream, with statistical multiplexing frantically doling out bits among the different programs “as needed.”

In the midst of this multiplex are two HD channels (WFMZ and WLVT) that, when I captured their bit stream, were allocating just 3 to 5 Mb/s a second for HD channels. Keep in mind that a decade ago, a 1080 HD broadcast required better than 14 Mb/s for acceptable video quality.

Now, encoder manufacturers think that same quality can be achieved with one-third to one-fourth as many bits. One trick they use to lower the bit rate is to use a longer Group of Pictures (GOP). Traditionally, the length of a GOP was anywhere from 15 to 30 frames, or about ½ to 1 second of video. Now, we’re seeing GOP lengths of 60 frames, or 2 seconds for 1080i video. (Streaming services typically use 90-frame GOPs.)

The upshot of all this? You really can’t make the claim anymore that over-the-air HD video is of better quality than what you get on cable. In some cases, cable HD quality will be noticeably better than broadcast if the station is packing its mux with numerous HD and SD services. ATSC 3.0 will help as it uses a more advanced codec (HEVC H.265), which can encode Full HD video with bit rates as low as 1 Mb/s for acceptable quality.

But adoption of ATSC 3.0 will take some time and require either new sidecar receivers or new TVs, as the modulation system (OFDM) is incompatible with 8VSB. There’s even talk of using a combination ATSC 3.0 receiver/802.11ax router to distribute channels over wireless networks.

No question about it – we’re definitely in a brave new world with TV broadcasts. Will picture quality matter to viewers in the future? Stay tuned…