What's the optimal load of SD and HD channels in a DTV signal's 19.4 Mbps bitstream?

[Current.org moderator]

Weighing viewers' rising quality expectations, what are the best combinations for a public TV station allocating capacity? What's the viewer experience like on the SD and HD channels?

[Gens Johnson]

I'll bet there is a different optimum for almost every broadcaster's situation! Are we looking to maximize viewers? contributors? delivery of "mission media?" Are we talking about the next few months, or a longer term view? Are we competing with cable, other DTV broadcasters, or the web for our viewers attention? Are we in a rural situation where the only local or regional programming being broadcast might be PTV? Are we specifically trying to serve the population that is not part of the cable/dish/broadband universe?

Yeah, that's not a "n-mbps per channel, x-channels" answer...but those are the bigger questions to answer before a station can decide on the "optimal."

[Current.org moderator]

Good point, Gens. Refined question: For urban stations for the next year or so, given present compression capabilities and viewers' present quality expectations, what is the best number of multilcast channels, SD and HD, for a public TV station to put on its DTV signal -- allocating enough bitstream to make an adequately impressive HD while broadening service (cume) with multiple SD streams?

And how is the answer different by daypart -- daytime, primetime and weekends? And how is it different for rural stations with high over-the-air potential, where variety may trump picture quality?