The Dish on Viacom
Thu Mar 11 21:13:37 EST 2004
<<On Thu, 11 Mar 2004 18:46:05 -0500, Mark Laurence <firstname.lastname@example.org> said:
> Both services use mpg streams, so they are similar in that way to
> Internet streaming video.
EchoStar and DirecTV both use MPEG-2 FlexMux and the MPEG-2 video
codec. However, EchoStar uses the European standard DVB-S delivery
system, while DirecTV uses something else. One or both of them
probably contract out the video encoding to the compression place in
Colorado that everybody else uses. I believe DVB-S uses the MPEG-2
layer III audio codec; I'm not sure what DirecTV uses for audio
(probably Dolby AC-3 aka ATSC A/52).
> For prime time sporting events and premium movie channels, they
> crank up the picture quality to its highest level, but if you're
> watching a less-watched show on an obscure network, you can see
> plenty of compression artifacts.
Both services determine for themselves the quality targets for each
channel they carry. The compression people then analyze the bandwidth
requirements and allocate satellite capacity on an ongoing basis in
response to program material. (The same thing is done, in many cases
by the same people, for cable.) For example, a high-bandwidth sports
or premium channel might be multiplexed with one or more low-bandwidth
channels like C-SPAN, The Weather Channel, and must-carry baggage like
local-into-local DayStar and TBN affiliates. The higher-value
channels are allowed to encroach on the bandwidth available to the
lower-value channels in the same multiplex.
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