[opendtv] Re: Time to give up on 1080i for football

  • From: "John Shutt" <shuttj@xxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Tue, 8 Dec 2009 15:19:14 -0500

True, the bit rates are capped so that the maximum bitrate of any one channel is total ATSC video payload (for us about 16.7 Mbps) minus the minimum bitrates of the other three streams. That results in bitrate constraints of 7Mbps to 14.4Mbps for the HD service, and 800 Kbps to 7.7 Mbps for each of the three SD services.


Minimum bitrates are determined by the vintage of our Tandberg encoders. Bits are of course further divvied up between encoders by weighting in the stat mux.

John

----- Original Message ----- From: "Tom Barry" <trbarry@xxxxxxxxxxx>

They may technically be VBR but I'd wager they still have some fairly
stringent peak bit rate limits that restrict the efficiency of the
encoding for the total program, sort of a compromise between optimizing
the average bit rate over a two hour movie and individually optimizing
each second or so.  That is, you can't save up bits displaying a still
scene or talking heads and then apply the bits to a explosion scene 10
minutes later like you could on a BD.




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