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  Magnificent Seven: What's New for Users in QuickTime 7
Subject:   A few comments on broadcast
Date:   2005-05-11 09:28:39
From:   benwaggoner
Hey, I am Ben Waggoner :).

Anyway, a few comments on IPTV/DBS style broadcasting. All the standard def digital cable and digital satellite today in the US uses "Half D1" which is 352x480 interlaced 29.97 fps. So there are actually quite a fewer pixels per second to process than with 640x480.

Also, today broadcasting uses statistical multiplexing, where they're doing a VBR across multiple simultaneous channels. So even if a channel averages 1 Mbps, it'll go up and down quite a lot during the connection.

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  • Chris Adamson photo Re: A few comments on broadcast
    2005-05-11 13:03:36  Chris Adamson | O'Reilly AuthorO'Reilly Blogger [View]

    Thanks for the clarification, Ben.

    Actually, I'd be delighted with 1.5 Mbps, so needing less than that is great news. A few jobs back, I worked in distributing MPEG-2 files to network affiliates and cable headends, and we were required to work in the 6-8 Mbps range (and some wanted to go up to 10). So, that kind of business could achieve a near order-of-magnitude bandwidth improvement by moving to H.264.

    But at any rate, I think your point is that the stress of the 1.5 Mbps, 640x480 encode in this article is more than is actually required by real-world SDTV, right?