Digital OTA broadcasts will be the best signal in terms of compression, no doubts about it. The only thing better is BluRay.
Part of this goes back to past discussions we've had on here about whether 1080i is better than 720p. The biggest reason for the difference you are seeing is in the framerate. 720p is progressive scanned, which means that they are scanning every line of video from top to bottom. 1080i is interlaced, meaning they only scan every other line and alternate between frames. This way you get appearance of a full image for only half the bandwidth, and that shows up in your measurements. So 1080i does have more lines of resolution, but 720p is sending more frames. And for you videophiles, yes I know I greatly oversimplified the progressive/interlaced, 3/2 pulldown and fps definitions for the sake of argument. --------------------------- Brian Weeden Technical Consultant Secure World Foundation <http://www.secureworldfoundation.org> +1 (514) 466-2756 Canada +1 (202) 683-8534 US On Wed, Apr 8, 2009 at 12:16 PM, James Maki <[email protected]>wrote: > Brian, > > I pay for HD and would like to think I get HD, but if comcast is only > giving > 2/3 of the bandwidth that is considered HD, I may look elsewhere. I have > read that digital over the air broadcasts better than analog. I am about > 30-40 miles from Seattle and Tacoma, where all the networks have broadcast > towers, so am thinking of investigating an antenna. It is a shame that we > have investing in a switch-over to HD only to not really be getting HD. > > I would rather have 100 quality stations than 600 crappy stations. But that > is just me. I am sure there are people who get cable just for the soap > network or game network, but not me. > > Anyway, I was just looking for confirmation or correction on my math. > > Thanks, > > Jim > > > -----Original Message----- > > From: Brian Weeden > > > If you looked at satellite HD broadcasts I would suspect you > > would find even > > worse bitrates among several of the HD stations. > > > > > Brian Weeden > > Technical Consultant > > > On Wed, Apr 8, 2009 at 1:35 AM, James Maki > > > > I discovered something this week and am trying to understand its > > > ramifications. I noticed lots of pixelation and motion blur > > > the last two weeks of Heroes. > > > > NBC is averaging about 4.8 GB per hour for a 1080i show. I > > > thought is a bit low > > > > I am wondering > > > if my math is correct). I am not sure how to factor in the > > > fps figures, if at all. > > > > > > If you can add some insight, it would be appreciated. > > > > > > Thanks, > > > > > > Jim Maki > > >
