Current broadcasts are either:Is this above statement accurate? I thought all broadcast (non PPV & VOD) HD channels are max 1080i/720p (~1024x720)... not 1080p (1920x1080) unless it's over VOD. Which means we're already below 1440x1080 for transponder channels. Also, you would never change the resolution. That would completely screw up how the image renders on you TV. DTV would need to add in extra compression to increase stations per transponder. Or am I just crazy?
1920x1080i
1280x720p
Rumor has it that Dish Network downresses 1920x1080i to 1440x1080i. Maybe this is how they get 8 HD channels per transponder.
Sure, you don't have to touch the resolution. You can use better encoders. Variable bit rate encoding. You can mix and match the right level of motion demanding channels, vs highly compressible static, slow moving channels. You wouldn't want to put say 6 channels that all show action movies and sports together. You would split it up with news style (talking heads), shopping, already highly compressed content, 720p content mixed with 1080i in the proper mixes, etc...
Cable uses advanced encoders by Imagine Communications, RGB Networks and Cisco Systems to get 3 HD channels in 6 MHz of bandwidth, as opposed to older encoders that only fit 2 HD channels in that same space. It works as long as the content is properly chosen. Perhaps 2 720p channels and 1 1080i channel. Or 1 720p channels, 1 1080i "talking head" (like HLN) and another 1080i like TNT or something.
Its the proper choice of content that helps minimize bit starving other networks on a very limited bandwidth transponder.