Originally Posted by jdspencer
I'm wondering if it is even possible to broadcast a 1080i and 720p signal together?
Apparently not. The engineers from Harris were pretty emphatic that both feeds need to be 720p -- at least for the NetVX encoder.
How much would the 1080i suffer if the bit rate were reduced in order to bring a 480i up to 720p. I'm thinking WBNG with The CW. I'd at least like to see The CW in letterboxed 16:9 instead of it being cropped to 4:3.
There are a couple of issues with this. First, CW is actually distributed to affiliates in 1080i... so the station is already doing a downconversion to get it to SD. Personally, I would just convert both the CBS and CW feeds to 720p and air both in HD... but it does get into some expense for conversion gear, switching, and encoding.
CW content is designed to be center-cut safe, so if you do downconvert it from 1080i to 480i center-cut, it yields very good SD at 640x480 resolution. But if you downconvert it to 480i letterbox, you are throwing away a considerable amount of detail to save those sidebars... the active picture area winds up becoming 640x360 pixels, if my quick math is right... this isn't going to look too wonderful when somebody's widescreen set stretches it back out.
Since it has been proven that two 720p feeds can be sent, then WICZ (Fox40) could do the same with MyNetwork, right?
Fox is something of a special case: while most networks supply satellite receivers that give you an uncompressed HD serial digital output to feed your switching and graphics gear, Fox uses a technique called stream splicing. The idea is, the station doesn't actually decode the compressed feed from the network, but switches between that and the encoded compressed feed from the local insertion gear. This wouldn't take advantage of the efficiencies of Harris's new encoders, so my guess is that it probably wouldn't work unless the station decoded the Fox feed, and did switching and re-encoding in a more traditional way.
I've had only limited experience with the Fox system at our Memphis station, so there might be other solutions to this by now.