How to broadcast TV without TV tuner?

How do TV stations broadcast in HD?

• I'm wondering because I was recording some over the air broadcast tv (on a computer) and the file size was rather big. Since it's a broadcast, that means the signal is broadcast once and it gets picked up by receivers, so the bandwidth used to broadcast isn't too much, right? But wouldn't that mean that cable and satellite has to broadcast to every suscriber individually? If so, would that explain why the same channels in the same area (I'm in Chicago) look different on OTA (over the air) than cable? My cousin noticed that OTA channels look better than his cable suscription. (compression probably) I have an HDTV USB TV Tuner, recording several channels give me different video sizes and resolutions since the software automatically records according to the resolution and bitrate? given. However, some channels broadcast in 720 at 59fps and others at 1080 at 30fps. How do I find the actual resolution of the broadcast? Even though some channels broadcast in 1080 or 720 as the recording software says it is, some of the tv programs don't look as sharp or clean as if they really were that resolution. Are some programs just being "upscaled? I'm asking because if they are being upscaled, I could just re-encode them in a smaller resolution and reduce the space they take up.

• Answer:

  >Oh, I meant to ask, if the broadcast can change resolution and bit rate from program to program, or is it fixed? Yes, both broadcast stations and cable companies can change the resolution & bit rate of the signals. In fact, they often do. ---------------------------------------… For example, a TV network distributes a prime time program at 1080i at the best possible quality. Each station has the same bandwidth ( 6 mhz, same as the old analog system) to work with. If the station only sends out the one program, the quality is as good as it gets. But a local station might have a couple of sub channels they want to broadcast as well. So something has to give. So to make room for the sub channels they compress the 1080i signal. This produces digital artifacts; you can make a 1080i signal look like c**p if you compress it enough.. Just because a TV signal is HD, doesn't mean it doesn't look like c**p. It's like a MP3 music file, if you use a high enough bit rate you can't tell the different between it and it's source. But if you use a low enough bit rate, it can sound like an old AM transistor radio. Or they could down convert the signal to 480i (and maybe compress the heck out of it too). If someone is watching on on a HDTV, the TV automatically up converts the picture. Up converting just means that a chip in the HDTV guesses at the missing information. Cable and satellite companies do the same kind of things. A cable company can only send so much signal down a coax cable. So how many channels they can offer depends on how much they compress signals and how much down converting they do. >I was recording some over the air broadcast tv (on a computer) and the file size was rather big. Broadcast stations use mpeg-2 (It as decided back in the 1990s). You can transcode it to mpeg-4 if you want to save space. You could transcode it to a lower bitrate and even down convert it if you want to go to the trouble. >since the software automatically records according to the resolution and bitrate? The software just saves the data stream ( Mpeg-2) in the TV signal. I've seen software that would automatically transcode the saved programs to Mpeg-4 to save space. The transcoding takes of lot of computing power. >But wouldn't that mean that cable and satellite has to broadcast to every suscriber individually? Only for view on demand type programs. Otherwise everyone gets the same signal.