Sorry if this a stupid question, I've just recently begun researching IPTV services.
My question is -- do they typically re-encode/re-compress the streams they get? Usually a cable provider will receive a high-bitrate stream from, for example CNN, something like 1080i H.264 sometimes 30+ mbps. And then they would compress it to maybe 10-12 mbps and send it to their subscribers. That's where I assume IPTV providers grab those streams and re-broadcast them to their customers.
But do they do any processing before they re-broadcast? I would assume transcoding every channel on demand in real time would consume a lot of CPU power, so my guess is that they don't. They just give you what they got from the source 1:1. Is this correct?
And further, how do they do the capturing and re-broadcasting? Is it screen capture (I hope not) or can they download the raw data and forward it to you in real time? I guess they all get their content from the same places, so it may already have been processed for them and all they have to do is pay for it and rebroadcast it, but I could be wrong about this.
Just wondering if anyone has insight on any of this, it would help me determine whether providers' quality varies significantly.
You are correct with some of your points, but you are kinda all over the place with your questions so it's a little tricky to answer them all.
But in short, IPTV providers do not transcode. They simply restream the content from their "sources".
"Sources" come from all around the world. It could be a kid transcoding in his parents basement, or it could be already in a digital format (think PS Vue, MLB, etc). It could be local OTA's. Could be anything really. Most providers have similar content because they "share" or trade with eachtoher. A provider that is missing some channels will offer some channels to another provider that does have them. There are lots of forums online with people trading feeds.
In most cases, if it's already a digital stream somewhere, then essentially a provider will just grab the direct links and restream them, no transcoding or anything. This is common for sports networks like MLB and NHL.
But basically yeah, providers just run a dedicated server that takes an input feed, and turns it into an output feed that all their customers can access.
Pretty simple stuff. Don't try to overthink it.