One of my co-workers just caught me up short. I was discussing the new NORTH BY NORTHWEST Blu-ray, which is amazing, and the TCM HD cablecast of VERTIGO, which was stunning. Now, what is an HD showing based on? I confess my ignorance.

Forgiven, but please rephrase everything. I have no idea what you're asking.

I think he's asking what the channel is actually playing when a high-def movie is on: a DVD, a Blu-ray disc, or something else entirely?

(The answer's Bachelor #3, but I'm not savvy enough to know exactly what format's being used. D5? HDCAM?)

It varies by broadcaster, but most channels are broadcasting from HDCAM. Some are accepting digital uploads, usually for advertising. I hear that some channels are accepting content on hard drive, which I imagine would make life very slightly easier for production companies.

HDCAM is shaping up to be the workhorse of the HD side of the industry, in the same way that Digi-Beta dominates SD.

It only carries four channels of audio, though*, so some companies are using HDCAM-SR, which offers twelve audio tracks, and so is more versatile (especially for broadcasters simultaneously offering several languages).

For the time being, tape is still the cheapest and most convenient way of moving the data needed for HD programming.

* four channels, but you can combine two of them to carry an encoded 5.1 signal instead.

My head is feeling more stuffed with new info by the minute!

Alan, thanks for clarifying what I meant. Jeffrey, I'll take all next summer and rephrase everything I've EVER said. :)

Please start from the beginning. Dang!

I haven't seen TCM-HD's Vertigo, but it was my understanding that the channel doesn't actually show any HD content - just upconversions (which may explain the 'windowbox' effect that all their film programming has). Compare this to a station like MGM-HD that shows actual HD transfers.