Originally Posted by hmurchison
another_steve. Yes yes yes. I forgot to state that I hope to the hardware move to 1080p playback with the explicit acknowledgement from Apple that there are no plans for iTunes HD movies to move to 1080p. This way I can play 1080p home created files or trailers in their full glory.
Okay, good. Then we're in agreement on the 1080p issue.
The Blu-ray rips that you speak of have been recompressed. There's no way to take a Blu-ray video file running 15GB and 30+ Megabits per second and compress that down to 4GB without hammering the mbps and stripping audio channels.
I don't know if that's true or not. I suspect it's not true as I've sometimes seen these files in their native format (file extension) at the same size. Further, ripping a standard DVD to H.264 usually results in a 1GB file. Full HD has roughly 6x the pixel count, so that's a bit less than what you describe. Also, just because a format has a maximum bit rate and can store many GB for a movie, doesn't mean they do. But, to be fair, I haven't done a comparison of actual Blu-ray disks to make that comparison.
Regarding the qualitative difference it's pretty clear 1080p video is a bigger pill to manage.
1280 * 720 = 921,600 bits per frame
921,600 * 24 frames per second = 22, 118,400 bits per second
22,118,400 / 8 = 2,764,800 MB
1920 * 1080 = 2, 073,600 bits per frame
2,073,600 * 24 fps = 49,766,400
49,766,400 / 8 = 6,220,800 MB
There's no way around it...if you want 1080p you have to use a lot more data.
Well, I certainly agree with the notion that 1080p requires more data. The question is how much is necessary? Not to be pedantic, but there are two things wrong with your analysis. Since you went to the trouble of "doing the math" in order to prove your case, I'll agree that your math is correct (not that I checked), but your assumptions are not. First, your "bits per frame" erroneously makes the assumption that each pixel only requires 1 bit. Second, every frame isn't compressed in its entirety. H.264 does use reference frames, but then it uses techniques like inter-picture prediction to essentially only encode the changes between frames, etc. Likewise, the size of a file needed to display an h.264 encoded movie does not necessarily fall into a simple math equation.
In any case, the bigger issue here is that we all agree that 1080p support is strongly desired and that iTunes support for this feature is a completely independent issue.
Update: It looks like this is all a moot point as Apple has just released their AppleTV 3.0 software, but no new hardware. Apparently, this is still just a hobby for them. This is sad. I may have to invest in a product from someone else to meet my needs apparently.http://www.macworld.com/article/1435...appletv_3.html