Posted March 17 2004 - 10:06 AM
| Here's the thing. Since BluRay holds 50GB of data isn't that enough to hold a hi-def MPEG2 movie at very, very high quality? Isn't bandwidth only an issue on digital delivery systems like cable, etc? |
In response to the first question, why do I want to settle
for very high quality when better than that is available? The answer is simple, I don't.
In response to the second question, bandwidth is always an issue. I'm wondering if you've done the calculations. That's 50 base 10 GBs, and all my calculations are done based on that factor. You have 400 billion bits available for storage.
Your maximum data rate is 36 million bits/second. At 3 hours and 5 minutes, you're out of space on the 50GB disc. You can't store any of the extended versions of Lord of the Rings on this.
So, let's back it down to 24 million bits/second. This is the same as D-VHS, which is "very very good" quality. Clearly this is an improvement over HDTV, which is a nice starting point
. This gives us about 4.5 hours of storage time, which is good. I've read, but have not confirmed that Blu-Ray is limited to 24 Megabits/second for video.
On the other hand, we have HD-DVD, which is limited to about 20 Megabits/second. At first glance, this seems like a tremendous disadvantage. True, if MPEG-2 encoding is used. However, HD-DVD has "mandatory" codecs of MPEG-2, MPEG-4/H.264 and WM-9/VC-9. It could be that either or both of the advanced codecs get pulled from the spec based on what the licensing costs will be. Mandatory in this sense means that players must support all these codecs, and that content providers must use one of these codecs.
Everything I've read, and everyone I've talked to about the topic indicate that both of the latter codecs have better performance than MPEG-2. Stacey is one, but he's biased, since he works for Microsoft.
Perry Sun has seen the demos, he too has indicated in WSR that WM-9 had demonstrably better performance. I don't know if he's seen MPEG-4 vs. MPEG-2.
I have not seen both on the same material, so I can't comment personally on head to head comparisons. I have seen WM-9 material, and the one thing I remember most was the lack of mosquito noise. I find mosquito noise quite distracting.
So to me, the backwards compability is addressed by HD-DVDs inclusion of MPEG-2 as a "mandatory" codec.
Then there's the manufacturing infrastructure for media, and clearly HD-DVD has the edge here since it can use the existing DVD infrastructure where Blu-Ray cannot.
As I said before, if Blu-Ray had the wisdom to choose one (or both) of the more advanced codecs then I would be supporting it as opposed to HD-DVD. But they didn't.