# Wal*Mart to support Blu-ray exclusively by June 1st, 2008

Discussion in 'DVD Video' started by ninphan, Feb 15, 2008.

1. ### RogerGuest

Bandwidth is no where near this simple to figure out.
The above would be true only if no two adjacent pixels are the same
and that every pixel changes all of its values every time a frame
changed. Not only that, but the new values would require the binary
values to make the maximum change. (IE if the previous value were
10101010 then the new value would need to be 01010101. In real life
the band width required would only be a fraction of the result shown
above.

In college, my networking class had to figure out the band width for
given signals. That was more work than calc one and two and required a
good proficiency in Calc two to do the calculations. There must be
someone on here that remembers enough to actually calculate
bandwidth. Of course the simplest way is to just look it up.
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)

Roger, Feb 23, 2008

2. ### Alan BrowneGuest

What you say is true (fancy finding you here Roger...) but the fact is
that the Bandwidth of BD is a lot higher (about 4:1) over what, for
example, apple movies initially offers for DL. To suggest that what
apple movies will deliver matches 1080p + 7.1 is a strong stretch.

So many rural people simply will not have the BW to DL movies in a
reasonable way. My ISP has started experimental deployment of 100 Mbps
capable cable modems (multi channel) and that would be sufficient,
and continue while DLing. Cost is another issue.

Alan Browne, Feb 23, 2008

3. ### The alMIGHTY NGuest

Similarly, if you're going to accuse someone of not spelling words
properly, you should make sure your own spelling and grammar are
correct.

The alMIGHTY N, Feb 23, 2008
4. ### ninphanGuest

Uncompressed bandwidth is just that simple to figure out, similarly to
uncompressed PCM.
Are you sure you're not thinking of bandwidth post-compression?
The 1100 Mbps figure is for all pixels in every frame being sent. BD's
maximum theoretical bandwidth is 400 Mbps with current video rate
capped at 40 Mbps, which is 3.636% of uncompressed 1080p24.

ninphan, Feb 25, 2008
5. ### dmasterGuest

Yes, uncompressed bandwidth is simple. But you are overlooking the
possibility of *lossless compression* bandwidth. In reality, all
broadcast HD content, whether OTA, cable, or Sat is compressed with a
*lossy* compression to decrease the bandwidth requirements. However,
any reasonable attempt at lossless HD delivery would still use
compression to reduce the bandwidth requirements. One technique is to
locate multiple pixels of the same color and encode them as X-pixels
of Y-value rather than repeating Y Y Y... X number of times.

Dan (Woj...)

dmaster, Feb 25, 2008
6. ### ninphanGuest

HI Dan,
I'm fully aware of lossless compression, I was merely stating the
bandwidth necessary for uncompressed 1080p24.
I have been involved with taping communities for years
using .flac, .shn and occassionally .wav files, including 24-bit .flac
files as most tapers these days record directly to digital in either
24/96, 24/176.4 or 24/192.
My point was that with Blu-ray's technical specifications we could see
a new version in 10 years supporting 335GB (10 @ 33/5GB/layer) and up
to 400 Mbps, which could allow for delivery of both losslessly
compressed audio and losslessly compressed video.
=D

ninphan, Feb 26, 2008