On 4/20/07, Dieter <[EMAIL PROTECTED]> wrote:
> > > 1080p
> > > Mpeg 1, 2 up to 80 Mbps
> > > Mpeg 4 up to 20 Mbps ( Is this really the worst case? Seems low. )
> > > H.264 up to 40 Mbps
> >
> > Are these right? According to my PS3 info display when playing a BluRay disk
> > (XMen-3, Mpeg-2 encoded I believe), the bandwidth is 20Mbps. That's playing
> > at 1080i. Assuming 1080p needs twice the bandwidth, that makes around
40Mbps.
> > Even for MPEG2.
> >
> > So your figures seem a little high... I'm not sure how accurate they are,
but
> > figures I've seen show DB tops out at 48Mbps, and HDDVD at 30Mbps... (HDDVD
> > uses mpeg4, while BD is mpeg2 IIUC). [Someone correct me if I'm wrong here]/
In engineering you need to design for the worst case. I have read lots
of complaints about players that cannot handle high bitrate video,
so this *is* a problem. Bad engineering. :-(
The numbers are from
http://xbitlabs.com/articles/video/display/video-playback.html
If someone knows of a more authorative source for maximum bitrates
please post it. If there even *is* a hard number for maximum bitrate?
OTA DTV has a hard max bitrate due to available RF bandwidth, and
presumably cable/sat do also. But are there hard limits on Blu-Ray
and HD-DVD? On something you download from the Internet?
If someone gets "artsy" and makes a video where every frame is
completely different from the previous frame, it is not going to be
very compressable, so the bitrate will skyrocket. And yes, people
do make videos like this. (I don't like the effect, but that is a
personal subjective opinion.) A real-time decoder has to handle the
peak rate, not just the average rate.
> isnt that the data rate for the decoded/uncompressed video stream?
> maybe that bandwidth is from video framebuffer to the tv not the
> compressed data from the hd dvd to cpu/memory.
Uncompressed 1080 with 24 bit color is 2,985,984,000 bits/sec @60 fps
minus whatever the 4:2:2 / 4:2:0 / 4:1:1 type compression gets you.
Is it as simple as 4:2:2 being 8/12 and 4:2:0 & 4:1:1 being 6/12?
I've read that most 1080 material was originally recorded as 24 fps
progressive. If that is true, you can multiply the above figure by
24/60 to get the actual data content. It would certainly be true
for most movies shot on film.
If the 40 Mbps H.264 figure is correct, I fear it will be a real
bear to decode in real time. :-(
maybe 256 bit simd with an fpga in a cpu socket will help?
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