Really? Aren't you an engineer? And you think that a large screen uses the
same amount of power as a small screen?
Ever wonder why the battery for a laptop is much bigger than the battery for
a mobile phone? And, the battery life is much shorter?
Ever wonder why the backlight on a cellphone only works for a few minutes
after the last keypush on a cellphone on battery power, but runs all the
time when connected to shore power?
Ever wonder why the same can be seen with a laptop? Think it might have
something to do with -- say -- the LARGE amount of power taken up by the
screen and backlight?
John Willkie
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Tom Barry
Enviado el: Wednesday, December 10, 2008 8:11 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: DVB considers SVC for 1080p and hierarchical
modulation
Interesting.
But I'm not sure that, except for decoding processing consumption, a
1920x1080 display needs to take any more electrical power than my
320x240 display on my phone if the same size. You can have more pixels
each giving off less light, or the reverse. The total illumination and
power consumption (display only) shouldn't have to change for any given
display size and viewing distance. Does it? Anybody know?
But if you mean Bert intends to put a 50" display in the back seat for
the kids then I guess I agree. ;-)
- Tom
John Willkie wrote:
No, Tom. Going only by public announcements, ATSC M/H will support
416x240
video, and I haven't heard any public announcements mentioning other video
formats. There was talk about an alternative video format, but it didn't
go
in the direction of more pixels.
Since you won't read it: ATSC M/H IS FOR MOBILE/PORTABLE VIDEO. 720p IS
FOR
HOME USE. Just because you can put an HDTV set into an automobile doesn't
mean that it's a reasonable thing to do. That takes care of mobile. How
many batteries do you think you'd need to carry to power a hand-held HDTV
set?
Don't be confused by Bert's interest in retrofitting his HDTV set for M/H;
it's pure folly.
There are uses for SVC beyond kludigly supplementing bad codec/frame sizes
written into law. Indeed, Qualcomm MediaFlo uses main and enhanced
layers,
with 12/15 fps in the main, and 24/30 capability (and more pixels) in the
enhancement layer.
I haven't read anything in public about M/H frame rates, so I can't go
further.
John Willkie
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Tom Barry
Enviado el: Wednesday, December 10, 2008 4:44 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: DVB considers SVC for 1080p and hierarchical
modulation
Will ATSC M/H even have enough throughput for a single decent 720p
stream after error correction? I'm not saying it won't but some other
figures bandied about on this list a couple months ago made me doubt
that. Is this public yet?
- Tom (not on the committee)
John Willkie wrote:
Sounds very kludgish to me. Wouldn't it be "neat" if ATSC M/H 1.0
provided
support for SVC?
SVC provides for a main and an enhanced layer, in my understanding, which
is
limited to AVC. Seems to me that you could have a 720p main layer and a
1080p enhanced layer. Not too elegant, if it works at all.
John Willkie
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Olivier Houot
Enviado el: Wednesday, December 10, 2008 1:02 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] DVB considers SVC for 1080p and hierarchical modulation
Some interesting perspectives in the last issue of DVB scene
(www.dvb.org).
There is an article about SVC (scalable video coding) that says it could
be useful for future 1080p services.
Since current boxes would not be compliant, there would be a need to
simulcast a 1080p and a 720p version of a program.
They consider 13 Mbps would be needed for the 1080p stream, and 8 Mbps
for 720p (perhaps a bit high, since this is the average bitrate of
current 1080i broadcasts). That would be a total of 21 Mbps.
But using SVC, a two layered 720p/1080p stream would use just 15,4 Mbps.
I have to say it is not clear to me how current boxes could extract the
720p stream without being designed for SVC , though.
Also, the idea of broadcasting a robust stream for difficult reception
conditions, with additionnal layered information in a more fragile but
higher bitrate stream permitted by hierarchical modulation makes a come
back. Tests performed with older MPEG2 system were unable to show a
clear advantage with this method in the past, but it seems the
efficiency of the new SVC scheme makes it worth to reconsider.
In the same DVB scene issue, they mention an OTA demo of DVB-T2 at 36
Mbps.
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