[opendtv] Re: 625 video quality is good enough....
- From: "Alan Roberts" <roberts.mugswell@xxxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 19 Oct 2004 16:45:18 +0100
Don't teach me to suck eggs, these are exactly the points I've been
hammering away at since 1987. Except your comment about frequency content.
You'll find that the current crop of cameras will happily produce content at
30MHz, I've measured it many times. The limit isn't the camera, it's the
lens, put a Zeiss prime on an HD camera and you'll easily get 30MHz. If
you're not seeing anything above 22-24MHz it's either because of filters of
poor lenses, don't blame the cameras.
----- Original Message -----
From: "Craig Birkmaier" <craig@xxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Tuesday, October 19, 2004 3:53 PM
Subject: [opendtv] Re: 625 video quality is good enough....
> At 12:25 PM -0700 10/18/04, Dale Kelly wrote:
> >I agree, 50/60P should be the ultimate format when technology can
> >accommodate. However, I don't know that it can be done in a transport
> >constrained to MPEG2.
>
> Don't confuse the transport and the method of video encoding. MPEG-2
> TS could care less about the content of the packets. The standard has
> already been updated to transport MPEG-4 content.
>
> And don't get hung up on the bandwidth needed to deal with 50/60P
> display refresh at higher pixel counts. Compression works more
> efficiently as image entropy is reduced. The real enemy of 1080@60P
> is not bandwidth - it's still expensive to deal with 150 msamples
> /sec, but it is clearly possible (e.g an Apple Cinema display).
>
> The real enemy of 1080@60P is noise. We cannot saturate the spectra
> of a 1920 x 1080 raster even at 24P today. HD cameras produce no
> useful information above 22-24 MHz. If we push the sampling rate
> higher, we capture significantly more noise and very little
> additional image detail. This is a compression killer.
>
> The reality is that the MPEG-2 encoding tools don't care. 1280 x 720
> @50P is fully supported by MPEG-2, as is 1080@50i. The limitation on
> MPEG-2 is the 62,668,800 samples per second clock. There is no good
> reason to EVER update MPEG-2 for 1080@50/60P. The encoding tools are
> already outdated. MPEG-4 part 10 (AVC) offers superior encoding
> tools and a far better path to the compression of 2Mpixel (and
> beyond) progressive formats.
>
> But let's not lose sight of the real objective. Acquisition and
> display are decoupled in our new digital world. There may well be
> good reasons to acquire 2 MPixel rasters (and beyond) for archival
> and post production purpose. But this DOES NOT mean that we need to
> use 2 Mpixel emission formats when 1 Mpixel displays are more than
> adequate for virtually EVERY consumer display application. We need to
> deliver high quality samples, not compression artifacts.
>
> >
> >I had forgotten about the advantage 50Hz countries have in the film
world.
> >The "pull down" conversion is one the more valued features of my DTV set.
>
>
> As we move to displays that present entire frames this issue too will
> go away. DLP, LCD and plasma display can present 24P without any
> pulldown.
>
> It seems that we should be promoting a path to real convergence in
> international video standards, rather than trying to sustain
> geographic differences designed to protect existing markets.
>
> Regards
> Craig
>
>
> ----------------------------------------------------------------------
> You can UNSUBSCRIBE from the OpenDTV list in two ways:
>
> - Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
>
> - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
>
>
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts:
