[opendtv] Re: Olympics picture quality
- From: "John Willkie" <johnwillkie@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 19 Aug 2004 21:12:44 -0700
From what I was told by the CE at an NBC o&o station in a brief telecon
(we'll have a sit-down after the show is over) the only things coming out of
New York is the news. His station's analog and HDTV feeds are COME DIRECTLY
OUT OF ATHENS. New York is upstream from Athens in this configuration, not
downstream.
Here's how I understand it: MPEG-2 elementary streams are encoded in Athens,
live, and they're decoded in the MPEG-2 section of digital TV sets in
millions of homes.
I haven't taken the time to check with the folks I talk to at the network,
but this is the first time I've heard of a non-CBS network doing something
like this: controlling stations from remote venues, not the TOC. Oh, yeah,
TOC's control networks (legacy mode) and not stations.
The biggest complaint one hears about this from CBS stations: "How come
just the o&o's get this degree of control?" I've been told -- and not from
official CBS folks handling this, who I've talked to more than a few times
this year on "another" topic -- that all the stations could have this
technology this year, after the o&o's work out the bugs.
I can't say -- at this point -- that is exactly what NBC is doing. I will
know within a week or two of the end of the games.
Distribution and contribution are 45 Mb/sec. Transmission is 18 Mb/sec.
And, of course, the stations do have to "decode" the 4:2:2 MPEG-2 signals to
make them 4:2:0 for transmission. That's still required. But, you used the
word "decode." Maybe I'm being pedantic/technical, but I tend to call that
"transcoding." And, since it requires one to throw away bits, of course
data is lost.
When one takes a DS-3 feed down to baseband, unless I'm missing something,
one should not assume that a single bit is lost.
John Willkie
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Terry Harvey
Sent: Thursday, August 19, 2004 8:01 PM
To: opendtv@xxxxxxxxxxxxx; opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Olympics picture quality
But are the NBC commercial inserts coming from Athens?
It seems to me that the MPEG-2 video is going through three encode-decode
cycles:
Encode Athens, decode/encode New York, decode/encode affiliate, decode
consumer.
Even at two cycles at 45Mb/s coupled with an 18Mb/s cycle there will be
sufficient loss to give MPEG blocking when there is sufficient motion in
the picture (eg. swinging Olympic logo).
I don't think NBC New York is passing the video through from Athens without
decoding.
Terry Harvey
At 01:56 PM 8/19/2004 -0700, John Willkie wrote:
>During the Olympics, NBC is being run out of Athens. Indeed, in the case
of
>o&o's, the local station is being switched out of Athens.
>
>All the nets use 45Mb/sec contribution feeds, save Fox (when their stream
>switcher goes on line) which will be using 19.29 Mb/sec transmission feed
to
>affiliates.
>
>John Willkie
>
>-----Original Message-----
>From: opendtv-bounce@xxxxxxxxxxxxx
>[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of tjharvey@xxxxxxx
>Sent: Thursday, August 19, 2004 10:58 AM
>To: opendtv@xxxxxxxxxxxxx; opendtv@xxxxxxxxxxxxx
>Subject: [opendtv] Re: Olympics picture quality
>
>
>Doug,
>
>I made mention of this last Sunday. I understand the pictures are incoming
>to NBC affiliates at DS3 rate of 45Mb/s, so the origination encoding from
>New York, or wherever else it is originating from in the US is sending it
>out at 45Mb/s. Affiliates decode and re-encode to 18Mb/s for transmission
>and so there is a generational loss but it should not be all that bad.
>
>My question is how is NBC receiving it at New York? I suspect a third
decode
>is occurring before its US distribution to insert commercials. Or else is
>the encode from Athens at a different rate from NBC's DS-3 distribution
rate
>which necessitates a third decode/ re-encode cycle?
>
>Anyhow, I see the artifacts too. In future the viewer is regularly going to
>have to put up with this as the broadcast 'bean-counters' force limited
>bandwidth. So just live with it and treat it as an interesting special
>effect.
>
>Terry Harvey
> >
> > From: Doug McDonald <mcdonald@xxxxxxxxxxxx>
> > Date: 2004/08/19 Thu PM 01:03:46 EDT
> > To: opendtv@xxxxxxxxxxxxx
> > Subject: [opendtv] Olympics picture quality
> >
> > Somebody here may well be able to answer my question
> > on the picture quality of the HD Olympics.
> >
> > Sinclair only turned on their true HD here for the
> > Olympics ... it was ready days earlier, but they absolutely
> > refused to let us see some regular HD programming before the
> > Olympics, so that's all I have seen.
> >
> > For static pictures, the quality (1080i) is certainly OK.
> > There seems to be zero detail that my 720p TV can't handle:
> > no change when I adjust the "sharpness" control, except for the
> > local bug, and at CC It saw no more detail on 1080i sets, including
> > the Sony XBR 950 set for "pro" mode, but it looks fine.
> >
> > However, when fast motion starts, such as the flying rings logo
> > they use for replays, all Hell breaks loose: the logo itself
> > breaks up into blocks, and is fuzzy to boot. I see no problem
> > with flying logos on MNF (720p). When they show from-above
> > distant shots of swimmers, the foam breaks up into total pixelated
> > mud.
> >
> > When they show fast gymnastics, when they pan to follow a running
> > gymnast, the background seems to move smoothly, so at least that
> > part of the 50i->60i conversion is passable. BUT ... when the
> > gymnasts have wailing arms or legs ... they actually disappear
> > entirely! No, they don't get blurry ... there is no blur, just
> > background behind where they should be. Well sometimes there is
> > some faint trace or blurry stuff in front of the background,
> > but not much.
> >
> > Clearly the broken up flying logos is a local encoder issue, but
> > what about the foam breakup and the missing arms? Is this local,
> > or due to the 50->60 problem? Has any of you people seen what the
> > un-19.3'd network feed looks like?
> >
> > Overall I would say that both swimming and gymnastics has moments
> > of simply unacceptably bad pictures.
> >
> > Mark Aitken: are you sure that the WICD people have got their
> > encoder set right? Are you using the same brand of encoders
> > at all your 1080i stations?
> >
> > Doug McDonald
> >
> >
> >
> >
> >
> > ----------------------------------------------------------------------
> > 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.
>
>
>
>----------------------------------------------------------------------
>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.
----------------------------------------------------------------------
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:
