[mythtv-users] Possibly a "dumb" question

[Brian Wood]

On Friday 05 February 2010 09:28:23 am Jim Morton wrote:
> Brian Wood wrote:
> > On Friday 05 February 2010 08:40:52 am Jim Morton wrote:
> >> Can someone explain this to me? I just don't get it...
> >>
> >> Myth records shows as mpeg or whatever is being broadcast with no
> >> decoding or other changes effectively capturing it unaltered.
> >> During playback, Myth has a myriad of ways to process and render
> >> video/audio to then deliver to the TV.
> >> Why can't it just stream the exact file to the TV and let the TV tuner
> >> receive/decode/render/interlace/deinterlace it. In other words hand it
> >> to the TV exactly as it were broadcast.
> >>
> >> I believe cable boxes do just that. Provide the broadcast stream on
> >> channel 3 or 4 and let the TV deal with it.
> >
> > If you mean a cable STV outputs ATSC, just like it would be received off
> > the air? I don't think so. Those I have seen output baseband video as
> > composite, S-Video or component, or RF modulated as NTSC.
> >
> > ATSC modulators are still expensive, much more than the entire STB, and
> > cable operators are cheap.
> >
> >> The TV should not know any difference between live OTA, live cable, and
> >> a playback of a recording from Myth...
> >
> > Most of us use the DVI, HDMI or VGA connector to connect the frontend to
> > the TV set, and nobody I am aware of outputs ATSC from their frontend.
> >
> > No TV set I am aware can accept ATSC as anything other than RF.
> > _______________________________________________
> 
> Take OTA for example. The best picture I have ever seen on any TV was
> from an antenna connected directly into a coax input of an HD TV.
> Stunning, crystal clear with a visible depth to the picture.
> 
> I guess it is not possible to capture _exactly_ what an antenna delivers
> (ATSC - RF?) and then send it back out on the coax at a later date... I
> suppose what I am glossing over is the role that the tuner plays to pick
> out just one channel and I suppose that also alters the signal such that
> it can't just be "put back on the wire" later.


It's technically easy, just financially difficult today.

The cable companies degrade the signal, so they can stuff more channels into 
the wire. They also want to control what you watch, as well as report that 
data to someone willing pay for the information.

Very few of the channels on a cable system today originate as off-air signals, 
they usually receive them off satellite, often with quality inferior to what 
OTA usually delivers, to save bandwidth on the satellite.

Of course OTA stations get their signals by satellite, sometimes with better 
quality than the cable networks deliver, but sometimes not. Fox, for example, 
delivers programming to affiliates as an MPEG stream, not as wide-band 
uncompressed video.