[mythtv-users] Possibly a "dumb" question

Robert McNamara robert.mcnamara at gmail.com
Fri Feb 5 15:55:13 UTC 2010


On Fri, Feb 5, 2010 at 7:40 AM, Jim Morton <Jim at morton.hrcoxmail.com> 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.
>

That would require an QAM modulator (ie, something to modulate it back
into the signal the TV expects to receive).  These items *start* in
the many thousands of dollars and go way, way up from there, as they
are cable headend equipment.

> I believe cable boxes do just that. Provide the broadcast stream on channel
> 3 or 4 and let the TV deal with it.
>

What you are talking about here is RF output, which is an analog,
Standard Definition output.  It is the worst of all outputs offered by
a cable box.  It is the lowest quality output available from the cable
box, and is not the original broadcast stream.  Every single output on
your set top box is better than this.

> The TV should not know any difference between live OTA, live cable, and a
> playback of a recording from Myth...
>
> It seems to me that this configuration would greatly reduce the video card
> and/or cpu requirements and setup/config efforts.
>
> Maybe I am waaay over-simplifying things...

Yup.  ;)

Robert


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