RE: AW: [mythtv-users] nvidia new drivers hdtv/interlacing, any benefit for us non HDTV people?

mikewright at iprimus.com.au mikewright at iprimus.com.au
Sun Jul 4 20:41:36 EDT 2004


>
>The problem is, TV-Out isnt interlaced, so real interlace modes on Tvout
>would be really helpfull. And i hoped that this would be the case on the
>new
>drivers. 

I think this is untrue. I think my investigations have shown me that there
is no such thing as "interlaced modes on the TV-out" 

I read the Chrontel 7007 datasheet and it is pretty clear to me how this
is all supposed to work.  The TV-out chip genterates the PAL signal in lock-step
with the RAMDAC as it scans through the framebuffer generating a VGA signal.

This is my understanding. A TV does not usually buffer any analog data that
comes from TV stations.  Therefore it make no sense to send the kind of interlaced
picture you are talking about.  In the analogue broadcast world the TV receives
one field completely and displays it.  Then it receives and displays the
next field.  This is how it comes down the aerial.

So it makes no sense then to send the TV both fields at once like I believe
you describe.  The TV would have to buffer them and then extract the fields
and then display them 1/60th of a second apart.

Therefore you want to send the TV one field at a time.  Not interlaced frames.

I hope that clears it up,
Michael




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