[mythtv-users] HDTV Video Modes with MythTV

David Griffith dgriffith at internode.on.net
Mon Aug 1 23:44:58 UTC 2005


Rob wrote:

>Plain old SDTV analog cable is 480i (I think).
>
>I get HDTV over-the-air, and even when it is mythtranscode'd down to
>720x480 (480p, I guess), the picture is still much better. I think
>what I am seeing is the difference between a clear digital signal and
>a noisy analog signal, and probably not so much to do with the
>increased resolution.
>
>  
>
This is what I find with my dual analog / SDTV setup. Analog captured at 
720x576 is noticeably fuzzier than my SDTV signals. The signal strength 
is solid - there's no noise on analog - it's just softer. I'm supposing 
it's because of the "analog -> crappy bttv capture" step. Luminance 
bandwidth on the video signal input to your capture chip is the key 
issue here, which is dependant on what tuner you've got on your card. 
Digital transmission doesn't suffer from this kind of problem so it ends 
up sharper. It *does* suffer from a heap of other things though, 
especially if broadcasters try and squeeeeeeze another channel in  :-)

Dave



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