[mythtv-users] Simple Question About TV Out Quality

James L. Paul james at mauibay.net
Wed Oct 22 14:56:43 EDT 2003


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Michael Starks wrote:
| It is hard to see how picture quality can, as a rule,
| exceed what you get from a standard TV on the cable.
|
| In the standard TV, the cable signal is decoded by
| the tuner and the resulting video is displayed.  With
| Myth (or TiVo, or Replay), you're substituting a
| different tuner and some additional signal processing....
| --------
|
| Thank you for the response, however that's not quite what I'm looking for.
| I'm interested to know if *subjectively*, people are as pleased with video
| out to a TV as they are with the tuner in their TV.  In other words, how
| does it look?  (Again, generally and subjectively speaking.)
|

Ahh, subjectivity. I'm good at that. ;)

The single largest threat to quality that I have is my cable signal
quality. That said, for most casual TV watching, anything anything
better than VHS-LP quality is perfectly fine to me. For archiving
recordings, I like to have as high quality as feasible.

I've used Tivo for 4 years and use "basic" quality for most everything.
I use "good" quality for special things, but rarely. I haven't used tape
since 1996, back when I switched to VCDs for storage. A couple years ago
I switched to CVD (an XSVCD format that happens to be DVD stream
compatible.)

So, I've been using TV-out in various forms since my first homebrew PVR
in 1996. There are 2 big factors in the quality, the first is the
quality of the capture card, the other is the TV-out video.

I'm using PVR-250 cards (Freestyle) and an nVidia GeForce II GTS for the
TV-out. The quality is very decent, but not as good as the Tivo on the
better quality modes. This isn't due to the capture card, it's due to
the TV-out.

I've recorded video captured on my MythTV box to DVD and when played
from a standalone DVD player it's fantastic quality because it's
properly interlaced. My MythTV box doesn't properly drive the NTSC
signal with the interlaced video source, it is just mirroring the
progressive-scan X desktop. So to remove the (minor) interlace artifacts
I need to turn on the deinterlacing filter, which significantly fuzzes
my image and blasts the contrast. I'm quite happy with the image when
the filter of off though, so it's not an issue for me.

The quality difference is enough that I'm not interested in playing DVDs
or other discs on my MythTV box, I have a perfectly good standalone
player that does a much higher quality job of that. For now. ;)

I've heard the PVR-350 cards have TV-out? Perhaps if the drivers are
more stable and if it's possible to drive the video-out directly from
the onboard decoder I would expect the quality to be quite high. I don't
know much about that card or the status of the project though.

No, the quality from my TV-out is not as high as the built-in tuner in
my TV. The only thing I have that beats that is my standalone DVD player
with the TV in widescreen scan mode. :)

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