[mythtv-users] Capture sharpness
mythtv at rodsbooks.com
Sun Nov 25 19:08:42 UTC 2007
On Sunday 25 November 2007 13:41:17 Jay Mallar wrote:
> I'm using a PVR-250 to capture TV via my DirecTV STB. On my TiVo, I get
> much better capture quality in terms of picture sharpness than I do with
> the PVR-250.
> I can't seem to find anything that will allow me to control the
> sharpness of the capture, is there a way to modify this? or is this
> just an indication that PVR-250's aren't as good as the Tivo captures?
There could be any of several factors at work here; you've not provided
information on this critical information:
- Is your TiVo a standalone (SA) unit or a DirecTiVo? If the latter, it will
produce better quality because it records the digital bitstream directly,
whereas MythTV records the decoded analog output from a set-top box, which
imposes an extra digital->analog->digital conversion cycle.
- What inputs are you using? S-video is better, composite is middle, and
coaxial (RF) is worst. If you're using S-video for your TiVo and RF for
MythTV, that could explain it.
- What are your quality settings? (Resolution and bitrate, mainly?) These
impact quality. SA TiVos also have quality settings, although they're
expressed as Best, High, Medium, and Basic, IIRC, and I don't know the
precise mapping of those to resolutions and bitrates.
- What type of DirecTV receiver(s) do you have? I've seen claims that they
vary in video output quality, so it's conceivable that you've got one with
better quality feeding your TiVo and one with worse quality feeding your
- Have you checked your cables? Loose or low-quality cables can cause
problems. (That said, the high-priced premium cables sold by many retailers
are overpriced scams, IMHO. Just be sure you're not using something very
old, frayed, or designed for the wrong purpose.)
These issues aside, I've never done a direct comparison of a TiVo to a
PVR-250, so I can't promise that the latter can equal the former in image
quality. I'd be surprised if the differences were huge, though.
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