[mythtv-users] Objective IVTV quality measurement instructions
dean vanden heuvel
deanv at cox.net
Sat Aug 14 23:10:39 EDT 2004
I myself have been experimenting with capture on the PVR-250. I can't decide with my eyes alone using normal content whether or not I gain anything by capturing 720x480 as opposed to 640x480 or even less. It takes too many keystrokes in Myth to go from one to the other, and by the time I display the alternate, I can't really say for sure if the higher resolution is better. I do receive (and capture) HD content that is broadcast @ 1280x720, but because I have only the S-video input for my PVR-250, I must use the S-video out from my satellite receiver, and thus some of that resolution is lost.
So, would your experience tell you that I can get replay that is *just as good* if I capture at 640 (or less), or should I stay with 720? for live TV, storage does not matter, but for recorded content, using the lower resolution and a lower bit rate could save space. Alternatively, using the lower resolution for capture and keeping the same bit rate, resulting in roughly equivalent storage requirement, MAY result in a BETTER picture, If I understand this correctly.
What would your experience tend to recommend?
-dvh
On Fri, 13 Aug 2004 09:50:43 -0400 (EDT)
Cory Papenfuss <papenfuss at juneau.me.vt.edu> wrote:
> I posted this awhile back, but I never got too many responses. My
> PVR-250 OEM has what I consider to be only adequate capture resolution. The TV
> it's connected to can do a better job of displaying cable TV signal and
> produces cleaner results. I've reduced the variables enough to know it's
> not my tvout on the mythtv box. Playing test patterns in a DVD player
> recording it with mythtv can help find this out. I mastered a burnable DVD
> image awhile back:
>
> http://www.ee.vt.edu/~mythtv/TEST.tar.bz2
>
> The EIA1956 test pattern is on there, at 720x480. Since it's limited
> to 720 pixels, the test pattern itself is only 720*3/4=540 "lines of
> resolution" on a 4:3 TV. My pvr250 can only resolve about 400-450 lines, even
> when capturing via the svid direct from the DVD at 720x480. The TV OTOH can
> resolve the full 540 lines when connected directly to the DVD player.
>
> Anyone who feels like testing this and reporting back would be
> appreciated. I discovered just how crappy my low-end BTTV card was (350-400
> max)... took it out of the box after that.
>
> -Cory
>
>
> *************************************************************************
> * Cory Papenfuss *
> * Electrical Engineering Ph.D. Graduate Student *
> * Virginia Polytechnic Institute and State University *
> *************************************************************************
>
>
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