Some channels stutter, others do not

[earthcitizen]

I am receiving ota in the sf bay area, and everything seems to be working great except that some channels come in perfectly fine while others seem to be dropping frames. All signals are 100% strength.

For instance, ABC is fine, but KQED HD seems stuttered. Is this because of their broadcast? Do some channels just not broadcast all frames? My computer doesn't seem to be overloaded. Has anyone else experienced something similar to this?

[Deusxmachina]

Off the top of my head...

if you haven't looked closely at what programming was/is playing, it might be video (sports, etc) stutters while film (most TV shows, movies) doesn't. Also, one channel might broadcast in 1080i while the other is 720p. 720p is much easier on bandwidth and hardware, particularly due to deinterlacing.

For instance, until recently after changing drivers and whatnot, I got stutter on video shows due to my video card maxing out when trying to deinterlace 1080i.

The above may not help specifically, but it may help point you on the right track. You didn't say want hardware you are using, so no one can give an opinion on that yet, either.

[earthcitizen]

hardware:
Nvidia 7200 gs 128m
p4 2.4(8?)
512 megs memory
Pinnacle PCTV HD

good point, I forgot about the possibility of different resolutions.

geez...are their utilities to determine the incoming signal?

that brings me to another idea I had earlier, are there utilities for discerning exactly what is coming down each frequency OTA? I mean...ac3, 1080i, 720p, etc...

[Deusxmachina]

Pretty sure the "TV Listings" plugin can show some of that extra info. Not sure, though, you'll have to check the wiki. I tried getting it to work once and couldn't so didn't bother with it again after a reformat.

Mediainfo will show the specifics of any media file on your computer. Very nice. Doesn't work on live TV of course unless you are recording it.

You can maybe look online to see what your stations broadcast in. ABC is 720p, which has me wondering what KQED is. They don't say what their HD is on their website. Stations only broadcast HD in either 720p or 1080i, never both, so once you know it you don't need to look at individual programs anymore other than for knowing whether a specific program is SDTV or HDTV.

I don't know of any program that can check the gpu usage of an Nvidia video card, but if your cpu usage is through the roof when you get the stutter, that might explain things right there. I don't know if a 2.8 P4 has enough oomph or not.

If you haven't tried it, whatever video decoder you are using, switch the deinterlacing to Weave and see if it helps. My video card was stuttering on Bob and usually on Auto (when it tried to do Bob, I assume). Weave deinterlacing cuts the usage way back.

How's your memory usage? I'm looking at my HTPC right now, and with only a few extra windows open it's using 630mb memory with Windows XP.