Stuttering: Saturday Night Live as a Test

[sjwoo]

I'm running XP, Athlon XP 2800+ Barton, ATI HD2400Pro, and HDHomeRun via Comcast cable, recording ClearQAM. Everything runs great except for a few programs. Yes, that's right -- programs, because this is not channel specific, nor is it resolution-specific. The best example I've found is Saturday Night Live.

NBC broadcasts in 1080i, and for my setup, programs 30 Rock and The Office stutter pretty badly. Programs like House (Fox, 720p), play back perfectly, so I thought the problem was the resolution, but it's not. Because Saturday Night Live recorded at 1080i plays back perfectly -- except for the Digital Short. The Digital Short stutters just like The Office and 30 Rock.

Here's another strange bit: some SD shows (recording at 480i) are stuttering. Grey's Anatomy, recorded at SD/480i, stutters. It seems as if shows that are movie-like stutter, while live shows (like SNL) do not. What is going on here? Way back, when I was encoding DVDs into the divx format, I remember reading about Film and IVTC, and I'm reminded of that here.

Can somebody enlighten me as to what's going on here? I'm hoping it's a simple solution I'm missing. I have DScaler deinterlacing disabled, as if I do that, Sage slows to a crawl and everything becomes unwatchable.

[briands]

Originally Posted by sjwoo

I'm running XP, Athlon XP 2800+ Barton, ATI HD2400Pro, and HDHomeRun via Comcast cable, recording ClearQAM. Everything runs great except for a few programs. Yes, that's right -- programs, because this is not channel specific, nor is it resolution-specific. The best example I've found is Saturday Night Live.

NBC broadcasts in 1080i, and for my setup, programs 30 Rock and The Office stutter pretty badly. Programs like House (Fox, 720p), play back perfectly, so I thought the problem was the resolution, but it's not. Because Saturday Night Live recorded at 1080i plays back perfectly -- except for the Digital Short. The Digital Short stutters just like The Office and 30 Rock.

Here's another strange bit: some SD shows (recording at 480i) are stuttering. Grey's Anatomy, recorded at SD/480i, stutters. It seems as if shows that are movie-like stutter, while live shows (like SNL) do not. What is going on here? Way back, when I was encoding DVDs into the divx format, I remember reading about Film and IVTC, and I'm reminded of that here.

Can somebody enlighten me as to what's going on here? I'm hoping it's a simple solution I'm missing. I have DScaler deinterlacing disabled, as if I do that, Sage slows to a crawl and everything becomes unwatchable.

it could be film vs video... Many TV shows (drama, sitcoms) are shot on film at 24 frames/second. Most "live" things are shot on video at 30 frames/second. Most displays are set up for 30 frames/sec and therefor you will see "judder" with film material as every 3rd frame is displayed twice to "stretch" the 24 film frames into your 30 display frames.

[sjwoo]

Originally Posted by briands

it could be film vs video... Many TV shows (drama, sitcoms) are shot on film at 24 frames/second. Most "live" things are shot on video at 30 frames/second. Most displays are set up for 30 frames/sec and therefor you will see "judder" with film material as every 3rd frame is displayed twice to "stretch" the 24 film frames into your 30 display frames.

Thanks, man. I think that's exactly what it is, as all of my recordings have a frame rate of 29.97, regardless of the video feed. So how can I resolve this?

[briands]

Originally Posted by sjwoo

Thanks, man. I think that's exactly what it is, as all of my recordings have a frame rate of 29.97, regardless of the video feed. So how can I resolve this?

I didn't see a mention of your display device. To eliminate judder, your display device has to display at some multiple of 24. Most direct view digital displays are stuck at 60Hz, so you may be out of luck.

Still not sure why the Fox shows would be OK... maybe its a deinterlacing problem that is compounded for 24fps content.

[sjwoo]

Originally Posted by briands

I didn't see a mention of your display device. To eliminate judder, your display device has to display at some multiple of 24. Most direct view digital displays are stuck at 60Hz, so you may be out of luck.

Still not sure why the Fox shows would be OK... maybe its a deinterlacing problem that is compounded for 24fps content.

Holy crap -- it never even occurred to me that might be the issue. I have two devices, a regular TV (tubes, i.e., not LCD or plasma) and an LCD projector. I just hooked into Sage via the Sage Client on my computer (LCD panels), and everything looks perfect. So it's the fact that it has to be displayed on the regular TV. Is there a solution to this? I hope the solution isn't "buy an LCD TV."

[sjwoo]

Originally Posted by briands

Still not sure why the Fox shows would be OK... maybe its a deinterlacing problem that is compounded for 24fps content.

I think I know the answer. The Fox shows are recorded in 720p, not 1080i. It looks like anything that's interlaced (i.e., 480 or 1080) and is film (shot at 24 fps) causes this issue. Again, it's only on the TV that this is a problem.

This was never an issue when I recorded off of the Hauppauge WinPVR-250. But the WinPVR was connected to the Comcast STB, so is it possible that the STB was doing the deinterlacing?

It seems as if the solution might be turning on Dscaler deinterlacing, but I can't do that -- it makes Sage unusuable (so slow that it becomes inoperative and the video goes in slo-mo).