Compression Techniques Forum
MPEG2 for HD broadcast
MPEG2 for HD broadcast
by Jeff Carbonneau on Feb 1, 2010 at 8:10:05 pm

I need to create an MPEG2 from Compressor out of Final Cut Pro. The TV station says it'll take my hd tv spot as an MPEG2 on a data dvd. Alright I get that, but I'm having a problem maintaining quality after I play back the spot in quicktime. It seems like it stutters, and my graphic moves are rough and crunchy. I created it as a program stream with a bit rate of 35mb/s. Can anyone help me out with this? I need to maximize my quality for the MPEG2. When I playback the timeline in FCP the spot looks great on my HD monitor, but after compression to an MPEG2 it looks horrible. I think I'm doing everything right, but is there any other suggestions from anyone? My frame rate is 29.97.... 1080i

Re: MPEG2 for HD broadcast
by Craig Seeman on Feb 1, 2010 at 8:14:20 pm

Maybe Quicktime is having problems playing back a high data rate MPEG 2 Program Stream and your encode is fine.

I can't speculate unless you provide computer specs and Quicktime version.

You might try playing back the file in VLC as well.

Re: MPEG2 for HD broadcast
by Jeff Carbonneau on Feb 1, 2010 at 8:21:51 pm

My mac: 2x3GHz Dual-Core Intel.... and 4GB of RAM
Quicktime Version 7.6.4

I'll see if VLC is available for MAC download

Re: MPEG2 for HD broadcast
by Jeff Carbonneau on Feb 1, 2010 at 8:45:26 pm

Wow... the clarity is much better on the VLC player and more like it looks natively, but it still very stroby... i'm mean i shot it in 24F on my XLH1, but then made my sequence 29.97... i mean it's stroby (because of the 24) in playback on FCP, but the MPEG seems to really stroby, like there's a frame rate issue... this wouldn't have anything to do with how i shot it right? because the canon doesn't shoot native 24, it still shoot 60 fields a second to make it look like 24... i don't know, i just seems like it's stuttering with the frames on playback in VLC, although the clarity is where i want it... any thoughts on the stuttering problem, and do you have reccommendation on the bit rate and field dominance?

Re: MPEG2 for HD broadcast
by Chris Blair on Feb 2, 2010 at 3:26:29 am

If your footage was shot 1080i and the timeline is 1080i, then regardless of what you edit in or export from your MPG2 output should use the same field dominance as the footage and timeline, which from what I've read is upper field first.

Properly shot 24P footage with pull-down should not look overly "stroby" as you describe it. The only time you get unacceptable judder is if you pan too quickly at certain focal lengths. There's a guide used with shooting film (16mm and 35mm) that give you acceptable panning speeds (meaning how fast you could pan) to avoid unacceptable judder (or strobing). The same holds for shooting 24P video, especially considering pulldown is being added electronically inside the camera.

If you have a lot of panning, especially if things in the shot are moving the opposite direction, you're hosed on the strobing thing. It's gonna strobe no matter what you do in the encode. If not, then it's probably a field order mismatch. Try outputting a short segment of the project with the opposite of the field order you did before.

Chris Blair
Magnetic Image, Inc.
Evansville, IN