[ This article was first published in the August, 2009, issue of
Larry’s Final Cut Pro Newsletter. Click here to subscribe. ]
Brian Galford writes:
I am creating a dance recital DVD with two cameras. One is an SD interlaced camera, the other the Sony EX-1, set to its lower 25 Mb/sec rating so I could get more time on the cards. This footage was recorded at 1080i/60. What I am seeing on the DVD that I burned is, I believe called “judder.” This manifests as sort of a shuddering, or ghosting repetition, of the moving parts of the image. Not the entire frame, just the parts that move quickly.
The sequence settings in FCP are set to DV NTSC, to match the SD camera, my lowest common denominator, as it were. I’m not sure that even matters, as I did not render the entire sequence before compressing. The total time of the program is 99 minutes, so I used the Best Quality 120 minutes setting inside Compressor.
Is there anything I can do to mitigate this judder?
Larry replies: Here are some initial thoughts you can try:
1. Convert your HD footage to SD using Compressor prior to editing
2. Try deinterlacing your files during compression.
3. Be SURE to compress in compressor, not DVD Studio Pro
4. See if increasing the data rate makes a difference – the judder may be caused by a data rate that’s too low. This may mean that you’ll need to do this on a dual-layer disc, or supply two discs.
The problem is that dance is all movement, which is VERY hard to compress to small sizes.
Brian then wrote back:
I did try your suggestion of converting to SD footage, and that did help. But then I had to figure out how to keep the footage from looking squished when HD 16:9 was turned into 4:3 SD. I finally found some cropping settings of 240 left and right, 120 top and bottom that worked.
But then I discovered something else. And part of it came in a letter to you from another person who changed his field dominance when compressing HDV to DVD, Bill Koepnick. However, he was only using HDV footage, and I am mixing SD and HD. I looked at his article again and wondered, could it be as easy as making sure the field dom was set to bottom upon choosing Best Quality 90 minutes? I tried that and saw that the field dominance was already set to bottom, and so that could not be my solution.
I noticed that when I dragged a copy of my original HDV camera file into Compressor, (before bringing any settings to bear) a look at the Inspector window revealed the A/V Attributes Native Field Dominance as Top First. I changed that to Bottom First, then clicked Save. I then chose the HD setting DVCPro1080i60 which I thought would best match the 60i frame setting of the original footage. (I also thought to create all I-frames while I am recompressing, instead of leaving the footage in HDV form.) Next I imported the newly encoded HD file into FCP, threw it onto a timeline with my SD footage, (replicating the environment in which I had the problem) and went back to Compressor to make a Best Quality 90 minutes DVD setting.
The DVD that ensued had no judder.
I wasn’t sure this would work, because when I examined the field dominance of my newly created footage in the FCP Browser window, it said Top, not Bottom.
So I could do this all one more time, this time turning on the Frame Controls, and setting everything for Best, but perhaps most importantly, setting the Output Fields to Bottom First. I do notice the Deinterlace setting cannot be turned off, which bothers me since I am working with interlaced footage and would prefer not to change that—otherwise I might as well choose a Progressive Frame setting like DVCPro HD 720p60. I actually started this type of compression, but noticed it took considerably longer than the previous method, which as I said, looked good upon output to DVD. So in the interests of time saving, since I am already late with this project, I think I’ll go with what works and takes the least amount of time. And chalk up this experience to “what doesn’t kill me makes me stronger.” Oh, and I bought another SxS card so I will never have to choose the 25Mb/s setting on my camera again. The whole reason I did it was because this show seemed extra long and the lower setting gave me more time on the cards.
One final note about the DVCPro1080i60 method, is that there’s no need to crop, as the footage starts and ends in 16:9.
Did I mention I hate HDV?
Larry adds: Thanks for all your great feed-back!