FCP - XDCAM HD - SD sequence - slo mo jitters
by Luke Renner
on
Sep 3, 2008 at 11:46:40 pm
I searched the forum before posting but found nothing useful.
In short, I have XDCAM HD footage (1440x1080i60 - 35mbps) that I am needing to co-mingle with SD footage within an SD sequence.
At times, I need to create my own slow motion effects and the XDCAM material is EXTREMELY jerky. I can apply a pretty massive motion blur to it, but then it becomes mud. I noticed that FCP 6.0.4 automatically adds the "shift fields" filter every time I drop a clip into the SD timeline. I have tried lots of methods but I am looking for that "magical" solution that will yield a pristine render.
BTW - I am rendering everything in ProRes. My sequence is 8-bit NTSC (720x486 - Lower).
Re: FCP - XDCAM HD - SD sequence - slow mo jitters by Luke Renner on Sep 4, 2008 at 1:06:38 am
Incidentally, I just tried going the other way (starting with an HD sequence 1440x1080i60) and the SD footage results in the same crappy jerkiness. Not good.
Re: FCP - XDCAM HD - SD sequence - slo mo jitters by Stephen Abbott on Sep 4, 2008 at 11:34:02 am
Hi Luke,
I had the same problem with DVPROHD 1080 50i (upper field first) footage in a DV PAL 50i (lower field first) timeline.
The solution: let FCP add the shift field filter to sort out the upper to lower. Then select the clip and pre-compose it (alt-C), then do the slow-down on that nested sequence. Smooth results, even though it's a bit of a mission. In the end I did this in online once I was happy with the cut, retaining editing flexibility (but ugly fields) in offline.
Something about the way FCP applies the shift fields filter *after* re-timing a wrong-field clip messes things up completely ... I guess.
Re: FCP - XDCAM HD - SD sequence - slo mo jitters by Luke Renner on Sep 4, 2008 at 4:08:58 pm
Stephen,
BRILLIANT!
Let me say, this worked perfectly.
For those who wish to better understand the logic applied...
FCP is good enough to automatically apply a "shift field" filter any time you place an "upper field first" clip into a "lower field first" sequence (or visa versa). It is critical for FCP to do this, for obvious reasons (field order has to match).
Since an FCP motion effect (i.e. slow motion) happens on the source side of the clip... that it to say, to the clip itself... FCP does not treat it as a "filter". That is why the clip's motion is not listed in the clip's "Filters" tab. Instead, it is always available in the clip's "Motion" tab. Because of this, a slow motion effect does not behave according to the filter hierarchy (wherein filters are applied in the order they are listed in the clip's "Filters" tab). Instead, FCP attempts to apply the motion effect (i.e. slow motion) AT THE SAME TIME as the "shift fields" filter. When you consider the amount of interpolation that must be done for FCP to achieve a smooth motion adjustment, it becomes easier to understand why FCP is unsure how to calculate a proper interpolation of motion while simultaneously trying to shift the fields down (or up). For FCP, these are two tasks that cannot be handled at the same time. Unfortunately, within the clip's tabs, there is no way to force FCP to apply the "shift fields" filter FIRST and then generate the motion effect (Slow Motion) AFTERWARD.
For that reason, you must record the clip to your sequence at its normal speed (with the "shift fields" filter applied) and then NEST THE CLIP. From here, apply your motion effect (i.e. slow motion) to the nested clip. This effectively forces FCP to apply the "shift fields" filter FIRST and then to apply the motion adjustment LAST.
Re: FCP - XDCAM HD - SD sequence - slo mo jitters by Rafael Amador on Sep 6, 2008 at 3:42:18 am
This problem comes from long and its affects every kind of footage, no only XDCAM.
In FC 6 Shift Fields and Speed Changes can not live together.
Just get rid of the Shift Fields filter. When you set 1080 lines on top of 480 lines, the Shift Fields filter is no necessary any more.
rafael
Re: FCP - XDCAM HD - SD sequence - slo mo jitters by Rafael Amador on Sep 6, 2008 at 3:57:46 am
Hi Luke,
Nothing to object to your explanation, but just try what I said.
I'm working in a daily base with EX-1 footage (Upper) in a DV time line (Lower).
When ever FC add the Shift Fields, I take it away. No jerking, no interlacing problems.
Shift Fields is a must when laying SD footage in an SD sequence. When you lie HD footage in a SD sequence the problem simply disappear.
Have a look by your self and try to understand why.
Rafael
Re: FCP - XDCAM HD - SD sequence - slo mo jitters by Luke Renner on Sep 6, 2008 at 4:00:48 am
All due respect, I have tried. When creating a slow motion effect with XDCAM HD footage (1440x1080i60), you have to nest the footage to get it to work.
Re: FCP - XDCAM HD - SD sequence - slo mo jitters by Rafael Amador on Sep 6, 2008 at 5:13:41 am
Hi Luke,
Sorry if I sound rude. My English is very poor and some times I don't know how to express my self.
I've been going through the same problem when trying to change the speed of footage with the shift fields on.
Yes, the only way is to nest the clips with the Shift Fields before to apply the Speed Changes.
We agree on that.
What I want you to see, is that shifting fields is no necessary any more when you put HD footage in an SD sequence.
There is a reason why. When you set SD footage in top of SD footage, you need that the 240 lines (NTSC) of each field falls on top of the same place.
If some of the footage have a different field order all the lines will fall in wrong place, so you need to shift them one line up or down.
When you are lying HD footage in top of SD footage, you put 540 HD lines (1080/2) on top of the 240 NTSC lines. Wether you shift or no shift the picture the lines won't fall in the wrong place.
I wish you can visualize this. For me is difficult to explain it, but with a simple graphic would be easy to understand.
So Luke, what I do is just take away the Shift Fields filter and apply the Speed change. Without the Sift Fields Filter is no necessary to nest the clips. And believe me, you won't have any interlacing problems.
Cheers,
rafael
Re: FCP - XDCAM HD - SD sequence - slo mo jitters by Luke Renner on Sep 6, 2008 at 5:30:09 am
You are not rude, nor do I wish to be rude by saying that what you suggest simply does not work... at least, not to create a creamy-smooth slow motion effect.
It is possible that the differences in media which you are using might be significant enough to make for a success on your end and a failure on mine.
What you suggest does not work. As a professional editor for 10 years, I am speaking after an enormous amount of testing. Clearly something is different between your edit bay and mine.
Re: FCP - XDCAM HD - SD sequence - slo mo jitters by Rafael Amador on Sep 6, 2008 at 5:53:54 am
Well, your 10 years as video editor and my 23 years doing the same job have nothing to do with the interlacing problems or the FC bugs :-)
I just talk about what I see in a pro monitor.
About to use FC to try to get a "creamy-smooth slow", I give up long ago and I use other better options.
Cheers,
rafael
