Steve Fermor wrote:
… my HD camcorder, always at 1080, … However, if I pan across a stationary car, the movement is jerky.
you're using 1080i (interlaced), right?
could be a 'field order problem' ...
do you import straight from cam, using iMovie Import from cam feature?
plus, try AppleMans advice first ...
in all these conversion processes, the correct field-order can get lost.
on the web, all material is progressive.
if the de-interlacer 'swaps' even and un-even fields, stutter occur on horizontal movements.
Many thanks for your swift reply.
I've checked my camcorder and it is1080i. I do import from the camera into iMovie.
When I export to make my movie using QuickTime, it does give me the option to deinterlace the source video under the size settings - should I be doing this? At present I leave it unchecked, but if my movies must be progressive as you say, that should transform it?
YouTube ask for the frame reordering box to be unchecked when exporting. I must be honest, I know very little about field order or what it actually does?
To see the problem in action, take a look at one of my videos here: http://www.youtube.com/watch?v=diByNZGSa9Q
As you suggest, I'll try Appleman's advice first, but I'm prepared to carry out further experiments.
On these movies, if anything such as a car drives across the camera view, it's fine. However, if I pan across a stationary car, the movement is jerky.
When a car drives "across the camera view", you're tracking it. So it's really not moving relative to the frame, which is probably why the movement is not jerky. But it appears that any panning in your movie is jerky. Watch the background as you follow a moving car.
And here's something really odd. If I play a PAL 25 fps DVD on my computer, it plays perfectly even though that refreshes at 30 fps. I don't understand that at all!
The monitor does not refresh 30 fps. As far as I know, you don't have to worry about frame rates on computer monitors.
That puzzles me a little, as if that is the case, why does iMovie and many other movie construction programmes give you options on frame rates, which as I understood it need to mirror the refresh rate of the screen - or is that just for creating DVDs? I need to do a little more research here as well I think.
You would not belive the countless hours of experimentation I've devoted to this over the years. Some information seems incredibly difficult to unearth. I think one of the reasons is that a lot of info you can get get is US-based, and for people who live there, everything is 30 fps whatever you do or need. 25 fps seems to cause great confusion - at least, it has with me.
Many thanks for quick reply.
This article may help, regarding "What is the Difference between NTSC and PAL":
Googling on the topic PAL v NTSC will bring up many other useful links, for example:
Some of the above is a little hard to digest, but may provide a better understanding of the different frame rates and resolutions. The best idea is to stick with the same frame rate throughout your shooting, editing and exporting steps. If your camcorder records at 25 frames per second (fps) - the PAL standard - then choose this when starting a new project in iMovie.
Most digital still cameras and mobile (cell) phones (such as the iPhone) record video at 30 fps (the NTSC standard). Again, if starting a project with video shot with one of these devices, choose the NTSC 30 fps option in iMovie. If burning a DVD from this project, stay with NTSC 30 fps (iDVD provides a choice when setting up the DVD authoring). Correspondingly, choose PAL 25 fps if burning a PAL project.
Problems arise when frame rates are mixed in an iMovie project. I've noticed jerky playback when including 30 fps video in a project set as 25 fps. My understanding is that iMovie is deleting 5 frames every second, so the natural outcome is jerkiness in playback. For this reason I try to maintain separate projects when working with differences in frame rates. For my iPhone, which normally records at 30 fps, I now use a 3rd party app called FILMic Pro (or FILMic Pro 2), available on the App Store. This app has options for different frame rates; being in Australia, which uses PAL, I choose the 25 fps option. It works great and allows me to use my iPhone footage in my PAL 25 fps projects, with no jerkiness!
For web delivery (such as YouTube, Vimeo or Facebook etc), just submit your video in whatever frame rate you've used throughout your editing process (as suggested by AppleMan1958 earlier in this thread).
Hope all this helps in some way Steve. I'm no expert in this area, having just a basic knowledge of these things, so trust I haven't got anything wrong!
Steve Fermor wrote:
… it does give me the option to deinterlace the source video under the size settings - should I be doing this? …
well, best practice is not to record in interlaced
the stuttering I'm noticing in your pans is - imho!! - based upon a 'not so well performed' 25>>30fps conversion. And not a wrong field-order - that would create a more 'shiver-like' panning, a much faster stutter. Yours 'hesitates' quite here and then, which - best to my knowledge - is that 25/30 conversion problem.
plus, we all lie talking of 30fps - it is 29.97fps. now, do the math to create a smooth conversion to 'stretch out' 25 frames onto a 29.97-timeline ... ....
I would stay in 25 on your side and look, what YT creates (I guess, they keep 25 too)
Steve Fermor wrote:
… To see the problem in action, take a look at one of my videos here: http://www.youtube.com/watch?v=diByNZGSa9Q
woooonderful cars - you make me jealous!
what a joy to see and drive (?) such pieces of art!
You can record interlaced at 25fps all day with field renders in the basement it doesn't matter. Your render out to YouTube will re-encode your video to what you need for youtube (which yes it's progressive, no interlace fields) I can see from your youbute video that the problem is in your render. Not sure what you are doing to render this video but the bit rate seems high in my first guess. For YouTube I render with H264 and preferably AAC audio. If you render at 30fps, the program will duplicate frames to make up the difference. That should make your panning even smoother. That's how I would render at 30fps (no fields) which is the same as progresive. And then after uploaded, youtube re-encodes it. I give them H264 it works great.
Many thanks for your reply. As you can see from this thread, the prevailing advice is to stick with what your camera shoots at.
I have carried out a couple of experiments. First, I used the first clip in the video you've all looked at. This was imported into iMovie at 30 fps, and dropping it into a 25 fps project didn't help - it was just as jerky, so I suspect that setting up iMovie to the correct frame setting is crucial to your project - no changes afterwards.
I then tried a clip that was imported at 25 fps, as it's part of a PAL DVD project. It was a slowly moving vehicle tracked with the camcorder, so it has elements of a fixed background I'm panning, plus movement.
I have to say the results of this test show much promise, as it looks on YouTube much the same as I shot it.
I wouldn't say this is conclusive, and I've more telling clips to import for test purposes, I just haven't had the chance yet. I will report back as soon as I have, because if I manage to make this work as I want, I'd be inclined to leave a demo pan on YouTube as reference for everybody, as I'm by no means the only person struggling with this.
I'm not able to experiment with an iPhone camera, as I don't have one (more's the pity) as my mobile usage is very low, and it's not worth the expense.
Additional thanks to Karsten and Cosme422 for your additional and further input, and I'm deeply grateful to everyone who has taken the trouble to help me with this.
More news soon!
Thanks Steve - that all makes sense. I usually try to avoid panning, unless I'm shooting a wedding video, where it's mostly unavoidable. That also applies to zooming, although with weddings it's generally necessary in order to change the framing from time to time so you can move from close-up to a wider angle without losing continuity (or vice versa). This particularly applies to the reception where you may be focussing on a close-up of a speaker and need to zoom out and pan across to the wedding party to get their reaction to the speaker's comments. At times like these, it would be great to have a multi-cam setup!
A visually pleasing approach with video is to frame your shots so that you intersperse between wide angle, medium shots and close-ups. Not always easy to apply though! For example, at a kid's birthday party you could start with a wide angle of a group at the party table, then show a medium shot of the birthday child with one or two guests, then finish the sequence with a close-up of the birthday boy or girl (or reverse this process so that you gradually reveal more information, much like zooming out). Quick cutting between these types of shots is generally better than continuously running the camera whilst panning and zooming. It also helps to eliminate any jerky movement in the video.
Your situation is a bit different, as you need to follow the movement of the vehicles, so panning is unavoidable of course.
Good luck with your testing Steve. Look forward to hearing how things "pan" out for you!
PS Sorry about carrying on a bit about technique, just thought it might be helpful.
Well, I can tell you from personal experience that if you can avoid changing frame rates, avoid it! I've been working with transferred Super 8 footage originally shot at 18fps. I had no choice but to convert it. So I tried 24. Certain things break in iMovie when you change frame rates: the keywords function no longer behaves in a rational, useful manner, for example. And transitions don't preview smoothly. The help pages even warn about performance problems when changing frame rates.
Only change frame rates when you have a good reason. As others have said, you don't need to change frame rates for playback on computers or websites.
Additionally, I have a new frame-rate-change problem! I'll be posting that soon. But first I need to prepare some useful test samples to post.
Hello everyone who has contributesd to this thread, and thanks to the additional input from John Cogdell and betaneptune.
I've carried out some further experiments, and there are two test videos posted for you all to look at if you have the time. Actually, they are the same video, but one goes against YouTube's advice and I've left the frame reordering box checked - they are titled accordingly so you can compare.
The links are:
The subject is not glamorous, but there is slow panning horizontal and vertical, and a slow zoom.
Settings for the movies are that the camcorder footage is interlaced - I can't shoot it any other way - and at 25 fps at 1920x1080 AVCHD. It was imported into iMovie 09 with preferences set to 25 fps. Both movies were exported via Quicktime at 720x1280, 25 fps. They are H.264 with key frames and data rate set to auto, and best quality selected. I did not deinterlace the video at this stage.
My own findings are that there is an improvement, and probably no longer any point in working in 30 fps. If nothing else, it means I can always burn a PAL DVD of my projects too. There is still some slight judder on a slow horizontal pan, vertical pan is fine, and the zoom seems ok too.
So which is best?
To be honest, I can't tell the difference. I don't understand what frame reordering does, so I'm not sure what I should be looking for?
The video is noticeably less smooth when playing it a full screen, but could the fact that the video is streamed create that difference?
Opinions are most welcome, and are there any other settings anyone would like me to try?