7D Video stuttering?

[Derek Reich]

I'm a real newbie to the SLR/HD world, so please bear with me here. I very recently picked up my new 7D. Almost immediately, I departed on a HD shoot and brought my new camera along to play with. I have been shooting much of the same content on my 7D as I have on my XDEX both for comparative purposes, as well as having a second camera on the shoot.

So far, I am extremely pleased, but have a concern that I'm not sure is a playback issue, a hardware issue, or pilot error?
I'm shooting 30p w/ 30th second shutter. The video looks beautiful, but when playing back clips with quicktime, the video looks like it's dropping frames or something.... kind of stutters now and then which I attributed to a playback issue on my MBP.
My client was interested in seeing some of the video from the camera, so I sent one clip via FTP to them. They commented that the stuttering was a real problem, and they were looking at it in an edit bay, with lots of processor power. They also reported that FCP wouldn't import the file normally, Final Cut would hang and they'd have to restart it. I thought these .mov files would import directly into Final Cut? Am I doing something wrong, here, or is there possibly a problem with my camera?
Thanks for any advice.... I'm going to be shooting more this week and would love to figure this out so the video can be used from this great little camera!

[Perrone Ford]

There is nothing wrong with your camera. There must be 100 threads on this exact same revelation by 5D/7D shooters. Take some time and read.

Shortcut: Transcode to ProRes and your problems will disappear

[David Chapman]

Two things.

1. If you are in 30p, then change your shutter to be 1/60th not 1/30th. Try to get as close as possible to doubling the shutter from the fps number. This could add to your stutter feeling, although your problem is mainly below.

2. You can't edit/deliver in that high bitrate H.264 format (still .mov extension). Use Compressor (part of Final Cut Studio) or download MPEG Streamclip (free) and convert the H.264 codec into something else more friendly with your system. I use Pro Res (Apple codec that others can get a reader codec for) but others include DVCProHD, HDV, etc.

[Robert Kennedy]

I thought some of my early 7D footage was stuttering so I transcoded it to a couple of formats I knew played perfectly cleanly. The "stuttering" persisted. I believe the rolling shutter and inadequate stabilization is causing this complaint.

With inadequate stabilization your frame may change very rapidly from one frame to the next. This is especially true if it is a momentary bump where the camera changes directions rapidly. If you go frame-by-frame over an area that consistently "stutters" at the same point you may notice that things appear a different size or shape relative to one another.

Ex. Put a person in front of a 7D and start rolling. Bump the camera. The person is skinnier in some frames and wider in other frames. When these two frames are immediately adjacent, our brain thinks "there are some frames missing there" and our familiarity with crappy video playback on computers leads us to think it's a playback issue.

Open up the movie properties in quicktime and watch the "fps" value to determine if your player is dropping frames or if you have found the achilles heel of the 7D.

-Robert

[Derek Reich]

Thanks for the input everyone..... Looks like I need to study up on this one. I didn't have time to read much of anything (much less the manual) before departing on this shoot, so I do apologize if this has been covered before.

I did try transcoding one clip to ProRes as suggested, and the stuttering persists. Robert, I'm familiar with rolling shutter issues (I also have an EX3) and this is definitely not a rolling shutter issue. The camera was locked down on a tripod. The image is wonderful, with the exception of the vehicles moving on the highway which seem to skip forward as they pass laterally across the frame. Other clips where vehicles are moving either toward or away from the camera do not seem to be as quite as bad....

[Perrone Ford]

You're shutter speed was not helping you. It's far too slow to capture that rate of motion smoothly. You should have been on at least a 1/60th shutter.

[Sylus Harrington]

Would there be a benefit to bumping the shutter to 1/120 at 30p? I also noticed that fast moving objects in a scene seem to stutter quite badly. For instance, a guitar player strumming the guitar vigorously will look pretty bad when you pay attention to the hand movement. When played frame by frame you can see quite a gap in the hand motion.

I also see this problem with my XHA1s in 30p, which where 60i usually has to come into play.

[Perrone Ford]

Originally Posted by Sylus Harrington

Would there be a benefit to bumping the shutter to 1/120 at 30p? I also noticed that fast moving objects in a scene seem to stutter quite badly. For instance, a guitar player strumming the guitar vigorously will look pretty bad when you pay attention to the hand movement. When played frame by frame you can see quite a gap in the hand motion.

I also see this problem with my XHA1s in 30p, which where 60i usually has to come into play.

Hear me out...

One of the things I often recommend to folks is taking a basic photography course when getting into this kind of filming. I don't mean that to sound condescending, but there is just SO MUCH you absorb by really learning the ins and outs of F-Stops, shutter speeds, framing, etc. I came from a photography background and there isn't a day that goes by when I am behind the lens that I am not thankful for those years of training and experience.

To answer your question, it's hard to say if going to a 1/120 shutter will improve the look. It certainly imparts a DIFFERENT look, but it's hard to say which is better, because that is totally subjective. Does that make sense?

[Sylus Harrington]

I hear yah, thanks. I think I understand shutter speeds in photography, but it seems to be a bit different from filming. To capture fast action stills you generally need a higher shutter speed, otherwise the shutter is not fast enough to freeze the fame - so to speak. That combined with fast glass and correct aperture will generally yield crisp - sharp fast action stills...as opposed to blurry ones. Like shooting water droplets...

It makes sense in photography and the results show it. But with filming it just isn't the same result, yeah? I can't simply up the shutter speed to compensate for fast action and expect to have a clean sequence in playback (like i would in photography). Which I guess was where my question came in. I think for myself the lack of knowledge is use of shutter in video, not photo. Never experimented with higher shutter speeds before.

Your answer does help reinforce that 24p and 30p generally yield poor fast action results, regardless of a higher shutter rate. Thanks for the tips!

[Perrone Ford]

Originally Posted by Sylus Harrington

But with filming it just isn't the same result, yeah?

I can't simply up the shutter speed to compensate for fast action and expect to have a clean sequence in playback (like i would in photography). Which I guess was where my question came in. I think for myself the lack of knowledge is use of shutter in video, not photo. Never experimented with higher shutter speeds before.

Your answer does help reinforce that 24p and 30p generally yield poor fast action results, regardless of a higher shutter rate. Thanks for the tips!

I think this is what catches many people out. For those who DO have a background in photography, you just need to learn how much shutter you can dial in before the video starts to strobe. There is no "frames per second" in stills (outside the motor drive) because photos are seen in isolation. So if you want to get smooth motion, you need to up the frame rate to say 60fps. But that's not suitable for broadcast (or the internet) so it's a balancing act.

Interlaced recording is really the broadcast answer to the motion problem because although it's doing fields, it's temporal movement is 60 fields per second. So fast moving things like cars, athletes, etc., tend to stay crisp. And staying with a 1/60 or 1/90 shutter tends to yield results more in line with what you'd want for that kind of action.

[Derek Reich]

Perrone, thank you very much for your input. While I may not sound like it, I have been a professional photographer for almost 30 years making my living off of broadcast video and still photography. I am definitely going to try a 60th shutter speed, but my experience in the past with Betacams was anything faster than that causes a strobing effect (not to be confused with what I am seeing in the 7D now) on fast lateral moving objects in the frame. Of course, Betacams never had adjustable frame rates, so everything was 60i. Perhaps that is part of my problem, but the stuttering I'm seeing appears to be more than just an improper setting on the camera, although I'm sure it can be making the problem worse or at least more noticeable.

These 'stutters' cause lateral moving objects (in this case, traffic) to jump what looks like a 4 or 5 frame drop distance in the frame. And, it's inconsistent.... a jump here, a jump there, but not consistent in a way that would be the result of an improper frame rate/shutter speed issue. A lot of what I've been reading out there seems to center on the bitrate of the H.264 codec, what version of FCP one is using, and even what type of flash card (speed) is used. As you pointed out, many people are experiencing the same issue, and I've tried some of the 'fixes' but to no avail. Curiously, others seem to have not experienced this issue at all, even when working with the native H.264 codec. This is confusing to me.
I will report back after I try the faster shutter speed, here's hopin'.

[Wm. Turner]

I've also experienced this, however just one time only. From what I can tell from my researching is that this is a memory card related matter. Apparently some cards don't play so well with the 7D. It doesn't seem to matter how quick they are from what I've read. I would look into trying a different CF card or manufacturer.

[Liam Hall]

Originally Posted by Perrone Ford

You're shutter speed was not helping you. It's far too slow to capture that rate of motion smoothly. You should have been on at least a 1/60th shutter.

No, you've got that round the wrong way. A 180 degree shutter will be more film like with more strobe. But you're right, a 180 degree shutter is best for this camera.

I agree, with William, it sounds like the camera is dropping frames, which is more than likely a card issue.

The CF card needs to be at least 133x.

[Derek Reich]

Thanks again, everyone. This is why I love these forums..... interesting input to ponder.

My CF card (recommended by the retailer, who is a high-end camera store, but admittedly not an experienced solid-state video store) is a SanDisk Extreme 16GB 60MB/sec. If what Liam tells me is correct, (and I've heard just the opposite too, Liam, which is adding to the confusion) then my CF card is woefully underpowered. While this also bears further investigation, how would it explain some people experiencing success in solving this problem by transcoding to ProRes?

None of my CF cards are faster than 80X, so I guess I'd better go shopping tomorrow....

Also, are there any requirements regarding the ingest hardware? I'm using an old CF card reader I've used for many years to ingest digital still images. I (maybe incorrectly) assumed that a reader is a reader is a reader... (it is firewire 400)

[Derek Reich]

I should be a little more specific about my CF card.... it is a 60MB/sec read/write UDMA card, 16GB capacity. But what I don't know is, what the 'x' write speed it is. I'm getting the feeling now that it is at least 133x, which means I'm back to square one with what is going on with my camera....