Can you fix my golf swing?

TeetimeNC wrote on 10/13/2008, 2:08 PM

Even a swing coach can't fix this swing, but maybe you can help me with a weird render problem.

I shot a golf swing with my new HMC150 (AVCHD) cam using HD 720 60p and a 1/2000 shutter speed. I dropped that clip on an HD 720 24p timeline in Vegas 8.0c. When I rendered at normal speed it looks correct. Then I added a velocity envelop set to 40% and it starts ok, but then starts a rapid jittering.

Any ideas what is going wrong here? You can see the clip here.

Jerry

Comments

Terry Esslinger wrote on 10/13/2008, 3:11 PM

What does it look like when you do a RAM render of a portion of it on the time line?

johnmeyer wrote on 10/13/2008, 3:27 PM

I just saw exactly this same thing yesterday when using VirtualDubMod to read an AVS script that was reading MPEG-2 video. I think in both my case and yours, there is something wrong with how pointers are being maintained in memory. In Vegas, my first advice would be to change the amount of RAM preview (Options -> Preferences -> Video.

I'd try setting it to 128 (a "safe" default value) and try rendering again. I think after you change it, and before you render, you should quit and then re-start Vegas in order for the change to take effect.

TeetimeNC wrote on 10/13/2008, 7:28 PM

Terry and John, when I do a RAM preview of the same portion it starts jittering much earlier. But if I step through frame by frame the jitter looks like the sample I posted.

The RAM preview was already set to 128 on this PC. I shut down Vegas, restarted and reopened the project and tried rendering (preview in player) that section again - same problem.

Then, for grins I set the RAM preview to the max setting (639Mb on my 2Gb PC). Guess what - RAM preview worked perfectly. So next I tried rendering to disk wiith RAM preview still set to the max setting and it also rendered correctly.

So, sounds like there is definitely some kind of problem with the RAM allocation - perhaps pointer getting trashed as you suggest John.

I will submit this as a bug report. I'll also see if I can get one of the other HMC150/Vegas owners to see if they can duplicate this problem on a different clip and PC.

Jerry

Jeff_Smith wrote on 10/13/2008, 9:27 PM

Your left hand grip is a bit strong, you should only be able to see only three knuckles on your left hand when sighting down the shaft and your left grip should be light enough to be able to slide a pencil in past your left pinky, but more than anything your head moves up near the top of your back swing. Some folks can live with a slight horiz movement of the head, but moving up and down is generally not good. ;)

As far as the video, once I had this problem with DV footage. I concluded that somehow the file was corrupted and I started over with a new project.

johnmeyer wrote on 10/13/2008, 9:33 PM

It seems like RAM preview settings have been at the center of dozens of Vegas bug reports over the years, even back in the days when Vegas was 100% rock solid.

TeetimeNC wrote on 10/14/2008, 4:36 AM

Hi Jeff. I had noticed the severe head bob, but not the strong left hand grip. In fact, I'm impressed that even as good as the resolution is on this clip that you can catch that. Can you elaborate on the "slide a pencil in past your left pinky" comment? I'm not sure what adjustment to make.

I guess it is possible that the clip is corrupt but the fact that it renders ok without a velocity envelope, or with RAM preview setting changed suggests to me it is a Vegas problem.

Hopefully I have more control over fixing my golf swing than fixing Vegas' memory problems.

Jerry

TeetimeNC wrote on 10/14/2008, 4:41 AM

I agree John. I wish Sony would take a look at the way After Effects does their preview. Instead of the user allocating memory, the user gets to set preview resolution AND frames to skip (e.g., render every fourth frame). The combination of these two settings gives you fast, reliable and flexible control over preview.

Jerry

Tim L wrote on 10/14/2008, 5:22 AM

Have you tried doing the slo-mo by right-clicking on the event, selecting properties, and then setting the playback rate to 0.4 -- instead of using the velocity envelope? It might help pin down whether the problem is specifically related to the velocity envelope.

I have to admit that I laughed when I first looked at the clip because it looked like a cartoon where the character swings a golf club and then spins around a half-dozen times. I was expecting your legs to be all twisted around like a rope, lol.

TeetimeNC wrote on 10/14/2008, 6:00 AM

Tim, just as you have reminded me - there are always at least two different ways to do something in Vegas. I tried changing the playback rate to 0.4 and it rendered perfectly.

Unfortunately, the head is still bobing though ;-).

Jerry

dibbkd wrote on 10/14/2008, 9:45 AM

The new camera looks great Jerry!

I haven't seen jittering exactly like that on my cam, but I have seen something similar. I have been converting my avchd files to mpg2 because I just can't edit the raw avchd files. Once in a while, it's like the video will skip or add a frame from a few seconds earlier in the clip. It's weird.

I am going to try bumping up my RAM setting to see if that fixes it as well.

Edit: It didn't fix my issue.

Jeff_Smith wrote on 10/14/2008, 1:23 PM

Jerry, some folks say that the left hand grip should be loose at the pinky, you should be able to slide a pencil between the underside of the shaft and your pinky. But everyone is different and it depends on what you want to do. If you want to try to snap hook it, roll both hands clockwise. search "golf grip" on youtube. Check out Jim Furyk to see someone that successfully breaks conventional rules.

TeetimeNC wrote on 10/14/2008, 7:17 PM

Correction to my previous post. Although the short 15 second segment of my clip rendered perfectly when I changed the playback rate to 0.4, when I tried this on the entire 25 minute clip it flickers wildly throughout. There is definitely still a problem with Vegas 8.0c here. Or maybe I just had way too much coffee before the trip to the range.

Jerry

TeetimeNC wrote on 10/16/2008, 3:06 AM

Just in case the problem is me....

I read over in DVXUser about folks shooting in 720-60p and then dropping the clip into a 24p timeline (FCP) and then "recomforming" the 720-60p to 720-24p to achieve high quality slomo.

I am trying to do the same with Vegas. I have set my project to 720-24p and dropped a 720-60p clip in it. I then adjust the framerate to 0.4. Then I rendered to 720-24p. Is this a valid approach in Vegas.

Recall that this yielded jittery footage for me.

Jerry

amendegw wrote on 10/16/2008, 6:08 PM

Grip looks fine to me. I'd like to see you get your left shoulder UNDER your chin while rotating around a constant spine angle.

Another Jerry

TeetimeNC wrote on 10/24/2008, 1:35 PM

Thanks to Matt at SCS Support, and others here, I've resolved my problem (which is spread across a few threads here and at DVXuser). Basically, the jitter was caused by me setting my project settings to match the desired output rather than to match the source footage. Here are the steps to conform 720p60 footage to 720p24 40% slow motion. When properly done, your slow motion will only use original frames; i.e., no intermediate frames generated by Vegas.

1. Use the stock Vegas HDV 720-30p (1280x720, 29.970 fps) template to set project properties.

2. Drop your HMC150 720p60 footage on the timeline.

3. Disable resampling to prevent generated frames.

4. Set velocity or playback rate to 40%

5. Extend the clip to its new length.

6. Render to 720p24.

This produces beautifully smooth slow motion.

Jerry

> read over in DVXUser about folks shooting in 720-60p and then dropping the clip into a 24p timeline (FCP) and then "recomforming" the 720-60p to 720-24p to achieve high quality slomo.