Sony Vegas Pro – Velocity Rendering

[John Rofrano]

[James Souter] “I have set the appropriate clips to “force resample” as well as tried “smart resmaple” but they all render as if “disable resample” was selected.”

What makes you say that? I get different results when I switch between disable and either of the two resample modes using velocity envelopes.
You are not going to see every frame blended but you should see some blending.

If you want the super slow motion of 300 you are asking a lot from Vegas alone. You really need a plug-in like Twixtor or Boris BCC7 Optical Flow. When I apply BCC7 Optical Flow I get a lot smoother blending.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Steve Rhoden]

Yes,Twixtor offers great results if you have after Effects.

Steve Rhoden
(Cow Leader)
Creative Arts Director and Film Maker.
Project Samples at:
http://www.youtube.com/hentys

[Jerry Irving]

Hi, James,

I believe that you may achieve what you’re hoping for, or at least closer to it, if you add a supersampling envelope to your video bus and us it to specify interpolation of your existing source video frames to fill in the project frames that fall between the original source frames.

As I understand it, the ‘resample’ task only ‘resamples’ each existing source frame (i.e. it will not provide new frames for source video that has been stretched to fill more time that it has frames available. It is useful when changing resolutions, pixel aspects, cropping, etc. The ‘supersampling’ task does create new, interpolated frames between the original source frames.

I’m using Vegas Pro 10.0 & in my pdf manual page 190 table at the bottom it says a “video bus [track] video supersampling [envelope] Calculates intermediate frames between the project frame rate to create smooth motion blurring.” There is more information there & other places in the manual, but the info is rather brief.

(my terminology:) You can set the supersampling envelope to integer values (e.g. 2, 3, 4, etc.) to cause creation of interpolated (‘tweened’) frames.

The manual also notes that there is a significant increase in rendering time when supersampling.

I just ran a test of 52 frames of source stretched to 208 frames output render and confirmed that this technique works.

-I placed on the timeline an event with 52 source frames of a person walking across a room.

-I stretched the source as far as I could (via ctrl+drag the end of the clip to the right) & confirmed via the event properties that playback rate was 0.250.

-I enabled the view of the video bus (View|Video Bus Track or ctrl+shift+b).

-I inserted a supersample envelope on the video bus track (right click the bus track header & select Insert/Remove Envelope|Video Supersampling)

-I dragged the envelope line up until it indicated ‘4’

-I rendered the project

-I inserted the newly rendered output video clip on the timeline.

-I confirmed that there were, indeed, appropriate & realistic interpolated frames with very acceptably interpolated images, including realistically repositioned elements (e.g. hands, etc.) in the interstitial frames between original source frames.

In other words, I started with 52 unique source frames and ended up with 208 unique rendered frames, each looking completely real and appropriate. Stepping through the resulting frames, I litterally can’t tell which are interpolated unless I compare to the stretched source. It’s very impressive.

Jerry

[John Rofrano]

[jerry irving] “As I understand it, the ‘resample’ task only ‘resamples’ each existing source frame (i.e. it will not provide new frames for source video that has been stretched to fill more time that it has frames available. It is useful when changing resolutions, pixel aspects, cropping, etc.”

Hmmm… that’s not correct. Here is what the Vegas manual says:

…video frames will be resampled when the frame rate of a media file is lower than the project’s frame rate. This can occur either when the event has a velocity envelope or when the frame rate of the original media is different than the Frame rate setting on the Video tab of the Project Properties dialog.

With resampling, the intervening frames are interpolated from the source frames, much like a crossfade effect between the original frames. This may solve some interlacing problems and other jittery output problems.

Resample is absolutely creating new frames between existing frames (i.e., “tweening”). If you don’t believe me, render a stretched video with force resample and then again with disable resample and watch them side by side and you’ll see the new resampled frames.

[jerry irving] “The ‘supersampling’ task does create new, interpolated frames between the original source frames.”

Yes, but not for video. 🙁 Here is what the Vegas manual says:

Video supersampling can improve the appearance of computer-generated animation by calculating intermediate frames between the project’s frame rate, allowing you to create smoother motion blurring or motion from sources such as track motion, event pan/crop, transitions, or keyframable effects.

Supersampling does not resample video frames. It smooths out frames created by Track Motion, Pan/Crop, etc. (i.e., motion that Vegas is creating).

[jerry irving] “I just ran a test of 52 frames of source stretched to 208 frames output render and confirmed that this technique works.”

I would be interested to know what tests you ran because that’s not what I’m seeing.

I just rendered a stretched video both with and without supersampling and I placed them back on two tracks with the composite mode set to Difference and the frames were absolutely black! i.e., no difference, pixel-for-pixel. I then watch both videos simultaneously using track motion to position them and each and every frame was identical. No difference with supersampling on or off.

This is a big misconception about Supersampling. It only supersamples motion created by Vegas like track motion or pan/crop. It does not supersample source video frames.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Jerry Irving]

Hi, John,
Thanks for correcting my assertions. I haven’t had time to revisit my testing on this, but apparently my analysis was flawed. I’ll try to re-do the testing & post back.

Just thinking back, I probably mistakenly compared a clip rendered with both re-sample and supersample to the original clip (thinking it was rendered with resample only) on the timeline. I did verify as I stepped frame-by-frame that the rendered video had newly created interpolated frames that looked very nicely accurate & realistic.

In particular, the hand swinging as the person was walking showed reasonably accurate images of the hand moving through space between the location hand in the original clip’s surrounding frames (hopefully, I’m explaining it clearly). The moving hands in the interpolated frames, moving through space not captured in the original clip, looked just as realistic to me as the hands in the original source frames.

I was quite impressed with the quality of the interpolation & was thinking that James Souter may benefit from knowing what I found.

I am currently intrigued with one question:
Why didn’t James see new interpolated frames between the original source frames? See context:

James Souter stated:
1. [In preview the scene looks how I want it to look, however upon rendering it only renders the frames that are there and does not create any intermittent frames.]
and
2. [I have set the appropriate clips to “force resample” as well as tried “smart resmaple” but they all render as if “disable resample” was selected.]

and John Refrano stated (in response to my post):
[Resample is absolutely creating new frames between existing frames (i.e., “tweening”).]

Thanks so much, John. You are a huge benefit to this Sony Vegas Community, sharing your formidable expertise so generously. I appreciate your help and guidance.

Jerry Irving

[John Rofrano]

Thanks for the kind words Jerry. I try my best to help out wherever I can.

[jerry irving] “Why didn’t James see new interpolated frames between the original source frames? See context:”

We will never know because he never posted back. I did not see what he was seeing and I can’t explain why he didn’t see intermediate frames unless, as I pointed out, he was expecting more frames than Vegas generated, but it does generate new frames.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[James Souter]

Hi Guys

Sorry for not posting back sooner, and thanks very much for the advice. Especially Jerry for his detailed response. I have tried your method Jerry but the results are ‘unpredictable’ so to speak and didn’t give the desired result. Interestingly enough – I added a velocity envelop to a DIFFERENT piece of footage as a test and it rendered as expected.

John – I’m not expecting Vegas to provide crystal clear frames – but I am expecting it to provide some level of blending. As you can’t see the footage I can only explain that on another piece of footage slowed to the same extent I get a nice blending effect from vegas – it just seems for some reason (a bug perhaps) that it will not work on this piece of footage in Vegas (both from the same camera).

I’ve also deleted and reimported the footage only to get the same result. I’ve stopped short of creating a new project and importing the footage because at this stage it’s purely academic as I’m going to use After Effects from now on.

Odd behavior and one that I hope I don’t see again as it took quite some time to get the velocity right.

The workaround for now is to use time remapping in After Effects, which seems to be able to provide the correct result.