Strategies for movement shift

[Bencuri]

I am editing a guitar tutorial video. The sound and the video were recorded separately, because it couldn't be solved to record the sound at the desired scene. Yet, the sync is okay, but there are a few moments when experienced viewers may spot the recording of the sound was not real time. The finger movements should be synced more precisely at those parts.

The method I thought of is using the CTRL + element stretch/shrink option in Vegas, that results in the element to play faster and slower. So I split the elements at the problematic parts, and I speed up/slow down the segments to match the sound. I made a test, it seems to work more or less.

But I wondered if it is the best solution indeed? And, if it is, what settings should i use in Vegas regarding the stretch/shrink? As I see there are element options: Smart Resampe / Force Resampe / Disable Resample. Which one should be selected? Any other setting that I should check? And finally, is it better for the video to be in 25p or 50i? While testing, I noticed, sometimes it is difficult to create the sync in case of 25p. An 'in between' frame would be often useful, but due to the framerate, it is not there, and this way the sync will never be that proper when adjusted. You cannot strecth the frame to 1 and a half frame, for example. In case I use 50i, can I have more fields on the timeline? How does Vegas insert the fields onto the timeline? It considers 2 fields as 1 frame and insert them like that on the timeline, or what you will have on the timeline are truly 50 fields per second? Because in the latter case the sync could be adjusted better.

[poisondeathray]

Yet, the sync is okay, but there are a few moments when experienced viewers may spot the recording of the sound was not real time. The finger movements should be synced more precisely at those parts.

How much off ? And how are you determining this ?

Was it uncompressed audio ?

But I wondered if it is the best solution indeed? And, if it is, what settings should i use in Vegas regarding the stretch/shrink? As I see there are element options: Smart Resampe / Force Resampe / Disable Resample. Which one should be selected? Any other setting that I should check?

Smart resample means blends , disable resample means duplicates . Blends are probably smoother and less noticable . When you're stretching something, you're adding frames

Deinterlace set to interpolate

And finally, is it better for the video to be in 25p or 50i?

"50i" or deinterlaced to 50p - because you have twice the number of samples per time compared to 25p .The granularity is more precise

How does Vegas insert the fields onto the timeline? It considers 2 fields as 1 frame and insert them like that on the timeline, or what you will have on the timeline are truly 50 fields per second? Because in the latter case the sync could be adjusted better.

On a 50i timeline, it retains 50i fields/s internally , but the preview is showing only half - you're seeing a deinterlaced version at 25p by default

On a 50p timeline, it's deinterlacing so each field becomes a frame. Every video time sample has it's own frame.

[Bencuri]

"How much off ? And how are you determining this ?"

This is something that you see when you have experience in editing such videos. I did not measure this precisely, but sometimes maybe just a frame off. But if you are looking at the video carefully (and this is what students do in case of these videos), you can spot here and there that there is no sync. When the tutor recorded it, he played a note there a fraction of a second earlier than on the video, and in case the movements are a particular kind, it can be noticed. It depends on certain factors, the type of the theme, speed of playing, adjacent notes. This could be made unnoticed in case I would film the lesson like a video clip, moving with the camera, different angles, different scenes, including video of the surrounding, etc. The problem is that the aim of the video does not let it to be made like that.

"but the preview is showing only half - you're seeing a deinterlaced version at 25p by default"

So I need to record in 50p to be able to follow precisely while editing how the sync is. At least it is possible anyway, I have such a camera. Not the best, but will do.

[poisondeathray]

So I need to record in 50p to be able to follow precisely while editing how the sync is. At least it is possible anyway, I have such a camera. Not the best, but will do.

No, you can still use the "50i" recording, there are still 50 samples/s recorded, but they are interlaced

You drop the recording onto a 50p timeline in vegas. Set the deinterlace mode to interpolate

But a 50p recording in the first place is better, because you usually have higher spatial resolution. Interlace and subsequent deinterlacing will predispose to artifacts as well. Things like guitar strings at an angle will look jagged - aliasing and deinterlacing artifacts

[Bencuri]

Yes, it will be easier in 50p.

Any other setting that my relate to this editing job and I need to check? I leave Smart resample, but any other option for the case of stretching/shrinking?