How to normalize footage captured in Slow Motion?

craftech wrote on 1/14/2010, 9:08 AM

Had a couple of damaged miniDV tapes (periodically scratched or sliced across the first 12-20 minutes of each tape shooting a dance recital). Not sure how that happened. The only backup I had was from a Hi8 camera - not ideal for a backup. One day shoot.

Aside from the lessons learned that I already realize I was able to eliminate a lot of the blockiness and color flashes by capturing the damaged portions using Slow Motion playback. The Sony VX2000 (PD150) both have that playback feature.

However, I could not find in the specs the playback rate the camera uses for Slow Playback so I don't know what to do in Vegas to bring the footage back up to the normal playback rate. I can synch other backup audio tracks to the video so that is not the problem. It's the video itself.

Anyone know how to do this?

1. The velocity envelope only asks how fast by percentage (which I don't know).

2. Compressing the event will also require that I know how much.

Don't forget, this is dance so it also matters if the audio and video are not in perfect synch.

Thanks for the help as always.

John

Comments

Chienworks wrote on 1/14/2010, 9:40 AM

Probably counting frames is the only way to go. Disable resampling. Start at the beginning of the clip and Alt-right-arrow to move one project frame at a time. You should see the source frames in the preview window change less than once for each project frame. If you get 3 project frames for every source frame then you know the speed is 1/3. It's more likely that the speed is something like 1/3.439257125 (i made that number up, don't expect it to be anywhere close), so that means you may have to count many frames (thousands?) to get a close value.

Maybe you could try adding the timecode effect to the clip in project media. That should cause vegas to show the source timecode. You could then pick two points a minute apart on the timeline and see what the timecode difference is in the source clip between those points. If it shows up as 13 seconds 4 frames then you know the speed is about 1/4.56853.

craftech wrote on 1/14/2010, 1:14 PM

Thanks Kelly,

In the preview window it moves every third keystroke so I guess that means roughly 1/3 speed.

In terms of what you suggested about timecode I am not having any luck.
If I add Sony timecode as an FX to the Project Media pool it shows up in the preview window, but the timecode for both seems to match frame by frame. Shouldn't they be different?

For example: The normal clip is 38:31;27 at point one and the Slow Mo clip is 38.30;08. At point two (one minute later) the normal clip is at 39:32;27 and the slow Mo is at 39:31;08. Same difference. Is there a setting I am not changing?

John

Former user wrote on 1/14/2010, 1:23 PM

Can you find the first frame of your footage at normal speed and the last frame and then do the same in the varispeeded footage and line them up using the speed change in Vegas?

Dave T2

Tim L wrote on 1/14/2010, 1:34 PM

If you captured the "slow motion" playback from the camcorder you must have captured the camcorder analog output through an analog-to-firewire type converter, like a Canopus ADVC100 or similar, right?

If that is the case, then the captured file on your pc is a 29.97fps regular speed recording of your slowmotion output, so it will have the same frames per second as a regular file. It has no idea that what you captured was slow motion. (For example, you could have the output of your camcorder on a freeze frame, and the converter would still be capturing 29.97 frames per second.)

Have you tried cleaning the heads on the camcorder to see if maybe that will fix (or improve) your playback?

craftech wrote on 1/14/2010, 1:37 PM

Can you find the first frame of your footage at normal speed and the last frame and then do the same in the varispeeded footage and line them up using the speed change in Vegas?
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Thanks Dave,

The normal one is part of a longer clip since only the first 12 minutes were screwed up.

Also, the beginning if each clip doesn't start from the same point.

I don't understand why the timecode (that is part of the tape) shouldn't be able to be used to line them up. Shouldn't they match at a given point or does this get screwed up by Scenalyzer when I captured at Slow Mo.

John

craftech wrote on 1/14/2010, 1:43 PM

If you captured the "slow motion" playback from the camcorder you must have captured the camcorder analog output through an analog-to-firewire type converter, like a Canopus ADVC100 or similar, right?

=================

Thanks Tim

The Slow Mo playback capture was via firewire from the camera to the computer not via analog.

The problem is on the tape itself. I opened the three tapes and would them manually with a pencil. There are scratches (diagonal lines) across the tape surface at the beginning of all three tapes (0 - 20 minutes at random intervals).
Slow Mo playback eliminates much of it. Head cleaning does not.

In terms of "guessing" at rougly 1/3 speed would you use a velocity envelope or compress the event using CTRL and dragging it smaller.

How would you judge whether it is speeding up fairly accurately to 300% (more or less)?

John

johnmeyer wrote on 1/14/2010, 4:41 PM

If you can post about 1 second of the footage, I'll take a look, field-by-field, and see if I can come up with a "formula" for getting back up to speed.

craftech wrote on 1/14/2010, 7:04 PM

If you can post about 1 second of the footage, I'll take a look, field-by-field, and see if I can come up with a "formula" for getting back up to speed.
===============
I'd really appreciate that John,

I experimented and came up with right clicking on the clip and changing the playback rate to 2.989 to normalize it. Then I rendered it to a new file and imported it into the project.

Let me know what you come up with.

Thanks for the help John.

Here is the file.

John

johnmeyer wrote on 1/14/2010, 11:33 PM

Wow, that is some really weird video.

I put it in Vegas and frameserved it into an AVISynth script that separates the fields and then turns them into frames. This lets me see how fields are duplicated, blended, etc.

I couldn't believe what I saw. There is field reversal (where one field is earlier in time than the previous field), but only on some frames. I thought I had something screwed up, so I put some normal DV footage on the Vegas timeline next to yours, and it came through the script normally. I then thought perhaps your video was top field first (not normal for DV), but I changed the script for TFF video, but everything was still screwed up.

I'm going to spend a few more minutes on this and see if I can figure out a pattern and, if so, a way to recover the original video exactly. Interesting challenge.

[Edit] OK, the pattern is simpler than I thought. It is simply repeating each frame three times. Thus, we need to decimate 2 out of every three frame. I'll see if I can do this in Vegas.

johnmeyer wrote on 1/14/2010, 11:49 PM

OK, the solution seems to be pretty simple.

Right-click on the event, select Properties, and Disable Resample. Then, set Playback Rate to 3.000

That's it!

As for your audio, speeding it up by a factor of three makes it sound awful because there simply aren't enough samples to create decent audio. If you can capture the tapes at normal speed and then use that audio I'd try that. Alternatively, if you have a sound board feed, you can sync that up and use it. Finally, if all else fails you can get the prerecorded music and do your best to subtly speed it up or slow it down (because it will probably be slightly off in speed compared to the audio that was actually played) and then try to sync that up.

Hope this helps!

craftech wrote on 1/15/2010, 6:33 AM

........Right-click on the event, select Properties, and Disable Resample. Then, set Playback Rate to 3.000.........As for your audio, speeding it up by a factor of three makes it sound awful because there simply aren't enough samples to create decent audio. If you can capture the tapes at normal speed and then use that audio I'd try that........

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Thanks for doing that John. I really appreciate that.

As I said above I had come up with a playback rate of 2.989, but if you feel that 3.00 is more accurate I'll use that. I rendered it and imported the rendered file into the project to make the final render easier.

In terms of the audio, I have audio from the hi8 backup tape that is in perfect condition. The only reason I used that camera is because (fortunately) the choreographer doesn't like the sound of pointe shoes on the floor so the feed to my camera from my mikes on the stage apron is only for the vocals and non-pointe numbers. The audio from the hi8 is perfect so it will be used for the first 0 to 20 minutes of each of the screwed up miniDV tapes in addition to the pointe numbers.

So thanks again John. Your dedication to helping the members of this forum are truly appreciated as well as all the endless hours of work you have done in developing various solutions for all of us to use for our craft.

Regards,

John

craftech wrote on 1/21/2010, 4:47 PM

I am having a problem with this in terms of synching the resampled video to the alternate soundtrack.

1. Load slow recorded captured clip onto Vegas 8 timeline.

2. Right click on video event on timeline. Choose properties. Change playback rate from 1.000 to 3.000

3. Render to bring video back up to proper speed works, but audio no longer is in synch with video because it remains at the same original playback rate (one third speed).

4. It would make it easier if audio playback rate could also be sped up to 3.000 along with the video so they would be in synch with each other.

5. Then I could more easily line up the alternate soundtrack with the video by matching peaks, etc.

6. In other words, how do I increase the playback rate of the audio to 3.000 as well?

John

Chienworks wrote on 1/21/2010, 6:42 PM

Not sure why your audio isn't speeding up. If it's in the same physical clip as the video then the playback rate should affect both.

However, since they don't seem to be, can you right-mouse-button click on the audio and change the speed in it's properties there?

craftech wrote on 1/21/2010, 6:56 PM

Thanks for the quick response Kelly.

The audio did not speed up. I too thought it would. If I right click on the audio event there is no choice to adjust the playback rate so I assumed (incorrectly) that it was tied to the video playback rate.

Visually,

When you right click on the video event and change the playback rate from 1.00 to 3.00 you can see the video separate and a squiggly line appear between many of the clips to visually indicate that the playback rate has changed. However the audio remains unchanged visually seemingly indicating that nothing has changed in terms of the playback rate.

If both should have changed, any ideas as to why they didn't?

When Johnmeyer tried a sample that I sent him he stated:

As for your audio, speeding it up by a factor of three makes it sound awful....... indicating that it sped up for him.

I tried disabling resample, smart resample, etc Loop checked. Loop unchecked. Nothing changed in terms of the audio from all those trials.

John

Tim L wrote on 1/21/2010, 7:04 PM

Right-click on the audio clip and select Properties.

In the bottom part of the window "Time Stretch / Pitch Shift" the Method setting probably says "None". Change it to "Classic" and some options will appear. Next to "Pitch Shift" you can tick "Lock to Stretch". Otherwise, you can manually set the DURATION of the playback, compared to the original file. It's a shame we don't have a simple "Playback Rate" setting like the video clips have.

EDIT: Ooops! If you've already ctrl-stretched the audio it will already have the Method set to "Classic" for you. You probably just need to tick the "Lock to Stretch" box.

craftech wrote on 1/21/2010, 7:25 PM

Right-click on the audio clip and select Properties.

---------------------------------

Thanks for the suggestion Tim. I haven't ctrl-stretched the audio so I took your suggestion to change "None" to "Classic" and checked off "Lock to Stretch". The duration of playback remained unchanged so I guess that's right.

However,

When I click OK it automatically reverts back to "None". The changes don't remain????

John

EDIT: I used Ctrl Drag to shrink both the video and audio at the same time until though trial and error) I was able to get the playback speed to 3.000. This time the audio did speed up with the video.

There has to be a simpler way.

Tim L wrote on 1/21/2010, 7:52 PM

I think it reverts because if you don't ctrl-stretch or ctrl-shrink the audio (or do the same manually via entering a "New Length" compared to the Original Length) then there is no "stretch" so no adjustment.

If you changed the video speed via the Playback Rate, you probably have three repetitions on the same video in the length of the original event. Look for the little triangle notches in your video on the timeline. (For example if you had a 9 minute video, and set playback rate to 3.00, then the event on the timeline stays at 9 minutes long, but if you look you'll actually see that your new 3-minute-long video repeats three times in that event.)

Drag the end of your video to the first notch so that your video is 1/3 of its original length. Now manually set the "New Length" of your audio properties to that same time. Alternatively, you could ctrl-shrink the audio until it shows 300% at which time it should allign with the end of your shrunken video clip.

Tim L

craftech wrote on 1/21/2010, 7:55 PM

Tim,

I was editing my post above when you wrote that. That sounds easier than what I did (trial and error). I'll do that. You were right, the video and audio was repeated three times without Ctrl / Drag being done.

1. Right click video properties. Change playback rate to 3.000
2. Un-group audio and video.
3. Drag video event down to first notch.
4. Ctrl / shrink audio down to line up with video.
5. Re-group

Thanks again. Learned something new today.

John