Time streching video

[Doug2006]

I have two videos and one is .637 seconds longer then the other. What I wanted to do was just time shift the longer one to be shorter and then I was going to work with them in mixing them to one video. My thinking was to fix this time difference up front and then the sound and everything would be right on. The video in question is 1hour 8 minutes and 6 seconds with 15 frames long. I put it in the time line and opened up the change playback speed in x2. I then saw a place called time shifting and in had a box with up and down arrows. So I shortened the video by making the six a five and the 15 frame box to 27 frames. This was a guess at approximately half a second. I thought that VS would then compress the video by speeding it up. It took about an hour to render and when I put the rendered one of the original in the time line they both say exactly the same thing. 1hr 8mins 6 seconds and 15 frames. What did I do wrong? Nothing changed.

[Black Lab]

I'm not familiar with the "time shifting", but if you use the playback speed adjustment you can make changes by percentage, minute, second, or frame.

[Trevor Andrew]

Hi Doug

Changing the playback speed would also stretch the audio.
Are you trying to sync¡¦ the two audios?

Add a colour clip to the beginning of the shorter video, make it .637 sec , although you would have to use frames.(about 19).
This is probably the best option as you can resize the colour clip at any time to readjust the main video position.

Or cut 19 frames from the start of the longer video.

[mitchell65]

So I shortened the video by making the six a five and the 15 frame box to 27 frames. This was a guess at approximately half a second.

If you are working in PAL then you will have 25 fps so 12 frames would be near enough to half a second. If your work in NTSC then you are in 30fps (actually 29.7fps) so 15fps would equate to half a second. I am interested to see how you got the duration of .637 of a second. Nothing in my setup of VS gives seconds in this way. Point 637 of a second in PAL would be .637 x 25 and in NTSC would be .637 x 30 and both answers would be in frames not seconds.
Have just looked at your "System". With only half a gig of RAM I wonder if you have enough "clout" to make these changes. Maybe someone else will comment on this

[Ron P.]

The Time-Stretch is just another means to speed up or slow down the clip. This can be used to do minor adjusting, in an attempt to sync up audio with video, however does not guarantee that they will remain in sync.

In video editing, the time-code is always displayed in the following format: HH:MM:SS:FF (Hours, Minutes, Seconds, Frames). The last 2 digits on the right, are Frames. So as Mitchell explained you need to do some math to figure out the correct number of frames. If you're using NTSC, ½ second would be 14.9 frames or rounding it up would be 15 frames. In you're case having slightly more than ½ second, you would be subtracting about 17 frames using NTSC..

[mitchell65]

What did I do wrong? Nothing changed.

Answer="Nothing"
I've had another look at this.
If you use the percentage Option in the "Playback Speed" window or the up and down arrows on Timestretch or use Shift and dragging the yellow handle at the end of the clip on the timeline you shorten or lengthen the playing time of the clip. What gets confusing is that when you make a change and then right click on the clip in the timeline then choose properties the clip will show the original running time and number of frames. This is because you don't alter the actual clip, you just alter the playing time. Like a car when you change gear, you don't alter the horse power (aren't I old fashioned) you alter the relative speed of the wheels!
If you set a time and altered your clip by say 10 minutes you would see the difference. Trying to measure and see the difference what 19 frames will make is next to impossible without a sophisticated duration measuring device.

[sjj1805]

I have two videos and one is .637 seconds longer then the other. What I wanted to do was just time shift the longer one to be shorter and then I was going to work with them in mixing them to one video. My thinking was to fix this time difference up front and then the sound and everything would be right on. The video in question is 1hour 8 minutes and 6 seconds with 15 frames long. I put it in the time line and opened up the change playback speed in x2. I then saw a place called time shifting and in had a box with up and down arrows. So I shortened the video by making the six a five and the 15 frame box to 27 frames. This was a guess at approximately half a second. I thought that VS would then compress the video by speeding it up. It took about an hour to render and when I put the rendered one of the original in the time line they both say exactly the same thing. 1hr 8mins 6 seconds and 15 frames. What did I do wrong? Nothing changed.

Do this the easy way.
It will be easier if you place the longer video on the video track and not the other way round. Consider this to be the main video.
The other video should then be place onto a overlay track and the sound muted. In fact one easy method here could be to render that second video as a video only (no sound) using smart render.

Now line up the two videos near the start of the project, at this time do not be too concerned that they become out of synch further along.
With this arrangement you will hear the sound from the video track but you will see the video from the overlay track.

Now decide which video you wish to see at a given point in time.
If the video you want to see is on the video track then use the scissors tool and cut away that piece of overlay video which is currently obscuring it.

When you revert to "watching" the video from the overlay track - check the synchronisation and simply drag it left/right as required. Unless you are zoomed in to someone speaking then you can get away with minor variations in lip synch. If lip synch is particularly noticeable at an given point - use the other track.