grimepoch

So, I've been trying to figure out how to scratch a video, and so far, not had a lot of great success.

I created a JSUI circle to drag forward and backward. I use this to send out 'rate' commands to a movie.

I created a JSUI circle to drag forward and backward.  I use this to send out 'rate' commands to a movie.

scratching-a-video

Try sending time or frame commands instead of rate.

btw, it's really important that you save your video without any delta compression (Photo-JPEG is standard)

If you want to change the rate by scratching, you could calculate the relationship between successive time/frame commands (that is, the elapsed time between them and how big a jump they represent), and then set the appropriate rate for the video to continue at when you lift the mouse button.

Tough to avoid those little clicks, though.

But if you want the video to be REALLY responsive - and you don't need audio - stop the video (or use @autostart 0) and then send it time/frame commands (of course, it will freeze when it isn't getting a command, but that's what makes it so responsive)

If you do want to use audio though you'll need sample accurate control to get a natural scratching effect. Which means you need to import the audio of the video in a buffer~ and use msp to drive the video (i.e. set rate to 0 and send time messages every 20 ms, for example by means of snapshot~).

So what would be the best way to get rid of clicks when passing through zero time? I have had limited success with setting a line object to duck the audio a range of frames on each side of zero time and for zero. Is better but till clicks sometimes though.

Quote: CarlR wrote on Mon, 23 July 2007 12:30

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> So what would be the best way to get rid of clicks when passing through zero time? I have had limited success with setting a line object to duck the audio a range of frames on each side of zero time and for zero. Is better but till clicks sometimes though. 

As you said, you could do a little volume duck/fade by checking the distance to the end/beginning of the file.

You've got both the actual position at any given moment and the length of the file, right? If this distance gets under a threshold, do 

The threshold determines the length of the fade, should be in the order of 5 ms.

Quote: CarlR wrote on Mon, 23 July 2007 12:30
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> So what would be the best way to get rid of clicks when passing through zero time? I have had limited success with setting a line object to duck the audio a range of frames on each side of zero time and for zero. Is better but till clicks sometimes though. 
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As you said, you could do a little volume duck/fade by checking the distance to the end/beginning of the file. 

You've got both the actual position at any given moment and the length of the file, right? If this distance gets under a threshold, do 
original volume * distance / threshold.
The threshold determines the length of the fade, should be in the order of 5 ms.

Thanks for that Mattijs. That has really confused me though. When scratching the video it passes through zero time every time the direction changes. I really can't conceptualise what you said.

I understand how to get duration. I understand how to get position. 

But I am still confused how this helps. When scratching I could be anywhere along the file and decide to change direction.

Thanks for that Mattijs. That has really confused me though. When scratching the video it passes through zero time every time the direction changes. I really can't conceptualise what you said. 

I understand how to get duration. I understand how to get position.  
But I am still confused how this helps. When scratching I could be anywhere along the file and decide to change direction.

Hmm, perhaps I misinterpreted your problem. Guess it would be best if you posted a patch that illustrates where you're stuck..

Quote: CarlR wrote on Thu, 26 July 2007 12:16

> Thanks for that Mattijs. That has really confused me though. When scratching the video it passes through zero time every time the direction changes. I really can't conceptualise what you said. 

> I understand how to get duration. I understand how to get position. 

> But I am still confused how this helps. When scratching I could be anywhere along the file and decide to change direction.

Quote: CarlR wrote on Thu, 26 July 2007 12:16
----------------------------------------------------
> Thanks for that Mattijs. That has really confused me though. When scratching the video it passes through zero time every time the direction changes. I really can't conceptualise what you said. 
>
> I understand how to get duration. I understand how to get position.  
> But I am still confused how this helps. When scratching I could be anywhere along the file and decide to change direction.
>
> Can you elaborate? 
>
>
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Scratching a Video...