AviSynth - Looping through frames?

[Mister Epic]

Hello.

Is there a way to loop through frames in a clip in an AviSynth script? Like a "For" or "While" loop structure, but in AVS? If there's no way to loop like this, is there any other way to loop through frames?

[poisondeathray]

http://forum.doom9.org/showthread.php?t=102929

gscript
http://forum.doom9.org/showthread.php?t=147846

[Mister Epic]

http://forum.doom9.org/showthread.php?t=102929

gscript
http://forum.doom9.org/showthread.php?t=147846

Thanks mate! I'll try GScript!

[jagabo]

If you don't need to loop infinitely you can just add the clip several times.

WhateverSource()
return(last+last+last+last+last...)

[Gavino]

If you don't need to loop infinitely you can just add the clip several times.

WhateverSource()
return(last+last+last+last+last...)

If you just want to repeat a clip (or part of a clip), you can use the Loop function:
WhateverSource()
Loop(5)

To repeat a series of script statements, use the 'for' or 'while' loop in GScript.

[jagabo]

If you just want to repeat a clip (or part of a clip), you can use the Loop function:
WhateverSource()
Loop(5)

Haha! Missed that. Ah and -1 means (nearly) infinite (10^32?).

[Gavino]

Ah and -1 means (nearly) infinite (10^32?).

-1 (the default) actually gives 10^7 output frames (which is over 100 hours at 25 fps).

[Anonymous344]

I'm sorry to bump an old thread, but I have a related question. Can one make multiple calls to Loop()?

x=whateversource()
edit= \
x.Trim(0,40000).Loop(10,25000,25000) ++\
x.Trim(40000,80000) ++\
x.Trim(80000,90000).Loop(10,88000,88000)
return edit

The first call to Loop() does what I want it to do. The second seems to do nothing.

[jagabo]

x.Trim(80000,90000).Loop(10,88000,88000)

The output of Trim(80000,90000) is a new 10001 frame clip with frames numbered 0 to 10000 (not the original frame numbers). So you can't loop() frame 88000. You want to Loop(10,8000,8000) -- assuming that was your intent.

[Anonymous344]

Oh, I understand now! Thanks.

Could I insert Loop() earlier to achieve the same effect?

x=whateversource()
edit= \
x.Trim(0,40000).Loop(10,25000,25000).Loop(10,88000,88000) ++\
x.Trim(40000,80000) ++\
x.Trim(80000,90000)
return edit

I suppose I could also loop before trimming.

x=whateversource()
edit= \
x.Trim(0,40000).Loop(10,25000,25000) ++\
x.Trim(40000,80000) ++\
x.Loop(10,88000,88000).Trim(80000,90000)
return edit

[jagabo]

Oh, I understand now! Thanks.

Could I insert Loop() earlier to achieve the same effect?

x.Trim(0,40000).Loop(10,25000,25000).Loop(10,88000,88000) ++\

This will have a similar problem. The output of the Trim() is a 40001 frame video. So you can't Loop() frame 88000. Further, the output of the first Loop() has 9 extra frames, so even if your second Loop() was within the trimmed video, you would need to account for the extra 9 frames.

I suppose I could also loop before trimming.

x=whateversource()
edit= \
x.Trim(0,40000).Loop(10,25000,25000) ++\
x.Trim(40000,80000) ++\
x.Loop(10,88000,88000).Trim(80000,90000)
return edit

That will work. Except you need to account for the extra 10 frames you added with the Loop(). Ie, as written, you are losing 9 frames at the end of the original video.

[Anonymous344]

This will have a similar problem. The output of the Trim() is a 40001 frame video. So you can't Loop() frame 88000.

I really should have thought of that...

Further, the output of the first Loop() has 10 extra frames, so even if your second Loop() was within the trimmed video, you would need to account for the extra 10 frames...

...That will work. Except you need to account for the extra 10 frames you added with the Loop(). Ie, as written, you are losing 10 frames at the end of the original video.

That all make sense. I'll have to change the way I think about the frame numbers because I keep thinking of them in terms of the original video, rather than the looped/edited video. It's a problem I have come across in the past when writing scripts with multiple calls to DeleteFrame() and DuplicateFrame(). Thanks again.

[jagabo]

It's a problem I have come across in the past when writing scripts with multiple calls to DeleteFrame() and DuplicateFrame(). Thanks again.

Yes, it's easiest to work from last to first in those circumstances. Ie, if you know you want to delete frames 10, 20 and 30 from the original video:

DeleteFrame(30)
DeleteFrame(20)
DeleteFrame(10)

is much easier than:

DeleteFrame(10)
DeleteFrame(19)
DeleteFrame(28)

[Anonymous344]

That's a good idea. I guess it would work with the situations I come across, in which my script is more like this.

WhateverSource()
DeleteFrame()
DuplicateFrame()
DeleteFrame()
DuplicateFrame()
DeleteFrame()

I usually obviate the confusion by using Trim() instead.

x=WhateverSource() \
.ShowFrameNumber(scroll=true)
edit= \
x.Trim(0,1000) ++\
x.Trim(1002,2000) ++ \
x.Trim(2000,1000) ++ \
return edit

This gets rid of 1001 and duplicates 2000. Obviously, it's a simple example: my scripts are often long. The advantage to me is that ShowFrameNumber() is applied to the original video, so I can see which frames are being added or omitted when scrolling through the video. I'm sure I'll figure out a way to adopt a similar approach when using Loop().