[HELP] Reducing frame rate 60fps ->30fps
#1
Windows 10
rev 2018.11.11.1

I need to reduce frame rate of my video clip from 60fps to 30fps without changing the duration of the clip. It comes from my mobile phone. I used Filtering->Speed Change->Scale Output Frame Rate. I set it to 30fps. 

When I play the output clip with VLC player audio is played normally however first half of the video is speeded up 2 times while the second half is just a still image (last frame of the first part). 

Any advice? What I'm doing wrong?

Thanks. Tom
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#2
Wild guess: Your video if vfr and not cfr and the time codes are messed up.
Try enabling Config->Internals->Handling->Ingore all input timecodes

Also instead of blindly dropping every second frame I would recommand to use:
a. Filtering->Vapoursynth->Restore->sRestore with Frate set to '30'
or
b. Filtering->Avisynth->Fra,es>Restore->sRestore with Frate set to '30'

Cu Selur
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#3
(08.12.2018, 23:33)Selur Wrote: Wild guess: Your video if vfr and not cfr and the time codes are messed up.

I don't know. This is my clip. I compressed it to .zip as otherwise google will process that video
https://drive.google.com/file/d/1qMSRRlx...sp=sharing


Quote:Try enabling Config->Internals->Handling->Ingore all input timecodes

I did but it didn't help


Quote:Also instead of blindly dropping every second frame I would recommand to use:
a. Filtering->Vapoursynth->Restore->sRestore with Frate set to '30'

I couldn't process the clip. Got error:

-> 22_06_44_0410_04_video crashed: ERROR: C:\Users\Tomek398\AppData\Local\Temp\22_06_44_0410_04.264 is too small! (byteSize: 0byte)

Aborting '22_06_44_0410_04_video' due to: ERROR: C:\Users\Tomek398\AppData\Local\Temp\22_06_44_0410_04.264 is too small! (byteSize: 0byte)


Quote:or
b. Filtering->Avisynth->Fra,es>Restore->sRestore with Frate set to '30'

Program was able to process the video but final effect was the same as before: 

https://youtu.be/YPOSNTY7I5U

Thanks for quick reply!
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#4
Okay, source is vfr and the problem is probably due to a high fluctuating frame rate.

On my way to bed now, but I did a quick test and:
  1. enabling 'Config->Input->Decoding->CFR output'
  2. enabling 'Filtering->Speed Change->Scale output frame rate' and setting it to 30fps
fixed the issue for me.
Using Avisynths sRestore instead of using ffmpeg Scale output frame rate also works when 'Config->Input->Decoding->CFR output' is enabled.
(Vapoursynth sRestore doesn't work as it should, due to a bug, which I will look into tomorrow.)
For your source content sRestore shouldn't be necessary, and ffmpegs scale should be fine. Smile

Cu Selur
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#5
OK, I'll try it. Many thanks. Good night.
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#6
(09.12.2018, 00:31)Selur Wrote: On my way to bed now, but I did a quick test and:
  1. enabling 'Config->Input->Decoding->CFR output'
  2. enabling 'Filtering->Speed Change->Scale output frame rate' and setting it to 30fps
fixed the issue for me.

This also worked for me.

Quote:Using Avisynths sRestore instead of using ffmpeg Scale output frame rate also works when 'Config->Input->Decoding->CFR output' is enabled.

Avisynths sRestore didn't work. I always get error message as cited above even when I enable CFR output.

Quote:(Vapoursynth sRestore doesn't work as it should, due to a bug, which I will look into tomorrow.)

Vapoursynth (+ sRestore) was able to process my video clip but the final effect was as I described in my first post. I mean setting CFR output didn't help here.


Thanks again for help.
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#7
Quote:Avisynths sRestore didn't work. I always get error message as cited above even when I enable CFR output.
Does the Avisynth Preview work for you?

Quote:Vapoursynth (+ sRestore) was able to process my video clip but the final effect was as I described in my first post.
Okay, that is as expected, since Vapoursynth doesn't do anything in respect to 'Config->Input->Decoding->CFR output'.

Cu Selur
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#8
Send you a link to a dev version for testing by PM which should fix the Vapoursynth problem.

Cu Selur
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#9
Quote:Does the Avisynth Preview work for you?

It seems to work


Quote:Send you a link to a dev version for testing by PM which should fix the Vapoursynth problem.

Thanks. I tested it with sRestore

If CFR output is NOT selected: program processed the clip but didn't finish the job and didn't save output file. Last line is:

If CFR output IS selected: Program seems to work fine. I only noticed that when I deselected 'Restore' output fps remained 30fps (input file is 60fps)
"delete C:\Users\Tomek398\AppData\Local\Temp\timecodeV2_21_00_20_6310.tc"
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#10
Okay.
Can you please create two DebugOutput level 9 outputs of the job processing?
- One where you enable 'Config->Input->Decoding->CFR output' and use Vapoursynth + sRestore with 30fps
and
- another one where you enable 'Config->Input->Decoding->CFR output' and use Avisynth + sRestore with 30fps.
Over here both ways worked fine with the dev version and I'm curious what might be the problem when you use it. Smile

Cu Selur
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