Removing frames?

[Chauceratemyhamster]

Have a file that claims to be 60fps but has just doubled the frames so is twice as big as it needs to be. How can I remove alternate? frames from the file without causing playback issues? Thanks.

[ProWo]

Load it into my clever FFmpeg-GUI, go to video conversion, set fps to 30, convert, remux the new created video stream with audio and sub from source file. Done.

[Chauceratemyhamster]

Thanks.

[butterw]

Changing framerate requires a video re-encode, no ? Filesize will not be half while maintaining the original quality.

If you are dealing with lossy compression that encodes frame differences (ex: h264) there may not in fact be any significant benefit to downconverting framerate of an existing video other than maybe compatibility ?

[jagabo]

Have a file that claims to be 60fps but has just doubled the frames so is twice as big as it needs to be. How can I remove alternate? frames from the file without causing playback issues? Thanks.

Unless your video is uncompressed, or uses intra-frame only compression (some lossless codecs, mjpeg, etc.), your whole premise is wrong. Exact duplicates require almost no bitrate with modern inter-frame codecs like h.264, h.265, etc. So removing all the duplicates will not reduce the file size by half. And re-encoding with a lossy codec can only reduce the quality.

[Chauceratemyhamster]

Have a file that claims to be 60fps but has just doubled the frames so is twice as big as it needs to be. How can I remove alternate? frames from the file without causing playback issues? Thanks.

Unless your video is uncompressed, or uses intra-frame only compression (some lossless codecs, mjpeg, etc.), your whole premise is wrong. Exact duplicates require almost no bitrate with modern inter-frame codecs like h.264, h.265, etc. So removing all the duplicates will not reduce the file size by half. And re-encoding with a lossy codec can only reduce the quality.

Well, it does reduce the frame count by 40,000 and when rendering, that is like 6-8 hours of GPU time. I removed the duplicates and the file reduced by 65%. You are right, the quality did reduce but I will be using DAIN to interpolate back up to 60fps and then enhance. My aim is to get 60fps motion, which the faux 60fps file did not have.

[jagabo]

Well, it does reduce the frame count by 40,000 and when rendering, that is like 6-8 hours of GPU time. I removed the duplicates and the file reduced by 65%.

The size reduction wasn't because you removed the duplicate frames.

My aim is to get 60fps motion

Yes, then you have to remove the duplicates. But that step is best done without an intermediate encoding. Or to an intermediate file with a lossless codec so you don't lose any quality.

[Chauceratemyhamster]

Well, it does reduce the frame count by 40,000 and when rendering, that is like 6-8 hours of GPU time. I removed the duplicates and the file reduced by 65%.

The size reduction wasn't because you removed the duplicate frames.

My aim is to get 60fps motion

Yes, then you have to remove the duplicates. But that step is best done without an intermediate encoding. Or to an intermediate file with a lossless codec so you don't lose any quality.

How is that done, if you don't mind me asking?

[jagabo]

You can create a lossless intermediate by using an editor that will open your source, remove the duplicate frames, and save with a lossless codec. VirtualDub2 can do that. The lossless intermediate file will be much larger than your source (assuming you're starting with a highly compressed source) but it's only going to be on your computer temporarily.

If your interpolation software has a decimation filter you can use that. Or maybe you can frame serve (the passing of uncompressed video frames from one program to another) from another program. VirtualDub2 has a frame server built in. I usually use AviSynth. Even if you're software doesn't support input from a frame server you can usually use a program like Avisynth Virtual File System -- it creates what looks like an AVI file to any other program, but frames are passed from AviSynth to the dummy file on demand.

[Chauceratemyhamster]

I have used virtualdub2 to decimate by 2 and compress to lossless h.265. The file is 6gb, do I just put that through the interpolation software?

[jagabo]

I have used virtualdub2 to decimate by 2 and compress to lossless h.265. The file is 6gb, do I just put that through the interpolation software?

I not familiar with the DAIN project but I assume you can just open the h.265 video with it. You can always use a short test video to check it out.

[manono]

As already mentioned, you're wasting time and unnecessarily degrading your video on the way to doing whatever it is you're trying to do.

How is that done, if you don't mind me asking?

AviSynth has the FillDrops filter that interpolates the second frame of duplicate frames.

[Chauceratemyhamster]

I have used virtualdub2 to decimate by 2 and compress to lossless h.265. The file is 6gb, do I just put that through the interpolation software?

I not familiar with the DAIN project but I assume you can just open the h.265 video with it. You can always use a short test video to check it out.

Looks like it is OK. Thanks for the instructions.