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Working with a 24-hour long recording. Need help splitting a long clip into manageable segments.

Explorer ,
Feb 03, 2023 Feb 03, 2023

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Hi,

I have a single 24-hour long recording of video game play, from which I need to make a highlights reel.  While I can see that the file appears to have imported, actually working with it is impossibly slow with respect to scrubbing, moving the playhead and asking for it to play, etc. 

 

Also, the media end number does not seem to be correct.  It lists as 00:32:03:26.  Looking at it, the actual recording was 24.5 hrs long, so it probably wrapped after 24 hrs.

 

Is there a way to non-destructively split the initial file into smaller 1-hour segments to work with?  Merely making sub-clips doesn't seem to work.  I click on the play head and tell it to play, and it doesn't start playing until 5 minutes later.

 

The source file is 71 GB.  There are 500 GB free on my hard drive.  I have a Mac Pro with 48 GB of Memory.

 

Any recommendations?

 

Thank you

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Export , How to , Import , Performance

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Explorer , Feb 04, 2023 Feb 04, 2023

I have found a solution.   I went to the mac command line.  I used XQuartz, but Terminal should do.  I repeatedly used the program "ffmpeg" to split it up into half-hour segments.  Because I have 6 audio streams in the source file, I needed to add the "-map 0" argument, but if you just have one audio stream, you shouldn't need it.

 

ffmpeg -i BigFilename.mp4 -map 0 -vcodec copy -acodec copy -ss 00:00:00 -t 30:00 chunk-00.mp4
ffmpeg -i BigFilename.mp4 -map 0 -vcodec copy -acodec copy -ss 00:30:00 -
...

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Community Expert ,
Feb 03, 2023 Feb 03, 2023

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Elizabeth,

 

I agree that you want to avoid adding the entire clip to your sequence/timeline.

 

Double-click the clip in the Project Panel.  This will open it in the Source Monitor. It will already have an in point at the beginning. Move to the 30 minute mark. Set an end point (type "o" or click the end point button).

 

Drag from the video itself in the Source Monitor to the "new" icon in the Project Panel. This will create a matching sequence with just the 30 minute clip.

 

Can you work with that?

 

Stan

 

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Explorer ,
Feb 03, 2023 Feb 03, 2023

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This creates a shorter "sequence" but that sequence still has a huge delay from the time I hit the space bar to play it to the time that the content actually starts playing, like several mintues of delay.  I have just freshly rebooted my computer.  

 

Do you know of any automated tool that will split the original video clip into smaller files that are more manageable?  Thanks.

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Explorer ,
Feb 04, 2023 Feb 04, 2023

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I have found a solution.   I went to the mac command line.  I used XQuartz, but Terminal should do.  I repeatedly used the program "ffmpeg" to split it up into half-hour segments.  Because I have 6 audio streams in the source file, I needed to add the "-map 0" argument, but if you just have one audio stream, you shouldn't need it.

 

ffmpeg -i BigFilename.mp4 -map 0 -vcodec copy -acodec copy -ss 00:00:00 -t 30:00 chunk-00.mp4
ffmpeg -i BigFilename.mp4 -map 0 -vcodec copy -acodec copy -ss 00:30:00 -t 30:00 chunk-01.mp4
ffmpeg -i BigFilename.mp4 -map 0 -vcodec copy -acodec copy -ss 01:00:00 -t 30:00 chunk-02.mp4
ffmpeg -i BigFilename.mp4 -map 0 -vcodec copy -acodec copy -ss 01:30:00 -t 30:00 chunk-03.mp4

etc. 49 times until I got to the end of the file.



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Community Expert ,
Feb 04, 2023 Feb 04, 2023

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Elizabeth,

 

I think that is a good approach. I would create a new project also, and import only one file to start. Are you still getting a long delay?

 

Stan

 

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Explorer ,
Feb 04, 2023 Feb 04, 2023

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When I cut the files down to only half an hour each, everything works fine.  Somewhere the 30fps vs. 29.97 problem creeps in because each clip is a few seconds short if I chunk it up exactly, but I solved the problem by creating 30:15 length clips every half hour, then if I need the missing few seconds in between, I've got them.  I've set every setting I can find to 30fps, but as it's not gating this project, I'm not inclined to investigate further.

 

It's easy to create short clips from these smaller files.  I haven't attempted to release the whole 24-hrs as a single file yet, and I may not ever need to do that, as I don't think there's that much demand for it.

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Advocate ,
Feb 04, 2023 Feb 04, 2023

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..problem creeps in because each clip is a few seconds short if I chunk it up exactly

By @Elizabeth23343770l1bf

That's normal behavior, because contrary to any intraframe codec the interframe ones (like h264/hevc) do not allow splitting with a single frame precision. You can only do that at the keyframe position. The GOP ('group of pictures') length typically varies in range of 0.5-10sec, hence the varience in chunk lenghts.

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