Editing Mp4s (Filter:Clueless)
January 25, 2020 12:51 PM   Subscribe

I am down a rabbit hole with the internet looking at so many pages and software to do this. I've read a couple of the others but even they have too many letters and names of things I don't know about. I just need to chop the beginning off of an MP4. The one program I'm looking at now seems to be designed for engineers or something. How hard could it possibly be (famous last words). Thanks so much!
posted by intrepid_simpleton to Computers & Internet (10 answers total) 2 users marked this as a favorite
You can easily do this by signing up for a 30-day free trial of Camtasia. Import the MP4 file, snip off what you want to remove, export as a new MP4. It's a bit of a heavyweight solution for a quick trim, but the user interface is very intuitive which helps a lot.
posted by neushoorn at 12:59 PM on January 25

Avidemux will do.
Open video, use slider to select points A and B (begin & end), set output muxer to “MP4 muxer", File>Save… and there's your trimmed MP4.
posted by farlukar at 1:36 PM on January 25 [3 favorites]

If you're on a Mac you can drum videos in QuickTime Player.
posted by jonathanhughes at 2:22 PM on January 25 [1 favorite]

missed the edit window.
posted by jonathanhughes at 2:51 PM on January 25 [1 favorite]

I also use Avidemux on my Windows boxes for all my video editing needs (MP4 is just a container format which can hold audio or video).

One thing I am careful about is to use the slider to pick a point and then use the double triangle buttons to move left or right to an indexed frame boundary before using the A or B keys. If you trim off an indexed boundary it can cause video stutter. So if I were doing it I would pick the rough point where I wanted to chop the beginning off, then use the double left or double tright triangle buttons to fine tune, then click the B button (which will select the end with the start of the video being the beginning), then hit the delete key, then use File Save to save under a different name (for safety). I wouldn't delete the original until I was sure all was well. FWIW and YMMV.
posted by forthright at 5:22 PM on January 25 [1 favorite]

The easy way is from the command line with FFmpeg.

$ ffmpeg -ss 2:00 -i input.mp4 -acodec copy -vcodec copy output.mp4

The `-ss` seek time is '[<hh>:]<mm>:<ss>[.<m>]', so the previous command would chop off the first 2 minutes from the video.
posted by zengargoyle at 6:12 PM on January 25 [3 favorites]

Seconding ffmpeg. Amazing tool.
posted by rmmcclay at 7:05 PM on January 25

As context, what you’re trying to do is edit a heavily-compressed media file. Imagine if you had a long scarf and wanted to cut a bit of fabric off one end — except the scarf is wadded up tightly inside a mesh bag. Most editing software is happier working with the scarf once you’ve taken it out of the bag and smoothed it out.

So a tool that will do this in one go is doing something a bit more complex. Some good recommendations above but hopefully this helps understand why it feels so complicated.
posted by sixswitch at 7:03 AM on January 26

For very basic trimming actions like this, I like online tools that will cut on the MPEG frame boundaries. That means it trims the compressed file (see scarf analogy above) without uncompressing and recompressing the file, which would degrade it further. The tradeoff of cutting on MPEG frame boundaries is that you might only have 1-2 second resolution instead of sub-second resolution; that means you can't pick the edit point absolutely perfectly, but may be able to get close enough. In my experience the tradeoff is worth it.

These online tools are common for MP3 audio files (I've used mp3cut.net many times), and I imagine by now they exist for MP4 files.

With that method, you don't need to install any software. You do need to suffer through the delay of uploading and downloading the file though, which could be a deal breaker for a large video file.
posted by intermod at 8:28 AM on January 26 [1 favorite]

Over a month late, but hopefully useful for future searchers:

If you're on a Windows 10 machine you can do this without extra software:

Right click on the MP4 file
Open with, Photos
Top right, "Edit & Create", Trim
Trim the start / end of the file by dragging the white circles.
Top right, "Save as"

posted by Suspicious Ninja at 3:23 PM on March 3

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