Comment by sorenjan

7 hours ago

I don't find trimming videos with ffmpeg particularly difficult, is just-ss xx -to xx -c copy basically. Sure, you need to get those time stamps using a media player, but you probably already have one so that isn't really an issue.

What I've found to be trickier is dividing a video into multiple clips, where one clip can start at the end of another, but not necessarily.

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sorenjan

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skeeter2020  3 minutes ago

I've been trying to cut precise clips from a long mp4 video over the past week or so and learned a lot. I started with ffmpeg on the command line but between getting accurate timestamps and keyframe/encoding issues it is not trivial. For my needs I want a very precise starting frame and best results came from first reencoding at much higher quality, then marking & batching with LossLessCut, then down coding my clips to desired quality. Even then there's still some manual review and touch-up. It's not crazy-hard, but by no means trivial or simple.

https://github.com/mifi/lossless-cut

neRok  30 minutes ago

There's nothing easy about it. Here's a taste.

  # make a 6 second long video that alternates from green to red every second.
  ffmpeg -f lavfi -i "color=red[a];color=green[b];[a][b]overlay='mod(floor(t)\,2)*w'" -t 6 master.mp4; # creates 150 frames @ 25fps.

  # try make a 1 second clip starting at 0sec. it should be all green.
  ffmpeg -ss 0 -i "master.mp4" -t 1 -c copy "clip1.mp4"; # exports 27 frames. you see some red.
  ffmpeg -ss 0 -t  1 -i "master.mp4" -c copy "clip2.mp4"; # exports 27 frames. you see some red.
  ffmpeg -ss 0 -to 1 -i "master.mp4" -c copy "clip3.mp4"; # exports 27 frames. you see some red.

  # -t and -to stop after the limit, so subtract a frame. but that leaves 26...
  # so perhaps offset the start time so that frame#0 is at 0.04 (ie, list starts at 1)?
  ffmpeg -itsoffset 0.04 -ss 0 -i "master.mp4" -t 0.96 -c copy "clip4.mp4"; # exports 25 frames, all green, time = 1.00. success.

  # try make another 1 second clip starting at 2sec. it should be all green.
  ffmpeg -itsoffset 0.04 -ss 2 -i "master.mp4" -t 0.96 -c copy "clip5.mp4"; # exports 75 frames, time = 1.08, and you see red-green-red.
  # maybe don't offset the start, and drop 2 at the end?
  ffmpeg -ss 2 -i "master.mp4" -t 0.92 -c copy "clip6.mp4"; # exports 75 frames, time = 1.08, and you see green-red.
  ffmpeg -ss 2 -t 0.92 -i "master.mp4" -c copy "clip7.mp4"; # exports 75 frames, time = 0.92, and you see green-red.
  
  # try something different...
  ffmpeg -ss 2 -i "master.mp4" -c copy -frames 25 "clip8.mp4"; # video is broken.
  ffmpeg -ss 2 -i "master.mp4" -c copy -frames 25 -avoid_negative_ts make_zero "clip9.mp4"; # exports 25 frames, all green, time = 1.00. success?
  # try export a red video the same way.
  ffmpeg -ss 3 -i "master.mp4" -c copy -frames 25 -avoid_negative_ts make_zero "clip10.mp4"; # oh no, it's all green!

ramon156  7 hours ago

I don't find Sharing files with people very difficult, just login to your FTP and give an account to another user. - Person commenting on OneDrive

  • sorenjan  7 hours ago

    Missed opportunity to reference the famous Dropbox hn comment.

    I just think there are other closely related use cases where a separate program can add more value, especially in the terminal. I wouldn't suggest most people should use ffmpeg instead of a gui, those are too dissimilar. Another example is cutting out a part of a video, with ffmpeg you need to make two temporary videos and then concatenate them, that process would greatly benefit from a better ux.

    • tptacek  6 hours ago

      Point of order: the Dropbox HN comment is famously misconstrued. People think it was about Dropbox; it was about the Dropbox YC application, and was both well-intentioned and constructive.

    • gyan  5 hours ago

      > with ffmpeg you need to make two temporary videos and then concatenate them

      It can be done in a single command, no temp files needed.

hiccuphippo  6 hours ago

I used a plugin in mpv to do it but I can't find it anymore. You just pressed a key to mark the start and end. And with . and , you could do it at keyframe resolution not just seconds.