VideoHelp Forum

+ Reply to Thread
Results 1 to 11 of 11
Thread
  1. Member
    Join Date
    Jun 2005
    Location
    Vermont
    Search Comp PM
    I'm trying to trim front and back of some videos. The back trims ok but the front is way off. I've tried a 7 second advance but that doesn't always work. It seems to me that there has to be something wrong if it's as much as 7 seconds off. And it's not just 1 but several. With some it works OK but with others it can anywhere from 5 to 8 or 9 seconds off. Any ideas?
    Quote Quote  
  2. In copy mode you can only trim on keyframes at the start of a segment.
    Quote Quote  
  3. Member
    Join Date
    Jun 2005
    Location
    Vermont
    Search Comp PM
    What constitutes a segment?
    Quote Quote  
  4. Anything you keep must start with a keyframe.

    The data for most frames in highly compressed video do not contain everything required to reconstruct the frame. The data only contains differences from prior or future frames (for example "this frame is the same as the last one, just make these changes..."). Only keyframes contain all data needed to reconstruct a frame (like a JPEG file). If you remove a keyframe that's referenced by later frames you can no longer reconstruct those later frames.
    Quote Quote  
  5. You have to use the two "Go to keyframe" buttons. Those will tell you where you can start a cut (for lossless trimming).

    If you want to cut from any other point you have to ditch copy-mode and re-encode instead.
    Quote Quote  
  6. Member
    Join Date
    Jun 2005
    Location
    Vermont
    Search Comp PM
    I've been looking all over but can not find keyframe buttons.
    Quote Quote  
  7. Member
    Join Date
    Mar 2008
    Location
    United States
    Search Comp PM
    I believe the up and down arrow keys are key frame navigation
    Quote Quote  
  8. Member
    Join Date
    Jun 2005
    Location
    Vermont
    Search Comp PM
    Thanks...Found them.
    Quote Quote  
  9. Member
    Join Date
    Mar 2011
    Location
    Nova Scotia, Canada
    Search Comp PM
    What types of video? If it's xvid/divx (most .avi files) it's possible to cut on non key frames. It'll do smart rendering to re encode the bits that weren't cut on key frames.

    With x264 (most .mp4 or .mkv, actually most video period) or HEVC you can't cut on non key frames without curruption of the output video. It won't do smart rendering qith those formats.
    Quote Quote  
  10. I've tried a 7 second advance
    With h.264/h.265 the keyframes may be 250 frames (10 sec) apart.
    Quote Quote  
  11. Member
    Join Date
    Jun 2005
    Location
    Vermont
    Search Comp PM
    Thanks for the replys...Hoser Rob, I am cutting MP4's & MKV's and I find that what you said is true. I'm now just cutting on the key frame which is close enough for what I'm doing.
    Quote Quote  



Similar Threads