Hi ;)
In order to trim and output a lossless (copy) video, it's better to cut on keyframes to avoid pixels corruption.
In most mp4 videos downloaded here and there, if I press Up / Down in Avidemux to jump from keyframe to keyframe, they're often set every 10 seconds or so. But in some other videos I downloaded, keyframe was set every 1 or 2 seconds. Which is VERY ! convenient when it comes to cutting/trimming precisely (without re-encoding).
Is it possible in Avidemux to change the original video keyframing without changing codec/compression, etc. ?
This way one could set a new keyframing (which would suppose a re-encoding I guess) before lossless-ly trimming videos.
I'm aware that playing with I-Frames options in the ouput configuration is what I want, but after reading a few articles about I-frames, GOP, and so on, I'm still a bit lost.
Could someone please explain simply :-\ how to use Gop Size and I-frame Threshold options and what those really mean ?
Thanks !
QuoteIs it possible in Avidemux to change the original video keyframing without changing codec/compression, etc. ?
Not without re-encoding the video, obviously, as the type of compressed frame is determined at the moment of encoding.
Smaller GOP sizes allow better seek granularity and strongly reduce compression rate.
Thanks eumagga0x2a.
I indeed managed to get the result I wanted putting much lower values for the GOP sizes.
Not sure what the i-frame is about then. I did some tests changing that value and couldn't really see any difference.
Cheers. Thanks for the answer.