[FFmpeg-user] Cutting video at i-frames to avoid recoding

Andy Civil andycivil at gmail.com
Sun Aug 19 04:07:00 CEST 2012

On 2012-08-18 5:43 PM, Stefano Sabatini wrote:

> I don't think skipping I-frames is a good idea if you want a decent
> footage quality (much better to re-code the file in that case).

Re-coding is unacceptable as a matter of principle; this is my 'stock footage', 
i.e. raw (as shot) out of my camera. I think movie editors refer to it as 
"assets". My objective is to cut out gigabytes of unwanted stuff, to save disk 
space; the stock footage must remain "original".

What I'm saying is that if the first few frames are trashed, it doesn't matter 
to me, because those seconds would never make it into a movie production anyway.

> You may have a look at the segment muxer, it may be useful depending
> on what you want to exactly achieve.

Actually, that could be an answer. Thank you for giving me something to google 
for "segment muxer" - sometimes, knowing what to look for is all the help a user 
needs - LOL.

It certainly looks like it splits files at i-frames, which is what I need. I 
could split my files into 10s segments and then delete ones which contain 
nothing useful. It would mean that I'd be loading multiple segments into my 
movie editor, but that's probably acceptable.

I wondered if I could concatenate the segments I want back together again, but 
I've been reading the old thread started by Acer Yang on 2012-02-12 and it looks 
like it's hard to get the "moov" atom to show the right time.

Thanks for the start, Stefano, if anyone else has any other ideas...


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