Alright, let’s talk about this ffmpeg trim thing. I ain’t no tech whiz, mind you, just a plain ol’ person tryin’ to figure this stuff out. So if I can get it, you can too. Don’t you worry none.
So, this ffmpeg, it’s like a magic wand for videos, see? You can do all sorts of things with it, and one of them fancy things is trimming. That just means cuttin’ out the parts you don’t want, like the end where your grandson forgot to turn off the camera and you got ten minutes of nothin’ but the floor.
Now, there’s a bunch of ways to skin this cat, but I’m gonna tell ya ’bout the ones that even I can understand. They use somethin’ called “-ss” and “-t”. Sounds complicated, but it ain’t, I promise.
The “-ss” and “-t” way
First off, you gotta tell ffmpeg where to start cuttin’. That’s where the “-ss” comes in. It’s like sayin’, “Hey ffmpeg, start here!” You gotta give it a time, like “00:00:10” if you wanna start ten seconds in. See? Easy peasy.
Then, you gotta tell it how long you want the cut piece to be. That’s what the “-t” is for. You put in how many seconds, minutes, or whatever. Like, if you want a 30-second clip, you put in “-t 30”.
- So, you put it all together like this:
ffmpeg -ss 00:00:10 -i your_*4 -t 30 output_*4 - This means: Start at 10 seconds (that’s the -ss 00:00:10 part), take 30 seconds from the video called your_*4 (that’s what the -i means, the input file), and make a new video called output_*4.
Now, where you put that “-ss” matters, believe it or not. If you put it before the “-i your_*4” part, ffmpeg is gonna be real quick about it. It’ll jump right to that start time and start cuttin’. That’s called “input seeking” in fancy talk. It’s faster, especially if your video is long as a country road.
But, if you put the “-ss” after the “-i your_*4” part, ffmpeg is gonna be a little slower. It’s gonna start from the beginnin’ and go through the whole video till it gets to your start time. That’s called “output seeking” and it’s more accurate, but who needs that accuracy when you just want to cut out the boring bits? I sure don’t. Time is money, even for an old lady like me.
Another way, kinda sneaky-like
Now, there’s another way to do this trimmin’, somethin’ about “keyframes” and “edit lists.” This one’s a bit trickier, but it’s faster sometimes, especially if you’re workin’ with those “mp4” videos. It’s like cuttin’ fabric along the grain, makes things smoother, ya know?
See, mp4 videos, they got these special points called “keyframes.” Think of ’em like markers in the video. If you cut right on a keyframe, ffmpeg can do it without re-encodin’ the whole thing. That means it’s quicker and the quality stays the same. Nobody wants a blurry video, right? It makes my eyes go all funny.
So, you use commands like “-copyts” and “-avoid_negative_ts make_zero”. Don’t ask me what they mean exactly, it’s just magic words as far as I’m concerned. You use ’em with “-ss” and “-to” (that’s like “-t” but instead of duration you say where it should end) to tell ffmpeg where to start and stop, makin’ sure it cuts on those keyframes. The command looks somethin’ like this:
ffmpeg -ss 00:00:10 -i your_*4 -to 00:00:40 -c copy -copyts -avoid_negative_ts make_zero output_*4- This means: Start at 10 seconds, end at 40 seconds from your_*4 and make a new video called output_*4. The “-c copy” part means ffmpeg should just copy the video and audio without changing them. All those other words just make sure it cuts at the right spots so it goes real fast and looks good.
This way is faster ’cause it ain’t re-encodin’ the whole video, just rearrangin’ it. But it only works good if you’re cuttin’ at those keyframes. If you ain’t, ffmpeg might have to re-encode anyway, and then it’s no faster than the first way.
Why would you even need to do this?
Well, maybe you got a long video of your grandkids’ play and you just want the part where little Timmy scored the goal. Or maybe you filmed a whole hour of your cat nappin’ and you just want the five seconds where he yawned real big. Or maybe, like them developer folks, you gotta cut videos for your fancy apps and gadgets. Whatever the reason, ffmpeg’s got you covered. It’s a powerful tool, even if it sounds like somethin’ a doctor would use.
So there you have it. Trimming videos with ffmpeg, explained in plain English, or as close as I can get to it. It ain’t so hard, is it? Just gotta remember those “-ss” and “-t” things, or that keyframe trick if you’re feelin’ fancy. Now go on and cut those videos, make ’em just the way you want ’em.
Tags: [ffmpeg, trim, video editing, cut video, mp4, keyframes, -ss, -t, -to, command line, tutorial]
