#Ffmpeg gui letterboxing how to#
#Ffmpeg gui letterboxing software#
#Ffmpeg gui letterboxing free#

It literally doesn't stop at the -t/-to timestamp for reason I don't know. The latter has a bug that happens frequently when I'm trimming MPEG-TS files recorded from HDTV. As you can see, the -ss part is before -i, and -t is after. In my Python script, I did input seeking for -ss (start point) part, and then output seeking for -t part (end point). I think I know where you're confused: from the guide it looks like there is only a difference where you put -ss but in reality, where you put -t/-to matters too. (You can also try to use -copyts to keep timestamp, but not recommended because it doesn't work if the video file has non-zero start time.) So instead of using -to, you should calculate -t (duration) yourself by subtracting -ss from -to, and use `-t duration` instead. However, this way, the timestamp will restart from 0 in output seeking. The best of the two worlds is to use input seeking for -ss and then output seeking for -to.

It could be off by a few seconds, or sometimes straight up does not work (for some mepeg-ts files recorded from TV). However, while -ss (seek start) works fine with input seeking, '-to/-t' (seek ending) is somehow vastly inaccurate in input seeking for FFMPEG. The output seeking is very slow (it needs to decode the whole video until the timestamp of your -ss) so you want to avoid it if unnecessary.

#Ffmpeg gui letterboxing how to#

How to keyframe-cut video properly with FFMPEGįFMPEG supports 'input seeking' and 'output seeking'.

#Ffmpeg gui letterboxing free#

Most of them are commercial though, I haven't find one that is free and good.Īlso, seeking in FFMPEG in practice, is actually more complicated than the guide you linked.īelow is a note I keep for own reference for keyframe-copy.

#Ffmpeg gui letterboxing software#

There are however, plenty of great software that can but at any frame and only re-encode the frames that are outside the whole GOP.

Yeah, it is literally not possible to not seek to keyframe if you are stream copying.

If you want to do this with 2160p24,p25 or p30 videos at several minute lengths, be prepared to have 150-160GB of scratch disk per y4m and per PNG-dump-directory. this is your static image reference baseline for subjective eyeballs.Ģ) take your raw uncompressed y4m file and encode it to x265 or whatever codec you're testing, at various different bitrates and encoder settingsģ) take your various encoded x265 files and also write those out to PNG files in separate directoriesģ) pick exactly the same frame number filename from your 'master' PNGs and your encoder-output PNGs, copy them and put them in the same directory so you can quickly flip back and forth between them in a image slideshow application. One of the interesting things you can do with ffmpeg, if you have a LOT of scratch disk space, and you're trying to compare subjective encoder quality (not VMAF, but human eyeballs) on a certain video file:ġ) take your raw uncompressed y4m file and write it out to a directory of PNG files, one png file per frame.