2024-05-16, 02:43 PM
(2024-05-16, 01:46 PM)Dzvon2 Wrote: Does anyone know what the difference between "JPEG quality" and "Qscale" is? If I also increase Qscale, will that decrease the file size of the images? Also, using JPEG was an interesting choice of image format... I thought JPEGs had a reputation for being overly large for the compression quality you get out of them. Using something like webp that is a really small file size makes more sense to me, but I am not sure if there were reasons why JPEG had to be what was used.
Quote:Does anyone know what the difference between "JPEG quality" and "Qscale" is?
"JPEG quality" affects the quality that the final tile picture that will be used and stored on your filesystem.
"Qscale" affects the ffmpeg's encoder's direct quality and is used as the intermediate image as temp files.
Quote:If I also increase Qscale, will that decrease the file size of the images?
For the intermediate temp images, yes, but it makes less sense as such temp files will get removed during automatic cleanups anyway.
Quote:Also, using JPEG was an interesting choice of image format... I thought JPEGs had a reputation for being overly large for the compression quality you get out of them. Using something like webp that is a really small file size makes more sense to me, but I am not sure if there were reasons why JPEG had to be what was used.
Because MJPEG is a valid video format that is widely supported and can have hardware encoders implemented, and is also a very fast format for CPU(modern CPUs can outperform common hardware encoders in Intel GPUs). Also, for pictures this small (320px width), compression efficiency does not mean that much because it is just too small and you will get probably less than 1kb per frame size saving by using a format with "better compression". MJPEG is picked mainly for compatibility and performance reasons, file size is sacrificed because of this, but current default settings generates less than 5M file for 1hr video, which is good enough to me.
