Hi,

I would like to convert some .mov files to a more standard format such as .mpeg,
however, I would like to keep the same quality.

ffmpeg -sameq does the job, however it produces a file which is about 5 time larger than the .mov file !

Of course, I can choose a lower bitrate and get a smaller file, but in that case I am not sure that the quality is the same.

Is this because .mov files can achieve a better quality with a much smaller
file size, or is there a way to really get the same quality with more or less the same size?

Thanks a lot

The problem is that you are trying to convert a video file from one compressed method to another. This can be done as you have witnessed, but it first needs to be uncompressed (which is probably done in ffmpeg) and then recompressed using the new alorithm. If you had the original file you could probably play with a variety of options and variables within ffmpeg or mencoder to achieve and equally viewable movie (looks about the same) in the mpeg container as you could in the .mov container. But without the originally content, you are stuck with a lossy video and making it yet more lossy; to compensate for this, the program will upsize the blocks, and then shrink them down on it's own, but the blocks it has to start with are still already 'blurry'.

So in short, you probably can't do exactly that. In long, if you play with the options you might be able to squeeze in a smaller filesize by allowing more blockiness and such where you don't mind it.

HTH

Cool

Thanks, I'll try, although it is strange: even if I try something like

ffmpeg -i filein.mov -sameq fileout.mov

i. e. I try to transform a quicktime file in another quicktime file with the same quality, I get that fileout.mov is about 5 time larger as the original filein.mov