[FFmpeg-user] Reducing video file size
noeck.marburg at gmx.de
Mon Nov 4 18:34:11 EET 2019
As others pointed out, this very much depends on what you want to
achieve (besides a small file size). But I try to offer a starting point
for you to try and find your own compromise of size and quality.
Usually, I would use a resolution of 1920x1080 (HD), but 1280x720 might
be an option to reduce the size. A frame rate of 25 frames per second
could be enough. But with typical codecs you will not get half the file
size by using half the frame rate. So 720p and 25 fps could be a
starting point. What is more important to you: a high resolution or a
smoothly moving image?
Then the vp9 codec (libvpx-vp9) and opus audio does a good job regarding
bitrate and a high CRF value reduces file size. Just try 32 and have a
look if you can tolerate the quality reduction and file size.
And only as a last resort go below a 480 resolution and 25 fps.
Audio bitrate is typically much smaller than video and there is not a
log to gain here. But with the opus codec you can go as low as 64kbit/s
if need be.
Of course there are many more ways to reach a small file size. The
numbers above are in the ball park of what could be reasonable for a
small web-quality video.
> Frame rate
> Color encoding
> Audio bit rate & compression
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