[FFmpeg-user] gain the highest quality with H264 at a certain bit rate
chronek at interia.eu
Mon Mar 27 23:04:21 EEST 2017
W dniu 2017-03-27 o 19:24, negin tebyani pisze:
> and yes, I need to use constant bitrate. do I need to use 2 pass with
> constant bitrate?
You do not need second pass with constant bitrate, but with 2 pass - in
first pass it log where it need bitrate and use that knowledge to
distrubuate in second pass, because even with constant bitrate you have
small variations along time.
I add deblock filter before because reencoding favors block artifacts.
From source info what you post i saw that you have the same
resolutions, you do not need scale. So you doing 1280:720/50fps/yuv422p
4,4 Mbps -> 1280:720/50fps/yuv422p 2 Mbps ?
I saw both samples and your was even more crispy sometimes, found that
you doing 5 reframes, when others 6 (it help with bitrate a bit).
So what you want improve? Dark parts? Or artifacts? Or fast motion scene
blocks? Or more sharpen?
ffmpeg -y -i in.mp4 -an -c:v libx264 -preset veryslow -b:v 2048k -bf
8**-qcomp 0.8 -pass 1 /dev/null
ffmpeg -y -i in.mp4 -c:a aac -b:a 128k -c:v libx264 -preset veryslow
-b:v 2048k -bf 8 -qcomp 0.8 -pass 2 out.mp4
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