Hi
Could someone help me with a code for ffmpeg to convert a 2160p video 60fps down to 1080p ?
I used the following code - ffmpeg -i input4kvid.mp4 -vf scale=1920:1080 -c:a copy output1080vid.mp4.
Everything's fine but the output size is down from 60gb to 3 gb!
What do I need to input to get an exact copy of audio and video without losing any quality? Can I change the output from hevc to x264 ?
Secondly could you clarify one more thing if you are aware - does converting a 60fps video down to 23.98 fps mean it'll drop frames and affect the quality of the video ? ANy way around it ?
Many Thanks![]()
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If you want less quality loss, larger filesizes - use a lower crf . The default for libx264 is 23
e.g. -crf 18
What do I need to input to get an exact copy of audio and video without losing any quality?Code:-c:a copy -c:v copy
Can I change the output from hevc to x264 ?
If you don't specify a codec for mp4, but default ffmpeg right now will select libx264 anyways
Secondly could you clarify one more thing if you are aware - does converting a 60fps video down to 23.98 fps mean it'll drop frames and affect the quality of the video ?
Re-encoding with lossy codec will negatively affect the quality in terms of each frame quatliy
ANy way around it ? -
My 2 cents, use zscale instead scale ( or perhaps libplacebo ), it may be required to perform HDR to SDR mapping, side to this you may need to perfrom frame rate conversion (libplacebo?) - i would add also small temporal blur to retain some motion fluidity ( tmix filter )
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Thanks @poisondeathray and @pandy
Would either of you care to provide me with the code ( I copied the old one from somewhere else) or look at this one if its alright for a copy with no quality loss (I know the size would increase).
ffmpeg -i input4kvid.mp4 -vf scale=1920:1080 -c:a copy -crf 0 preset very slow output1080vid.mp4
It somehow looks clunky! Obviously I'd change the preset and -crf to match the quality I need. -
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