[FFmpeg-user] Slight blur on converted video

Andy Furniss adf.lists at gmail.com
Sat Mar 25 22:12:21 EET 2017

Dave wrote:

> The full ffmpeg output is:
> $ ./ffmpeg -y -i in.mp4 -acodec pcm_s16le -vcodec prores_ks -profile:v 1 -vf scale=interl=1 -sws_flags full_chroma_inp+full_chroma_int -copytb -1 out.mov

FWIW I tested a bit the format conversion + various flags and the
only ones that made the ssim/psnr better 420 -> 422 10 bit and
back were accurate_rnd or bitexact, both gave the same score.

interl=1 recently got improved, I don't know if that fix is in
current release or not.

Whatever the flags, there is no softening and the psnr/ssim are
high for chroma (exact for luma).

So as has been said - try throwing more bits at it.

On the face of it going from 10mbit h264 to 80mbit prores may
seem plenty, but prores is I frame only. If you look at libh264
stats when encoding you will see that the (normally sparse) I
frames are generally 10x the size of the others. I frame compression
is "expensive".

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