[FFmpeg-user] Quality Reduced when Burning Subtitles

Moritz Barsnick barsnick at gmx.net
Sun Sep 5 17:33:10 EEST 2021

On Sun, Sep 05, 2021 at 13:43:22 +0000, Veronica & Stephen McGuckin wrote:
> ffmpeg -i c:\video\input.mkv -filter_complex "[0:v][0:s]overlay[v]" -c:v libx265 -pix_fmt yuv420p10le -profile:v high  -x265-params "-crf=10 -film -hdr10+=1 -preset slow" -map "[v]" -map 0:a:0 -c:a copy c:\video\output.mkv

Please show us the complete, uncut console output of the command. It
would e.g. show which CRF actually takes effect.

I would actually expect an error from this option:
  -x265-params "-crf=10 -film -hdr10+=1 -preset slow"
That's not the correct syntax for x265-params.


    Set x265 options using a list of key=value couples separated by ":". See x265 --help for a list of options.
    For example to specify libx265 encoding options with ‘-x265-params’:
      ffmpeg -i input -c:v libx265 -x265-params crf=26:psy-rd=1 output.mp4

Perhaps you meant to use those "x265-params" as actual ffmpeg options.

> When the conversion is complete the output file is 143 mb with a bit rate of 279 b/s.

I honestly doubt the 279 b/s. That would mean your video is 4299537
seconds long (if you mean 143 MB size - 537442 seconds if you mean 143
Mb). Did you mean 279 kbit/s?


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