FFmpeg hardcoded subtitles revert to default font if subtitle is html Here's how I'm using ffmpeg to hardcode the subtitles:

ffmpeg -i tmp/input.mp4 -vf "subtitles=tmp/input.mp4:force_style='OutlineColour=&amp;H80000000,BorderStyle=3,Outline=1,Shadow=0,MarginV=20,Fontname=Liberation Mono'" -avoid_negative_ts make_zero tmp/output.mp4


which works fine if the subtitle is plain text but if it has html tags in it, then it reverts back to using system's default font. &lt;i&gt; hello &lt;/i&gt; for example causes problem.

I've tried cleaning up html tags and then using -vf "subtitles=cleanedsubs.srt:..." but it doesn't work even on plain texts. 

How can I force same font even on italic / bold / any other forms?

Extra info

Running:

ffmpeg -i tmp/input.mp4 -filter_complex "subtitles=tmp/input.mp4:force_style='fontname=Liberation Mono'" -f null -


Shows:

[Parsed_subtitles_0 @ 0x55ad579abd00] Using font provider fontconfig
Stream mapping:
  Stream #0:1 (h264) -&gt; subtitles (graph 0)
  subtitles (graph 0) -&gt; Stream #0:0 (wrapped_avframe)
  Stream #0:0 -&gt; #0:1 (aac (native) -&gt; pcm_s16le (native))
Press [q] to stop, [?] for help
[Parsed_subtitles_0 @ 0x55ad579aa3c0] Shaper: FriBidi 0.19.7 (SIMPLE) HarfBuzz-ng 1.7.2 (COMPLEX)
[Parsed_subtitles_0 @ 0x55ad579aa3c0] Using font provider fontconfig
[Parsed_subtitles_0 @ 0x55ad579aa3c0] fontselect: (Liberation Mono, 400, 0) -&gt; /usr/share/fonts/truetype/liberation/LiberationMono-Regular.ttf, 0, LiberationMono
[Parsed_subtitles_0 @ 0x55ad579aa3c0] fontselect: (Liberation Mono, 400, 100) -&gt; /usr/share/fonts/truetype/liberation/LiberationMono-Italic.ttf, 0, LiberationMono-Italic
[Parsed_subtitles_0 @ 0x55ad579aa3c0] fontselect: (Serif, 400, 100) -&gt; /usr/share/fonts/truetype/dejavu/DejaVuSerif-Italic.ttf, 0, DejaVuSerif-Italic
                                                    ↑                                  
                                                 problem
Possible bug when feeding mov_text to subtitles filter. I can reproduce the issue in git master branch. I did not investigate further.

Workaround is to provide the subtitles filter the SRT subtitle stream present in your original MKV input (file.mkv):

ffmpeg -i file.mkv -map 0:a:0 -map 0:v -c:v libx264 -c:a aac -vf "subtitles=file.mkv:stream_index=6:force_style='OutlineColour=&amp;H80000000,BorderStyle=3,Outline=1,Shadow=0,MarginV=20,Fontname=Liberation Mono'" output.mp4


Make sure stream_index is referencing the desired subtitle stream. See subtitles filter documentation.