Can't render .ass subtitles with melt using mlt_service=text, even though text filter is present

[thursdaybw]

I'm trying to render .ass subtitles using melt. Here's what I've confirmed so far:

The subtitles render perfectly with FFmpeg using:

ffmpeg -i myvideo.mp4 -vf "ass=mysubtitles.ass" -c:a copy out.mp4

melt -query filters | grep text returns:

- avfilter.drawtext
- dynamictext
- text
- gpstext
- qtext

So text is available, and libass is installed.

I tried the following minimal melt command to render subtitles:

melt \
    myvideo.mp4 out=2209 \
    -filter loader:resource=mysubtitles.ass:mlt_service=text \
    -consumer sdl2

But I get no subtitles displayed.

Is this the correct way to use .ass with melt? Should it work as expected, or is there a different method needed to burn in .ass subtitles?

Any working example or guidance would be super appreciated.

Thanks!

[ddennedy]

Text filters don't read subtitles files. MLT only supports SRT subtitles through:
https://mltframework.org/plugins/FilterSubtitle/

You might be able to use libavfilter's ass filter as well in MLT as avfilter.ass. I have not tried.

Also, "loader:resource=mysubtitles.ass:mlt_service=text" is completely the wrong way to specify filters in MLT or melt.
Shotcut and Kdenlive support subtitles and might be more suitable for you.

[thursdaybw]

Oh, you gave me just the hint I needed, thank you.

melt input.mp4 -filter avfilter.ass av.filename=mycaptions.ass

That works. Excellent! thank you! :D