I have a complicated video file (.mkv, 12.78 GB, 2160p) with two audio streams (MLP FBA 16-ch and AC-3, respectively), and 11 subtitle streams (all of format PGS and Muxing mode zlib). The native Media Player on my LG C2 does not recognise the subtitles, and only one of the audio streams (I'm not sure which one). I want to end up with an MKV file (preferably, any that the player will recognise will suffice) containing only the first audio stream and only the first and fifth (English and Dutch, respectively) subtitle streams, but converted to one that this Media Player does recognise (e.g., SRT). I have some affinity with FFmpeg, but, even after wrestling with GTP-3.5 a lot, have been unsuccessful. I must add that my MacBook on which I am trying this is quite old (Late-2013), and cannot update its os beyond Big Sur 11.7.10, which prevents newer updates of FFmpeg being installed. I can provide the MediaInfo information if necessary.
I think the closest I've gotten (i.e., the command running without error, but also changing very little) is via the command
ffmpeg -i 32_-_2_-_The_Winter_Line.mkv -map 0 -c:v copy -map 0:a:0 -c:a:0 copy -map 0:s:0 -c:s:0 copy -map 0:s:4 -c:s:1 copy output_1.mkv
Am I close? The main error I seem to encounter that
[ssa @ 0x7fc575045600] Only SUBTITLE_ASS type supported..42 bitrate= 74.5kbits/s speed=4.85x
I'm pretty sure that .ass has worked before, but maybe this has to do with the FFmpeg version (4.0.2) I am using.
EDIT: this is my first question on this SE, and I haven't been programming for about 8 years, so I might pose the question ill-defined..
EDIT2: When running
ffmpeg -i 32_-_2_-_The_Winter_Line.mkv -map 0 -c:v copy -map 0:a:0 -c:a:0 copy -map 0:s:0 -c:s:0 ass -map 0:s:4 -c:s:1 ass output_1.mkv
which I expected to work, I get an error, the last lines of which are
[ass @ 0x7fda8780c800] Only SUBTITLE_ASS type supported..89 bitrate= 64.0kbits/s speed=5.78x Subtitle encoding failed [libvorbis @ 0x7fda8780b600] 47 frames left in the queue on closing [libvorbis @ 0x7fda88849200] 43 frames left in the queue on closing Conversion failed!```