[FFmpeg-user] Converting MPEG-TS to MKV with hard coded subtitles produces error message

[Stuart]

Hello Nicolas,

Thank you for the reply. I've now tried adding the "-s:s 720x576"
option as you suggested but the result has not changed. Is the
position significant? The command is now:

ffmpeg -i Suburgatory-20121110-1024.TS
        -s:s 720x576
        -filter_complex "[0:v][0:s]overlay"
        -sn sub.mkv

The canvas does not appear to have changed size and I still get the
"sub2video: rectangle overflowing" messages. The output contains:

[mpegts @ 000000000068fa60] sub2video: using 704x576 canvas

Having found the "-s" option in the documentation I wonder if the
optiononly applies to video streams?

Many thanks,
Stuart