[FFmpeg-user] Converting mkv to mp3 failures

[JD]

Some of the mkv files being converted to mp3 are causing
ffmpeg to belch out huge amounts of this message:

  Application provided invalid, non monotonically increasing dts to 
muxer in stream 0: 722678111 >= 720923999

of course, at different offsets in same file and also in other files.

So, again, it seems to me that mkv is some kind of weird format OR
youtube-dl which generates it is making some type of errors????