In v31 of mythtv, playback and editing of matroska-formatted
containers does not work well--seeking is broken so bookmarks,
jumping, etc. do not work.
So, an option to set the container format/muxer has been added to
FFMPEG-SPLIT+TRANSCODE-RECORDING, namely FFMPEG-TRANSCODED-FILE-MUXER,
and this is set to mpegts by default.
Because we relied on defaults for the matroska container, we have made
some things explicit (like using libx264 for the video codec). The
preset is also now veryfast, rather than slow, which is a recommended
setting on the ffmpeg users' mailing list.
FFMPEG-SPLIT+TRANSCODE-RECORDING also uses FFMPEG-TRANSCODING-OPTIONS
now, rather than hard-coded options.