The master track is the topmost track in the track hierarchy. Its main purpose is to route the combined mix of all the child tracks to an audio output. You can select the output on the master track header. As a secondary purpose the master track is by default configured as a bounce track. The bounce sound on the master track is thus used to render the master output of the arrangement to a wave file. You can remove the bounce option on the master track if you don’t intend to export your arrangement for mp3 encoding etc.
Is there a way to get it to automatically fit to the rest of the tracks?
Not currently. I plan to add an option to the track properties that will autosize sequence/sound events to the full length of the arrangement. Bounce tracks will have this option enabled by default.
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