My mental image of the XSEQ file is like an Excel Spreadsheet.
Down the Left Side in the Rows are all the DMX and Pixelnet channel numbers (from 1 down to 16k).
Across the top are the Column headings. 20 per second. So, a 2:51 (2 minute 51 seconds) song will have 3420 columns.
The original question involved having too few columns created (too short). My method creates a new version with the correct number.
If you are using an MP3 or WAV file, then the Time (number of columns) is done for you.