Odd lengths are due to special processing, e.g. to remove blank passages, and output at 64 kbps. Thus tape 21, side 1 is still only 2 hours, despite its size of 60 Mb. Tape 21, side 2 (unprocessed) is also 2 hours, even though its size is 30 Mb.
You can redistribute all my programs, and/or modify them, under the terms of
The Perl License, a copy of which is available via: http://dev.perl.org/licenses/