This prevents various values from getting an insanely huge exponent.
If someone knows a cleaner solution, thats welcome!

This is similar to commit 8978c743 for aacsbr.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
(cherry picked from commit 0e36a14a)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>