User's Manual

116 Voice API Programming Guide — June 2005
Speed and Volume Control
The default speed modification table is shown in Table 11.
Consider the following usage information on the speed modification table:
• Each entry in the table is a percentage deviation from the default play speed (“origin”). For
example, the decrease[6] position reduces speed by 40%. This is four steps from the origin.
• The total speed modification range is from -50% to +50%. In this table, the lowest position
used is the decrease[5] position. The remaining decrease fields are set to -128 (80h). If these
“nonadjustment” positions are selected, the default action is to play at the decrease[5] speed.
• These fields can be reset, as long as no values lower than -50 are used. For example, you could
spread the 50% speed decrease over 10 steps rather than 5. Similarly, you could spread the
50% speed increase over 10 steps rather than 5.
• The default entries for index values -10 to -6 and +6 to +10 are -128 which represent a null-
entry. To customize the table entries, you must use the dx_setsvmt( ) function.
• On DM3 boards, when adjustment is associated with a DTMF digit, speed can be increased or
decreased in increments of 1 (10%) only. To achieve an increase in speed of 30% for example,
the user would press the DTMF digit three times.
Table 11. Default Speed Modification Table
Table Entry Default Value (%) Absolute Position
decrease[0] -128 (80h) -10
decrease[1] -128 (80h) -9
decrease[2] -128 (80h) -8
decrease[3] -128 (80h) -7
decrease[4] -128 (80h) -6
decrease[5] -50 -5
decrease[6] -40 -4
decrease[7] -30 -3
decrease[8] -20 -2
decrease[9] -10 -1
origin 0 0
increase[0] +10 1
increase[1] +20 2
increase[2] +30 3
increase[3] +40 4
increase[4] +50 5
increase[5] -128 (80h) 6
increase[6] -128 (80h) 7
increase[7] -128 (80h) 8
increase[8] -128 (80h) 9
increase[9] -128 (80h) 10