User's Manual

Voice API Programming Guide — June 2005 117
Speed and Volume Control
The default volume modification table is shown in Table 12.
Consider the following usage information on the volume modification table:
• Each entry in the table is a deviation in decibels from the starting point or volume (“origin”).
Each entry in the table is equivalent to 2 dB from the origin. Volume can be decreased 2 dB by
specifying position 1 in the table, or by moving one step down. For example, the increase[1]
position (two steps from the origin) increases volume by 4 dB.
• The total volume modification range is from -20 dB to +10 dB. In this table, the highest
position utilized is the increase[4] position. The remaining increase fields are set to -128 (80h).
If these “non-adjustment” positions are selected, the default action is to play at the increase[4]
volume. These fields can be reset, as long as no values higher than +10 are used; for example,
you could spread the 10 dB volume increase over 10 steps rather than 5.
• In the volume modification table, the default entries for index values +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, volume can be increased
or decreased in increments of 1 (2 dB) only. To achieve an increase in volume of 6 dB for
example, the user would press the DTMF digit three times.
Table 12. Default Volume Modification Table
Table Entry Default Value (dB) Absolute Position
decrease[0] -20 -10
decrease[1] -18 -9
decrease[2] -16 -8
decrease[3] -14 -7
decrease[4] -12 -6
decrease[5] -10 -5
decrease[6] -08 -4
decrease[7] -06 -3
decrease[8] -04 -2
decrease[9] -02 -1
origin 0 0
increase[0] +02 1
increase[1] +04 2
increase[2] +06 3
increase[3] +08 4
increase[4] +10 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