7.2. Voice Software Speed and Volume Support

• 7.2.1. Speed and Volume Convenience Functions

• 7.2.2. Speed and Volume Adjustment Functions
• 7.2.3. Speed and Volume Modification Tables
• 7.2.4. Play Adjustment Digits

7.2.1. Speed and Volume Convenience Functions

The convenience functions set a digit that will adjust speed or volume, but do not use any data structures. These convenience functions will only function properly if you use the default settings of the Speed or Volume Modification Tables. These functions assume that the Modification Tables have not been modified. The speed or volume convenience functions are:

• dx_addspddig( ) - adds a digit that will modify speed by a specified amount.
• dx_addvoldig( ) - adds a digit that will modify volume by a specified amount.

7.2.2. Speed and Volume Adjustment Functions

Speed or volume can be adjusted explicitly or can be set to adjust in response to a pre-set condition, such as a specific digit. For example, speed could be set to increase a certain amount when "1" is pressed on the telephone keypad. The functions used for speed and volume adjustment are:

• dx_setsvcond( ) - sets conditions that adjust speed or volume. Use this if you want to adjust speed or volume in response to a DTMF digit, or start of play.
• dx_adjsv( ) - adjusts speed or volume explicitly. Use this if your adjustment condition is not a digit or start of play. For example, the application could call this function after detecting a spoken word (voice recognition) or a certain key on the keyboard.

See the Voice Software Reference: Programmer's Guide for detailed information about these functions.

7.2.3. Speed and Volume Modification Tables

Each channel has a Speed or Volume Modification Table for play speed or play volume adjustments. Except for the value of the settings, the table is the same for speed and volume.

Each Speed or Volume Modification table has 21 entries, 20 entries that allow for a maximum of 10 increases and decreases in speed or volume; the entry in the middle of the table is referred to as the "origin" entry that represents normal speed or volume. The normal speed or volume is how playback occurs when the Speed and Volume Control feature is not used. The normal speed or volume is the basis for all settings in the table.

Typically, the origin is set to 0. The normal speed or volume is the basis for all settings in the table. Speed and volume increases or decreases by moving up or down the tables.

Other entries in the table specify a speed or volume setting in terms of a deviation from normal. For example, if a Speed Modification Table (SMT) entry is -10, this value represents a 10% decrease from the normal speed.

Although the origin is typically set to normal speed/volume, changing the setting of the origin does not affect the other settings, because all values in the SVMT are based on a deviation from normal speed/volume.

Speed and Volume Control adjustments are specified by moving the current speed/volume pointer in the table to another SVMT table entry; this translates to increasing or decreasing the current speed/volume to the value specified in the table entry.

A speed/volume adjustment stays in effect until the next adjustment on that channel or until a system reset.

The SVMT is like a 21-speed bicycle. You can select the gear ratio for each of the 21 speeds before you go for a ride (by changing the values in the SVMT). And you can select any gear once you are on the bike, like adjusting the current speed/volume to any setting in the SVMT.

The Speed or Volume Modification Table can be set or reset using the dx_setsvmt( ) function which uses the DX_SVMT data structure. The current values of these tables can also be returned to the DX_SVMT structure using dx_getsvmt( ). The DX_SVCB data structure uses this table when setting adjustment conditions. See the Voice Software Reference: Programmer's Guide for information about the DX_SVMT and DX_SVCB data structures.

Adjustments to speed or volume are made by dx_adjsv( ) and dx_setsvcond( ) according to the Speed or Volume Modification Table settings. These functions adjust speed or volume to one of the following:

• a specified level (for example, to a specified absolute position in the speed table or volume table)
• a change in level (for example, by a specified number of steps up or down in the speed table or volume table)

For example: By default, each entry in the Volume Modification Table is equivalent to 2 decibels from the origin. Volume could be decreased by 2 decibels by specifying position 1 in the table, or by moving 1 step down.

The Speed Modification Table is shown in Table 12. 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.

Table 12. Speed Modification Table

Table Entry	Default Value (%)	Absolute Position
decrease[0]	-128 (0x80)	-10
decrease[1]	-128 (0x80)	-9
decrease[2]	-128 (0x80)	-8
decrease[3]	-128 (0x80)	-7
decrease[4]	-128 (0x80)	-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[5]	-128 (0x80)	6
increase[6]	-128 (0x80)	7
increase[7]	-128 (0x80)	8
increase[8]	-128 (0x80)	9
increase[9]	-128 (0x80)	10

NOTE:

In this table, the lowest position utilized is the decrease[5] position. The remaining decrease fields are set to -128 (0x80). If these "non-adjustment" 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).

The Volume Modification Table is shown in Table 13. Each entry in the table is a deviation of n dB from the starting point or volume ("origin"). For example, the increase[1] position increases volume by 4 dB. This is two steps from the origin.

Table 13. 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 (0x80)	6
increase[6]	-128 (0x80)	7
increase[7]	-128 (0x80)	8
increase[8]	-128 (0x80)	9
increase[9]	-128 (0x80)	10

NOTE:

In this table, the highest position utilized is the increase[4] position. The remaining increase fields are set to -128 (0x80). 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).

7.2.4. Play Adjustment Digits

The Voice Software processes play adjustment digits differently from normal digits:

• If a play adjustment digit is entered during playback, it causes a play adjustment only and has no other effect. This means that the digit is not added to the digit queue, it cannot be retrieved with the dx_getdig( ) or dx_getdigbuf( ) function, and it does not affect any termination condition.
• If the digit queue contains adjustment digits when a play begins and play adjustment is set to be level sensitive, the digits will affect the speed or volume and then be removed from the queue.

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