Overview

Measures the sample rate of the input signal

Discussion

Sample rate measurement module. The module is designed measure the sample rate of the signal on single channel. Seperate modules are required to measure the sample rate on different channels. The module compares the measured sample rate with the allowable sample rates and estimates the nearest value. The measured sample rate will be displayed on the inspector.

The module can also compute the sample rate averaged over multiple blocks. .numBlocksToAverage specifies how many blocks to use for the averaging.

The module also optionally outputs the measured sample rate on an output pin. This option is selected by setting the argument SROUTPIN to true. The sample rate value is output an an integer.

Type Definition

typedef struct _ModuleSampleRate
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    FLOAT32 procSpeed;                            // Processor clock speed in MHz
    INT32 numBlocksToAverage;                     // Number of blocks to process before the sample rate is retured
    INT32 lastCount;                              // Holds the last call cycle count
    INT32 averageDeltaCount;                      // Holds the average delta count of numBlocksToAverage calls
    INT32 SRArrayLength;                          // Number of sample rates that can be estimated
    INT32 initialized;                            // Specifies whether the last cycle counter has been initialized
    INT32 dataValid;                              // Indicates whether the sample rate measurement is valid
    FLOAT32 measuredSR;                           // Readback variable. Displays the measured sample rate on the inspector
    FLOAT32 prevMeasuredSR;                       // Last measured sample rate
    FLOAT32 prevPrevMeasuredSR;                   // Previous to last measured sample rate
    INT32 SROutPin;                               // Boolean specifies whether module will have output pin
    INT32 blockCounter;                           // Counts up to numBlocksToAverage
    FLOAT32* allowableSR;                         // Array of possible sample rates
} ModuleSampleRateClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
procSpeed	float	parameter	0	10	Unrestricted
numBlocksToAverage	int	parameter	0	100	1:16384
lastCount	int	state	0	0	Unrestricted
averageDeltaCount	int	state	0	0	Unrestricted
SRArrayLength	int	const	0	3	Unrestricted
initialized	int	state	0	0	Unrestricted
dataValid	int	state	0	0	0:1
measuredSR	float	state	0	48000	Unrestricted
prevMeasuredSR	float	state	0	0	Unrestricted
prevPrevMeasuredSR	float	state	0	0	Unrestricted
SROutPin	int	const	0	1	Unrestricted
blockCounter	int	state	0	0	Unrestricted
allowableSR	float*	parameter	0	[3 x 1]	Unrestricted

Pins

Input Pins

Name: in

Description: Input data pin

Data type: {int, float, fract32}

Channel range: Unrestricted

Block size range: Unrestricted

Sample rate range: Unrestricted

Complex support: Real

Output Pins

Name: out

Description: Measured sample rate

Data type: int

MATLAB Usage

File Name: measure_sample_rate_module.m

 M=measure_sample_rate_module(NAME, SRARRAYLEN, SROUTPIN)
 Creates a sample rate measure module for use with the Audio
 Weaver.  Arguments:
     NAME - name of the module.
     SRARRAYLEN - Array length of the allowable sample rates
     SROUTPIN - Boolean which specifies whether module outputs detected 
                sample rate that can be used as the input to sample rate
                switch module