(8.D.1.2) WAVInterpOneShotSource
- Catherine Spain
Overview
Periodic one shot WAV playback with linear interpolation
Discussion
This module outputs blocks of audio data by interpolating from the upstream wave data. The input pin .ptr is a pointer to the upstream wave data module, which is periodic_streaming_module. Input pin .trigger is a boolean to initiate playback. When it goes from 1->0 then the module starts generating output audio by interpolating the wave data. The input pin .fRatio controls the playback speed as a decimal ratio, where 1.0 is the default speed, increasing above 1.0 speeds up the playback speed, and decreasing below 1.0 slows down the playback speed. Any negative fRatio value will be replaced with a zero internally. This module assumes the wave data from upstream module is a float data type.
Type Definition
typedef struct _ModuleWAVInterpOneShotSource
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
FLOAT32 smoothingTime; // Time constant of the smoothing process
INT32 circularBufferSize; // Size of the upstream circular buffer.
INT32 extensionSize; // Size of the extension region of the circular buffer
FLOAT32 currentFRatio; // Specifies rate at which audio is read from the input buffer
FLOAT32 smoothingCoeff; // Smoothing coefficient
FLOAT32 fIndex; // state index
INT32 psObjectID; // Object ID of the upstream PeriodicStreaming module
ModuleInstanceDescriptor ** psObjectPtr; // Points to the upstream PeriodicStreaming module
} ModuleWAVInterpOneShotSourceClass;Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
smoothingTime | float | parameter | 0 | 10 | 0:1000 | msec |
circularBufferSize | int | const | 0 | 0 | Unrestricted | Â |
extensionSize | int | parameter | 0 | 0 | Unrestricted | Â |
currentFRatio | float | parameter | 1 | 1 | Unrestricted | Â |
smoothingCoeff | float | derived | 1 | 0.03278 | Unrestricted | Â |
fIndex | float | state | 1 | 0 | Unrestricted | Â |
psObjectID | int | state | 1 | -1 | Unrestricted | Â |
psObjectPtr | ModuleInstanceDescriptor ** | state | 1 | Â | Unrestricted | Â |
Pins
Input Pins
Name: ptr
Description: Pointer to the streaming transfer object
Data type: int
Channel range: 1
Block size range: 1
Sample rate range: Unrestricted
Complex support: Real
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Name: trigger
Description: Boolean trigger signal
Data type: int
Channel range: 1
Block size range: 1
Sample rate range: Unrestricted
Complex support: Real
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Name: fRatio
Description: Specifies sample rate ratio
Data type: float
Channel range: 1
Block size range: 1
Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: output data
Data type: float
MATLAB Usage
File Name: wav_interp_oneshot_source_module.m
M=wav_interp_oneshot_source_module(NAME, NUMCHANNELS, BLOCKSIZE, SAMPLERATE)
Creates a source module that connects to a streaming buffer module and outputs blocks
of data. The function includes linear interpolation allowing playback to be slowed down and
speeded up. This version uses float wave data and a float fIndex register for efficient
implementation. This version is a "one shot player" in which the playback is triggered
by an input pin and then stops after the WAV data has been played once. Arguments:
NAME - name of the module.
NUMCHANNELS - number of interleaved channels in each output pin.
By default, NUMCHANNELS = 1;
BLOCKSIZE - number of samples per output channel. By default,
BLOCKSIZE = 32.
SAMPLERATE - sample rate of the output signal, in Hz. By default,
SAMPLERATE = 48000.Â