PlaybackWav Class

PlaybackWav Class

Description
A class used for control and playback of .wav file format audio data.

Syntax
class PlaybackWav

Members

Public Constructors 
PlaybackWav::PlaybackWavCreate an instance of the PlaybackWav class
Public Methods 
PlaybackWav::openFileOpen a .wav file for playback
PlaybackWav::closeFileClose a previously opened file
PlaybackWav::fileOpenedCheck if a .wav file is already opened
PlaybackWav::getSampleRateGet the sample rate of the .wav file
PlaybackWav::getChannelCountGet the number of audio channels in the .wav file
PlaybackWav::getBitDepthGet the bit depth of each sample in the .wav file
PlaybackWav::getLengthMillisGet the playback length of the .wav file in milliseconds
PlaybackWav::getPositionMillisGet the current playback position in milliseconds
PlaybackWav::setPositionMillisSet the current playback position in milliseconds
PlaybackWav::millisToBytesConvert a playback duration to equivalent number of bytes
PlaybackWav::bytesToMillisConvert number of bytes to an equivalent playback duration
PlaybackWav::readAudioDataRead audio data from the .wav file

PlaybackWav::PlaybackWav

Description
Create a PlaybackWav class object.

Syntax
void PlaybackWav(void);

Parameters
The function requires no input parameter.

Returns
The function returns nothing.

Example Code
NA

Notes and Warnings
NA

PlaybackWav::fileOpened

Description
Check if a .wav file is already opened.

Syntax
bool fileOpened(void);

Parameters
The function requires no input parameter.

Returns
The function returns true if a .wav file is already open, false otherwise.

Example Code
Example: RecordPlaybackWav

Notes and Warnings
NA

PlaybackWav::getSampleRate

Description
Get the sample rate of the .wav file.

Syntax
uint32_t getSampleRate(void);

Parameters
The function requires no input parameter.

Returns
The function returns sampling rate encoded in the .wav file header.

Example Code
Example: PlaybackWavFile

Notes and Warnings
NA

PlaybackWav::getChannelCount

Description
Get the number of audio channels in the .wav file.

Syntax
uint16_t getChannelCount(void);

Parameters
The function requires no input parameter.

Returns
The function returns channel count encoded in the .wav file header.

Example Code
Example: PlaybackWavFile

Notes and Warnings
NA

PlaybackWav::getBitDepth

Description
Get the bit depth of each sample in the .wav file.

Syntax
uint16_t getBitDepth(void);

Parameters
The function requires no input parameter.

Returns
The function returns bit depth encoded in the .wav file header.

Example Code
Example: PlaybackWavFile

Notes and Warnings
NA

PlaybackWav::getLengthMillis

Description
Get the playback length of the .wav file in milliseconds.

Syntax
uint32_t getLengthMillis(void);

Parameters
The function requires no input parameter.

Returns
The function returns the total playback length of the currently open .wav file in milliseconds.

Example Code
Example: PlaybackWavFile

Notes and Warnings
NA

PlaybackWav::getPositionMillis

Description
Get the current playback position in milliseconds.

Syntax
uint32_t getPositionMillis(void);

Parameters
The function requires no input parameter.

Returns
The function returns the current playback position of the currently open .wav file in milliseconds.

Example Code
Example: PlaybackWavFile

Notes and Warnings
NA

PlaybackWav::setPositionMillis

Description
Set the current playback position in milliseconds.

Syntax
void setPositionMillis(uint32_t pos);

Parameters
pos: The desired playback position expressed in milliseconds.

Returns
The function returns nothing.

Example Code
Example: PlaybackWavFile

Notes and Warnings
Any changes to playback position will only take effect on the next call to PlaybackWav::readAudioData. If the desired playback position is beyond the total playback length of the file, the playback position will be set to the end of file, and no audio data will be output on subsequent data reads.

PlaybackWav::millisToBytes

Description
Convert a playback duration to equivalent number of bytes.

Syntax
uint32_t millisToBytes(uint32_t ms);

Parameters
ms: playback duration in milliseconds.

Returns
The function returns the number of bytes that is equivalent to the input playback duration, converted using the current sample rate, number of channels and bit depth.

Example Code
NA

Notes and Warnings
NA

PlaybackWav::bytesToMillis

Description
Convert number of bytes to an equivalent playback duration.

Syntax
uint32_t bytesToMillis(uint32_t bytes);

Parameters
bytes: playback duration in number of bytes.

Returns
The function returns the time duration in milliseconds that is equivalent to the input number of bytes, converted using the current sample rate, number of channels and bit depth.

Example Code
NA

Notes and Warnings
NA

PlaybackWav::readAudioData

Description
Read audio data from the .wav file.

Syntax
uint32_t readAudioData(int8_t* dst, uint32_t len);
uint32_t readAudioData(int16_t* dst, uint32_t len);

Parameters
dst: pointer to array to store data read from .wav file.
len: number of audio samples to read from .wav file.

Returns
The function returns number of audio samples read.

Example Code
Example: PlaybackWavFile

Notes and Warnings
NA

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