audiorecorder

Create object for recording audio

Syntax

recorder = audiorecorder
recorder = audiorecorder(Fs,nBits,nChannels)
recorder = audiorecorder(Fs,nBits,nChannels,ID)


Description

recorder = audiorecorder creates an 8000 Hz, 8-bit, 1-channel audiorecorder object.

recorder = audiorecorder(Fs,nBits,nChannels) sets the sample rate Fs (in Hz), the sample size nBits, and the number of channels nChannels.

recorder = audiorecorder(Fs,nBits,nChannels,ID) sets the audio input device to the device specified by ID.

Input Arguments

Fs	Sampling rate in Hz. Valid values depend on both the sample rates permitted by MATLAB® and the specific audio hardware on your system. MATLAB has a hard restriction of 1000 Hz <= Fs <= 384000 Hz, although further hardware-dependent restrictions apply. Typical values supported by most sound cards are 8000, 11025, 22050, 44100, 48000, and 96000 Hz. Default: 8000
nBits	Bits per sample. Valid values depend on the audio hardware installed: 8, 16, or 24. Default: 8
nChannels	The number of channels: 1 (mono) or 2 (stereo). Default: 1
ID	Device identifier. To obtain the ID of a device, use the audiodevinfo function. Default: -1 (default device)

Methods

Note

When calling any method, include the audiorecorder object name using function syntax, such as stop(recorder).

get	Query properties of audiorecorder object.
getaudiodata	Create an array that stores the recorded signal values.
getplayer	Create an audioplayer object.
isrecording	Query whether recording is in progress: returns true or false.
pause	Pause recording.
play	Play recorded audio. This method returns an audioplayer object.
record	Start recording.
recordblocking	Record, and do not return control until recording completes. This method requires a second input for the length of the recording in seconds: recordblocking(recorder,length)
resume	Restart recording from paused position.
set	Set properties of audiorecorder object.
stop	Stop recording.

See the reference pages for get, getaudiodata, play, record, recordblocking, and set for additional syntax options.

Properties

BitsPerSample	Number of bits per sample. (Read-only)
CurrentSample	Current sample that the audio input device is recording. If the device is not recording, CurrentSample is the next sample to record with record or resume. (Read-only)
DeviceID	Identifier for audio device. (Read-only)
NumberOfChannels	Number of audio channels. (Read-only)
Running	Status of the audio recorder: 'on' or 'off'. (Read-only)
SampleRate	Sampling frequency in Hz. (Read-only)
TotalSamples	Total length of the audio data in samples. (Read-only)
Tag	Label of the object.
Type	Name of the class: 'audiorecorder'. (Read-only)
UserData	Any type of additional data to store with the object.

The following four properties apply to callback functions. The first two inputs to your callback function must be the audiorecorder object and an event structure.
StartFcn	Function to execute one time when recording starts.
StopFcn	Function to execute one time when recording stops.
TimerFcn	Function to execute repeatedly during recording. To specify time intervals for the repetitions, use the TimerPeriod property.
TimerPeriod	Time in seconds between TimerFcn callbacks. Default: .05

audiorecorder ignores any specified values for these properties, which will be removed in a future release.
BufferLength	Length of buffer in seconds.
NumberOfBuffers	Number of buffers.

Examples

Create an audiorecorder object for CD-quality audio in stereo, and view its properties:

recObj = audiorecorder(44100, 16, 2);
get(recObj)

Collect a sample of your speech with a microphone, and plot the signal data:

% Record your voice for 5 seconds.
recObj = audiorecorder;
disp('Start speaking.')
recordblocking(recObj, 5);
disp('End of Recording.');

% Play back the recording.
play(recObj);

% Store data in double-precision array.
myRecording = getaudiodata(recObj);

% Plot the waveform.
plot(myRecording);

Tips

• To use an audiorecorder object, your system must have a properly installed and configured sound card.

• audiorecorder is not intended for long, high-sample-rate recording. audiorecorder uses system memory for storage and does not use disk buffering. When you attempt a large recording, your MATLAB performance sometimes degrades over time.