Import and Play Audio File Data in Signal Labeler

Use Signal Labeler to import audio files and labeled signal sets that point to audioDatastore objects or audio files. Create custom labeling functions to perform automated labeling and sublabeling tasks. You can also play audio files or signals with time information in the app.

Note

Importing and playing audio file data in Signal Labeler requires an Audio Toolbox™ license. For an example on how to create an audioDatastore object, see audioDatastore Object Pointing to Audio Files (Audio Toolbox).

Supported Audio File Extensions

When importing audio files, Signal Labeler supports single and multichannel signals with the following audio file extensions:

• .wav

• .avi

• .aif

• .aifc

• .aiff

• .mp3

• .au

• .snd

• .mp4

• .m4a

• .flac

• .ogg

• .mov

• .opus

Time Information

The audio signals you import into Signal Labeler are automatically labeled in time based on the sample rate information. You cannot import or export audio signals with time information in samples.

Import Audio Signals from Files or Folder

To import signals into Signal Labeler from audio files or a folder containing audio files, on the Labeler tab, click Import and select From Audio Files or From Audio Folder in the Members list. In the dialog box, browse to select the audio files or folder that contains the audio signals you want to import. Each imported audio file is treated as a member of the labeled signal set. All the signals contained in one audio file belong to a single member and are labeled together. All members to import must use a file extension listed in Supported Audio File Extensions.

Note

Importing labeledSignalSet objects using From Audio Files or From Audio Folder is not supported. To import a labeledSignalSet object, load it into the MATLAB^® Workspace and import it from there.

Import labeledSignalSet from MATLAB Workspace

To import a labeledSignalSet object into Signal Labeler from the MATLAB Workspace, on the Labeler tab, click Import and select From Workspace in the Members list. In the dialog box, select the labeledSignalSet you want to import. Each audio signal in the labeledSignalSet is treated as a member of the labeled signal set and can be labeled individually.

To be imported successfully, labeled signal sets should follow these guidelines:

• If the selection includes two or more labeledSignalSet objects, each must have unique signal label definitions. If two or more sets share a label definition, the definition must have the same type and data type for all sets. For more information, see Create or Import Signal Label Definitions.

• If the selection includes two or more labeledSignalSet objects, each must have unique member names. You cannot change member names from within Signal Labeler. To change the name of a member of a labeled signal set, use setMemberNames at the command line.

• If you select two or more labeledSignalSet objects for labeling, Signal Labeler merges them and creates a single labeled signal set containing all the members and label values of the input sets. This action is equivalent to using merge at the command line.

• Label values in labeledSignalSet objects must be scalars. Signal Labeler ignores those labels which do not have scalar values.

Note

• You cannot modify the time information of a labeledSignalSet object from within Signal Labeler.

• Audio labeled signal sets cannot be merged with non-audio labeled signal sets.

Play Audio Signals and Regions of Interest

You can use the Signal Labeler app to play audio signals or other signals with a constant sample rate in the range [1, 384] kHz. Select the signal you want to play in the Labeled Signal Set Members browser. On the Audio tab, select an audio player device from the Playback Device list. Click Play in the Playback section of the toolstrip to play the entire signal once. Select Play in Loop and then click Play to play the signal repeatedly. You can also select a region of interest to play. Select the region in the Labeled Signal Set Members browser or click on the region directly in the plot, then choose a playback option to listen to the signal.

Note

Signal Labeler uses audioDeviceWriter (Audio Toolbox) to play audio. Audio playback is not supported in MATLAB Online.