Setting up the speech recognition application to detect a wakeup word may be done using series of Audio Elements linked into a pipeline shown below.
blockdiag speech_recognition_pipeline {
# global attributes default_shape = roundedbox; default_group_color = lightgrey; span_width = 40; node_width = 80; span_height = 30;
# labels of diagram nodes MICROPHONE [label="Mic", shape=beginpoint]; CODEC_CHIP [label="Codecn chip"]; I2S_STREAM [label="I2Sn stream"]; FILTER [label="Filter"]; RAW_STREAM [label="RAWn stream"]; SPEECH_RECOGNITION [label="Speechn recognition", shape=box, height=60];
# node connections MICROPHONE -> CODEC_CHIP -> I2S_STREAM -> FILTER -> RAW_STREAM -> SPEECH_RECOGNITION;
}
Configuration and use of particular elements is demonstrated in several examples <examples> linked to elsewhere in this documentation. What may need clarification is use of the Filter and the RAW stream. The filter is used to adjust the sample rate of the I2S stream to match the sample rate of the speech recognition model. The RAW stream is the way to feed the audio input to the model.
The :example_file:`speech_recognition/wwe/main/main.c` example demonstrates how to initialize the model, determine the number of samples and the sample rate of voice data to feed to the model, and detect the wakeup word.
Implementation of the speech recognition API is demonstrated in that example.
For the latest API reference please refer to Espressif Speech recognition repository.