src/constants.js

/**
 * Sample rate of the input audio.
 * Coindicentally, this is the same for both models (Moonshine and Silero VAD)
 */
export const INPUT_SAMPLE_RATE = 16000;
const INPUT_SAMPLE_RATE_MS = INPUT_SAMPLE_RATE / 1000;

/**
 * Probabilities ABOVE this value are considered as SPEECH
 */
export const SPEECH_THRESHOLD = 0.3;

/**
 * If current state is SPEECH, and the probability of the next state
 * is below this value, it is considered as NON-SPEECH.
 */
export const EXIT_THRESHOLD = 0.1;

/**
 * After each speech chunk, wait for at least this amount of silence
 * before considering the next chunk as a new speech chunk
 */
export const MIN_SILENCE_DURATION_MS = 400;
export const MIN_SILENCE_DURATION_SAMPLES =
  MIN_SILENCE_DURATION_MS * INPUT_SAMPLE_RATE_MS;

/**
 * Pad the speech chunk with this amount each side
 */
export const SPEECH_PAD_MS = 80;
export const SPEECH_PAD_SAMPLES = SPEECH_PAD_MS * INPUT_SAMPLE_RATE_MS;

/**
 * Final speech chunks below this duration are discarded
 */
export const MIN_SPEECH_DURATION_SAMPLES = 250 * INPUT_SAMPLE_RATE_MS; // 250 ms

/**
 * Maximum duration of audio that can be handled by Moonshine
 */
export const MAX_BUFFER_DURATION = 30;

/**
 * Size of the incoming buffers
 */
export const NEW_BUFFER_SIZE = 512;

/**
 * The number of previous buffers to keep, to ensure the audio is padded correctly
 */
export const MAX_NUM_PREV_BUFFERS = Math.ceil(
  SPEECH_PAD_SAMPLES / NEW_BUFFER_SIZE,
);