nihility-listener 0.3.1

mod silero;

use crate::error::*;
use crate::vad::silero::{Silero, SileroConfig};
use serde::{Deserialize, Serialize};
use std::collections::VecDeque;
use tokio::sync::broadcast::{channel, Receiver, Sender};
use tracing::{debug, error};

/// 语音活动检测配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct VoiceActivityDetectionConfig {
    pub speech_channel_size: usize,
    pub probability_channel_size: usize,
    pub padding_size: usize,
    pub threshold: f32,
    pub silero_config: SileroConfig,
}

/// 语音活动检测
pub struct VoiceActivityDetection {
    silero: Silero,
    config: VoiceActivityDetectionConfig,
    sample_receiver: Receiver<f32>,
    speech_sender: Sender<Vec<f32>>,
    probability_sender: Option<Sender<f32>>,
    buffer: VecDeque<f32>,
    silence_count: usize,
    is_speech_active: bool,
    cumulative_sample_count: usize,
}

impl VoiceActivityDetection {
    /// 初始化语音活动检测实例，传入音频采样接收实例以及语音活动音频数据发送实例
    pub fn init(
        config: VoiceActivityDetectionConfig,
        sample_receiver: Receiver<f32>,
    ) -> Result<Self> {
        debug!("Initializing NihilityAsrVad with config {:?}", &config);
        let silero = Silero::init(config.silero_config.clone())?;
        let buffer = VecDeque::with_capacity(silero.config.chunk_size * (config.padding_size + 2));
        let (speech_sender, _) = channel(config.speech_channel_size);
        let probability_sender = if config.probability_channel_size > 0 {
            let (probability_sender, _) = channel(config.probability_channel_size);
            Some(probability_sender)
        } else {
            None
        };
        Ok(Self {
            silero,
            config,
            sample_receiver,
            speech_sender,
            probability_sender,
            buffer,
            silence_count: 0,
            is_speech_active: false,
            cumulative_sample_count: 0,
        })
    }

    pub fn get_probability_receiver(&self) -> Result<Receiver<f32>> {
        self.probability_sender
            .as_ref()
            .ok_or(NihilityListenerError::Init(
                "probability channel size must greater than zero".to_string(),
            ))
            .map(|sender| sender.subscribe())
    }

    pub fn get_speech_receiver(&self) -> Receiver<Vec<f32>> {
        self.speech_sender.subscribe()
    }

    /// 运行语音活动检测线程
    pub async fn run(&mut self) -> Result<()> {
        while let Ok(sample) = self.sample_receiver.recv().await {
            self.buffer.push_back(sample);
            self.cumulative_sample_count += 1;
            // 当新样本数量积累到一个块大小时进行识别
            if self.cumulative_sample_count == self.silero.config.chunk_size {
                // 重置新样本数量计数
                self.cumulative_sample_count = 0;
                let probability = self.silero.predict(
                    &self
                        .buffer
                        .range((self.buffer.len() - self.silero.config.chunk_size)..)
                        .copied()
                        .collect::<Vec<f32>>(),
                )?;
                if let Some(probability_sender) = self.probability_sender.as_ref()
                    && let Err(e) = probability_sender.send(probability)
                {
                    error!("Error sending probability: {:?}", e);
                }
                // 当预测结果大于等于设定阈值
                if probability >= self.config.threshold {
                    self.is_speech_active = true;
                    self.silence_count = 0;
                } else {
                    self.silence_count += 1;
                    if self.silence_count >= self.config.padding_size {
                        if self.is_speech_active {
                            // 如果当前处于活动状态，标志活动语言结束，发送当前缓冲区内所有数据，并且重置缓冲区
                            self.is_speech_active = false;
                            self.silence_count = 0;
                            self.speech_sender.send(self.buffer.drain(..).collect())?;
                        } else {
                            // 当静音块数量超过设置边界数量，移除最早的音频数据块
                            if self.silence_count != self.config.padding_size {
                                self.silence_count -= 1;
                                self.buffer.drain(..self.silero.config.chunk_size);
                            }
                        }
                    }
                }
            }
        }
        Ok(())
    }
}

impl Default for VoiceActivityDetectionConfig {
    fn default() -> Self {
        Self {
            speech_channel_size: 5,
            silero_config: SileroConfig::default(),
            padding_size: 4,
            threshold: 0.01,
            probability_channel_size: 0,
        }
    }
}