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| 1 | +use libwebrtc::{ |
| 2 | + audio_source::native::NativeAudioSource, |
| 3 | + prelude::{AudioFrame, AudioSourceOptions, RtcAudioSource}, |
| 4 | +}; |
| 5 | +use livekit::{ |
| 6 | + options::TrackPublishOptions, |
| 7 | + track::{LocalAudioTrack, LocalTrack}, |
| 8 | + Room, RoomResult, |
| 9 | +}; |
| 10 | +use std::sync::Arc; |
| 11 | +use tokio::{sync::oneshot, task::JoinHandle}; |
| 12 | + |
| 13 | +/// Parameters for the sine wave generated with [`SineTrack`]. |
| 14 | +#[derive(Clone, Debug)] |
| 15 | +pub struct SineParameters { |
| 16 | + pub sample_rate: u32, |
| 17 | + pub freq: f64, |
| 18 | + pub amplitude: f64, |
| 19 | + pub num_channels: u32, |
| 20 | +} |
| 21 | + |
| 22 | +/// Audio track which generates and publishes a sine wave. |
| 23 | +/// |
| 24 | +/// This implementation was taken from the *wgpu_room* example. |
| 25 | +/// |
| 26 | +pub struct SineTrack { |
| 27 | + rtc_source: NativeAudioSource, |
| 28 | + params: SineParameters, |
| 29 | + room: Arc<Room>, |
| 30 | + handle: Option<TrackHandle>, |
| 31 | +} |
| 32 | + |
| 33 | +struct TrackHandle { |
| 34 | + close_tx: oneshot::Sender<()>, |
| 35 | + track: LocalAudioTrack, |
| 36 | + task: JoinHandle<()>, |
| 37 | +} |
| 38 | + |
| 39 | +impl SineTrack { |
| 40 | + pub fn new(room: Arc<Room>, params: SineParameters) -> Self { |
| 41 | + Self { |
| 42 | + rtc_source: NativeAudioSource::new( |
| 43 | + AudioSourceOptions::default(), |
| 44 | + params.sample_rate, |
| 45 | + params.num_channels, |
| 46 | + 1000, |
| 47 | + ), |
| 48 | + params, |
| 49 | + room, |
| 50 | + handle: None, |
| 51 | + } |
| 52 | + } |
| 53 | + |
| 54 | + pub async fn publish(&mut self) -> RoomResult<()> { |
| 55 | + let (close_tx, close_rx) = oneshot::channel(); |
| 56 | + let track = LocalAudioTrack::create_audio_track( |
| 57 | + "sine-track", |
| 58 | + RtcAudioSource::Native(self.rtc_source.clone()), |
| 59 | + ); |
| 60 | + let task = |
| 61 | + tokio::spawn(Self::track_task(close_rx, self.rtc_source.clone(), self.params.clone())); |
| 62 | + self.room |
| 63 | + .local_participant() |
| 64 | + .publish_track(LocalTrack::Audio(track.clone()), TrackPublishOptions::default()) |
| 65 | + .await?; |
| 66 | + let handle = TrackHandle { close_tx, track, task }; |
| 67 | + self.handle = Some(handle); |
| 68 | + Ok(()) |
| 69 | + } |
| 70 | + |
| 71 | + pub async fn unpublish(&mut self) -> RoomResult<()> { |
| 72 | + if let Some(handle) = self.handle.take() { |
| 73 | + handle.close_tx.send(()).ok(); |
| 74 | + handle.task.await.ok(); |
| 75 | + self.room.local_participant().unpublish_track(&handle.track.sid()).await?; |
| 76 | + } |
| 77 | + Ok(()) |
| 78 | + } |
| 79 | + |
| 80 | + async fn track_task( |
| 81 | + mut close_rx: oneshot::Receiver<()>, |
| 82 | + rtc_source: NativeAudioSource, |
| 83 | + params: SineParameters, |
| 84 | + ) { |
| 85 | + let num_channels = params.num_channels as usize; |
| 86 | + let samples_count = (params.sample_rate / 100) as usize * num_channels; |
| 87 | + let mut samples_10ms = vec![0; samples_count]; |
| 88 | + let mut phase = 0; |
| 89 | + loop { |
| 90 | + if close_rx.try_recv().is_ok() { |
| 91 | + break; |
| 92 | + } |
| 93 | + for i in (0..samples_count).step_by(num_channels) { |
| 94 | + let val = params.amplitude |
| 95 | + * f64::sin( |
| 96 | + std::f64::consts::PI |
| 97 | + * 2.0 |
| 98 | + * params.freq |
| 99 | + * (phase as f64 / params.sample_rate as f64), |
| 100 | + ); |
| 101 | + phase += 1; |
| 102 | + for c in 0..num_channels { |
| 103 | + // WebRTC uses 16-bit signed PCM |
| 104 | + samples_10ms[i + c] = (val * 32768.0) as i16; |
| 105 | + } |
| 106 | + } |
| 107 | + let frame = AudioFrame { |
| 108 | + data: samples_10ms.as_slice().into(), |
| 109 | + sample_rate: params.sample_rate, |
| 110 | + num_channels: params.num_channels, |
| 111 | + samples_per_channel: samples_count as u32 / params.num_channels, |
| 112 | + }; |
| 113 | + rtc_source.capture_frame(&frame).await.unwrap(); |
| 114 | + } |
| 115 | + } |
| 116 | +} |
| 117 | + |
| 118 | +/// Analyzes samples to estimate the frequency of the signal using the zero crossing method. |
| 119 | +#[derive(Clone)] |
| 120 | +pub struct FreqAnalyzer { |
| 121 | + zero_crossings: usize, |
| 122 | + samples_analyzed: usize, |
| 123 | +} |
| 124 | + |
| 125 | +impl FreqAnalyzer { |
| 126 | + pub fn new() -> Self { |
| 127 | + Self { zero_crossings: 0, samples_analyzed: 0 } |
| 128 | + } |
| 129 | + |
| 130 | + pub fn analyze(&mut self, samples: impl IntoIterator<Item = i16>) { |
| 131 | + let mut iter = samples.into_iter(); |
| 132 | + let mut prev = match iter.next() { |
| 133 | + Some(v) => v, |
| 134 | + None => return, |
| 135 | + }; |
| 136 | + let mut count = 0; |
| 137 | + for curr in iter { |
| 138 | + if (prev >= 0 && curr < 0) || (prev < 0 && curr >= 0) { |
| 139 | + self.zero_crossings += 1; |
| 140 | + } |
| 141 | + prev = curr; |
| 142 | + count += 1; |
| 143 | + } |
| 144 | + self.samples_analyzed += count + 1; |
| 145 | + } |
| 146 | + |
| 147 | + pub fn estimated_freq(&self, sample_rate: u32) -> f64 { |
| 148 | + let num_cycles = self.zero_crossings as f64 / 2.0; |
| 149 | + let duration_seconds = self.samples_analyzed as f64 / sample_rate as f64; |
| 150 | + if duration_seconds == 0.0 { |
| 151 | + return 0.0; |
| 152 | + } |
| 153 | + num_cycles / duration_seconds |
| 154 | + } |
| 155 | +} |
| 156 | + |
| 157 | +pub trait ChannelIterExt<'a> { |
| 158 | + /// Returns an iterator over the samples in a specific channel. |
| 159 | + /// |
| 160 | + /// # Arguments |
| 161 | + /// * `channel_index` - Index of the channel to iterate over (must be less than `num_channels`). |
| 162 | + /// |
| 163 | + /// # Panics |
| 164 | + /// Panics if `channel_index` is greater than or equal to `num_channels`. |
| 165 | + /// |
| 166 | + fn channel_iter(&'a self, channel_index: usize) -> ChannelIter<'a>; |
| 167 | +} |
| 168 | + |
| 169 | +impl<'a> ChannelIterExt<'a> for AudioFrame<'a> { |
| 170 | + fn channel_iter(&'a self, channel_index: usize) -> ChannelIter<'a> { |
| 171 | + assert!(channel_index < self.num_channels as usize); |
| 172 | + ChannelIter { frame: self, channel_index, index: 0 } |
| 173 | + } |
| 174 | +} |
| 175 | + |
| 176 | +/// Iterator over an individual channel in an interleaved [`AudioFrame`]. |
| 177 | +pub struct ChannelIter<'a> { |
| 178 | + frame: &'a AudioFrame<'a>, |
| 179 | + channel_index: usize, |
| 180 | + index: usize, |
| 181 | +} |
| 182 | + |
| 183 | +impl<'a> Iterator for ChannelIter<'a> { |
| 184 | + type Item = i16; |
| 185 | + |
| 186 | + fn next(&mut self) -> Option<Self::Item> { |
| 187 | + let inner_index = |
| 188 | + self.index * (self.frame.num_channels as usize) + (self.channel_index as usize); |
| 189 | + if inner_index >= self.frame.data.len() { |
| 190 | + return None; |
| 191 | + } |
| 192 | + let sample = self.frame.data[inner_index]; |
| 193 | + self.index += 1; |
| 194 | + Some(sample) |
| 195 | + } |
| 196 | +} |
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