web_codecs/audio/
decoder.rs

1use bytes::{Bytes, BytesMut};
2use tokio::sync::{mpsc, watch};
3use wasm_bindgen::{prelude::*, JsCast};
4
5use super::AudioData;
6use crate::{EncodedFrame, Error};
7
8#[derive(Debug, Default, Clone)]
9pub struct AudioDecoderConfig {
10	/// The codec mimetype string.
11	pub codec: String,
12
13	/// Some codec formats use a description to configure the decoder.
14	pub description: Option<Bytes>,
15
16	/// The number of channels in the audio.
17	pub channel_count: u32,
18
19	/// The sample rate of the audio.
20	pub sample_rate: u32,
21}
22
23impl AudioDecoderConfig {
24	pub fn new<T: Into<String>>(codec: T, channel_count: u32, sample_rate: u32) -> Self {
25		Self {
26			codec: codec.into(),
27			channel_count,
28			sample_rate,
29			..Default::default()
30		}
31	}
32
33	/// Check if the configuration is supported by this browser.
34	/// Returns an error if the configuration is invalid, and false if just unsupported.
35	pub async fn is_supported(&self) -> Result<bool, Error> {
36		let res =
37			wasm_bindgen_futures::JsFuture::from(web_sys::AudioDecoder::is_config_supported(&self.into())).await?;
38		let support: web_sys::AudioDecoderSupport = res.unchecked_into();
39		Ok(support.get_supported().unwrap_or(false))
40	}
41
42	pub fn build(self) -> Result<(AudioDecoder, AudioDecoded), Error> {
43		let (frames_tx, frames_rx) = mpsc::unbounded_channel();
44		let (closed_tx, closed_rx) = watch::channel(Ok(()));
45		let closed_tx2 = closed_tx.clone();
46
47		let on_error = Closure::wrap(Box::new(move |e: JsValue| {
48			closed_tx.send_replace(Err(Error::from(e))).ok();
49		}) as Box<dyn FnMut(_)>);
50
51		let on_frame = Closure::wrap(Box::new(move |e: JsValue| {
52			let frame: web_sys::AudioData = e.unchecked_into();
53			let frame = AudioData::from(frame);
54
55			if frames_tx.send(frame).is_err() {
56				closed_tx2.send_replace(Err(Error::Dropped)).ok();
57			}
58		}) as Box<dyn FnMut(_)>);
59
60		let init = web_sys::AudioDecoderInit::new(on_error.as_ref().unchecked_ref(), on_frame.as_ref().unchecked_ref());
61		let inner: web_sys::AudioDecoder = web_sys::AudioDecoder::new(&init).unwrap();
62		inner.configure(&(&self).into())?;
63
64		let decoder = AudioDecoder {
65			inner,
66			on_error,
67			on_frame,
68		};
69
70		let decoded = AudioDecoded {
71			frames: frames_rx,
72			closed: closed_rx,
73		};
74
75		Ok((decoder, decoded))
76	}
77}
78
79impl From<&AudioDecoderConfig> for web_sys::AudioDecoderConfig {
80	fn from(this: &AudioDecoderConfig) -> Self {
81		let config = web_sys::AudioDecoderConfig::new(&this.codec, this.channel_count, this.sample_rate);
82
83		if let Some(description) = &this.description {
84			config.set_description(&js_sys::Uint8Array::from(description.as_ref()));
85		}
86
87		config
88	}
89}
90
91impl From<web_sys::AudioDecoderConfig> for AudioDecoderConfig {
92	fn from(this: web_sys::AudioDecoderConfig) -> Self {
93		let description = this.get_description().map(|d| {
94			// TODO: An ArrayBuffer, a TypedArray, or a DataView containing a sequence of codec-specific bytes, commonly known as "extradata".
95			let buffer = js_sys::Uint8Array::new(&d);
96			let size = buffer.byte_length() as usize;
97
98			let mut payload = BytesMut::with_capacity(size);
99			payload.resize(size, 0);
100			buffer.copy_to(&mut payload);
101
102			payload.freeze()
103		});
104
105		let channels = this.get_number_of_channels();
106		let sample_rate = this.get_sample_rate();
107
108		Self {
109			codec: this.get_codec(),
110			description,
111			channel_count: channels,
112			sample_rate,
113		}
114	}
115}
116
117pub struct AudioDecoder {
118	inner: web_sys::AudioDecoder,
119
120	// These are held to avoid dropping them.
121	#[allow(dead_code)]
122	on_error: Closure<dyn FnMut(JsValue)>,
123	#[allow(dead_code)]
124	on_frame: Closure<dyn FnMut(JsValue)>,
125}
126
127impl AudioDecoder {
128	pub fn decode(&self, frame: EncodedFrame) -> Result<(), Error> {
129		let chunk_type = match frame.keyframe {
130			true => web_sys::EncodedAudioChunkType::Key,
131			false => web_sys::EncodedAudioChunkType::Delta,
132		};
133
134		let chunk = web_sys::EncodedAudioChunkInit::new(
135			&js_sys::Uint8Array::from(frame.payload.as_ref()),
136			frame.timestamp.as_micros() as _,
137			chunk_type,
138		);
139
140		let chunk = web_sys::EncodedAudioChunk::new(&chunk)?;
141		self.inner.decode(&chunk)?;
142
143		Ok(())
144	}
145
146	pub async fn flush(&self) -> Result<(), Error> {
147		wasm_bindgen_futures::JsFuture::from(self.inner.flush()).await?;
148		Ok(())
149	}
150
151	pub fn queue_size(&self) -> u32 {
152		self.inner.decode_queue_size()
153	}
154}
155
156impl Drop for AudioDecoder {
157	fn drop(&mut self) {
158		let _ = self.inner.close();
159	}
160}
161
162pub struct AudioDecoded {
163	frames: mpsc::UnboundedReceiver<AudioData>,
164	closed: watch::Receiver<Result<(), Error>>,
165}
166
167impl AudioDecoded {
168	pub async fn next(&mut self) -> Result<Option<AudioData>, Error> {
169		tokio::select! {
170			biased;
171			frame = self.frames.recv() => Ok(frame),
172			Ok(()) = self.closed.changed() => Err(self.closed.borrow().clone().err().unwrap()),
173		}
174	}
175}
web_codecs/audio/decoder.rs

web_codecs/audio/
decoder.rs
