7e4392ae68
This implements a proof-of-concept for an improved audio frontend. The largest change is the introduction of events and event handling: both by time elapsed and by track events, such as ending or looping. Following on from this, the library now includes a basic, event-driven track queue system (which people seem to ask for unusually often). A new sample, `examples/13_voice_events`, demonstrates both the `TrackQueue` system and some basic events via the `~queue` and `~play_fade` commands. Locks are removed from around the control of `Audio` objects, which should allow the backend to be moved to a more granular futures-based backend solution in a cleaner way.
70 lines
1.7 KiB
Rust
70 lines
1.7 KiB
Rust
mod frame;
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pub use frame::*;
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use super::CodecType;
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use byteorder::{LittleEndian, ReadBytesExt};
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use std::{
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fmt::Debug,
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io::{Read, Result as IoResult},
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mem,
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};
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/// Marker and state for decoding framed input files.
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#[non_exhaustive]
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#[derive(Clone, Copy, Debug)]
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pub enum Container {
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/// Raw, unframed input.
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Raw,
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/// Framed input, beginning with a JSON header.
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///
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/// Frames have the form `{ len: i16, payload: [u8; len]}`.
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Dca {
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/// Byte index of the first frame after the JSON header.
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first_frame: usize,
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},
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}
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impl Container {
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/// Tries to read the header of the next frame from an input stream.
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pub fn next_frame_length(
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&mut self,
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mut reader: impl Read,
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input: CodecType,
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) -> IoResult<Frame> {
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use Container::*;
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match self {
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Raw => Ok(Frame {
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header_len: 0,
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frame_len: input.sample_len(),
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}),
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Dca { .. } => reader.read_i16::<LittleEndian>().map(|frame_len| Frame {
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header_len: mem::size_of::<i16>(),
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frame_len: frame_len.max(0) as usize,
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}),
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}
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}
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/// Tries to seek on an input directly using sample length, if the input
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/// is unframed.
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pub fn try_seek_trivial(&self, input: CodecType) -> Option<usize> {
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use Container::*;
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match self {
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Raw => Some(input.sample_len()),
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_ => None,
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}
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}
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/// Returns the byte index of the first frame containing audio payload data.
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pub fn input_start(&self) -> usize {
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use Container::*;
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match self {
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Raw => 0,
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Dca { first_frame } => *first_frame,
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}
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}
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}
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