librespot/playback/src/player.rs
2021-04-10 14:06:41 +02:00

1918 lines
68 KiB
Rust

use std::cmp::max;
use std::future::Future;
use std::io::{self, Read, Seek, SeekFrom};
use std::pin::Pin;
use std::task::{Context, Poll};
use std::time::{Duration, Instant};
use std::{mem, thread};
use byteorder::{LittleEndian, ReadBytesExt};
use futures_util::stream::futures_unordered::FuturesUnordered;
use futures_util::{future, StreamExt, TryFutureExt};
use tokio::sync::{mpsc, oneshot};
use crate::audio::{AudioDecoder, AudioError, AudioPacket, PassthroughDecoder, VorbisDecoder};
use crate::audio::{AudioDecrypt, AudioFile, StreamLoaderController};
use crate::audio::{
READ_AHEAD_BEFORE_PLAYBACK_ROUNDTRIPS, READ_AHEAD_BEFORE_PLAYBACK_SECONDS,
READ_AHEAD_DURING_PLAYBACK_ROUNDTRIPS, READ_AHEAD_DURING_PLAYBACK_SECONDS,
};
use crate::audio_backend::Sink;
use crate::config::{Bitrate, NormalisationMethod, NormalisationType, PlayerConfig};
use crate::core::session::Session;
use crate::core::spotify_id::SpotifyId;
use crate::core::util::SeqGenerator;
use crate::metadata::{AudioItem, FileFormat};
use crate::mixer::AudioFilter;
pub const SAMPLE_RATE: u32 = 44100;
pub const NUM_CHANNELS: u8 = 2;
pub const SAMPLES_PER_SECOND: u32 = SAMPLE_RATE as u32 * NUM_CHANNELS as u32;
const PRELOAD_NEXT_TRACK_BEFORE_END_DURATION_MS: u32 = 30000;
const DB_VOLTAGE_RATIO: f32 = 20.0;
pub struct Player {
commands: Option<mpsc::UnboundedSender<PlayerCommand>>,
thread_handle: Option<thread::JoinHandle<()>>,
play_request_id_generator: SeqGenerator<u64>,
}
#[derive(PartialEq, Debug, Clone, Copy)]
pub enum SinkStatus {
Running,
Closed,
TemporarilyClosed,
}
pub type SinkEventCallback = Box<dyn Fn(SinkStatus) + Send>;
struct PlayerInternal {
session: Session,
config: PlayerConfig,
commands: mpsc::UnboundedReceiver<PlayerCommand>,
state: PlayerState,
preload: PlayerPreload,
sink: Box<dyn Sink>,
sink_status: SinkStatus,
sink_event_callback: Option<SinkEventCallback>,
audio_filter: Option<Box<dyn AudioFilter + Send>>,
event_senders: Vec<mpsc::UnboundedSender<PlayerEvent>>,
limiter_active: bool,
limiter_attack_counter: u32,
limiter_release_counter: u32,
limiter_peak_sample: f32,
limiter_factor: f32,
limiter_strength: f32,
}
enum PlayerCommand {
Load {
track_id: SpotifyId,
play_request_id: u64,
play: bool,
position_ms: u32,
},
Preload {
track_id: SpotifyId,
},
Play,
Pause,
Stop,
Seek(u32),
AddEventSender(mpsc::UnboundedSender<PlayerEvent>),
SetSinkEventCallback(Option<SinkEventCallback>),
EmitVolumeSetEvent(u16),
}
#[derive(Debug, Clone)]
pub enum PlayerEvent {
// Fired when the player is stopped (e.g. by issuing a "stop" command to the player).
Stopped {
play_request_id: u64,
track_id: SpotifyId,
},
// The player started working on playback of a track while it was in a stopped state.
// This is always immediately followed up by a "Loading" or "Playing" event.
Started {
play_request_id: u64,
track_id: SpotifyId,
position_ms: u32,
},
// Same as started but in the case that the player already had a track loaded.
// The player was either playing the loaded track or it was paused.
Changed {
old_track_id: SpotifyId,
new_track_id: SpotifyId,
},
// The player is delayed by loading a track.
Loading {
play_request_id: u64,
track_id: SpotifyId,
position_ms: u32,
},
// The player is preloading a track.
Preloading {
track_id: SpotifyId,
},
// The player is playing a track.
// This event is issued at the start of playback of whenever the position must be communicated
// because it is out of sync. This includes:
// start of a track
// un-pausing
// after a seek
// after a buffer-underrun
Playing {
play_request_id: u64,
track_id: SpotifyId,
position_ms: u32,
duration_ms: u32,
},
// The player entered a paused state.
Paused {
play_request_id: u64,
track_id: SpotifyId,
position_ms: u32,
duration_ms: u32,
},
// The player thinks it's a good idea to issue a preload command for the next track now.
// This event is intended for use within spirc.
TimeToPreloadNextTrack {
play_request_id: u64,
track_id: SpotifyId,
},
// The player reached the end of a track.
// This event is intended for use within spirc. Spirc will respond by issuing another command
// which will trigger another event (e.g. Changed or Stopped)
EndOfTrack {
play_request_id: u64,
track_id: SpotifyId,
},
// The player was unable to load the requested track.
Unavailable {
play_request_id: u64,
track_id: SpotifyId,
},
// The mixer volume was set to a new level.
VolumeSet {
volume: u16,
},
}
impl PlayerEvent {
pub fn get_play_request_id(&self) -> Option<u64> {
use PlayerEvent::*;
match self {
Loading {
play_request_id, ..
}
| Unavailable {
play_request_id, ..
}
| Started {
play_request_id, ..
}
| Playing {
play_request_id, ..
}
| TimeToPreloadNextTrack {
play_request_id, ..
}
| EndOfTrack {
play_request_id, ..
}
| Paused {
play_request_id, ..
}
| Stopped {
play_request_id, ..
} => Some(*play_request_id),
Changed { .. } | Preloading { .. } | VolumeSet { .. } => None,
}
}
}
pub type PlayerEventChannel = mpsc::UnboundedReceiver<PlayerEvent>;
#[derive(Clone, Copy, Debug)]
pub struct NormalisationData {
track_gain_db: f32,
track_peak: f32,
album_gain_db: f32,
album_peak: f32,
}
impl NormalisationData {
pub fn db_to_ratio(db: f32) -> f32 {
f32::powf(10.0, db / DB_VOLTAGE_RATIO)
}
pub fn ratio_to_db(ratio: f32) -> f32 {
ratio.log10() * DB_VOLTAGE_RATIO
}
fn parse_from_file<T: Read + Seek>(mut file: T) -> io::Result<NormalisationData> {
const SPOTIFY_NORMALIZATION_HEADER_START_OFFSET: u64 = 144;
file.seek(SeekFrom::Start(SPOTIFY_NORMALIZATION_HEADER_START_OFFSET))?;
let track_gain_db = file.read_f32::<LittleEndian>()?;
let track_peak = file.read_f32::<LittleEndian>()?;
let album_gain_db = file.read_f32::<LittleEndian>()?;
let album_peak = file.read_f32::<LittleEndian>()?;
let r = NormalisationData {
track_gain_db,
track_peak,
album_gain_db,
album_peak,
};
Ok(r)
}
fn get_factor(config: &PlayerConfig, data: NormalisationData) -> f32 {
let [gain_db, gain_peak] = match config.normalisation_type {
NormalisationType::Album => [data.album_gain_db, data.album_peak],
NormalisationType::Track => [data.track_gain_db, data.track_peak],
};
let normalisation_power = gain_db + config.normalisation_pregain;
let mut normalisation_factor = Self::db_to_ratio(normalisation_power);
if normalisation_factor * gain_peak > config.normalisation_threshold {
let limited_normalisation_factor = config.normalisation_threshold / gain_peak;
let limited_normalisation_power = Self::ratio_to_db(limited_normalisation_factor);
if config.normalisation_method == NormalisationMethod::Basic {
warn!("Limiting gain to {:.2} for the duration of this track to stay under normalisation threshold.", limited_normalisation_power);
normalisation_factor = limited_normalisation_factor;
} else {
warn!(
"This track will at its peak be subject to {:.2} dB of dynamic limiting.",
normalisation_power - limited_normalisation_power
);
}
warn!("Please lower pregain to avoid.");
}
debug!("Normalisation Data: {:?}", data);
debug!("Normalisation Type: {:?}", config.normalisation_type);
debug!(
"Normalisation Threshold: {:.1}",
Self::ratio_to_db(config.normalisation_threshold)
);
debug!("Normalisation Method: {:?}", config.normalisation_method);
debug!("Normalisation Factor: {}", normalisation_factor);
if config.normalisation_method == NormalisationMethod::Dynamic {
debug!("Normalisation Attack: {:?}", config.normalisation_attack);
debug!("Normalisation Release: {:?}", config.normalisation_release);
debug!("Normalisation Knee: {:?}", config.normalisation_knee);
}
normalisation_factor
}
}
impl Player {
pub fn new<F>(
config: PlayerConfig,
session: Session,
audio_filter: Option<Box<dyn AudioFilter + Send>>,
sink_builder: F,
) -> (Player, PlayerEventChannel)
where
F: FnOnce() -> Box<dyn Sink> + Send + 'static,
{
let (cmd_tx, cmd_rx) = mpsc::unbounded_channel();
let (event_sender, event_receiver) = mpsc::unbounded_channel();
let handle = thread::spawn(move || {
debug!("new Player[{}]", session.session_id());
let internal = PlayerInternal {
session,
config,
commands: cmd_rx,
state: PlayerState::Stopped,
preload: PlayerPreload::None,
sink: sink_builder(),
sink_status: SinkStatus::Closed,
sink_event_callback: None,
audio_filter,
event_senders: [event_sender].to_vec(),
limiter_active: false,
limiter_attack_counter: 0,
limiter_release_counter: 0,
limiter_peak_sample: 0.0,
limiter_factor: 1.0,
limiter_strength: 0.0,
};
// While PlayerInternal is written as a future, it still contains blocking code.
// It must be run by using block_on() in a dedicated thread.
futures_executor::block_on(internal);
debug!("PlayerInternal thread finished.");
});
(
Player {
commands: Some(cmd_tx),
thread_handle: Some(handle),
play_request_id_generator: SeqGenerator::new(0),
},
event_receiver,
)
}
fn command(&self, cmd: PlayerCommand) {
self.commands.as_ref().unwrap().send(cmd).unwrap();
}
pub fn load(&mut self, track_id: SpotifyId, start_playing: bool, position_ms: u32) -> u64 {
let play_request_id = self.play_request_id_generator.get();
self.command(PlayerCommand::Load {
track_id,
play_request_id,
play: start_playing,
position_ms,
});
play_request_id
}
pub fn preload(&self, track_id: SpotifyId) {
self.command(PlayerCommand::Preload { track_id });
}
pub fn play(&self) {
self.command(PlayerCommand::Play)
}
pub fn pause(&self) {
self.command(PlayerCommand::Pause)
}
pub fn stop(&self) {
self.command(PlayerCommand::Stop)
}
pub fn seek(&self, position_ms: u32) {
self.command(PlayerCommand::Seek(position_ms));
}
pub fn get_player_event_channel(&self) -> PlayerEventChannel {
let (event_sender, event_receiver) = mpsc::unbounded_channel();
self.command(PlayerCommand::AddEventSender(event_sender));
event_receiver
}
pub async fn await_end_of_track(&self) {
let mut channel = self.get_player_event_channel();
while let Some(event) = channel.recv().await {
if matches!(
event,
PlayerEvent::EndOfTrack { .. } | PlayerEvent::Stopped { .. }
) {
return;
}
}
}
pub fn set_sink_event_callback(&self, callback: Option<SinkEventCallback>) {
self.command(PlayerCommand::SetSinkEventCallback(callback));
}
pub fn emit_volume_set_event(&self, volume: u16) {
self.command(PlayerCommand::EmitVolumeSetEvent(volume));
}
}
impl Drop for Player {
fn drop(&mut self) {
debug!("Shutting down player thread ...");
self.commands = None;
if let Some(handle) = self.thread_handle.take() {
match handle.join() {
Ok(_) => (),
Err(_) => error!("Player thread panicked!"),
}
}
}
}
struct PlayerLoadedTrackData {
decoder: Decoder,
normalisation_factor: f32,
stream_loader_controller: StreamLoaderController,
bytes_per_second: usize,
duration_ms: u32,
stream_position_pcm: u64,
}
enum PlayerPreload {
None,
Loading {
track_id: SpotifyId,
loader: Pin<Box<dyn Future<Output = Result<PlayerLoadedTrackData, ()>> + Send>>,
},
Ready {
track_id: SpotifyId,
loaded_track: Box<PlayerLoadedTrackData>,
},
}
type Decoder = Box<dyn AudioDecoder + Send>;
enum PlayerState {
Stopped,
Loading {
track_id: SpotifyId,
play_request_id: u64,
start_playback: bool,
loader: Pin<Box<dyn Future<Output = Result<PlayerLoadedTrackData, ()>> + Send>>,
},
Paused {
track_id: SpotifyId,
play_request_id: u64,
decoder: Decoder,
normalisation_factor: f32,
stream_loader_controller: StreamLoaderController,
bytes_per_second: usize,
duration_ms: u32,
stream_position_pcm: u64,
suggested_to_preload_next_track: bool,
},
Playing {
track_id: SpotifyId,
play_request_id: u64,
decoder: Decoder,
normalisation_factor: f32,
stream_loader_controller: StreamLoaderController,
bytes_per_second: usize,
duration_ms: u32,
stream_position_pcm: u64,
reported_nominal_start_time: Option<Instant>,
suggested_to_preload_next_track: bool,
},
EndOfTrack {
track_id: SpotifyId,
play_request_id: u64,
loaded_track: PlayerLoadedTrackData,
},
Invalid,
}
impl PlayerState {
fn is_playing(&self) -> bool {
use self::PlayerState::*;
match *self {
Stopped | EndOfTrack { .. } | Paused { .. } | Loading { .. } => false,
Playing { .. } => true,
Invalid => panic!("invalid state"),
}
}
#[allow(dead_code)]
fn is_stopped(&self) -> bool {
use self::PlayerState::*;
matches!(self, Stopped)
}
fn is_loading(&self) -> bool {
use self::PlayerState::*;
matches!(self, Loading { .. })
}
fn decoder(&mut self) -> Option<&mut Decoder> {
use self::PlayerState::*;
match *self {
Stopped | EndOfTrack { .. } | Loading { .. } => None,
Paused {
ref mut decoder, ..
}
| Playing {
ref mut decoder, ..
} => Some(decoder),
Invalid => panic!("invalid state"),
}
}
fn stream_loader_controller(&mut self) -> Option<&mut StreamLoaderController> {
use self::PlayerState::*;
match *self {
Stopped | EndOfTrack { .. } | Loading { .. } => None,
Paused {
ref mut stream_loader_controller,
..
}
| Playing {
ref mut stream_loader_controller,
..
} => Some(stream_loader_controller),
Invalid => panic!("invalid state"),
}
}
fn playing_to_end_of_track(&mut self) {
use self::PlayerState::*;
match mem::replace(self, Invalid) {
Playing {
track_id,
play_request_id,
decoder,
duration_ms,
bytes_per_second,
normalisation_factor,
stream_loader_controller,
stream_position_pcm,
..
} => {
*self = EndOfTrack {
track_id,
play_request_id,
loaded_track: PlayerLoadedTrackData {
decoder,
duration_ms,
bytes_per_second,
normalisation_factor,
stream_loader_controller,
stream_position_pcm,
},
};
}
_ => panic!("Called playing_to_end_of_track in non-playing state."),
}
}
fn paused_to_playing(&mut self) {
use self::PlayerState::*;
match ::std::mem::replace(self, Invalid) {
Paused {
track_id,
play_request_id,
decoder,
normalisation_factor,
stream_loader_controller,
duration_ms,
bytes_per_second,
stream_position_pcm,
suggested_to_preload_next_track,
} => {
*self = Playing {
track_id,
play_request_id,
decoder,
normalisation_factor,
stream_loader_controller,
duration_ms,
bytes_per_second,
stream_position_pcm,
reported_nominal_start_time: None,
suggested_to_preload_next_track,
};
}
_ => panic!("invalid state"),
}
}
fn playing_to_paused(&mut self) {
use self::PlayerState::*;
match ::std::mem::replace(self, Invalid) {
Playing {
track_id,
play_request_id,
decoder,
normalisation_factor,
stream_loader_controller,
duration_ms,
bytes_per_second,
stream_position_pcm,
reported_nominal_start_time: _,
suggested_to_preload_next_track,
} => {
*self = Paused {
track_id,
play_request_id,
decoder,
normalisation_factor,
stream_loader_controller,
duration_ms,
bytes_per_second,
stream_position_pcm,
suggested_to_preload_next_track,
};
}
_ => panic!("invalid state"),
}
}
}
struct PlayerTrackLoader {
session: Session,
config: PlayerConfig,
}
impl PlayerTrackLoader {
async fn find_available_alternative(&self, audio: AudioItem) -> Option<AudioItem> {
if audio.available {
Some(audio)
} else if let Some(alternatives) = &audio.alternatives {
let alternatives: FuturesUnordered<_> = alternatives
.iter()
.map(|alt_id| AudioItem::get_audio_item(&self.session, *alt_id))
.collect();
alternatives
.filter_map(|x| future::ready(x.ok()))
.filter(|x| future::ready(x.available))
.next()
.await
} else {
None
}
}
fn stream_data_rate(&self, format: FileFormat) -> usize {
match format {
FileFormat::OGG_VORBIS_96 => 12 * 1024,
FileFormat::OGG_VORBIS_160 => 20 * 1024,
FileFormat::OGG_VORBIS_320 => 40 * 1024,
FileFormat::MP3_256 => 32 * 1024,
FileFormat::MP3_320 => 40 * 1024,
FileFormat::MP3_160 => 20 * 1024,
FileFormat::MP3_96 => 12 * 1024,
FileFormat::MP3_160_ENC => 20 * 1024,
FileFormat::MP4_128_DUAL => 16 * 1024,
FileFormat::OTHER3 => 40 * 1024, // better some high guess than nothing
FileFormat::AAC_160 => 20 * 1024,
FileFormat::AAC_320 => 40 * 1024,
FileFormat::MP4_128 => 16 * 1024,
FileFormat::OTHER5 => 40 * 1024, // better some high guess than nothing
}
}
async fn load_track(
&self,
spotify_id: SpotifyId,
position_ms: u32,
) -> Option<PlayerLoadedTrackData> {
let audio = match AudioItem::get_audio_item(&self.session, spotify_id).await {
Ok(audio) => audio,
Err(_) => {
error!("Unable to load audio item.");
return None;
}
};
info!("Loading <{}> with Spotify URI <{}>", audio.name, audio.uri);
let audio = match self.find_available_alternative(audio).await {
Some(audio) => audio,
None => {
warn!("<{}> is not available", spotify_id.to_uri());
return None;
}
};
assert!(audio.duration >= 0);
let duration_ms = audio.duration as u32;
// (Most) podcasts seem to support only 96 bit Vorbis, so fall back to it
let formats = match self.config.bitrate {
Bitrate::Bitrate96 => [
FileFormat::OGG_VORBIS_96,
FileFormat::OGG_VORBIS_160,
FileFormat::OGG_VORBIS_320,
],
Bitrate::Bitrate160 => [
FileFormat::OGG_VORBIS_160,
FileFormat::OGG_VORBIS_96,
FileFormat::OGG_VORBIS_320,
],
Bitrate::Bitrate320 => [
FileFormat::OGG_VORBIS_320,
FileFormat::OGG_VORBIS_160,
FileFormat::OGG_VORBIS_96,
],
};
let entry = formats.iter().find_map(|format| {
if let Some(&file_id) = audio.files.get(format) {
Some((*format, file_id))
} else {
None
}
});
let (format, file_id) = match entry {
Some(t) => t,
None => {
warn!("<{}> is not available in any supported format", audio.name);
return None;
}
};
let bytes_per_second = self.stream_data_rate(format);
let play_from_beginning = position_ms == 0;
// This is only a loop to be able to reload the file if an error occured
// while opening a cached file.
loop {
let encrypted_file = AudioFile::open(
&self.session,
file_id,
bytes_per_second,
play_from_beginning,
);
let encrypted_file = match encrypted_file.await {
Ok(encrypted_file) => encrypted_file,
Err(_) => {
error!("Unable to load encrypted file.");
return None;
}
};
let is_cached = encrypted_file.is_cached();
let stream_loader_controller = encrypted_file.get_stream_loader_controller();
if play_from_beginning {
// No need to seek -> we stream from the beginning
stream_loader_controller.set_stream_mode();
} else {
// we need to seek -> we set stream mode after the initial seek.
stream_loader_controller.set_random_access_mode();
}
let key = match self.session.audio_key().request(spotify_id, file_id).await {
Ok(key) => key,
Err(_) => {
error!("Unable to load decryption key");
return None;
}
};
let mut decrypted_file = AudioDecrypt::new(key, encrypted_file);
let normalisation_factor = match NormalisationData::parse_from_file(&mut decrypted_file)
{
Ok(normalisation_data) => {
NormalisationData::get_factor(&self.config, normalisation_data)
}
Err(_) => {
warn!("Unable to extract normalisation data, using default value.");
1.0_f32
}
};
let audio_file = Subfile::new(decrypted_file, 0xa7);
let result = if self.config.passthrough {
match PassthroughDecoder::new(audio_file) {
Ok(result) => Ok(Box::new(result) as Decoder),
Err(e) => Err(AudioError::PassthroughError(e)),
}
} else {
match VorbisDecoder::new(audio_file) {
Ok(result) => Ok(Box::new(result) as Decoder),
Err(e) => Err(AudioError::VorbisError(e)),
}
};
let mut decoder = match result {
Ok(decoder) => decoder,
Err(e) if is_cached => {
warn!(
"Unable to read cached audio file: {}. Trying to download it.",
e
);
// unwrap safety: The file is cached, so session must have a cache
if !self.session.cache().unwrap().remove_file(file_id) {
return None;
}
// Just try it again
continue;
}
Err(e) => {
error!("Unable to read audio file: {}", e);
return None;
}
};
if position_ms != 0 {
if let Err(err) = decoder.seek(position_ms as i64) {
error!("Vorbis error: {}", err);
}
stream_loader_controller.set_stream_mode();
}
let stream_position_pcm = PlayerInternal::position_ms_to_pcm(position_ms);
info!("<{}> ({} ms) loaded", audio.name, audio.duration);
return Some(PlayerLoadedTrackData {
decoder,
normalisation_factor,
stream_loader_controller,
bytes_per_second,
duration_ms,
stream_position_pcm,
});
}
}
}
impl Future for PlayerInternal {
type Output = ();
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
// While this is written as a future, it still contains blocking code.
// It must be run on its own thread.
let passthrough = self.config.passthrough;
loop {
let mut all_futures_completed_or_not_ready = true;
// process commands that were sent to us
let cmd = match self.commands.poll_recv(cx) {
Poll::Ready(None) => return Poll::Ready(()), // client has disconnected - shut down.
Poll::Ready(Some(cmd)) => {
all_futures_completed_or_not_ready = false;
Some(cmd)
}
_ => None,
};
if let Some(cmd) = cmd {
self.handle_command(cmd);
}
// Handle loading of a new track to play
if let PlayerState::Loading {
ref mut loader,
track_id,
start_playback,
play_request_id,
} = self.state
{
match loader.as_mut().poll(cx) {
Poll::Ready(Ok(loaded_track)) => {
self.start_playback(
track_id,
play_request_id,
loaded_track,
start_playback,
);
if let PlayerState::Loading { .. } = self.state {
panic!("The state wasn't changed by start_playback()");
}
}
Poll::Ready(Err(_)) => {
warn!("Unable to load <{:?}>\nSkipping to next track", track_id);
assert!(self.state.is_loading());
self.send_event(PlayerEvent::EndOfTrack {
track_id,
play_request_id,
})
}
Poll::Pending => (),
}
}
// handle pending preload requests.
if let PlayerPreload::Loading {
ref mut loader,
track_id,
} = self.preload
{
match loader.as_mut().poll(cx) {
Poll::Ready(Ok(loaded_track)) => {
self.send_event(PlayerEvent::Preloading { track_id });
self.preload = PlayerPreload::Ready {
track_id,
loaded_track: Box::new(loaded_track),
};
}
Poll::Ready(Err(_)) => {
debug!("Unable to preload {:?}", track_id);
self.preload = PlayerPreload::None;
// Let Spirc know that the track was unavailable.
if let PlayerState::Playing {
play_request_id, ..
}
| PlayerState::Paused {
play_request_id, ..
} = self.state
{
self.send_event(PlayerEvent::Unavailable {
track_id,
play_request_id,
});
}
}
Poll::Pending => (),
}
}
if self.state.is_playing() {
self.ensure_sink_running();
if let PlayerState::Playing {
track_id,
play_request_id,
ref mut decoder,
normalisation_factor,
ref mut stream_position_pcm,
ref mut reported_nominal_start_time,
duration_ms,
..
} = self.state
{
let packet = decoder.next_packet().expect("Vorbis error");
if !passthrough {
if let Some(ref packet) = packet {
*stream_position_pcm +=
(packet.samples().len() / NUM_CHANNELS as usize) as u64;
let stream_position_millis =
Self::position_pcm_to_ms(*stream_position_pcm);
let notify_about_position = match *reported_nominal_start_time {
None => true,
Some(reported_nominal_start_time) => {
// only notify if we're behind. If we're ahead it's probably due to a buffer of the backend and we;re actually in time.
let lag = (Instant::now() - reported_nominal_start_time)
.as_millis()
as i64
- stream_position_millis as i64;
lag > 1000
}
};
if notify_about_position {
*reported_nominal_start_time = Some(
Instant::now()
- Duration::from_millis(stream_position_millis as u64),
);
self.send_event(PlayerEvent::Playing {
track_id,
play_request_id,
position_ms: stream_position_millis as u32,
duration_ms,
});
}
}
} else {
// position, even if irrelevant, must be set so that seek() is called
*stream_position_pcm = duration_ms.into();
}
self.handle_packet(packet, normalisation_factor);
} else {
unreachable!();
};
}
if let PlayerState::Playing {
track_id,
play_request_id,
duration_ms,
stream_position_pcm,
ref mut stream_loader_controller,
ref mut suggested_to_preload_next_track,
..
}
| PlayerState::Paused {
track_id,
play_request_id,
duration_ms,
stream_position_pcm,
ref mut stream_loader_controller,
ref mut suggested_to_preload_next_track,
..
} = self.state
{
if (!*suggested_to_preload_next_track)
&& ((duration_ms as i64 - Self::position_pcm_to_ms(stream_position_pcm) as i64)
< PRELOAD_NEXT_TRACK_BEFORE_END_DURATION_MS as i64)
&& stream_loader_controller.range_to_end_available()
{
*suggested_to_preload_next_track = true;
self.send_event(PlayerEvent::TimeToPreloadNextTrack {
track_id,
play_request_id,
});
}
}
if self.session.is_invalid() {
return Poll::Ready(());
}
if (!self.state.is_playing()) && all_futures_completed_or_not_ready {
return Poll::Pending;
}
}
}
}
impl PlayerInternal {
fn position_pcm_to_ms(position_pcm: u64) -> u32 {
(position_pcm * 10 / 441) as u32
}
fn position_ms_to_pcm(position_ms: u32) -> u64 {
position_ms as u64 * 441 / 10
}
fn ensure_sink_running(&mut self) {
if self.sink_status != SinkStatus::Running {
trace!("== Starting sink ==");
if let Some(callback) = &mut self.sink_event_callback {
callback(SinkStatus::Running);
}
match self.sink.start() {
Ok(()) => self.sink_status = SinkStatus::Running,
Err(err) => error!("Could not start audio: {}", err),
}
}
}
fn ensure_sink_stopped(&mut self, temporarily: bool) {
match self.sink_status {
SinkStatus::Running => {
trace!("== Stopping sink ==");
self.sink.stop().unwrap();
self.sink_status = if temporarily {
SinkStatus::TemporarilyClosed
} else {
SinkStatus::Closed
};
if let Some(callback) = &mut self.sink_event_callback {
callback(self.sink_status);
}
}
SinkStatus::TemporarilyClosed => {
if !temporarily {
self.sink_status = SinkStatus::Closed;
if let Some(callback) = &mut self.sink_event_callback {
callback(SinkStatus::Closed);
}
}
}
SinkStatus::Closed => (),
}
}
fn handle_player_stop(&mut self) {
match self.state {
PlayerState::Playing {
track_id,
play_request_id,
..
}
| PlayerState::Paused {
track_id,
play_request_id,
..
}
| PlayerState::EndOfTrack {
track_id,
play_request_id,
..
}
| PlayerState::Loading {
track_id,
play_request_id,
..
} => {
self.ensure_sink_stopped(false);
self.send_event(PlayerEvent::Stopped {
track_id,
play_request_id,
});
self.state = PlayerState::Stopped;
}
PlayerState::Stopped => (),
PlayerState::Invalid => panic!("invalid state"),
}
}
fn handle_play(&mut self) {
if let PlayerState::Paused {
track_id,
play_request_id,
stream_position_pcm,
duration_ms,
..
} = self.state
{
self.state.paused_to_playing();
let position_ms = Self::position_pcm_to_ms(stream_position_pcm);
self.send_event(PlayerEvent::Playing {
track_id,
play_request_id,
position_ms,
duration_ms,
});
self.ensure_sink_running();
} else {
warn!("Player::play called from invalid state");
}
}
fn handle_pause(&mut self) {
if let PlayerState::Playing {
track_id,
play_request_id,
stream_position_pcm,
duration_ms,
..
} = self.state
{
self.state.playing_to_paused();
self.ensure_sink_stopped(false);
let position_ms = Self::position_pcm_to_ms(stream_position_pcm);
self.send_event(PlayerEvent::Paused {
track_id,
play_request_id,
position_ms,
duration_ms,
});
} else {
warn!("Player::pause called from invalid state");
}
}
fn handle_packet(&mut self, packet: Option<AudioPacket>, normalisation_factor: f32) {
match packet {
Some(mut packet) => {
if !packet.is_empty() {
if let AudioPacket::Samples(ref mut data) = packet {
if let Some(ref editor) = self.audio_filter {
editor.modify_stream(data)
}
if self.config.normalisation
&& (f32::abs(normalisation_factor - 1.0) < f32::EPSILON
|| self.config.normalisation_method != NormalisationMethod::Basic)
{
for sample in data.iter_mut() {
let mut actual_normalisation_factor = normalisation_factor;
if self.config.normalisation_method == NormalisationMethod::Dynamic
{
if self.limiter_active {
// "S"-shaped curve with a configurable knee during attack and release:
// - > 1.0 yields soft knees at start and end, steeper in between
// - 1.0 yields a linear function from 0-100%
// - between 0.0 and 1.0 yields hard knees at start and end, flatter in between
// - 0.0 yields a step response to 50%, causing distortion
// - Rates < 0.0 invert the limiter and are invalid
let mut shaped_limiter_strength = self.limiter_strength;
if shaped_limiter_strength > 0.0
&& shaped_limiter_strength < 1.0
{
shaped_limiter_strength = 1.0
/ (1.0
+ f32::powf(
shaped_limiter_strength
/ (1.0 - shaped_limiter_strength),
-1.0 * self.config.normalisation_knee,
));
}
actual_normalisation_factor =
(1.0 - shaped_limiter_strength) * normalisation_factor
+ shaped_limiter_strength * self.limiter_factor;
};
// Always check for peaks, even when the limiter is already active.
// There may be even higher peaks than we initially targeted.
// Check against the normalisation factor that would be applied normally.
let abs_sample =
((*sample as f64 * normalisation_factor as f64) as f32)
.abs();
if abs_sample > self.config.normalisation_threshold {
self.limiter_active = true;
if self.limiter_release_counter > 0 {
// A peak was encountered while releasing the limiter;
// synchronize with the current release limiter strength.
self.limiter_attack_counter = (((SAMPLES_PER_SECOND
as f32
* self.config.normalisation_release)
- self.limiter_release_counter as f32)
/ (self.config.normalisation_release
/ self.config.normalisation_attack))
as u32;
self.limiter_release_counter = 0;
}
self.limiter_attack_counter =
self.limiter_attack_counter.saturating_add(1);
self.limiter_strength = self.limiter_attack_counter as f32
/ (SAMPLES_PER_SECOND as f32
* self.config.normalisation_attack);
if abs_sample > self.limiter_peak_sample {
self.limiter_peak_sample = abs_sample;
self.limiter_factor =
self.config.normalisation_threshold
/ self.limiter_peak_sample;
}
} else if self.limiter_active {
if self.limiter_attack_counter > 0 {
// Release may start within the attack period, before
// the limiter reached full strength. For that reason
// start the release by synchronizing with the current
// attack limiter strength.
self.limiter_release_counter = (((SAMPLES_PER_SECOND
as f32
* self.config.normalisation_attack)
- self.limiter_attack_counter as f32)
* (self.config.normalisation_release
/ self.config.normalisation_attack))
as u32;
self.limiter_attack_counter = 0;
}
self.limiter_release_counter =
self.limiter_release_counter.saturating_add(1);
if self.limiter_release_counter
> (SAMPLES_PER_SECOND as f32
* self.config.normalisation_release)
as u32
{
self.reset_limiter();
} else {
self.limiter_strength = ((SAMPLES_PER_SECOND as f32
* self.config.normalisation_release)
- self.limiter_release_counter as f32)
/ (SAMPLES_PER_SECOND as f32
* self.config.normalisation_release);
}
}
}
*sample =
(*sample as f64 * actual_normalisation_factor as f64) as f32;
// Extremely sharp attacks, however unlikely, *may* still clip and provide
// undefined results, so strictly enforce output within [-1.0, 1.0].
if *sample < -1.0 {
*sample = -1.0;
} else if *sample > 1.0 {
*sample = 1.0;
}
}
}
}
if let Err(err) = self.sink.write(&packet) {
error!("Could not write audio: {}", err);
self.ensure_sink_stopped(false);
}
}
}
None => {
self.state.playing_to_end_of_track();
if let PlayerState::EndOfTrack {
track_id,
play_request_id,
..
} = self.state
{
self.send_event(PlayerEvent::EndOfTrack {
track_id,
play_request_id,
})
} else {
unreachable!();
}
}
}
}
fn reset_limiter(&mut self) {
self.limiter_active = false;
self.limiter_release_counter = 0;
self.limiter_attack_counter = 0;
self.limiter_peak_sample = 0.0;
self.limiter_factor = 1.0;
self.limiter_strength = 0.0;
}
fn start_playback(
&mut self,
track_id: SpotifyId,
play_request_id: u64,
loaded_track: PlayerLoadedTrackData,
start_playback: bool,
) {
let position_ms = Self::position_pcm_to_ms(loaded_track.stream_position_pcm);
if start_playback {
self.ensure_sink_running();
self.send_event(PlayerEvent::Playing {
track_id,
play_request_id,
position_ms,
duration_ms: loaded_track.duration_ms,
});
self.state = PlayerState::Playing {
track_id,
play_request_id,
decoder: loaded_track.decoder,
normalisation_factor: loaded_track.normalisation_factor,
stream_loader_controller: loaded_track.stream_loader_controller,
duration_ms: loaded_track.duration_ms,
bytes_per_second: loaded_track.bytes_per_second,
stream_position_pcm: loaded_track.stream_position_pcm,
reported_nominal_start_time: Some(
Instant::now() - Duration::from_millis(position_ms as u64),
),
suggested_to_preload_next_track: false,
};
} else {
self.ensure_sink_stopped(false);
self.state = PlayerState::Paused {
track_id,
play_request_id,
decoder: loaded_track.decoder,
normalisation_factor: loaded_track.normalisation_factor,
stream_loader_controller: loaded_track.stream_loader_controller,
duration_ms: loaded_track.duration_ms,
bytes_per_second: loaded_track.bytes_per_second,
stream_position_pcm: loaded_track.stream_position_pcm,
suggested_to_preload_next_track: false,
};
self.send_event(PlayerEvent::Paused {
track_id,
play_request_id,
position_ms,
duration_ms: loaded_track.duration_ms,
});
}
}
fn handle_command_load(
&mut self,
track_id: SpotifyId,
play_request_id: u64,
play: bool,
position_ms: u32,
) {
if !self.config.gapless {
self.ensure_sink_stopped(play);
}
// emit the correct player event
match self.state {
PlayerState::Playing {
track_id: old_track_id,
..
}
| PlayerState::Paused {
track_id: old_track_id,
..
}
| PlayerState::EndOfTrack {
track_id: old_track_id,
..
}
| PlayerState::Loading {
track_id: old_track_id,
..
} => self.send_event(PlayerEvent::Changed {
old_track_id,
new_track_id: track_id,
}),
PlayerState::Stopped => self.send_event(PlayerEvent::Started {
track_id,
play_request_id,
position_ms,
}),
PlayerState::Invalid { .. } => panic!("Player is in an invalid state."),
}
// Now we check at different positions whether we already have a pre-loaded version
// of this track somewhere. If so, use it and return.
// Check if there's a matching loaded track in the EndOfTrack player state.
// This is the case if we're repeating the same track again.
if let PlayerState::EndOfTrack {
track_id: previous_track_id,
..
} = self.state
{
if previous_track_id == track_id {
let mut loaded_track = match mem::replace(&mut self.state, PlayerState::Invalid) {
PlayerState::EndOfTrack { loaded_track, .. } => loaded_track,
_ => unreachable!(),
};
if Self::position_ms_to_pcm(position_ms) != loaded_track.stream_position_pcm {
loaded_track
.stream_loader_controller
.set_random_access_mode();
let _ = loaded_track.decoder.seek(position_ms as i64); // This may be blocking.
// But most likely the track is fully
// loaded already because we played
// to the end of it.
loaded_track.stream_loader_controller.set_stream_mode();
loaded_track.stream_position_pcm = Self::position_ms_to_pcm(position_ms);
}
self.preload = PlayerPreload::None;
self.start_playback(track_id, play_request_id, loaded_track, play);
if let PlayerState::Invalid = self.state {
panic!("start_playback() hasn't set a valid player state.");
}
return;
}
}
// Check if we are already playing the track. If so, just do a seek and update our info.
if let PlayerState::Playing {
track_id: current_track_id,
ref mut stream_position_pcm,
ref mut decoder,
ref mut stream_loader_controller,
..
}
| PlayerState::Paused {
track_id: current_track_id,
ref mut stream_position_pcm,
ref mut decoder,
ref mut stream_loader_controller,
..
} = self.state
{
if current_track_id == track_id {
// we can use the current decoder. Ensure it's at the correct position.
if Self::position_ms_to_pcm(position_ms) != *stream_position_pcm {
stream_loader_controller.set_random_access_mode();
let _ = decoder.seek(position_ms as i64); // This may be blocking.
stream_loader_controller.set_stream_mode();
*stream_position_pcm = Self::position_ms_to_pcm(position_ms);
}
// Move the info from the current state into a PlayerLoadedTrackData so we can use
// the usual code path to start playback.
let old_state = mem::replace(&mut self.state, PlayerState::Invalid);
if let PlayerState::Playing {
stream_position_pcm,
decoder,
stream_loader_controller,
bytes_per_second,
duration_ms,
normalisation_factor,
..
}
| PlayerState::Paused {
stream_position_pcm,
decoder,
stream_loader_controller,
bytes_per_second,
duration_ms,
normalisation_factor,
..
} = old_state
{
let loaded_track = PlayerLoadedTrackData {
decoder,
normalisation_factor,
stream_loader_controller,
bytes_per_second,
duration_ms,
stream_position_pcm,
};
self.preload = PlayerPreload::None;
self.start_playback(track_id, play_request_id, loaded_track, play);
if let PlayerState::Invalid = self.state {
panic!("start_playback() hasn't set a valid player state.");
}
return;
} else {
unreachable!();
}
}
}
// Check if the requested track has been preloaded already. If so use the preloaded data.
if let PlayerPreload::Ready {
track_id: loaded_track_id,
..
} = self.preload
{
if track_id == loaded_track_id {
let preload = std::mem::replace(&mut self.preload, PlayerPreload::None);
if let PlayerPreload::Ready {
track_id,
mut loaded_track,
} = preload
{
if Self::position_ms_to_pcm(position_ms) != loaded_track.stream_position_pcm {
loaded_track
.stream_loader_controller
.set_random_access_mode();
let _ = loaded_track.decoder.seek(position_ms as i64); // This may be blocking
loaded_track.stream_loader_controller.set_stream_mode();
}
self.start_playback(track_id, play_request_id, *loaded_track, play);
return;
} else {
unreachable!();
}
}
}
// We need to load the track - either from scratch or by completing a preload.
// In any case we go into a Loading state to load the track.
self.ensure_sink_stopped(play);
self.send_event(PlayerEvent::Loading {
track_id,
play_request_id,
position_ms,
});
// Try to extract a pending loader from the preloading mechanism
let loader = if let PlayerPreload::Loading {
track_id: loaded_track_id,
..
} = self.preload
{
if (track_id == loaded_track_id) && (position_ms == 0) {
let mut preload = PlayerPreload::None;
std::mem::swap(&mut preload, &mut self.preload);
if let PlayerPreload::Loading { loader, .. } = preload {
Some(loader)
} else {
None
}
} else {
None
}
} else {
None
};
self.preload = PlayerPreload::None;
// If we don't have a loader yet, create one from scratch.
let loader = loader.unwrap_or_else(|| Box::pin(self.load_track(track_id, position_ms)));
// Set ourselves to a loading state.
self.state = PlayerState::Loading {
track_id,
play_request_id,
start_playback: play,
loader,
};
}
fn handle_command_preload(&mut self, track_id: SpotifyId) {
debug!("Preloading track");
let mut preload_track = true;
// check whether the track is already loaded somewhere or being loaded.
if let PlayerPreload::Loading {
track_id: currently_loading,
..
}
| PlayerPreload::Ready {
track_id: currently_loading,
..
} = self.preload
{
if currently_loading == track_id {
// we're already preloading the requested track.
preload_track = false;
} else {
// we're preloading something else - cancel it.
self.preload = PlayerPreload::None;
}
}
if let PlayerState::Playing {
track_id: current_track_id,
..
}
| PlayerState::Paused {
track_id: current_track_id,
..
}
| PlayerState::EndOfTrack {
track_id: current_track_id,
..
} = self.state
{
if current_track_id == track_id {
// we already have the requested track loaded.
preload_track = false;
}
}
// schedule the preload of the current track if desired.
if preload_track {
let loader = self.load_track(track_id, 0);
self.preload = PlayerPreload::Loading {
track_id,
loader: Box::pin(loader),
}
}
}
fn handle_command_seek(&mut self, position_ms: u32) {
if let Some(stream_loader_controller) = self.state.stream_loader_controller() {
stream_loader_controller.set_random_access_mode();
}
if let Some(decoder) = self.state.decoder() {
match decoder.seek(position_ms as i64) {
Ok(_) => {
if let PlayerState::Playing {
ref mut stream_position_pcm,
..
}
| PlayerState::Paused {
ref mut stream_position_pcm,
..
} = self.state
{
*stream_position_pcm = Self::position_ms_to_pcm(position_ms);
}
}
Err(err) => error!("Vorbis error: {:?}", err),
}
} else {
warn!("Player::seek called from invalid state");
}
// If we're playing, ensure, that we have enough data leaded to avoid a buffer underrun.
if let Some(stream_loader_controller) = self.state.stream_loader_controller() {
stream_loader_controller.set_stream_mode();
}
// ensure we have a bit of a buffer of downloaded data
self.preload_data_before_playback();
if let PlayerState::Playing {
track_id,
play_request_id,
ref mut reported_nominal_start_time,
duration_ms,
..
} = self.state
{
*reported_nominal_start_time =
Some(Instant::now() - Duration::from_millis(position_ms as u64));
self.send_event(PlayerEvent::Playing {
track_id,
play_request_id,
position_ms,
duration_ms,
});
}
if let PlayerState::Paused {
track_id,
play_request_id,
duration_ms,
..
} = self.state
{
self.send_event(PlayerEvent::Paused {
track_id,
play_request_id,
position_ms,
duration_ms,
});
}
}
fn handle_command(&mut self, cmd: PlayerCommand) {
debug!("command={:?}", cmd);
match cmd {
PlayerCommand::Load {
track_id,
play_request_id,
play,
position_ms,
} => self.handle_command_load(track_id, play_request_id, play, position_ms),
PlayerCommand::Preload { track_id } => self.handle_command_preload(track_id),
PlayerCommand::Seek(position_ms) => self.handle_command_seek(position_ms),
PlayerCommand::Play => self.handle_play(),
PlayerCommand::Pause => self.handle_pause(),
PlayerCommand::Stop => self.handle_player_stop(),
PlayerCommand::AddEventSender(sender) => self.event_senders.push(sender),
PlayerCommand::SetSinkEventCallback(callback) => self.sink_event_callback = callback,
PlayerCommand::EmitVolumeSetEvent(volume) => {
self.send_event(PlayerEvent::VolumeSet { volume })
}
}
}
fn send_event(&mut self, event: PlayerEvent) {
let mut index = 0;
while index < self.event_senders.len() {
match self.event_senders[index].send(event.clone()) {
Ok(_) => index += 1,
Err(_) => {
self.event_senders.remove(index);
}
}
}
}
fn load_track(
&self,
spotify_id: SpotifyId,
position_ms: u32,
) -> impl Future<Output = Result<PlayerLoadedTrackData, ()>> + Send + 'static {
// This method creates a future that returns the loaded stream and associated info.
// Ideally all work should be done using asynchronous code. However, seek() on the
// audio stream is implemented in a blocking fashion. Thus, we can't turn it into future
// easily. Instead we spawn a thread to do the work and return a one-shot channel as the
// future to work with.
let loader = PlayerTrackLoader {
session: self.session.clone(),
config: self.config.clone(),
};
let (result_tx, result_rx) = oneshot::channel();
std::thread::spawn(move || {
let data = futures_executor::block_on(loader.load_track(spotify_id, position_ms));
if let Some(data) = data {
let _ = result_tx.send(data);
}
});
result_rx.map_err(|_| ())
}
fn preload_data_before_playback(&mut self) {
if let PlayerState::Playing {
bytes_per_second,
ref mut stream_loader_controller,
..
} = self.state
{
// Request our read ahead range
let request_data_length = max(
(READ_AHEAD_DURING_PLAYBACK_ROUNDTRIPS
* (0.001 * stream_loader_controller.ping_time_ms() as f64)
* bytes_per_second as f64) as usize,
(READ_AHEAD_DURING_PLAYBACK_SECONDS * bytes_per_second as f64) as usize,
);
stream_loader_controller.fetch_next(request_data_length);
// Request the part we want to wait for blocking. This effecively means we wait for the previous request to partially complete.
let wait_for_data_length = max(
(READ_AHEAD_BEFORE_PLAYBACK_ROUNDTRIPS
* (0.001 * stream_loader_controller.ping_time_ms() as f64)
* bytes_per_second as f64) as usize,
(READ_AHEAD_BEFORE_PLAYBACK_SECONDS * bytes_per_second as f64) as usize,
);
stream_loader_controller.fetch_next_blocking(wait_for_data_length);
}
}
}
impl Drop for PlayerInternal {
fn drop(&mut self) {
debug!("drop PlayerInternal[{}]", self.session.session_id());
}
}
impl ::std::fmt::Debug for PlayerCommand {
fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
match *self {
PlayerCommand::Load {
track_id,
play,
position_ms,
..
} => f
.debug_tuple("Load")
.field(&track_id)
.field(&play)
.field(&position_ms)
.finish(),
PlayerCommand::Preload { track_id } => {
f.debug_tuple("Preload").field(&track_id).finish()
}
PlayerCommand::Play => f.debug_tuple("Play").finish(),
PlayerCommand::Pause => f.debug_tuple("Pause").finish(),
PlayerCommand::Stop => f.debug_tuple("Stop").finish(),
PlayerCommand::Seek(position) => f.debug_tuple("Seek").field(&position).finish(),
PlayerCommand::AddEventSender(_) => f.debug_tuple("AddEventSender").finish(),
PlayerCommand::SetSinkEventCallback(_) => {
f.debug_tuple("SetSinkEventCallback").finish()
}
PlayerCommand::EmitVolumeSetEvent(volume) => {
f.debug_tuple("VolumeSet").field(&volume).finish()
}
}
}
}
impl ::std::fmt::Debug for PlayerState {
fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
use PlayerState::*;
match *self {
Stopped => f.debug_struct("Stopped").finish(),
Loading {
track_id,
play_request_id,
..
} => f
.debug_struct("Loading")
.field("track_id", &track_id)
.field("play_request_id", &play_request_id)
.finish(),
Paused {
track_id,
play_request_id,
..
} => f
.debug_struct("Paused")
.field("track_id", &track_id)
.field("play_request_id", &play_request_id)
.finish(),
Playing {
track_id,
play_request_id,
..
} => f
.debug_struct("Playing")
.field("track_id", &track_id)
.field("play_request_id", &play_request_id)
.finish(),
EndOfTrack {
track_id,
play_request_id,
..
} => f
.debug_struct("EndOfTrack")
.field("track_id", &track_id)
.field("play_request_id", &play_request_id)
.finish(),
Invalid => f.debug_struct("Invalid").finish(),
}
}
}
struct Subfile<T: Read + Seek> {
stream: T,
offset: u64,
}
impl<T: Read + Seek> Subfile<T> {
pub fn new(mut stream: T, offset: u64) -> Subfile<T> {
stream.seek(SeekFrom::Start(offset)).unwrap();
Subfile { stream, offset }
}
}
impl<T: Read + Seek> Read for Subfile<T> {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
self.stream.read(buf)
}
}
impl<T: Read + Seek> Seek for Subfile<T> {
fn seek(&mut self, mut pos: SeekFrom) -> io::Result<u64> {
pos = match pos {
SeekFrom::Start(offset) => SeekFrom::Start(offset + self.offset),
x => x,
};
let newpos = self.stream.seek(pos)?;
if newpos > self.offset {
Ok(newpos - self.offset)
} else {
Ok(0)
}
}
}