subsonic-tui/vendor/github.com/ebitengine/oto/v3/internal/mux/mux.go
Sagi Dayan 26e526f07e
initial commit
Signed-off-by: Sagi Dayan <sagidayan@gmail.com>
2024-02-20 19:10:14 +02:00

560 lines
10 KiB
Go

// Copyright 2021 The Oto Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package mux offers APIs for a low-level multiplexer of audio players.
// Usually you don't have to use this.
package mux
import (
"errors"
"fmt"
"io"
"math"
"runtime"
"sync"
"time"
)
// Format must sync with oto's Format.
type Format int
const (
FormatFloat32LE Format = iota
FormatUnsignedInt8
FormatSignedInt16LE
)
func (f Format) ByteLength() int {
switch f {
case FormatFloat32LE:
return 4
case FormatUnsignedInt8:
return 1
case FormatSignedInt16LE:
return 2
}
panic(fmt.Sprintf("mux: unexpected format: %d", f))
}
// Mux is a low-level multiplexer of audio players.
type Mux struct {
sampleRate int
channelCount int
format Format
players map[*playerImpl]struct{}
buf []float32
cond *sync.Cond
}
// New creates a new Mux.
func New(sampleRate int, channelCount int, format Format) *Mux {
m := &Mux{
sampleRate: sampleRate,
channelCount: channelCount,
format: format,
cond: sync.NewCond(&sync.Mutex{}),
}
go m.loop()
return m
}
func (m *Mux) shouldWait() bool {
for p := range m.players {
if p.canReadSourceToBuffer() {
return false
}
}
return true
}
func (m *Mux) wait() {
m.cond.L.Lock()
defer m.cond.L.Unlock()
for m.shouldWait() {
m.cond.Wait()
}
}
func (m *Mux) loop() {
var players []*playerImpl
for {
m.wait()
m.cond.L.Lock()
for i := range players {
players[i] = nil
}
players = players[:0]
for p := range m.players {
players = append(players, p)
}
m.cond.L.Unlock()
allZero := true
for _, p := range players {
n := p.readSourceToBuffer()
if n != 0 {
allZero = false
}
}
// Sleeping is necessary especially on browsers.
// Sometimes a player continues to read 0 bytes from the source and this loop can be a busy loop in such case.
if allZero {
time.Sleep(time.Millisecond)
}
}
}
func (m *Mux) addPlayer(player *playerImpl) {
m.cond.L.Lock()
defer m.cond.L.Unlock()
if m.players == nil {
m.players = map[*playerImpl]struct{}{}
}
m.players[player] = struct{}{}
m.cond.Signal()
}
func (m *Mux) removePlayer(player *playerImpl) {
m.cond.L.Lock()
defer m.cond.L.Unlock()
delete(m.players, player)
m.cond.Signal()
}
// ReadFloat32s fills buf with the multiplexed data of the players as float32 values.
func (m *Mux) ReadFloat32s(buf []float32) {
m.cond.L.Lock()
players := make([]*playerImpl, 0, len(m.players))
for p := range m.players {
players = append(players, p)
}
m.cond.L.Unlock()
for i := range buf {
buf[i] = 0
}
for _, p := range players {
p.readBufferAndAdd(buf)
}
m.cond.Signal()
}
type Player struct {
p *playerImpl
}
type playerState int
const (
playerPaused playerState = iota
playerPlay
playerClosed
)
type playerImpl struct {
mux *Mux
src io.Reader
prevVolume float64
volume float64
err error
state playerState
tmpbuf []byte
buf []byte
eof bool
bufferSize int
m sync.Mutex
}
func (m *Mux) NewPlayer(src io.Reader) *Player {
pl := &Player{
p: &playerImpl{
mux: m,
src: src,
prevVolume: 1,
volume: 1,
bufferSize: m.defaultBufferSize(),
},
}
runtime.SetFinalizer(pl, (*Player).Close)
return pl
}
func (p *Player) Err() error {
return p.p.Err()
}
func (p *playerImpl) Err() error {
p.m.Lock()
defer p.m.Unlock()
return p.err
}
func (p *Player) Play() {
p.p.Play()
}
func (p *playerImpl) Play() {
// Goroutines don't work effiently on Windows. Avoid using them (hajimehoshi/ebiten#1768).
if runtime.GOOS == "windows" {
p.m.Lock()
defer p.m.Unlock()
p.playImpl()
} else {
ch := make(chan struct{})
go func() {
p.m.Lock()
defer p.m.Unlock()
close(ch)
p.playImpl()
}()
<-ch
}
}
func (p *Player) SetBufferSize(bufferSize int) {
p.p.setBufferSize(bufferSize)
}
func (p *playerImpl) setBufferSize(bufferSize int) {
p.m.Lock()
defer p.m.Unlock()
orig := p.bufferSize
p.bufferSize = bufferSize
if bufferSize == 0 {
p.bufferSize = p.mux.defaultBufferSize()
}
if orig != p.bufferSize {
p.tmpbuf = nil
}
}
func (p *playerImpl) ensureTmpBuf() []byte {
if p.tmpbuf == nil {
p.tmpbuf = make([]byte, p.bufferSize)
}
return p.tmpbuf
}
// read reads the source to buf.
// read unlocks the mutex temporarily and locks when reading finishes.
// This avoids locking during an external function call Read (#188).
//
// When read is called, the mutex m must be locked.
func (p *playerImpl) read(buf []byte) (int, error) {
p.m.Unlock()
defer p.m.Lock()
return p.src.Read(buf)
}
// addToPlayers adds p to the players set.
//
// When addToPlayers is called, the mutex m must be locked.
func (p *playerImpl) addToPlayers() {
p.m.Unlock()
defer p.m.Lock()
p.mux.addPlayer(p)
}
// removeFromPlayers removes p from the players set.
//
// When removeFromPlayers is called, the mutex m must be locked.
func (p *playerImpl) removeFromPlayers() {
p.m.Unlock()
defer p.m.Lock()
p.mux.removePlayer(p)
}
func (p *playerImpl) playImpl() {
if p.err != nil {
return
}
if p.state != playerPaused {
return
}
p.state = playerPlay
if !p.eof {
buf := p.ensureTmpBuf()
for len(p.buf) < p.bufferSize {
n, err := p.read(buf)
if err != nil && err != io.EOF {
p.setErrorImpl(err)
return
}
p.buf = append(p.buf, buf[:n]...)
if err == io.EOF {
p.eof = true
break
}
}
}
if p.eof && len(p.buf) == 0 {
p.state = playerPaused
}
p.addToPlayers()
}
func (p *Player) Pause() {
p.p.Pause()
}
func (p *playerImpl) Pause() {
p.m.Lock()
defer p.m.Unlock()
if p.state != playerPlay {
return
}
p.state = playerPaused
}
func (p *Player) Seek(offset int64, whence int) (int64, error) {
return p.p.Seek(offset, whence)
}
func (p *playerImpl) Seek(offset int64, whence int) (int64, error) {
p.m.Lock()
defer p.m.Unlock()
// If a player is playing, keep playing even after this seeking.
if p.state == playerPlay {
defer p.playImpl()
}
// Reset the internal buffer.
p.resetImpl()
// Check if the source implements io.Seeker.
s, ok := p.src.(io.Seeker)
if !ok {
return 0, errors.New("mux: the source must implement io.Seeker")
}
return s.Seek(offset, whence)
}
func (p *Player) Reset() {
p.p.Reset()
}
func (p *playerImpl) Reset() {
p.m.Lock()
defer p.m.Unlock()
p.resetImpl()
}
func (p *playerImpl) resetImpl() {
if p.state == playerClosed {
return
}
p.state = playerPaused
p.buf = p.buf[:0]
p.eof = false
}
func (p *Player) IsPlaying() bool {
return p.p.IsPlaying()
}
func (p *playerImpl) IsPlaying() bool {
p.m.Lock()
defer p.m.Unlock()
return p.state == playerPlay
}
func (p *Player) Volume() float64 {
return p.p.Volume()
}
func (p *playerImpl) Volume() float64 {
p.m.Lock()
defer p.m.Unlock()
return p.volume
}
func (p *Player) SetVolume(volume float64) {
p.p.SetVolume(volume)
}
func (p *playerImpl) SetVolume(volume float64) {
p.m.Lock()
defer p.m.Unlock()
p.volume = volume
if p.state != playerPlay {
p.prevVolume = volume
}
}
func (p *Player) BufferedSize() int {
return p.p.BufferedSize()
}
func (p *playerImpl) BufferedSize() int {
p.m.Lock()
defer p.m.Unlock()
return len(p.buf)
}
func (p *Player) Close() error {
runtime.SetFinalizer(p, nil)
return p.p.Close()
}
func (p *playerImpl) Close() error {
p.m.Lock()
defer p.m.Unlock()
return p.closeImpl()
}
func (p *playerImpl) closeImpl() error {
p.removeFromPlayers()
if p.state == playerClosed {
return p.err
}
p.state = playerClosed
p.buf = nil
return p.err
}
func (p *playerImpl) readBufferAndAdd(buf []float32) int {
p.m.Lock()
defer p.m.Unlock()
if p.state != playerPlay {
return 0
}
format := p.mux.format
bitDepthInBytes := format.ByteLength()
n := len(p.buf) / bitDepthInBytes
if n > len(buf) {
n = len(buf)
}
prevVolume := float32(p.prevVolume)
volume := float32(p.volume)
channelCount := p.mux.channelCount
rateDenom := float32(n / channelCount)
src := p.buf[:n*bitDepthInBytes]
for i := 0; i < n; i++ {
var v float32
switch format {
case FormatFloat32LE:
v = math.Float32frombits(uint32(src[4*i]) | uint32(src[4*i+1])<<8 | uint32(src[4*i+2])<<16 | uint32(src[4*i+3])<<24)
case FormatUnsignedInt8:
v8 := src[i]
v = float32(v8-(1<<7)) / (1 << 7)
case FormatSignedInt16LE:
v16 := int16(src[2*i]) | (int16(src[2*i+1]) << 8)
v = float32(v16) / (1 << 15)
default:
panic(fmt.Sprintf("mux: unexpected format: %d", format))
}
if volume == prevVolume {
buf[i] += v * volume
} else {
rate := float32(i/channelCount) / rateDenom
if rate > 1 {
rate = 1
}
buf[i] += v * (volume*rate + prevVolume*(1-rate))
}
}
p.prevVolume = p.volume
copy(p.buf, p.buf[n*bitDepthInBytes:])
p.buf = p.buf[:len(p.buf)-n*bitDepthInBytes]
if p.eof && len(p.buf) == 0 {
p.state = playerPaused
}
return n
}
func (p *playerImpl) canReadSourceToBuffer() bool {
p.m.Lock()
defer p.m.Unlock()
if p.eof {
return false
}
return len(p.buf) < p.bufferSize
}
func (p *playerImpl) readSourceToBuffer() int {
p.m.Lock()
defer p.m.Unlock()
if p.err != nil {
return 0
}
if p.state == playerClosed {
return 0
}
if len(p.buf) >= p.bufferSize {
return 0
}
buf := p.ensureTmpBuf()
n, err := p.read(buf)
if err != nil && err != io.EOF {
p.setErrorImpl(err)
return 0
}
p.buf = append(p.buf, buf[:n]...)
if err == io.EOF {
p.eof = true
if len(p.buf) == 0 {
p.state = playerPaused
}
}
return n
}
func (p *playerImpl) setErrorImpl(err error) {
p.err = err
p.closeImpl()
}
// TODO: The term 'buffer' is confusing. Name each buffer with good terms.
// defaultBufferSize returns the default size of the buffer for the audio source.
// This buffer is used when unreading on pausing the player.
func (m *Mux) defaultBufferSize() int {
bytesPerSample := m.channelCount * m.format.ByteLength()
s := m.sampleRate * bytesPerSample / 2 // 0.5[s]
// Align s in multiples of bytes per sample, or a buffer could have extra bytes.
return s / bytesPerSample * bytesPerSample
}