audio

package
v1.5.0 Latest Latest
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Published: Jun 9, 2017 License: Apache-2.0 Imports: 9 Imported by: 0

Documentation

Overview

Package audio provides audio players. This can be used with or without ebiten package.

The stream format must be 16-bit little endian and 2 channels.

An audio context has a sample rate you can set and all streams you want to play must have the same sample rate. However, decoders like audio/vorbis and audio/wav adjust sample rate, and you don't have to care about it as long as you use those decoders.

An audio context can generate 'players' (instances of audio.Player), and you can play sound by calling Play function of players. When multiple players play, mixing is automatically done. Note that too many players may cause distortion.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Context

type Context struct {
	// contains filtered or unexported fields
}

A Context is a current state of audio.

There should be at most one Context object. This means only one constant sample rate is valid in your one application.

The typical usage with ebiten package is:

var audioContext *audio.Context

func update(screen *ebiten.Image) error {
    // Update updates the audio stream by 1/60 [sec].
    if err := audioContext.Update(); err != nil {
        return err
    }
    // ...
}

func main() {
    audioContext, err = audio.NewContext(sampleRate)
    if err != nil {
        panic(err)
    }
    ebiten.Run(run, update, 320, 240, 2, "Audio test")
}

This is 'sync mode' in that game's (logical) time and audio time are synchronized. You can also call Update independently from the game loop as 'async mode'. In this case, audio goes on even when the game stops e.g. by diactivating the screen.

func NewContext

func NewContext(sampleRate int) (*Context, error)

NewContext creates a new audio context with the given sample rate (e.g. 44100).

Error returned by NewContext is always nil as of 1.5.0-alpha.

NewContext panics when an audio context is already created.

func (*Context) SampleRate

func (c *Context) SampleRate() int

SampleRate returns the sample rate.

func (*Context) Update

func (c *Context) Update() error

Update proceeds the inner (logical) time of the context by 1/60 second.

This is expected to be called in the game's updating function (sync mode) or an independent goroutine with timers (async mode). In sync mode, the game logical time syncs the audio logical time and you will find audio stops when the game stops e.g. when the window is deactivated. In async mode, the audio never stops even when the game stops.

Update returns error when IO error occurs in the underlying IO object.

type InfiniteLoop added in v1.5.0

type InfiniteLoop struct {
	// contains filtered or unexported fields
}

InfiniteLoop represents a loop which never ends.

func NewInfiniteLoop added in v1.5.0

func NewInfiniteLoop(stream ReadSeekCloser, size int64) *InfiniteLoop

NewInfiniteLoop creates a new infinite loop stream with a stream and size in bytes.

func (*InfiniteLoop) Close added in v1.5.0

func (l *InfiniteLoop) Close() error

Close is implementation of ReadSeekCloser.

func (*InfiniteLoop) Read added in v1.5.0

func (i *InfiniteLoop) Read(b []byte) (int, error)

Read is implementation of ReadSeekCloser.

func (*InfiniteLoop) Seek added in v1.5.0

func (i *InfiniteLoop) Seek(offset int64, whence int) (int64, error)

Seek is implementation of ReadSeekCloser.

type Player

type Player struct {
	// contains filtered or unexported fields
}

Player is an audio player which has one stream.

func NewPlayer

func NewPlayer(context *Context, src ReadSeekCloser) (*Player, error)

NewPlayer creates a new player with the given stream.

src's format must be linear PCM (16bits little endian, 2 channel stereo) without a header (e.g. RIFF header). The sample rate must be same as that of the audio context.

Note that the given src can't be shared with other Players.

NewPlayer tries to rewind src by calling Seek to get the current position. NewPlayer returns error when the Seek returns error.

func NewPlayerFromBytes added in v1.5.0

func NewPlayerFromBytes(context *Context, src []uint8) (*Player, error)

NewPlayerFromBytes creates a new player with the given bytes.

As opposed to NewPlayer, you don't have to care if src is already used by another player or not. src can be shared by multiple players.

The format of src should be same as noted at NewPlayer.

NewPlayerFromBytes's error is always nil as of 1.5.0-alpha.

func (*Player) Close

func (p *Player) Close() error

Close closes the stream. Ths source stream passed by NewPlayer will also be closed.

When closing, the stream owned by the player will also be closed by calling its Close.

Close is concurrent safe.

Close returns error when closing the source returns error.

func (*Player) Current

func (p *Player) Current() time.Duration

Current returns the current position.

Current is concurrent safe.

func (*Player) IsPlaying

func (p *Player) IsPlaying() bool

IsPlaying returns boolean indicating whether the player is playing.

IsPlaying is concurrent safe.

func (*Player) Pause

func (p *Player) Pause() error

Pause pauses the playing.

Pause is concurrent safe.

Pause always returns nil.

func (*Player) Play

func (p *Player) Play() error

Play plays the stream.

Play always returns nil.

Play is concurrent safe.

func (*Player) Rewind

func (p *Player) Rewind() error

Rewind rewinds the current position to the start.

Rewind is concurrent safe.

Rewind returns error when seeking the source returns error.

func (*Player) Seek

func (p *Player) Seek(offset time.Duration) error

Seek seeks the position with the given offset.

Seek is concurrent safe.

Seek returns error when seeking the source returns error.

func (*Player) SetVolume

func (p *Player) SetVolume(volume float64)

SetVolume sets the volume of this player. volume must be in between 0 and 1. This function panics otherwise.

SetVolume is concurrent safe.

func (*Player) Volume

func (p *Player) Volume() float64

Volume returns the current volume of this player [0-1].

Volume is concurrent safe.

type ReadSeekCloser

type ReadSeekCloser interface {
	io.ReadSeeker
	io.Closer
}

ReadSeekCloser is an io.ReadSeeker and io.Closer.

func BytesReadSeekCloser added in v1.5.0

func BytesReadSeekCloser(b []uint8) ReadSeekCloser

BytesReadSeekCloser creates ReadSeekCloser from bytes.

A returned stream is concurrent safe.

Directories

Path Synopsis
internal
Package vorbis provides Ogg/Vorbis decoder.
Package vorbis provides Ogg/Vorbis decoder.
Package wav provides WAV (RIFF) decoder.
Package wav provides WAV (RIFF) decoder.

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