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playback.go
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playback.go
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package pulse
import "github.com/jfreymuth/pulse/proto"
// A PlaybackStream is used for playing audio.
// When creating a stream, the user must provide a callback that will be used to buffer audio data.
type PlaybackStream struct {
c *Client
index uint32
state streamState
underflow bool
err error
front, back []byte
requested int
request chan int
started chan bool
r Reader
createRequest proto.CreatePlaybackStream
createReply proto.CreatePlaybackStreamReply
bytesPerSample int
}
// EndOfData is a special error value that can be returned by a reader to stop the stream.
const EndOfData endOfData = false
// NewPlayback creates a playback stream.
// The created stream wil not be running, it must be started with Start().
// If the reader returns any error, the stream will be stopped. The special error value EndOfData
// can be used to intentionally stop the stream from within the callback.
// The order of options is important in some cases, see the documentation of the individual PlaybackOptions.
func (c *Client) NewPlayback(r Reader, opts ...PlaybackOption) (*PlaybackStream, error) {
p := &PlaybackStream{
c: c,
createRequest: proto.CreatePlaybackStream{
SinkIndex: proto.Undefined,
ChannelMap: proto.ChannelMap{proto.ChannelMono},
SampleSpec: proto.SampleSpec{Format: r.Format(), Channels: 1, Rate: 44100},
BufferMaxLength: proto.Undefined,
Corked: true,
BufferTargetLength: proto.Undefined,
BufferPrebufferLength: proto.Undefined,
BufferMinimumRequest: proto.Undefined,
Properties: proto.PropList{},
},
bytesPerSample: bytes(r.Format()),
r: r,
}
for _, opt := range opts {
opt(p)
}
if p.createRequest.ChannelVolumes == nil {
cvol := make(proto.ChannelVolumes, len(p.createRequest.ChannelMap))
for i := range cvol {
cvol[i] = 0x100
}
p.createRequest.ChannelVolumes = cvol
}
err := c.c.Request(&p.createRequest, &p.createReply)
if err != nil {
return nil, err
}
p.index = p.createReply.StreamIndex
p.front = make([]byte, p.createReply.BufferMaxLength)
p.back = make([]byte, p.createReply.BufferMaxLength)
p.request = make(chan int)
p.started = make(chan bool)
c.mu.Lock()
c.playback[p.index] = p
c.mu.Unlock()
go p.run()
return p, nil
}
func (p *PlaybackStream) run() {
for n := range p.request {
if p.state != running {
continue
}
p.requested += n
for p.requested > 0 {
n, err := p.r.Read(p.front[:p.requested])
if n > 0 {
p.c.c.Send(p.index, p.front[:n])
p.requested -= n
p.front, p.back = p.back, p.front
}
if err != nil {
if err != EndOfData {
p.err = err
}
p.state = idle
break
}
select {
case n = <-p.request:
p.requested += n
default:
}
}
}
}
// Start starts playing audio.
func (p *PlaybackStream) Start() {
if p.state == idle {
p.c.c.Request(&proto.FlushPlaybackStream{StreamIndex: p.index}, nil)
p.state = running
p.err = nil
p.request <- int(p.createReply.BufferTargetLength)
p.underflow = false
p.c.c.Request(&proto.CorkPlaybackStream{StreamIndex: p.index, Corked: false}, nil)
<-p.started
}
}
// Stop stops playing audio; the callback will no longer be called.
// If the buffer size/latency is large, audio may continue to play for some time after the call to Stop.
func (p *PlaybackStream) Stop() {
if p.state == running || p.state == paused {
p.state = idle
}
}
// Pause stops playing audio immediately.
func (p *PlaybackStream) Pause() {
if p.state == running {
p.c.c.Request(&proto.CorkPlaybackStream{StreamIndex: p.index, Corked: true}, nil)
p.state = paused
}
}
// Resume resumes a paused stream.
func (p *PlaybackStream) Resume() {
if p.state == paused {
p.c.c.Request(&proto.CorkPlaybackStream{StreamIndex: p.index, Corked: false}, nil)
p.state = running
p.underflow = false
}
}
// Drain waits until the playback has ended.
// Drain does not return when the stream is paused.
func (p *PlaybackStream) Drain() {
if p.state == running {
p.c.c.Request(&proto.DrainPlaybackStream{StreamIndex: p.index}, nil)
}
}
// Volume returns the volume of each channel in the playback.
func (p *PlaybackStream) Volume() (proto.ChannelVolumes, error) {
reply := proto.GetSinkInputInfoReply{}
err := p.c.c.Request(&proto.GetSinkInputInfo{
SinkInputIndex: p.createReply.SinkInputIndex,
}, &reply)
if err != nil {
return nil, err
}
return reply.ChannelVolumes, nil
}
// SetVolume changes the volume of each channel in the playback.
//
// Do not set the volume when opening a playback stream, PulseAudio will pick an
// appropriate volume for the stream automatically (and may save it for next
// time). In particular, don't set it to 100% because depending on the
// configuration this could actually set the volume to the maximum volume the
// hardware is capable of which is usually way too loud. Instead, only change
// the volume as a direct result of user input.
//
// If you use this API, you should also query the volume on startup and listen
// for playback volume changes from the system mixer (many desktops allow users
// to change application volume from the system tray). That way, you can keep
// the volume slider in the application synchronized with the system volume
// mixer.
func (p *PlaybackStream) SetVolume(volumes proto.ChannelVolumes) error {
return p.c.c.Request(&proto.SetSinkInputVolume{
SinkInputIndex: p.createReply.SinkInputIndex,
ChannelVolumes: volumes,
}, nil)
}
// Close closes the stream.
func (p *PlaybackStream) Close() {
if !p.Closed() {
p.c.c.Request(&proto.DeletePlaybackStream{StreamIndex: p.index}, nil)
p.state = closed
close(p.request)
p.c.mu.Lock()
delete(p.c.playback, p.index)
p.c.mu.Unlock()
}
}
// Closed returns wether the stream was closed.
func (p *PlaybackStream) Closed() bool { return p.state == closed || p.state == serverLost }
// Running returns wether the stream is currently playing.
func (p *PlaybackStream) Running() bool { return p.state == running }
// Underflow returns true if any underflows happend since the last call to Start or Resume.
// Underflows usually happen because the latency/buffer size is too low or because the callback
// takes too long to run.
func (p *PlaybackStream) Underflow() bool { return p.underflow }
// Error returns the last error returned by the stream's reader.
func (p *PlaybackStream) Error() error { return p.err }
// SampleRate returns the stream's sample rate (samples per second).
func (p *PlaybackStream) SampleRate() int {
return int(p.createReply.Rate)
}
// Channels returns the number of channels.
func (p *PlaybackStream) Channels() int {
return int(p.createReply.Channels)
}
// BufferSize returns the size of the server-side buffer in samples.
func (p *PlaybackStream) BufferSize() int {
s := int(p.createReply.BufferTargetLength) / int(p.createReply.Channels)
return s / p.bytesPerSample
}
// BufferSizeBytes returns the size of the server-side buffer in bytes.
func (p *PlaybackStream) BufferSizeBytes() int {
return int(p.createReply.BufferTargetLength)
}
// StreamIndex returns the stream index.
// This should only be used together with (*Cient).RawRequest.
func (p *PlaybackStream) StreamIndex() uint32 {
return p.index
}
func (p *PlaybackStream) StreamInputIndex() uint32 {
return p.createReply.SinkInputIndex
}
// A PlaybackOption supplies configuration when creating streams.
type PlaybackOption func(*PlaybackStream)
// PlaybackMono sets a stream to a single channel.
var PlaybackMono PlaybackOption = func(p *PlaybackStream) {
p.createRequest.ChannelMap = proto.ChannelMap{proto.ChannelMono}
p.createRequest.Channels = 1
}
// PlaybackStereo sets a stream to two channels.
var PlaybackStereo PlaybackOption = func(p *PlaybackStream) {
p.createRequest.ChannelMap = proto.ChannelMap{proto.ChannelLeft, proto.ChannelRight}
p.createRequest.Channels = 2
}
// PlaybackChannels sets a stream to use a custom channel map.
func PlaybackChannels(m proto.ChannelMap) PlaybackOption {
if len(m) == 0 {
panic("pulse: invalid channel map")
}
return func(p *PlaybackStream) {
p.createRequest.ChannelMap = m
p.createRequest.Channels = byte(len(m))
}
}
// PlaybackSampleRate sets the stream's sample rate.
func PlaybackSampleRate(rate int) PlaybackOption {
return func(p *PlaybackStream) {
p.createRequest.Rate = uint32(rate)
}
}
// PlaybackBufferSize sets the size of the server-side buffer.
// Setting the buffer size too small causes underflows, resulting in audible artifacts.
//
// Buffer size and latency should not be set at the same time.
func PlaybackBufferSize(samples int) PlaybackOption {
return func(p *PlaybackStream) {
p.createRequest.BufferTargetLength = uint32(samples * p.bytesPerSample)
p.createRequest.AdjustLatency = false
}
}
// PlaybackLatency sets the stream's latency in seconds.
// Setting the latency too low causes underflows, resulting in audible artifacts.
// Applications should generally use the highest acceptable latency.
//
// This should be set after sample rate and channel options.
//
// Buffer size and latency should not be set at the same time.
func PlaybackLatency(seconds float64) PlaybackOption {
return func(p *PlaybackStream) {
p.createRequest.BufferTargetLength = uint32(seconds*float64(p.createRequest.Rate)) * uint32(p.createRequest.Channels) * uint32(p.bytesPerSample)
p.createRequest.BufferMaxLength = 2 * p.createRequest.BufferTargetLength
p.createRequest.AdjustLatency = true
}
}
// PlaybackSink sets the sink the stream should send audio to.
func PlaybackSink(sink *Sink) PlaybackOption {
return func(p *PlaybackStream) {
p.createRequest.SinkIndex = sink.info.SinkIndex
}
}
// PlaybackMediaName sets the streams media name.
// This will e.g. be displayed by a volume control application to identity the stream.
func PlaybackMediaName(name string) PlaybackOption {
return func(p *PlaybackStream) {
p.createRequest.Properties["media.name"] = proto.PropListString(name)
}
}
// PlaybackMediaIconName sets the streams media icon using an xdg icon name.
// This will e.g. be displayed by a volume control application to identity the stream.
func PlaybackMediaIconName(name string) PlaybackOption {
return func(p *PlaybackStream) {
p.createRequest.Properties["media.icon_name"] = proto.PropListString(name)
}
}
// PlaybackRawOption can be used to create custom options.
//
// This is an advanced function, similar to (*Client).RawRequest.
func PlaybackRawOption(o func(*proto.CreatePlaybackStream)) PlaybackOption {
return func(p *PlaybackStream) {
o(&p.createRequest)
}
}
type endOfData bool
func (endOfData) Error() string { return "end of data" }