PipeAudio Class Reference

A concrete implementation of Audio as a 'pipe'. More...

#include <audio.hpp>

Inheritance diagram for PipeAudio:

Collaboration diagram for PipeAudio:

Public Member Functions
	PipeAudio (std::unique_ptr< AudioSource > src, std::unique_ptr< AudioSink > sink)
	Constructs a PipeAudio from a source and a sink. More...
Audio::State	Update () override
	Performs an update cycle on this Audio. More...
const std::string &	File () const override
	This Audio's current file. More...
void	SetPlaying (bool playing) override
	Sets whether this Audio should be playing or not. More...
Audio::State	CurrentState () const override
	The state of this Audio. More...
void	SetPosition (std::uint64_t position) override
	Attempts to seek to the given position. More...
std::uint64_t	Position () const override
	This Audio's current position. More...
Public Member Functions inherited from Audio
virtual	~Audio ()=default
	Virtual, empty destructor for Audio.

Private Member Functions
void	ClearFrame ()
	Clears the current frame and its iterator.
bool	DecodeIfFrameEmpty ()
	Decodes a new frame, if the current frame is empty. More...
bool	FrameFinished () const
	Returns whether the current frame has been finished. More...
void	TransferFrame ()
	Transfers as much of the current frame as possible to the sink.

Private Attributes
std::unique_ptr< AudioSource >	src
	The source of audio data.
std::unique_ptr< AudioSink >	sink
	The sink to which audio data is sent.
AudioSource::DecodeVector	frame
	The current decoded frame.
AudioSource::DecodeVector::iterator	frame_iterator
	The current position in the current decoded frame.

Additional Inherited Members
Public Types inherited from Audio
enum	State : uint8_t { State::NONE, State::STOPPED, State::PLAYING, State::AT_END }
	Enumeration of possible states for this Audio. More...

Detailed Description

A concrete implementation of Audio as a 'pipe'.

PipeAudio is comprised of a 'source', which decodes frames from a file, and a 'sink', which plays out the decoded frames. Updating consists of shifting frames from the source to the sink.

See also

Audio

AudioSink

AudioSource

Definition at line 147 of file audio.hpp.

Constructor & Destructor Documentation

PipeAudio()

PipeAudio::PipeAudio	(	std::unique_ptr< AudioSource >	src,
		std::unique_ptr< AudioSink >	sink
	)

Constructs a PipeAudio from a source and a sink.

Parameters

src	The source of decoded audio frames.
sink	The target of decoded audio frames.

See also

AudioSystem::Load

Definition at line 62 of file audio.cpp.

References ClearFrame().

    : src(std::move(src)), sink(std::move(sink))
{
    this->ClearFrame();
}

Member Function Documentation

CurrentState()

Audio::State PipeAudio::CurrentState ( ) const

overridevirtual

The state of this Audio.

Returns

this Audio's current state.

Implements Audio.

Definition at line 85 of file audio.cpp.

References sink.

{
    return this->sink->State();
}

DecodeIfFrameEmpty()

bool PipeAudio::DecodeIfFrameEmpty ( )

private

Decodes a new frame, if the current frame is empty.

Returns

True if more frames are available to decode; false otherwise.

Definition at line 153 of file audio.cpp.

References AudioSource::END_OF_FILE, frame, frame_iterator, FrameFinished(), and src.

Referenced by Update().

{
    // Either the current frame is in progress, or has been emptied.
    // AdvanceFrameIterator() establishes this assertion by emptying a
    // frame as soon as it finishes.
    assert(this->frame.empty() || !this->FrameFinished());

    // If we still have a frame, don't bother decoding yet.
    if (!this->FrameFinished()) return true;

    assert(this->src != nullptr);
    AudioSource::DecodeResult result = this->src->Decode();

    this->frame = result.second;
    this->frame_iterator = this->frame.begin();

    return result.first != AudioSource::DecodeState::END_OF_FILE;
}

File()

const std::string & PipeAudio::File ( ) const

overridevirtual

This Audio's current file.

Returns

The filename of this current file.

Exceptions

NoAudioError

if the current state is NONE.

Implements Audio.

Definition at line 69 of file audio.cpp.

References src.

{
    return this->src->Path();
}

FrameFinished()

bool PipeAudio::FrameFinished ( ) const

private

Returns whether the current frame has been finished.

If this is true, then either the frame is empty, or all of the samples in the frame have been fed to the ringbuffer.

Returns

True if the frame is finished; false otherwise.

Definition at line 172 of file audio.cpp.

References frame, and frame_iterator.

Referenced by DecodeIfFrameEmpty(), TransferFrame(), and Update().

{
    return this->frame.end() <= this->frame_iterator;
}

Position()

std::uint64_t PipeAudio::Position ( ) const

overridevirtual

This Audio's current position.

As this may be executing whilst the playing callback is running, do not expect it to be highly accurate.

Returns

The current position, in microseconds.

Exceptions

NoAudioError

if the current state is NONE.

See also

Seek

Implements Audio.

Definition at line 90 of file audio.cpp.

References sink, and src.

{
    assert(this->sink != nullptr);
    assert(this->src != nullptr);

    return this->src->MicrosFromSamples(this->sink->Position());
}

SetPlaying()

void PipeAudio::SetPlaying ( bool  playing )

overridevirtual

Sets whether this Audio should be playing or not.

Parameters

playing

True for playing; false for stopped.

Exceptions

NoAudioError

if the current state is NONE.

Implements Audio.

Definition at line 74 of file audio.cpp.

References sink.

{
    assert(this->sink != nullptr);

    if (playing) {
        this->sink->Start();
    } else {
        this->sink->Stop();
    }
}

SetPosition()

void PipeAudio::SetPosition ( std::uint64_t  position )

overridevirtual

Attempts to seek to the given position.

Parameters

position

The position to seek to, in microseconds.

Exceptions

NoAudioError

if the current state is NONE.

See also

Position

Implements Audio.

Definition at line 98 of file audio.cpp.

References ClearFrame(), sink, and src.

{
    assert(this->sink != nullptr);
    assert(this->src != nullptr);

    auto in_samples = this->src->SamplesFromMicros(position);
    auto out_samples = this->src->Seek(in_samples);
    this->sink->SetPosition(out_samples);

    // We might still have decoded samples from the old position in
    // our frame, so clear them out.
    this->ClearFrame();
}

Update()

Audio::State PipeAudio::Update ( )

overridevirtual

Performs an update cycle on this Audio.

Depending on the Audio implementation, this may do actions such as performing a decoding round, checking for end-of-file, transferring frames, and so on.

Returns

The state of the Audio after updating.

See also

State

Implements Audio.

Definition at line 118 of file audio.cpp.

References DecodeIfFrameEmpty(), FrameFinished(), sink, src, and TransferFrame().

{
    assert(this->sink != nullptr);
    assert(this->src != nullptr);

    bool more_available = this->DecodeIfFrameEmpty();
    if (!more_available) this->sink->SourceOut();

    if (!this->FrameFinished()) this->TransferFrame();

    return this->sink->State();
}

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The documentation for this class was generated from the following files:

• src/audio/audio.hpp
• src/audio/audio.cpp