// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROMECAST_PUBLIC_MEDIA_EXTERNAL_AUDIO_PIPELINE_SHLIB_H_
#define CHROMECAST_PUBLIC_MEDIA_EXTERNAL_AUDIO_PIPELINE_SHLIB_H_
#include <memory>
#include <string>
#include "cast_media_shlib.h"
#include "chromecast_export.h"
#include "media_pipeline_backend.h"
#include "mixer_output_stream.h"
namespace chromecast {
namespace media {
class CHROMECAST_EXPORT ExternalAudioPipelineShlib {
public:
// Represents a media input source of the external media pipeline.
enum class MediaInputSource {
UNKNOWN_INPUT_SOURCE,
HDMI,
AIRPLAY,
};
// Represents a media playback state of the external media pipeline.
enum class MediaPlaybackState {
UNKNOWN_STATE,
STOPPED,
PAUSED,
PLAYING,
};
// Observer for reporting requests for media volume change/muting from the
// external media pipeline. The external pipeline should communicate the media
// volume change requests through this observer and otherwise shouldn't change
// the media volume in any way. Cast pipeline will call
// SetExternalMediaVolume/SetExternalMediaMuted to actually change the volume
// of the external media. The external pipeline must only apply the received
// volume to the external (non-Cast) audio. It specifically must not be
// applied to the mixer output stream. The received volume should also not be
// reported again through this observer.
class ExternalMediaVolumeChangeRequestObserver {
public:
// Called by the external pipeline to request a media volume change by the
// cast pipeline.
virtual void OnVolumeChangeRequest(float new_volume) = 0;
// Called by the external pipeline to request muting/unmuting media volume
// by the cast pipeline.
virtual void OnMuteChangeRequest(bool new_muted) = 0;
protected:
virtual ~ExternalMediaVolumeChangeRequestObserver() = default;
};
// Media metadata which can be acquired from the external pipeline.
struct ExternalMediaMetadata {
ExternalMediaMetadata();
ExternalMediaMetadata(const ExternalMediaMetadata& other);
~ExternalMediaMetadata();
std::string title;
std::string artist;
std::string album;
std::string genre;
int track_num = -1;
MediaInputSource source = MediaInputSource::HDMI;
std::string source_description;
MediaPlaybackState state = MediaPlaybackState::UNKNOWN_STATE;
};
// Observer for reporting media metadata change from the external media
// pipeline, e.g., title, artist, input source, play back state, and etc.
class ExternalMediaMetadataChangeObserver {
public:
// Called when media metadata is updated.
virtual void OnExternalMediaMetadataChanged(
const ExternalMediaMetadata& metadata) = 0;
protected:
virtual ~ExternalMediaMetadataChangeObserver() = default;
};
// Observer for audio loopback data.
class LoopbackAudioObserver {
public:
// Called whenever audio data is about to be output. The |timestamp| is the
// estimated time in microseconds (relative to CLOCK_MONOTONIC_RAW) that
// the audio will actually be output. |length| is the length of the audio
// |data| in bytes. The format of the data is given by |sample_format| and
// |num_channels|.
// This method may be called by any thread, and MUST not block or take very
// much time (to avoid audio underruns).
virtual void OnLoopbackAudio(int64_t timestamp,
SampleFormat sample_format,
int sample_rate,
int num_channels,
uint8_t* data,
int length) = 0;
// Called if the loopback data is not continuous (ie, does not accurately
// represent the actual output) for any reason. For example, if there is an
// output underflow, or if output is disabled due to no output streams.
// This method could be called from any thread.
virtual void OnLoopbackInterrupted() = 0;
// Called once this observer has been fully removed by a call to
// RemoveLoopbackAudioObserver(). After this is called, no more calls to
// OnLoopbackAudio() or OnLoopbackInterrupted() will be made for this
// observer unless it is added again. This method could be called from any
// thread.
virtual void OnRemoved() = 0;
protected:
virtual ~LoopbackAudioObserver() {}
};
// Returns whether this shlib is supported. If this returns true, it indicates
// that the platform uses an external audio pipeline that needs to be combined
// with Cast's media pipeline.
static bool IsSupported();
// Adds an external media volume observer.
static void AddExternalMediaVolumeChangeRequestObserver(
ExternalMediaVolumeChangeRequestObserver* observer);
// Removes an external media volume observer. After this is called, the
// implementation must not call any more methods on the observer.
static void RemoveExternalMediaVolumeChangeRequestObserver(
ExternalMediaVolumeChangeRequestObserver* observer);
// Sets the effective volume that the external pipeline must apply. The volume
// must be applied only to external (non-Cast) audio. Cast audio must never
// be affected. The pipeline should not report it back through the volume
// observer. The volume |level| is in the range [0.0, 1.0].
static void SetExternalMediaVolume(float level);
// Sets the effective muted state that the external pipeline must apply. The
// mute state must be applied only to external (non-Cast) audio. Cast audio
// must never be affected. The pipeline should not report this state back
// through the volume observer.
static void SetExternalMediaMuted(bool muted);
// Adds a loopback audio observer. An observer will not be added more than
// once without being removed first.
static void AddExternalLoopbackAudioObserver(LoopbackAudioObserver* observer);
// Removes a loopback audio observer. An observer will not be removed unless
// it was previously added, and will not be removed more than once without
// being added again first.
// Once the observer is fully removed (ie. once it is certain that
// OnLoopbackAudio() will not be called again for the observer), the
// observer's OnRemoved() method must be called. The OnRemoved() method must
// be called once for each time that RemoveLoopbackAudioObserver() is called
// for a given observer, even if the observer was not added. The
// implementation may call OnRemoved() from any thread.
// This function is optional to implement.
static void RemoveExternalLoopbackAudioObserver(
LoopbackAudioObserver* observer);
// Adds an external media metadata observer.
static void AddExternalMediaMetadataChangeObserver(
ExternalMediaMetadataChangeObserver* observer);
// Removes an external media volume observer. After this is called, the
// implementation must not call any more methods on the observer.
static void RemoveExternalMediaMetadataChangeObserver(
ExternalMediaMetadataChangeObserver* observer);
// Returns an instance of MixerOutputStream from the shared library.
// Caller will take ownership of the returned pointer.
static std::unique_ptr<MixerOutputStream> CreateMixerOutputStream();
};
inline ExternalAudioPipelineShlib::ExternalMediaMetadata::
ExternalMediaMetadata() = default;
inline ExternalAudioPipelineShlib::ExternalMediaMetadata::ExternalMediaMetadata(
const ExternalMediaMetadata& other) = default;
inline ExternalAudioPipelineShlib::ExternalMediaMetadata::
~ExternalMediaMetadata() = default;
} // namespace media
} // namespace chromecast
#endif // CHROMECAST_PUBLIC_MEDIA_EXTERNAL_AUDIO_PIPELINE_SHLIB_H_
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