mpd-dbcreate/src/output/Filtered.hxx

// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright The Music Player Daemon Project

#ifndef MPD_FILTERED_AUDIO_OUTPUT_HXX
#define MPD_FILTERED_AUDIO_OUTPUT_HXX

#include "pcm/AudioFormat.hxx"
#include "filter/Observer.hxx"

#include <chrono>
#include <map>
#include <memory>
#include <span>
#include <string>

class FilterFactory;
class PreparedFilter;
class EventLoop;
class Mixer;
class MixerListener;
struct MixerPlugin;
struct ConfigBlock;
class AudioOutput;
struct AudioOutputDefaults;
struct ReplayGainConfig;
struct Tag;

struct FilteredAudioOutput {
	const char *const plugin_name;

	/**
	 * The device's configured display name.
	 */
	const char *name;

private:
	/**
	 * A string describing this devicee in log messages.  It is
	 * usually in the form "NAME (PLUGIN)".
	 */
	std::string log_name;

public:
	/**
	 * The plugin which implements this output device.
	 */
	std::unique_ptr<AudioOutput> output;

	/**
	 * The #mixer object associated with this audio output device.
	 * May be nullptr if none is available, or if software volume is
	 * configured.
	 */
	Mixer *mixer = nullptr;

	/**
	 * The configured audio format.
	 */
	AudioFormat config_audio_format;

	/**
	 * The #AudioFormat which is emitted by the #Filter, with
	 * #config_audio_format already applied.  This is used to
	 * decide whether this object needs to be closed and reopened
	 * upon #AudioFormat changes.
	 */
	AudioFormat filter_audio_format;

	/**
	 * The audio_format which is really sent to the device.  This
	 * is basically config_audio_format (if configured) or
	 * in_audio_format, but may have been modified by
	 * plugin->open().
	 */
	AudioFormat out_audio_format;

	/**
	 * The filter object of this audio output.  This is a chain of
	 * #PreparedTwoFilter instances.
	 */
	std::unique_ptr<PreparedFilter> prepared_filter;

	/**
	 * The #VolumeFilter instance of this audio output.  It is
	 * used by the #SoftwareMixer.
	 */
	FilterObserver volume_filter;

	/**
	 * The replay_gain_filter_plugin instance of this audio
	 * output.
	 */
	std::unique_ptr<PreparedFilter> prepared_replay_gain_filter;

	/**
	 * The replay_gain_filter_plugin instance of this audio
	 * output, to be applied to the second chunk during
	 * cross-fading.
	 */
	std::unique_ptr<PreparedFilter> prepared_other_replay_gain_filter;

	/**
	 * The convert_filter_plugin instance of this audio output.
	 * It is the last item in the filter chain, and is responsible
	 * for converting the input data into the appropriate format
	 * for this audio output.
	 */
	FilterObserver convert_filter;

	/**
	 * Throws on error.
	 */
	FilteredAudioOutput(const char *_plugin_name,
			    std::unique_ptr<AudioOutput> &&_output,
			    const ConfigBlock &block,
			    const AudioOutputDefaults &defaults,
			    FilterFactory *filter_factory);

	~FilteredAudioOutput();

private:
	void Configure(const ConfigBlock &block,
		       const AudioOutputDefaults &defaults,
		       FilterFactory *filter_factory);

public:
	void Setup(EventLoop &event_loop,
		   const ReplayGainConfig &replay_gain_config,
		   const MixerPlugin *mixer_plugin,
		   MixerListener &mixer_listener,
		   const ConfigBlock &block,
		   const AudioOutputDefaults &defaults);

	const char *GetName() const {
		return name;
	}

	const char *GetPluginName() const noexcept {
		return plugin_name;
	}

	const char *GetLogName() const noexcept {
		return log_name.c_str();
	}

	/**
	 * Does the plugin support enabling/disabling a device?
	 */
	[[gnu::pure]]
	bool SupportsEnableDisable() const noexcept;

	/**
	 * Does the plugin support pausing a device?
	 */
	[[gnu::pure]]
	bool SupportsPause() const noexcept;

	std::map<std::string, std::string, std::less<>> GetAttributes() const noexcept;
	void SetAttribute(std::string &&name, std::string &&value);

	/**
	 * Throws on error.
	 */
	void Enable();

	void Disable() noexcept;

	/**
	 * Close everything: the output (via CloseOutput()) and the
	 * software mixer (via CloseSoftwareMixer()).
	 *
	 * Caller must not lock the mutex.
	 */
	void Close(bool drain) noexcept;

	void ConfigureConvertFilter();

	/**
	 * Invoke OutputPlugin::open() and configure the
	 * #ConvertFilter.
	 *
	 * Throws on error.
	 *
	 * Caller must not lock the mutex.
	 */
	void OpenOutputAndConvert(AudioFormat audio_format);

	/**
	 * Invoke AudioOutput::Close(), but nothing else.
	 *
	 * Mutex must not be locked.
	 */
	void CloseOutput(bool drain) noexcept;

	/**
	 * Mutex must not be locked.
	 */
	void OpenSoftwareMixer() noexcept;

	/**
	 * Mutex must not be locked.
	 */
	void CloseSoftwareMixer() noexcept;

	void Interrupt() noexcept;

	[[gnu::pure]]
	std::chrono::steady_clock::duration Delay() noexcept;

	void SendTag(const Tag &tag);

	std::size_t Play(std::span<const std::byte> src);

	void Drain();
	void Cancel() noexcept;

	void BeginPause() noexcept;
	bool IteratePause();

	void EndPause() noexcept{
	}
};

/**
 * Throws on error.
 */
std::unique_ptr<FilteredAudioOutput>
audio_output_new(EventLoop &event_loop, EventLoop &rt_event_loop,
		 const ReplayGainConfig &replay_gain_config,
		 const ConfigBlock &block,
		 const AudioOutputDefaults &defaults,
		 FilterFactory *filter_factory,
		 MixerListener &mixer_listener);

#endif