/* * audiointerface.h * Interface definition for audio and MIDI backends. * * for Denemo, a gtk+ frontend to GNU Lilypond * Copyright (C) 2011 Dominic Sacré * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. */ #ifndef AUDIOINTERFACE_H #define AUDIOINTERFACE_H #include #include "smf.h" /** * The common interface for all audio and MIDI backends. */ typedef struct backend_t { /** * Initializes the backend with the given configuration. * * FIXME: the DenemoPrefs argument is both too general (backend-specific * settings would be enough) and redundant (there's a global instance * anyway). * * @param config the configuration object containing the backend's settings * * @return zero on success, a negative error code on failure */ int (*initialize) (DenemoPrefs * config); /** * Destroys the backend and cleans up all its resources. * * @return zero on success, a negative error code on failure */ int (*destroy) (); /** * Changes the backend's configuration, if possible without destroying and * recreating the backend. * * This is not used by any backends at the moment, but will be needed, for * example, to configure the audio input settings. * * @return zero on success, a negative error code on failure */ int (*reconfigure) (DenemoPrefs * config); /** * Called when playback is started. * * @return zero on success, a negative error code on failure */ int (*start_playing) (); /** * Called when playback is stopped. * * @return zero on success, a negative error code on failure */ int (*stop_playing) (); /** * Sends a MIDI panic CC and/or resets the synth engine. * * @return zero on success, a negative error code on failure */ int (*panic) (); } backend_t; /** * An enum that identifies a backend's type. */ typedef enum backend_type_t { /** * The default backend (either audio or MIDI) */ DEFAULT_BACKEND = -1, /** * The audio backend */ AUDIO_BACKEND = 0, /** * The MIDI backend */ MIDI_BACKEND = 1 } backend_type_t; // we only have two backends at the same time: audio and MIDI #define NUM_BACKENDS 2 /** * An enum that specifies a backend's priority regarding the playback time. */ typedef enum backend_timebase_prio_t { /** * The backend synchronizes to an external sample clock */ TIMEBASE_PRIO_AUDIO = 3, /** * The backend is not bound to any external clock */ TIMEBASE_PRIO_MIDI = 2, /** * The backend requires no timing information */ TIMEBASE_PRIO_DUMMY = 1 } backend_timebase_prio_t; typedef struct midi_event_t { backend_type_t backend; int port; int length; unsigned char data[3]; } midi_event_t; /** * Initializes the audio/MIDI subsystem. * * @return zero on success, a negative error code on failure */ int audio_initialize (DenemoPrefs * config); /** * Destroys and cleans up the audio/MIDI subsystem. * * @return zero on success, a negative error code on failure */ int audio_shutdown (); /** * Starts playing the current movement. */ void midi_play (gchar * callback); /** * Starts playing the current movements source audio. */ void audio_play (void); /** * Stops playing the current movement. */ void midi_stop (); /** * Plays a single MIDI event. * * @param backend the type of backend to be used * @param port the number of the backend's output port to be used. ignored * by most backends. * @param buffer the MIDI data to be sent */ int play_midi_event (backend_type_t backend, int port, unsigned char *buffer); /** * Plays a single note. * * @param backend the type of backend to be used * @param port the number of the backend's output port to be used. ignored * by most backends. * @param channel the note's MIDI channel * @param key the MIDI note number * @param duration the note's duration in milliseconds * @param volume the note's volume (1-127) */ int play_note (backend_type_t backend, int port, int channel, int key, int duration, int volume); /** * Plays a chord. * * @param backend the type of backend to be used * @param port the number of the backend's output port to be used. ignored * by most backends. * @param channel the note's MIDI channel * @param chord the chord structure containing the individual notes to be played */ int play_notes (backend_type_t backend, int port, int channel, chord * chord_to_play); /** * Not yet implemented. */ int rhythm_feedback (backend_type_t backend, int duration, gboolean rest, gboolean dot); /** * Sends a MIDI panic CC and/or resets the synth engine. * * @param backend the backend to be reset */ int panic (backend_type_t backend); /** * Sends a MIDI panic CC and/or resets the synth engine for all active * backends. */ int panic_all (void); /** * Called by a backend to read midi events queued for playback. * * @param backend the type of backend * @param[out] event_buffer the event data * @param[out] event_length the length of the event in bytes * @param[out] event_time the time of the event (in seconds from the start * of the score) * @param until_time the playback time up to which events should be * returned * * @return TRUE if an event was written to the output * parameters, FALSE if there is no event to be * played */ gboolean read_event_from_queue (backend_type_t backend, unsigned char *event_buffer, size_t * event_length, double *event_time, double until_time); gboolean read_event_from_mixer_queue (backend_type_t backend, unsigned char *event_buffer, size_t * event_length); #ifdef _HAVE_RUBBERBAND_ gboolean read_event_from_rubberband_queue (backend_type_t backend, unsigned char *event_buffer, size_t * event_length); gboolean write_samples_to_rubberband_queue (backend_type_t backend, float *sample, gint len); #endif /** * Called by a backend to notify the audio subsystem that the current playback * time changed. Usually this is called once per period during playback. * * @param prio the backend's timebase priority * @param new_time the new playback time in milliseconds */ void update_playback_time (backend_timebase_prio_t prio, double new_time); /** * Returns the current playback time in milliseconds. */ double get_playback_time (); /** * sets the current playback slowdown factor. */ void set_playback_speed (double speed); /** * Called by a backend when an incoming MIDI event was received. * * @param backend the backend that received the event * @param port the port that received the event (zero if there is only * one port) * @param buffer the MIDI event data */ void input_midi_event (backend_type_t backend, int port, unsigned char *buffer); /** * Queues a full redraw of the GUI. */ void queue_redraw_all (); /** * Queues a redraw of the playhead. */ void queue_redraw_playhead (smf_event_t * event); extern GMutex smfmutex; gboolean have_midi (void); void advance_time (gdouble seconds); /* * Returns a slowdown factor; the backend is only emitting audio at this rate * */ gdouble get_playback_speed (void); #endif // AUDIOINTERFACE_H