mpd/src/player_thread.c

/* the Music Player Daemon (MPD)
 * Copyright (C) 2003-2007 by Warren Dukes (warren.dukes@gmail.com)
 * This project's homepage is: http://www.musicpd.org
 *
 * 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "player_thread.h"
#include "player_control.h"
#include "decoder_control.h"
#include "audio.h"
#include "pcm_volume.h"
#include "path.h"
#include "event_pipe.h"
#include "crossfade.h"
#include "song.h"
#include "pipe.h"
#include "idle.h"
#include "main.h"

#include <glib.h>

#undef G_LOG_DOMAIN
#define G_LOG_DOMAIN "player_thread"

enum xfade_state {
	XFADE_DISABLED = -1,
	XFADE_UNKNOWN = 0,
	XFADE_ENABLED = 1
};

struct player {
	/**
	 * are we waiting for buffered_before_play?
	 */
	bool buffering;

	/**
	 * true if the decoder is starting and did not provide data
	 * yet
	 */
	bool decoder_starting;

	/**
	 * is the player paused?
	 */
	bool paused;

	/**
	 * is there a new song in pc.next_song?
	 */
	bool queued;

	/**
	 * the song currently being played
	 */
	struct song *song;

	/**
	 * is cross fading enabled?
	 */
	enum xfade_state xfade;

	/**
	 * index of the first chunk of the next song, -1 if there is
	 * no next song
	 */
	int next_song_chunk;
};

static void player_command_finished(void)
{
	assert(pc.command != PLAYER_COMMAND_NONE);

	pc.command = PLAYER_COMMAND_NONE;
	notify_signal(&main_notify);
}

static void player_stop_decoder(void)
{
	dc_stop(&pc.notify);
	pc.state = PLAYER_STATE_STOP;
	event_pipe_emit(PIPE_EVENT_PLAYLIST);
}

static int player_wait_for_decoder(struct player *player)
{
	dc_command_wait(&pc.notify);

	if (decoder_has_failed()) {
		assert(dc.next_song == NULL || dc.next_song->url != NULL);
		pc.errored_song = dc.next_song;
		pc.error = PLAYER_ERROR_FILE;
		return -1;
	}

	pc.total_time = pc.next_song->tag != NULL
		? pc.next_song->tag->time : 0;
	pc.bit_rate = 0;
	audio_format_clear(&pc.audio_format);

	player->song = pc.next_song;
	pc.next_song = NULL;
	pc.elapsed_time = 0;
	player->queued = false;
	player->decoder_starting = true;

	/* call syncPlaylistWithQueue() in the main thread */
	event_pipe_emit(PIPE_EVENT_PLAYLIST);

	return 0;
}

static bool player_seek_decoder(struct player *player)
{
	double where;
	bool ret;

	if (decoder_current_song() != pc.next_song) {
		dc_stop(&pc.notify);
		player->next_song_chunk = -1;
		music_pipe_clear();
		dc_start_async(pc.next_song);
		player_wait_for_decoder(player);
	}

	where = pc.seek_where;
	if (where > pc.total_time)
		where = pc.total_time - 0.1;
	if (where < 0.0)
		where = 0.0;

	ret = dc_seek(&pc.notify, where);
	if (ret)
		pc.elapsed_time = where;

	player_command_finished();

	return ret;
}

static void player_process_command(struct player *player)
{
	switch (pc.command) {
	case PLAYER_COMMAND_NONE:
	case PLAYER_COMMAND_PLAY:
	case PLAYER_COMMAND_STOP:
	case PLAYER_COMMAND_EXIT:
	case PLAYER_COMMAND_CLOSE_AUDIO:
		break;

	case PLAYER_COMMAND_QUEUE:
		assert(pc.next_song != NULL);
		assert(!player->queued);
		assert(player->next_song_chunk == -1);

		player->queued = true;
		player_command_finished();
		break;

	case PLAYER_COMMAND_PAUSE:
		player->paused = !player->paused;
		if (player->paused) {
			audio_output_pause_all();
			pc.state = PLAYER_STATE_PAUSE;
		} else {
			if (openAudioDevice(NULL)) {
				pc.state = PLAYER_STATE_PLAY;
			} else {
				char *uri = song_get_uri(dc.next_song);
				g_warning("problems opening audio device "
					  "while playing \"%s\"", uri);
				g_free(uri);

				assert(dc.next_song == NULL || dc.next_song->url != NULL);
				pc.errored_song = dc.next_song;
				pc.error = PLAYER_ERROR_AUDIO;

				player->paused = true;
			}
		}
		player_command_finished();
		break;

	case PLAYER_COMMAND_SEEK:
		dropBufferedAudio();
		if (player_seek_decoder(player)) {
			player->xfade = XFADE_UNKNOWN;

			/* abort buffering when the user has requested
			   a seek */
			player->buffering = false;
		}
		break;

	case PLAYER_COMMAND_CANCEL:
		if (pc.next_song == NULL) {
			/* the cancel request arrived too later, we're
			   already playing the queued song...  stop
			   everything now */
			pc.command = PLAYER_COMMAND_STOP;
			return;
		}

		if (player->next_song_chunk != -1) {
			/* the decoder is already decoding the song -
			   stop it and reset the position */
			dc_stop(&pc.notify);
			music_pipe_chop(player->next_song_chunk);
			player->next_song_chunk = -1;
		}

		pc.next_song = NULL;
		player->queued = false;
		player_command_finished();
		break;
	}
}

static int
play_chunk(struct song *song, struct music_chunk *chunk,
	   const struct audio_format *format, double sizeToTime)
{
	pc.elapsed_time = chunk->times;
	pc.bit_rate = chunk->bit_rate;

	if (chunk->tag != NULL) {
		sendMetadataToAudioDevice(chunk->tag);

		if (!song_is_file(song)) {
			/* always update the tag of remote streams */
			struct tag *old_tag = song->tag;

			song->tag = tag_dup(chunk->tag);

			if (old_tag != NULL)
				tag_free(old_tag);

			/* the main thread will update the playlist
			   version when he receives this event */
			event_pipe_emit(PIPE_EVENT_TAG);

			/* notify all clients that the tag of the
			   current song has changed */
			idle_add(IDLE_PLAYER);
		}
	}

	if (chunk->length == 0)
		return 0;

	pcm_volume(chunk->data, chunk->length,
		   format, pc.software_volume);

	if (!playAudio(chunk->data, chunk->length))
		return -1;

	pc.total_play_time += sizeToTime * chunk->length;
	return 0;
}

static void do_play(void)
{
	struct player player = {
		.buffering = true,
		.decoder_starting = false,
		.paused = false,
		.queued = false,
		.song = NULL,
		.xfade = XFADE_UNKNOWN,
		.next_song_chunk = -1,
	};
	unsigned int crossFadeChunks = 0;
	/** the position of the next cross-faded chunk in the next
	    song */
	int nextChunk = 0;
	static const char silence[CHUNK_SIZE];
	struct audio_format play_audio_format;
	double sizeToTime = 0.0;

	music_pipe_clear();
	music_pipe_set_lazy(false);

	dc_start(&pc.notify, pc.next_song);
	if (player_wait_for_decoder(&player) < 0) {
		player_stop_decoder();
		player_command_finished();
		return;
	}

	pc.elapsed_time = 0;
	pc.state = PLAYER_STATE_PLAY;
	player_command_finished();

	while (1) {
		player_process_command(&player);
		if (pc.command == PLAYER_COMMAND_STOP ||
		    pc.command == PLAYER_COMMAND_EXIT ||
		    pc.command == PLAYER_COMMAND_CLOSE_AUDIO) {
			dropBufferedAudio();
			break;
		}

		if (player.buffering) {
			if (music_pipe_available() < pc.buffered_before_play &&
			    !decoder_is_idle()) {
				/* not enough decoded buffer space yet */
				notify_wait(&pc.notify);
				continue;
			} else {
				/* buffering is complete */
				player.buffering = false;
				music_pipe_set_lazy(true);
			}
		}

		if (player.decoder_starting) {
			if (decoder_has_failed()) {
				/* the decoder failed */
				assert(dc.next_song == NULL || dc.next_song->url != NULL);
				pc.errored_song = dc.next_song;
				pc.error = PLAYER_ERROR_FILE;
				break;
			}
			else if (!decoder_is_starting()) {
				/* the decoder is ready and ok */
				player.decoder_starting = false;
				if (!openAudioDevice(&dc.out_audio_format)) {
					char *uri = song_get_uri(dc.next_song);
					g_warning("problems opening audio device "
						  "while playing \"%s\"", uri);
					g_free(uri);

					assert(dc.next_song == NULL || dc.next_song->url != NULL);
					pc.errored_song = dc.next_song;
					pc.error = PLAYER_ERROR_AUDIO;
					break;
				}

				if (player.paused)
					closeAudioDevice();

				pc.total_time = dc.total_time;
				pc.audio_format = dc.in_audio_format;
				play_audio_format = dc.out_audio_format;
				sizeToTime = audioFormatSizeToTime(&dc.out_audio_format);
			}
			else {
				/* the decoder is not yet ready; wait
				   some more */
				notify_wait(&pc.notify);
				continue;
			}
		}

#ifndef NDEBUG
		/*
		music_pipe_check_format(&play_audio_format,
					player.next_song_chunk,
					&dc.out_audio_format);
		*/
#endif

		if (decoder_is_idle() && player.queued) {
			/* the decoder has finished the current song;
			   make it decode the next song */
			assert(pc.next_song != NULL);
			assert(player.next_song_chunk == -1);

			player.queued = false;
			player.next_song_chunk = music_pipe_tail_index();
			dc_start_async(pc.next_song);
		}
		if (player.next_song_chunk >= 0 &&
		    player.xfade == XFADE_UNKNOWN &&
		    !decoder_is_starting()) {
			/* enable cross fading in this song?  if yes,
			   calculate how many chunks will be required
			   for it */
			crossFadeChunks =
				cross_fade_calc(pc.cross_fade_seconds, dc.total_time,
						&dc.out_audio_format,
						music_pipe_size() -
						pc.buffered_before_play);
			if (crossFadeChunks > 0) {
				player.xfade = XFADE_ENABLED;
				nextChunk = -1;
			} else
				/* cross fading is disabled or the
				   next song is too short */
				player.xfade = XFADE_DISABLED;
		}

		if (player.paused)
			notify_wait(&pc.notify);
		else if (!music_pipe_is_empty() &&
			 !music_pipe_head_is(player.next_song_chunk)) {
			struct music_chunk *beginChunk = music_pipe_peek();
			unsigned int fadePosition;
			if (player.xfade == XFADE_ENABLED &&
			    player.next_song_chunk >= 0 &&
			    (fadePosition = music_pipe_relative(player.next_song_chunk))
			    <= crossFadeChunks) {
				/* perform cross fade */
				if (nextChunk < 0) {
					/* beginning of the cross fade
					   - adjust crossFadeChunks
					   which might be bigger than
					   the remaining number of
					   chunks in the old song */
					crossFadeChunks = fadePosition;
				}
				nextChunk = music_pipe_absolute(crossFadeChunks);
				if (nextChunk >= 0) {
					music_pipe_set_lazy(true);
					cross_fade_apply(beginChunk,
							 music_pipe_get_chunk(nextChunk),
							 &dc.out_audio_format,
							 fadePosition,
							 crossFadeChunks);
				} else {
					/* there are not enough
					   decoded chunks yet */
					if (decoder_is_idle()) {
						/* the decoder isn't
						   running, abort
						   cross fading */
						player.xfade = XFADE_DISABLED;
					} else {
						/* wait for the
						   decoder */
						music_pipe_set_lazy(false);
						notify_signal(&dc.notify);
						notify_wait(&pc.notify);

						/* set nextChunk to a
						   non-negative value
						   so the next
						   iteration doesn't
						   assume crossfading
						   hasn't begun yet */
						nextChunk = 0;
						continue;
					}
				}
			}

			/* play the current chunk */
			if (play_chunk(player.song, beginChunk,
				       &play_audio_format, sizeToTime) < 0)
				break;
			music_pipe_shift();

			/* this formula should prevent that the
			   decoder gets woken up with each chunk; it
			   is more efficient to make it decode a
			   larger block at a time */
			if (music_pipe_available() <= (pc.buffered_before_play + music_pipe_size() * 3) / 4)
				notify_signal(&dc.notify);
		} else if (music_pipe_head_is(player.next_song_chunk)) {
			/* at the beginning of a new song */

			if (player.xfade == XFADE_ENABLED && nextChunk >= 0) {
				/* the cross-fade is finished; skip
				   the section which was cross-faded
				   (and thus already played) */
				music_pipe_skip(crossFadeChunks);
			}

			player.xfade = XFADE_UNKNOWN;

			player.next_song_chunk = -1;
			if (player_wait_for_decoder(&player) < 0)
				return;
		} else if (decoder_is_idle()) {
			break;
		} else {
			size_t frame_size =
				audio_format_frame_size(&play_audio_format);
			/* this formula ensures that we don't send
			   partial frames */
			unsigned num_frames = CHUNK_SIZE / frame_size;

			/*DEBUG("waiting for decoded audio, play silence\n");*/
			if (!playAudio(silence, num_frames * frame_size))
				break;
		}
	}

	player_stop_decoder();
}

static gpointer player_task(G_GNUC_UNUSED gpointer arg)
{
	while (1) {
		switch (pc.command) {
		case PLAYER_COMMAND_PLAY:
		case PLAYER_COMMAND_QUEUE:
			do_play();
			break;

		case PLAYER_COMMAND_STOP:
		case PLAYER_COMMAND_SEEK:
		case PLAYER_COMMAND_PAUSE:
			player_command_finished();
			break;

		case PLAYER_COMMAND_CLOSE_AUDIO:
			closeAudioDevice();
			player_command_finished();
			break;

		case PLAYER_COMMAND_EXIT:
			dc_quit(&pc.notify);
			closeAudioDevice();
			player_command_finished();
			g_thread_exit(NULL);
			break;

		case PLAYER_COMMAND_CANCEL:
			pc.next_song = NULL;
			player_command_finished();
			break;

		case PLAYER_COMMAND_NONE:
			notify_wait(&pc.notify);
			break;
		}
	}
	return NULL;
}

void player_create(void)
{
	GError *e = NULL;
	GThread *t;

	if (!(t = g_thread_create(player_task, NULL, FALSE, &e)))
		g_error("Failed to spawn player task: %s", e->message);
}