core rewrite (decode,player,outputBuffer,playlist)

This is a huge refactoring of the core mpd process.  The
queueing/buffering mechanism is heavily reworked.

The player.c code has been merged into outputBuffer (the actual
ring buffering logic is handled by ringbuf.c); and decode.c
actually handles decoding stuff.

The end result is several hundreds of lines shorter, even though
we still have a lot of DEBUG statements left in there for
tracing and a lot of assertions, too.

1 files changed, 476 insertions, 185 deletions

diff --git a/src/outputBuffer.c b/src/outputBuffer.c
index b0cfc00df..26e6077f2 100644
--- a/src/outputBuffer.c
+++ b/src/outputBuffer.c
@@ -20,252 +20,543 @@
 
 #include "utils.h"
 #include "normalize.h"
-#include "playerData.h"
-
-void ob_init(unsigned int size)
+#include "ringbuf.h"
+#include "condition.h"
+#include "song.h"
+#include "main_notify.h"
+#include "player_error.h"
+#include "log.h"
+#include "action_status.h"
+
+/* typically have 2048-4096 of these structs, so pack tightly */
+struct ob_chunk {
+	mpd_uint16 len; /* 0: skip this chunk */
+	mpd_uint16 bit_rate;
+	float time;
+	mpd_uint8 seq; /* see seq_ok() for explanation */
+	char data[CHUNK_SIZE];
+};
+
+enum ob_xfade_state {
+	XFADE_DISABLED = 0,
+	XFADE_ENABLED
+};
+
+static struct condition ob_action_cond = STATIC_COND_INITIALIZER;
+static struct condition ob_halt_cond = STATIC_COND_INITIALIZER;
+static struct condition ob_seq_cond = STATIC_COND_INITIALIZER;
+
+struct output_buffer {
+	struct ringbuf *index; /* index for chunks */
+	struct ob_chunk *chunks;
+	size_t nr_bpp; /* nr (chunks) buffered before play */
+	enum ob_state state; /* protected by ob_action_cond */
+	enum ob_action action; /* protected by ob_action_cond */
+	enum ob_xfade_state xfade_state; /* thread-internal */
+	int sw_vol;
+	int bit_rate;
+	float total_time;
+	float elapsed_time;
+	AudioFormat audio_format;
+	size_t xfade_cur;
+	size_t xfade_max;
+	float xfade_time;
+	void *conv_buf;
+	size_t conv_buf_len;
+	pthread_t thread;
+	ConvState conv_state;
+	unsigned int seq_drop;
+	unsigned int seq_player; /* only gets changed by ob.thread */
+	mpd_uint8 seq_decoder; /* only gets changed by dc.thread */
+	struct ringbuf preseek_index;
+	enum ob_state preseek_state;
+	mpd_uint16 *preseek_len;
+};
+
+static struct output_buffer ob;
+
+#include "outputBuffer_xfade.h"
+#include "outputBuffer_accessors.h"
+
+static void ob_free(void)
 {
-	assert(size > 0);
-
-	memset(&ob.convState, 0, sizeof(ConvState));
-	ob.chunks = xmalloc(size * sizeof(*ob.chunks));
-	ob.size = size;
-	ob.begin = 0;
-	ob.end = 0;
-	ob.lazy = 0;
-	ob.chunks[0].chunkSize = 0;
+	free(ob.chunks);
+	ringbuf_free(ob.index);
 }
 
-void ob_free(void)
+static enum action_status ob_do_stop(void);
+static void stop_playback(void)
 {
-	assert(ob.chunks != NULL);
-	free(ob.chunks);
+	assert(pthread_equal(pthread_self(), ob.thread));
+	cond_enter(&ob_action_cond);
+	ob_do_stop();
+	cond_leave(&ob_action_cond);
 }
 
-void ob_clear(void)
+void ob_trigger_action(enum ob_action action)
 {
-	ob.end = ob.begin;
-	ob.chunks[ob.end].chunkSize = 0;
+	/*
+	 * This can be called by both dc.thread and main_thread, but only one
+	 * action can be in progress at once.  So we use this private mutex
+	 * to protect against simultaneous invocations stepping over
+	 * each other
+	 */
+	static pthread_mutex_t trigger_lock = PTHREAD_MUTEX_INITIALIZER;
+	pthread_mutex_lock(&trigger_lock);
+	DEBUG(__FILE__": %d action: %d\n", __LINE__, action);
+	assert(!pthread_equal(pthread_self(), ob.thread));
+	DEBUG(__FILE__":%s %d\n", __func__, __LINE__);
+	cond_enter(&ob_action_cond);
+	DEBUG(__FILE__":%s %d\n", __func__, __LINE__);
+	assert(ob.action == OB_ACTION_NONE);
+
+	if (pthread_equal(pthread_self(), dc.thread))
+		assert(action == OB_ACTION_PLAY ||
+		       action == OB_ACTION_SEEK_START ||
+		       action == OB_ACTION_SEEK_FINISH);
+	else
+		assert(action != OB_ACTION_PLAY &&
+		       action != OB_ACTION_SEEK_START &&
+		       action != OB_ACTION_SEEK_FINISH);
+	ob.action = action;
+	do {
+		switch (ob.state) {
+		case OB_STATE_PAUSE:
+		case OB_STATE_STOP:
+		case OB_STATE_SEEK:
+			DEBUG(__FILE__":%s %d\n", __func__, __LINE__);
+			cond_signal_sync(&ob_halt_cond);
+			DEBUG(__FILE__":%s %d\n", __func__, __LINE__);
+			break;
+		default: break;
+		}
+		DEBUG(__FILE__":%s %d\n", __func__, __LINE__);
+		cond_wait(&ob_action_cond);
+	} while (ob.action != OB_ACTION_NONE);
+	DEBUG(__FILE__":%s %d\n", __func__, __LINE__);
+	assert(ob.action == OB_ACTION_NONE);
+	cond_leave(&ob_action_cond);
+	DEBUG(__FILE__":%s %d\n", __func__, __LINE__);
+	pthread_mutex_unlock(&trigger_lock);
 }
 
-/** return the index of the chunk after i */
-static inline unsigned successor(unsigned i)
+static enum action_status ob_finalize_action(void)
 {
-	assert(i <= ob.size);
-
-	++i;
-	return i == ob.size ? 0 : i;
+	assert(pthread_equal(pthread_self(), ob.thread));
+	ob.action = OB_ACTION_NONE;
+	/* DEBUG(__FILE__ ":%s signaling %d\n", __func__, __LINE__); */
+	cond_signal(&ob_action_cond);
+	cond_leave(&ob_action_cond);
+	return AS_COMPLETE;
 }
 
-/**
- * Mark the tail chunk as "full" and wake up the player if is waiting
- * for the decoder.
- */
-static void output_buffer_expand(unsigned i)
+/* marks all buffered chunks with sequence number matching `seq' as invalid */
+static enum action_status ob_do_drop(void)
 {
-	int was_empty = !ob.lazy || ob_is_empty();
-
-	assert(i == (ob.end + 1) % ob.size);
-	assert(i != ob.end);
-
-	ob.end = i;
-	ob.chunks[i].chunkSize = 0;
-	if (was_empty)
-		/* if the buffer was empty, the player thread might be
-		   waiting for us; wake it up now that another decoded
-		   buffer has become available. */
-		decoder_wakeup_player();
+	struct iovec vec[2];
+	long i;
+	unsigned int seq_drop;
+
+	cond_enter(&ob_seq_cond);
+	seq_drop = ob.seq_drop;
+	/* drop the audio that we've already pushed to the device, too */
+	if (seq_drop == ob.seq_player)
+		dropBufferedAudio();
+	cond_leave(&ob_seq_cond);
+
+	assert(pthread_equal(pthread_self(), ob.thread));
+	for (i = (long)ringbuf_get_read_vector(ob.index, vec); --i >= 0; ) {
+		struct ob_chunk *c = get_chunk(vec, i);
+		assert(c);
+		if (c->seq == seq_drop)
+			c->len = 0;
+	}
+	return ob_finalize_action();
 }
 
-void ob_flush(void)
+static void close_audio_devices(void);
+static enum action_status ob_do_pause(void)
 {
-	ob_chunk *chunk = ob_get_chunk(ob.end);
-
-	if (chunk->chunkSize > 0) {
-		unsigned int next = successor(ob.end);
-		if (next == ob.begin)
-			/* all buffers are full; we have to wait for
-			   the player to free one, so don't flush
-			   right now */
-			return;
+	assert(pthread_equal(pthread_self(), ob.thread));
+	ob.xfade_state = XFADE_DISABLED;
+	/*
+	 * This will eventually set certain outputs (like shout) into 'pause'
+	 * state where it'll just play silence instead of disconnecting
+	 * listeners
+	 */
+	close_audio_devices();
+	ob.state = OB_STATE_PAUSE;
+	return AS_INPROGRESS;
+}
 
-		output_buffer_expand(next);
+static void reader_reset_buffer(void)
+{
+	struct iovec vec[2];
+	size_t nr;
+	long i;
+
+	assert(pthread_equal(pthread_self(), ob.thread));
+	nr = ringbuf_get_read_vector(ob.index, vec);
+	for (i = nr; --i >= 0; ) {
+		struct ob_chunk *c = get_chunk(vec, i);
+		assert(c);
+		c->len = 0;
 	}
+	ringbuf_read_advance(ob.index, nr);
 }
 
-void ob_set_lazy(int lazy)
+static void ob_seq_player_set(unsigned int seq_num)
 {
-	ob.lazy = lazy;
+	cond_enter(&ob_seq_cond);
+	ob.seq_player = seq_num;
+	cond_signal(&ob_seq_cond);
+	cond_leave(&ob_seq_cond);
 }
 
-int ob_is_empty(void)
+static enum action_status ob_do_stop(void)
 {
-	return ob.begin == ob.end;
+	assert(pthread_equal(pthread_self(), ob.thread));
+	if (ob.state != OB_STATE_STOP) {
+		ob.elapsed_time = 0;
+		reader_reset_buffer();
+		ob.xfade_state = XFADE_DISABLED;
+		close_audio_devices();
+		ob.state = OB_STATE_STOP;
+		ob_seq_player_set((unsigned int)ob.seq_decoder);
+	}
+	return AS_INPROGRESS;
 }
 
-void ob_shift(void)
+/*
+ * we need to reset the buffer *before* we seek because the decoder
+ * _may_ try to flush out the last remnants of the previously decoded audio,
+ * so we need to ensure there is space available for that
+ */
+static enum action_status ob_do_seek_start(void)
 {
-	assert(ob.begin != ob.end);
-	assert(ob.begin < ob.size);
-
-	ob.begin = successor(ob.begin);
+	int i;
+
+	assert(pthread_equal(pthread_self(), ob.thread));
+
+	/* preserve pre-seek ringbuf and state information */
+	memcpy(&ob.preseek_index, ob.index, sizeof(struct ringbuf));
+	for (i = ob.preseek_index.size; --i >= 0; )
+		ob.preseek_len[i] = ob.chunks[i].len;
+	ob.preseek_state = ob.state;
+	ob.state = OB_STATE_SEEK;
+	reader_reset_buffer();
+	return AS_INPROGRESS;
 }
 
-unsigned int ob_relative(const unsigned i)
+static enum action_status ob_do_seek_finish(void)
 {
-	if (i >= ob.begin)
-		return i - ob.begin;
-	else
-		return i + ob.size - ob.begin;
+	assert(pthread_equal(pthread_self(), ob.thread));
+	assert(ob.state == OB_STATE_SEEK);
+	ob.state = ob.preseek_state;
+	if (dc.seek_where < 0) {
+		int i;
+		assert(dc.seek_where == DC_SEEK_MISMATCH ||
+		       dc.seek_where == DC_SEEK_ERROR);
+
+		/* restore the old ringbuf index if we failed to seek */
+		memcpy(ob.index, &ob.preseek_index, sizeof(struct ringbuf));
+		for (i = ob.preseek_index.size; --i >= 0; )
+			ob.chunks[i].len = ob.preseek_len[i];
+	} else {
+		assert(dc.seek_where >= 0);
+		ob.xfade_state = XFADE_DISABLED;
+		ob.elapsed_time = dc.seek_where;
+		ob.total_time = dc.total_time;
+		reader_reset_buffer();
+		dropBufferedAudio();
+		ob_seq_player_set((unsigned int)ob.seq_decoder);
+	}
+	return ob_finalize_action();
 }
 
-unsigned ob_available(void)
+static enum action_status ob_take_action(void)
 {
-	return ob_relative(ob.end);
+	assert(pthread_equal(pthread_self(), ob.thread));
+	if (mpd_likely(ob.action == OB_ACTION_NONE))
+		return AS_COMPLETE;
+	DEBUG(__FILE__": %s %d\n", __func__, __LINE__);
+	cond_enter(&ob_action_cond);
+	DEBUG(__FILE__": %s %d action: %d\n", __func__, __LINE__, ob.action);
+	switch (ob.action) {
+	case OB_ACTION_NONE: return ob_finalize_action();
+	case OB_ACTION_PLAY: ob.state = OB_STATE_PLAY; break;
+	case OB_ACTION_DROP: return ob_do_drop();
+	case OB_ACTION_SEEK_START: return ob_do_seek_start();
+	case OB_ACTION_SEEK_FINISH: return ob_do_seek_finish();
+	case OB_ACTION_PAUSE_SET:
+		if (ob.state == OB_STATE_PLAY)
+			return ob_do_pause();
+		ob.state = OB_STATE_PAUSE;
+		break;
+	case OB_ACTION_PAUSE_UNSET:
+		if (ob.state == OB_STATE_PAUSE)
+			ob.state = OB_STATE_PLAY;
+		break;
+	case OB_ACTION_PAUSE_FLIP:
+		switch (ob.state) {
+		case OB_STATE_PLAY: return ob_do_pause();
+		case OB_STATE_PAUSE: ob.state = OB_STATE_PLAY; break;
+		default: break;
+		}
+		break;
+	case OB_ACTION_STOP: return ob_do_stop();
+	case OB_ACTION_QUIT:
+		close_audio_devices();
+		ob.state = OB_STATE_QUIT;
+		return AS_INPROGRESS;
+	}
+	return ob_finalize_action();
 }
 
-int ob_absolute(const unsigned relative)
+/*
+ * looks up the chunk given by index `i', returns NULL if `i' is beyond
+ * the end of the buffer.  This allows us to treat our chunks array
+ * like an infinite, rotating buffer.  The first available chunk
+ * is always indexed as `0', the second one as `1', and so on...
+ */
+static struct ob_chunk *get_chunk(struct iovec vec[2], size_t i)
 {
-	unsigned i, max;
-
-	max = ob.end;
-	if (max < ob.begin)
-		max += ob.size;
-	i = (unsigned)ob.begin + relative;
-	if (i >= max)
-		return -1;
+	if (vec[0].iov_len > i)
+		return &ob.chunks[vec[0].iov_base + i - ob.index->buf];
+	if (vec[1].iov_base) {
+		assert(vec[0].iov_len > 0);
+		i -= vec[0].iov_len;
+		if (vec[1].iov_len > i)
+			return &ob.chunks[vec[1].iov_base + i - ob.index->buf];
+	}
+	return NULL;
+}
 
-	if (i >= ob.size)
-		i -= ob.size;
+static void prevent_buffer_underrun(void)
+{
+	static const char silence[CHUNK_SIZE];
+	if (playAudio(silence, sizeof(silence)) < 0)
+		stop_playback();
+}
 
-	return (int)i;
+/* causes ob_do_drop() to be called (and waits for completion) */
+void ob_drop_audio(enum ob_drop_type type)
+{
+	assert(!pthread_equal(pthread_self(), ob.thread));
+	assert(!pthread_equal(pthread_self(), dc.thread));
+	assert(dc.state == DC_STATE_STOP); /* not needed, just a good idea */
+	cond_enter(&ob_seq_cond);
+	switch (type) {
+	case OB_DROP_DECODED: ob.seq_drop = ob.seq_decoder; break;
+	case OB_DROP_PLAYING: ob.seq_drop = ob.seq_player; break;
+	}
+	cond_leave(&ob_seq_cond);
+	/* DEBUG("dropping %u\n", ob.seq_drop); */
+	ob_trigger_action(OB_ACTION_DROP);
+	/* DEBUG("done dropping %u\n", ob.seq_drop); */
 }
 
-ob_chunk * ob_get_chunk(const unsigned i)
+void ob_wait_sync(void)
 {
-	assert(i < ob.size);
+	assert(!pthread_equal(pthread_self(), dc.thread));
+	assert(!pthread_equal(pthread_self(), ob.thread));
+
+	/* DEBUG(__FILE__": %s %d\n", __func__, __LINE__); */
+	cond_enter(&ob_seq_cond);
+	while (ob.seq_player != ob.seq_decoder) {
+		/* DEBUG("%s %d seq_player:%u seq_decoder:%u\n", */
+		      /* __func__, __LINE__, ob.seq_player, ob.seq_decoder); */
+		cond_wait(&ob_seq_cond);
+		/* DEBUG("%s %d seq_player:%u seq_decoder:%u\n", */
+		      /* __func__, __LINE__, ob.seq_player, ob.seq_decoder); */
+	}
+	cond_leave(&ob_seq_cond);
+	/* DEBUG(__FILE__": %s %d\n", __func__, __LINE__); */
+}
 
-	return &ob.chunks[i];
+/* call this exactly once before decoding each song */
+void ob_advance_sequence(void)
+{
+	assert(pthread_equal(pthread_self(), dc.thread));
+	DEBUG(__FILE__": %s %d\n", __func__, __LINE__);
+	cond_enter(&ob_seq_cond);
+	++ob.seq_decoder;
+	cond_leave(&ob_seq_cond);
+	DEBUG(__FILE__": %s %d\n", __func__, __LINE__);
+	DEBUG("ob.seq_decoder: %d\n", ob.seq_decoder);
 }
 
-/**
- * Return the tail chunk which has room for additional data.  If there
- * is no room in the queue, this function blocks until the player
- * thread has finished playing its current chunk.
- *
- * @return the positive index of the new chunk; OUTPUT_BUFFER_DC_SEEK
- * if another thread requested seeking; OUTPUT_BUFFER_DC_STOP if
- * another thread requested stopping the decoder.
+/*
+ * Returns true if output buffer is playing the song we're decoding
  */
-static int tailChunk(InputStream * inStream,
-		     int seekable, float data_time, mpd_uint16 bitRate)
+int ob_synced(void)
 {
-	unsigned int next;
-	ob_chunk *chunk;
-
-	chunk = ob_get_chunk(ob.end);
-	assert(chunk->chunkSize <= sizeof(chunk->data));
-	if (chunk->chunkSize == sizeof(chunk->data)) {
-		/* this chunk is full; allocate a new chunk */
-		next = successor(ob.end);
-		while (ob.begin == next) {
-			/* all chunks are full of decoded data; wait
-			   for the player to free one */
-
-			if (dc.stop)
-				return OUTPUT_BUFFER_DC_STOP;
-
-			if (dc.seek) {
-				if (seekable) {
-					return OUTPUT_BUFFER_DC_SEEK;
-				} else {
-					dc.seekError = 1;
-					dc.seek = 0;
-					decoder_wakeup_player();
-				}
-			}
-			if (!inStream || bufferInputStream(inStream) <= 0) {
-				decoder_sleep();
-			}
-		}
+	int ret;
+	assert(!pthread_equal(pthread_self(), dc.thread));
+	assert(!pthread_equal(pthread_self(), ob.thread));
+	/* assert(pthread_equal(pthread_self(), main_thread)); */
+	cond_enter(&ob_seq_cond);
+	ret = (ob.seq_decoder == ob.seq_player);
+	cond_leave(&ob_seq_cond);
+	return ret;
+}
+
+static void new_song_chunk(struct ob_chunk *a)
+{
+	assert(pthread_equal(pthread_self(), ob.thread));
+	ob.xfade_state = XFADE_DISABLED;
+	ob.total_time = dc.total_time;
+	/* DEBUG("ob.total_time: %f\n", ob.total_time); */
+	ob_seq_player_set((unsigned int)a->seq);
+	wakeup_main_task(); /* sync playlist */
+}
+
+#include "outputBuffer_audio.h"
 
-		output_buffer_expand(next);
-		chunk = ob_get_chunk(next);
-		assert(chunk->chunkSize == 0);
+static void play_next_chunk(void)
+{
+	struct iovec vec[2];
+	struct ob_chunk *a;
+	size_t nr;
+	static float last_time;
+
+	assert(pthread_equal(pthread_self(), ob.thread));
+
+	nr = ringbuf_get_read_vector(ob.index, vec);
+	if (mpd_unlikely(!nr &&
+			 (dc.state == DC_STATE_STOP) &&
+	                 ! playlist_playing())) {
+		stop_playback();
+		return;
+	}
+	if (nr < ((ob.xfade_time <= 0) ? ob.nr_bpp : xfade_chunks_needed(vec)))
+	{
+		prevent_buffer_underrun();
+		return;
 	}
 
-	if (chunk->chunkSize == 0) {
-		/* if the chunk is empty, nobody has set bitRate and
-		   times yet */
+	a = get_chunk(vec, 0);
+	assert(a);
+	if (! a->len)
+		goto out;
 
-		chunk->bitRate = bitRate;
-		chunk->times = data_time;
+	if (nr > 1 && ob.xfade_state == XFADE_ENABLED) {
+		struct ob_chunk *b = get_chunk(vec, ob.xfade_max);
+		xfade_mix(a, b);
 	}
 
-	return ob.end;
+	last_time = ob.elapsed_time = a->time;
+	ob.bit_rate = a->bit_rate;
+
+	if (mpd_unlikely(ob.seq_player != a->seq)) {
+		if (open_audio_devices(1) < 0)
+			return;
+		new_song_chunk(a);
+	}
+	/* pcm_volumeChange(a->data, a->len, &ob.audio_format, ob.sw_vol); */
+	if (playAudio(a->data, a->len) < 0)
+		stop_playback();
+	a->len = 0; /* mark the chunk as empty for ob_send() */
+out:
+	ringbuf_read_advance(ob.index, 1);
+
+	/* unblock ob_send() if it was waiting on a full buffer */
+	dc_try_unhalt();
 }
 
-int ob_send(InputStream * inStream,
-			   int seekable, void *dataIn,
-			   size_t dataInLen, float data_time, mpd_uint16 bitRate,
-			   ReplayGainInfo * replayGainInfo)
+static void * ob_task(mpd_unused void *arg)
 {
-	size_t dataToSend;
-	char *data;
-	size_t datalen;
-	static char *convBuffer;
-	static size_t convBufferLen;
-	ob_chunk *chunk = NULL;
-
-	if (cmpAudioFormat(&(ob.audioFormat), &(dc.audioFormat)) == 0) {
-		data = dataIn;
-		datalen = dataInLen;
-	} else {
-		datalen = pcm_sizeOfConvBuffer(&(dc.audioFormat), dataInLen,
-		                               &(ob.audioFormat));
-		if (datalen > convBufferLen) {
-			if (convBuffer != NULL)
-				free(convBuffer);
-			convBuffer = xmalloc(datalen);
-			convBufferLen = datalen;
+	enum action_status as;
+
+	assert(pthread_equal(pthread_self(), ob.thread));
+	cond_enter(&ob_halt_cond);
+	while (1) {
+		as = ob_take_action();
+		switch (ob.state) {
+		case OB_STATE_PLAY:
+			assert(as == AS_COMPLETE);
+			if (open_audio_devices(0) >= 0)
+				play_next_chunk();
+			break;
+		case OB_STATE_STOP:
+		case OB_STATE_PAUSE:
+		case OB_STATE_SEEK:
+			assert(as != AS_DEFERRED);
+			if (as == AS_INPROGRESS)
+				ob_finalize_action();
+			cond_wait(&ob_halt_cond);
+			break;
+		case OB_STATE_QUIT: goto out;
 		}
-		data = convBuffer;
-		datalen = pcm_convertAudioFormat(&(dc.audioFormat), dataIn,
-		                                 dataInLen, &(ob.audioFormat),
-		                                 data, &(ob.convState));
 	}
+out:
+	cond_leave(&ob_halt_cond);
+	assert(ob.state == OB_STATE_QUIT);
+	assert(as == AS_INPROGRESS);
+	ob_finalize_action();
+	return NULL;
+}
 
-	if (replayGainInfo && (replayGainState != REPLAYGAIN_OFF))
-		doReplayGain(replayGainInfo, data, datalen, &ob.audioFormat);
-	else if (normalizationEnabled)
-		normalizeData(data, datalen, &ob.audioFormat);
-
-	while (datalen) {
-		int chunk_index = tailChunk(inStream, seekable,
-					    data_time, bitRate);
-		if (chunk_index < 0)
-			return chunk_index;
-
-		chunk = ob_get_chunk(chunk_index);
-
-		dataToSend = sizeof(chunk->data) - chunk->chunkSize;
-		if (dataToSend > datalen)
-			dataToSend = datalen;
-
-		memcpy(chunk->data + chunk->chunkSize, data, dataToSend);
-		chunk->chunkSize += dataToSend;
-		datalen -= dataToSend;
-		data += dataToSend;
-	}
+void ob_init(size_t size)
+{
+	pthread_attr_t attr;
+	assert(size > 0 && !ob.index && !ob.chunks);
+	ob.index = ringbuf_create(size);
+	ob.chunks = xcalloc(ob.index->size, sizeof(struct ob_chunk));
+	ob.preseek_len = xmalloc(ob.index->size * sizeof(ob.chunks[0].len));
+	ob.nr_bpp = 1;
+	ob.state = OB_STATE_STOP;
+
+	pthread_attr_init(&attr);
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+	if (pthread_create(&ob.thread, &attr, ob_task, NULL))
+		FATAL("Failed to spawn player task: %s\n", strerror(errno));
+	atexit(ob_free);
+}
 
-	if (chunk != NULL && chunk->chunkSize == sizeof(chunk->data))
-		ob_flush();
+void ob_seek_start(void)
+{
+	assert(pthread_equal(pthread_self(), dc.thread));
+	assert(dc.seek_where >= 0);
+	ob_trigger_action(OB_ACTION_SEEK_START);
+}
 
-	return 0;
+void ob_seek_finish(void)
+{
+	assert(pthread_equal(pthread_self(), dc.thread));
+	ob_trigger_action(OB_ACTION_SEEK_FINISH);
 }
 
-void ob_skip(unsigned num)
+/*
+ * if there are any partially written chunk, flush them out to
+ * the output process _before_ decoding the next track
+ */
+void ob_flush(void)
 {
-	int i = ob_absolute(num);
-	if (i >= 0)
-		ob.begin = i;
+	struct iovec vec[2];
+
+	assert(pthread_equal(pthread_self(), dc.thread));
+	/* DEBUG(__FILE__":%s %d\n", __func__, __LINE__); */
+
+	if (ringbuf_get_write_vector(ob.index, vec)) {
+		/* DEBUG(__FILE__":%s %d\n", __func__, __LINE__); */
+		struct ob_chunk *c = get_chunk(vec, 0);
+		assert(c);
+		if (c->len) {
+			assert(ob.seq_decoder == c->seq);
+			switch (ob.state) {
+			case OB_STATE_SEEK:
+				assert(0);
+			case OB_STATE_PLAY:
+			case OB_STATE_PAUSE: /* should we assert if paused? */
+				ringbuf_write_advance(ob.index, 1);
+				break;
+			case OB_STATE_STOP:
+			case OB_STATE_QUIT:
+				c->len = 0;
+			}
+		}
+	}
 }
+
+#include "outputBuffer_ob_send.h"