player_thread: move cross-fading to output thread

Remove cross_fade_apply(), and call pcm_mix() in the output thread,
mixing the chunk and chunk->other together.

4 files changed, 40 insertions, 0 deletions

diff --git a/src/output_control.c b/src/output_control.c
index 17edc3d72..bcedae247 100644
--- a/src/output_control.c
+++ b/src/output_control.c
@@ -301,4 +301,6 @@ void audio_output_finish(struct audio_output *ao)
 	g_mutex_free(ao->mutex);
 
 	filter_free(ao->filter);
+
+	pcm_buffer_deinit(&ao->cross_fade_buffer);
 }
diff --git a/src/output_init.c b/src/output_init.c
index 6ee340edc..a091e749a 100644
--- a/src/output_init.c
+++ b/src/output_init.c
@@ -191,6 +191,8 @@ audio_output_init(struct audio_output *ao, const struct config_param *param,
 	ao->pause = false;
 	ao->fail_timer = NULL;
 
+	pcm_buffer_init(&ao->cross_fade_buffer);
+
 	/* set up the filter chain */
 
 	ao->filter = filter_chain_new();
diff --git a/src/output_internal.h b/src/output_internal.h
index 06df9531b..06e209374 100644
--- a/src/output_internal.h
+++ b/src/output_internal.h
@@ -21,6 +21,7 @@
 #define MPD_OUTPUT_INTERNAL_H
 
 #include "audio_format.h"
+#include "pcm_buffer.h"
 
 #include <glib.h>
 
@@ -135,6 +136,11 @@ struct audio_output {
 	struct audio_format out_audio_format;
 
 	/**
+	 * The buffer used to allocate the cross-fading result.
+	 */
+	struct pcm_buffer cross_fade_buffer;
+
+	/**
 	 * The filter object of this audio output.  This is an
 	 * instance of chain_filter_plugin.
 	 */
diff --git a/src/output_thread.c b/src/output_thread.c
index c3e064c3f..7f1e4935e 100644
--- a/src/output_thread.c
+++ b/src/output_thread.c
@@ -24,6 +24,7 @@
 #include "chunk.h"
 #include "pipe.h"
 #include "player_control.h"
+#include "pcm_mix.h"
 #include "filter_plugin.h"
 #include "filter/convert_filter_plugin.h"
 #include "filter/replay_gain_filter_plugin.h"
@@ -299,6 +300,35 @@ ao_filter_chunk(struct audio_output *ao, const struct music_chunk *chunk,
 		ao->replay_gain_serial = chunk->replay_gain_serial;
 	}
 
+	/* cross-fade */
+
+	if (chunk->other != NULL) {
+		size_t other_length;
+		const char *other_data = ao_chunk_data(ao, chunk->other,
+						       &other_length);
+		if (other_length == 0) {
+			*length_r = 0;
+			return data;
+		}
+
+		/* if the "other" chunk is longer, then that trailer
+		   is used as-is, without mixing; it is part of the
+		   "next" song being faded in, and if there's a rest,
+		   it means cross-fading ends here */
+
+		if (length > other_length)
+			length = other_length;
+
+		char *dest = pcm_buffer_get(&ao->cross_fade_buffer,
+					    other_length);
+		memcpy(dest, other_data, other_length);
+		pcm_mix(dest, data, length, &ao->in_audio_format,
+			1.0 - chunk->mix_ratio);
+
+		data = dest;
+		length = other_length;
+	}
+
 	/* apply filter chain */
 
 	data = filter_filter(ao->filter, data, length, &length, &error);