1 files changed, 118 insertions, 0 deletions
diff --git a/src/pcm_mix.c b/src/pcm_mix.c
new file mode 100644
index 000000000..208805831
--- /dev/null
+++ b/src/pcm_mix.c
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * 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 "pcm_mix.h"
+#include "pcm_volume.h"
+#include "pcm_utils.h"
+#include "audio_format.h"
+
+#include <glib.h>
+
+#include <math.h>
+
+#undef G_LOG_DOMAIN
+#define G_LOG_DOMAIN "pcm"
+
+static void
+pcm_add_8(int8_t *buffer1, const int8_t *buffer2,
+	  unsigned num_samples, int volume1, int volume2)
+{
+	while (num_samples > 0) {
+		int32_t sample1 = *buffer1;
+		int32_t sample2 = *buffer2++;
+
+		sample1 = ((sample1 * volume1 + sample2 * volume2) +
+			   pcm_dither() + PCM_VOLUME_1 / 2) / PCM_VOLUME_1;
+
+		*buffer1++ = pcm_range(sample1, 8);
+		--num_samples;
+	}
+}
+
+static void
+pcm_add_16(int16_t *buffer1, const int16_t *buffer2,
+	   unsigned num_samples, int volume1, int volume2)
+{
+	while (num_samples > 0) {
+		int32_t sample1 = *buffer1;
+		int32_t sample2 = *buffer2++;
+
+		sample1 = ((sample1 * volume1 + sample2 * volume2) +
+			   pcm_dither() + PCM_VOLUME_1 / 2) / PCM_VOLUME_1;
+
+		*buffer1++ = pcm_range(sample1, 16);
+		--num_samples;
+	}
+}
+
+static void
+pcm_add_24(int32_t *buffer1, const int32_t *buffer2,
+	   unsigned num_samples, unsigned volume1, unsigned volume2)
+{
+	while (num_samples > 0) {
+		int64_t sample1 = *buffer1;
+		int64_t sample2 = *buffer2++;
+
+		sample1 = ((sample1 * volume1 + sample2 * volume2) +
+			   pcm_dither() + PCM_VOLUME_1 / 2) / PCM_VOLUME_1;
+
+		*buffer1++ = pcm_range(sample1, 24);
+		--num_samples;
+	}
+}
+
+static void
+pcm_add(char *buffer1, const char *buffer2, size_t size,
+	int vol1, int vol2,
+	const struct audio_format *format)
+{
+	switch (format->bits) {
+	case 8:
+		pcm_add_8((int8_t *)buffer1, (const int8_t *)buffer2,
+			  size, vol1, vol2);
+		break;
+
+	case 16:
+		pcm_add_16((int16_t *)buffer1, (const int16_t *)buffer2,
+			   size / 2, vol1, vol2);
+		break;
+
+	case 24:
+		pcm_add_24((int32_t*)buffer1,
+			   (const int32_t*)buffer2,
+			   size / 4, vol1, vol2);
+		break;
+
+	default:
+		g_error("%u bits not supported by pcm_add!\n", format->bits);
+	}
+}
+
+void
+pcm_mix(char *buffer1, const char *buffer2, size_t size,
+	const struct audio_format *format, float portion1)
+{
+	int vol1;
+	float s = sin(M_PI_2 * portion1);
+	s *= s;
+
+	vol1 = s * PCM_VOLUME_1 + 0.5;
+	vol1 = vol1 > PCM_VOLUME_1 ? PCM_VOLUME_1 : (vol1 < 0 ? 0 : vol1);
+
+	pcm_add(buffer1, buffer2, size, vol1, PCM_VOLUME_1 - vol1, format);
+}