replay_gain: refactor API, move code to replay_gain_state.c

The replay_gain_state struct holds the precalculated scale factor,
which is removed from struct replay_gain_info.

1 files changed, 142 insertions, 0 deletions

diff --git a/src/replay_gain_state.c b/src/replay_gain_state.c
new file mode 100644
index 000000000..c14ff6e10
--- /dev/null
+++ b/src/replay_gain_state.c
@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2003-2010 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "replay_gain_state.h"
+#include "pcm_volume.h"
+
+#include <glib.h>
+
+#include <assert.h>
+#include <math.h>
+
+struct replay_gain_state {
+	float preamp, missing_preamp;
+
+	enum replay_gain_mode mode;
+
+	struct replay_gain_info *info;
+
+	float scale;
+};
+
+struct replay_gain_state *
+replay_gain_state_new(float preamp, float missing_preamp)
+{
+	struct replay_gain_state *state = g_new(struct replay_gain_state, 1);
+
+	state->preamp = preamp;
+	state->missing_preamp = missing_preamp;
+	state->mode = REPLAY_GAIN_OFF;
+	state->info = NULL;
+
+	return state;
+}
+
+void
+replay_gain_state_free(struct replay_gain_state *state)
+{
+	assert(state != NULL);
+
+	if (state->info != NULL)
+		replay_gain_info_free(state->info);
+
+	g_free(state);
+}
+
+static float
+calc_replay_gain_scale(float gain, float peak, float preamp)
+{
+	float scale;
+
+	if (gain == 0.0)
+		return (1);
+	scale = pow(10.0, gain / 20.0);
+	scale *= preamp;
+	if (scale > 15.0)
+		scale = 15.0;
+
+	if (scale * peak > 1.0) {
+		scale = 1.0 / peak;
+	}
+	return (scale);
+}
+
+static void
+replay_gain_state_calc_scale(struct replay_gain_state *state)
+{
+	assert(state != NULL);
+
+	if (state->mode == REPLAY_GAIN_OFF || state->info == NULL)
+		return;
+
+	const struct replay_gain_tuple *tuple =
+		&state->info->tuples[state->mode];
+
+	g_debug("computing ReplayGain scale with gain %f, peak %f",
+		tuple->gain, tuple->peak);
+
+	state->scale = calc_replay_gain_scale(tuple->gain, tuple->peak,
+					      state->preamp);
+}
+
+void
+replay_gain_state_set_mode(struct replay_gain_state *state,
+			   enum replay_gain_mode mode)
+{
+	assert(state != NULL);
+
+	if (mode == state->mode)
+		return;
+
+	state->mode = mode;
+
+	replay_gain_state_calc_scale(state);
+}
+
+void
+replay_gain_state_set_info(struct replay_gain_state *state,
+			   const struct replay_gain_info *info)
+{
+	assert(state != NULL);
+
+	if (state->info != NULL)
+		replay_gain_info_free(state->info);
+
+	state->info = info != NULL
+		? replay_gain_info_dup(info)
+		: NULL;
+
+	replay_gain_state_calc_scale(state);
+}
+
+void
+replay_gain_state_apply(const struct replay_gain_state *state,
+			void *buffer, size_t size,
+			const struct audio_format *format)
+{
+	assert(state != NULL);
+
+	if (state->mode == REPLAY_GAIN_OFF)
+		return;
+
+	float scale = state->info != NULL
+		? state->scale : state->missing_preamp;
+	pcm_volume(buffer, size, format, pcm_float_to_volume(scale));
+}