1 files changed, 130 insertions, 0 deletions
diff --git a/src/pcm/Volume.hxx b/src/pcm/Volume.hxx
new file mode 100644
index 000000000..a156fc72e
--- /dev/null
+++ b/src/pcm/Volume.hxx
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2003-2014 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.
+ */
+
+#ifndef MPD_PCM_VOLUME_HXX
+#define MPD_PCM_VOLUME_HXX
+
+#include "AudioFormat.hxx"
+#include "PcmBuffer.hxx"
+#include "PcmDither.hxx"
+
+#include <stdint.h>
+#include <stddef.h>
+
+#ifndef NDEBUG
+#include <assert.h>
+#endif
+
+class Error;
+template<typename T> struct ConstBuffer;
+
+/**
+ * Number of fractional bits for a fixed-point volume value.
+ */
+static constexpr unsigned PCM_VOLUME_BITS = 10;
+
+/**
+ * This value means "100% volume".
+ */
+static constexpr unsigned PCM_VOLUME_1 = 1024;
+static constexpr int PCM_VOLUME_1S = PCM_VOLUME_1;
+
+struct AudioFormat;
+
+/**
+ * Converts a float value (0.0 = silence, 1.0 = 100% volume) to an
+ * integer volume value (1000 = 100%).
+ */
+static inline int
+pcm_float_to_volume(float volume)
+{
+	return volume * PCM_VOLUME_1 + 0.5;
+}
+
+static inline float
+pcm_volume_to_float(int volume)
+{
+	return (float)volume / (float)PCM_VOLUME_1;
+}
+
+/**
+ * A class that converts samples from one format to another.
+ */
+class PcmVolume {
+	SampleFormat format;
+
+	unsigned volume;
+
+	PcmBuffer buffer;
+	PcmDither dither;
+
+public:
+	PcmVolume()
+		:volume(PCM_VOLUME_1) {
+#ifndef NDEBUG
+		format = SampleFormat::UNDEFINED;
+#endif
+	}
+
+#ifndef NDEBUG
+	~PcmVolume() {
+		assert(format == SampleFormat::UNDEFINED);
+	}
+#endif
+
+	unsigned GetVolume() const {
+		return volume;
+	}
+
+	/**
+	 * @param _volume the volume level in the range
+	 * [0..#PCM_VOLUME_1]; may be bigger than #PCM_VOLUME_1, but
+	 * then it will most likely clip a lot
+	 */
+	void SetVolume(unsigned _volume) {
+		volume = _volume;
+	}
+
+	/**
+	 * Opens the object, prepare for Apply().
+	 *
+	 * @param format the sample format
+	 * @param error location to store the error
+	 * @return true on success
+	 */
+	bool Open(SampleFormat format, Error &error);
+
+	/**
+	 * Closes the object.  After that, you may call Open() again.
+	 */
+	void Close() {
+#ifndef NDEBUG
+		assert(format != SampleFormat::UNDEFINED);
+		format = SampleFormat::UNDEFINED;
+#endif
+	}
+
+	/**
+	 * Apply the volume level.
+	 */
+	gcc_pure
+	ConstBuffer<void> Apply(ConstBuffer<void> src);
+};
+
+#endif