1 files changed, 43 insertions, 3 deletions

diff --git a/src/pcm/PcmDither.hxx b/src/pcm/PcmDither.hxx
index 106382307..54b0f7315 100644
--- a/src/pcm/PcmDither.hxx
+++ b/src/pcm/PcmDither.hxx
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * 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
@@ -22,6 +22,8 @@
 
 #include <stdint.h>
 
+enum class SampleFormat : uint8_t;
+
 class PcmDither {
 	int32_t error[3];
 	int32_t random;
@@ -30,6 +32,18 @@ public:
 	constexpr PcmDither()
 		:error{0, 0, 0}, random(0) {}
 
+	/**
+	 * Shift the given sample by #SBITS-#DBITS to the right, and
+	 * apply dithering.
+	 *
+	 * @param ST the input sample type
+	 * @param SBITS the input bit width
+	 * @param DBITS the output bit width
+	 * @param sample the input sample value
+	 */
+	template<typename ST, unsigned SBITS, unsigned DBITS>
+	ST DitherShift(ST sample);
+
 	void Dither24To16(int16_t *dest, const int32_t *src,
 			  const int32_t *src_end);
 
@@ -37,8 +51,34 @@ public:
 			  const int32_t *src_end);
 
 private:
-	int16_t Dither24To16(int_fast32_t sample);
-	int16_t Dither32To16(int_fast32_t sample);
+	/**
+	 * Shift the given sample by #scale_bits to the right, and
+	 * apply dithering.
+	 *
+	 * @param T the input sample type
+	 * @param MIN the minimum input sample value
+	 * @param MAX the maximum input sample value
+	 * @param scale_bits the number of bits to be discarded
+	 * @param sample the input sample value
+	 */
+	template<typename T, T MIN, T MAX, unsigned scale_bits>
+	T Dither(T sample);
+
+	/**
+	 * Convert the given sample from one sample format to another,
+	 * discarding bits.
+	 *
+	 * @param ST the input #SampleTraits class
+	 * @param ST the output #SampleTraits class
+	 * @param sample the input sample value
+	 */
+	template<typename ST, typename DT>
+	typename DT::value_type DitherConvert(typename ST::value_type sample);
+
+	template<typename ST, typename DT>
+	void DitherConvert(typename DT::pointer_type dest,
+			   typename ST::const_pointer_type src,
+			   typename ST::const_pointer_type src_end);
 };
 
 #endif