pcm/export: support DSD_U16

Makefile.am

@@ -575,6 +575,7 @@ PCM_LIBS = \
 
 if ENABLE_DSD
 libpcm_a_SOURCES += \
+	src/pcm/Dsd16.cxx src/pcm/Dsd16.hxx \
 	src/pcm/Dsd32.cxx src/pcm/Dsd32.hxx \
 	src/pcm/PcmDsd.cxx src/pcm/PcmDsd.hxx \
 	src/pcm/dsd2pcm/dsd2pcm.c src/pcm/dsd2pcm/dsd2pcm.h

src/pcm/Dsd16.cxx

+/*
+ * Copyright 2003-2017 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 "Dsd16.hxx"
+#include "PcmBuffer.hxx"
+#include "util/ConstBuffer.hxx"
+
+/**
+ * Construct a 16 bit integer from two bytes.
+ */
+static constexpr inline uint16_t
+Construct16(uint8_t a, uint8_t b)
+{
+	/* "a" is the oldest byte, which must be in the most
+	   significant byte */
+
+	return uint16_t(b) | (uint16_t(a) << 8);
+}
+
+static constexpr inline uint16_t
+Dsd8To16Sample(const uint8_t *src, unsigned channels)
+{
+	return Construct16(src[0], src[channels]);
+}
+
+ConstBuffer<uint16_t>
+Dsd8To16(PcmBuffer &buffer, unsigned channels, ConstBuffer<uint8_t> _src)
+{
+	const size_t in_frames = _src.size / channels;
+	const size_t out_frames = in_frames / 2;
+	const size_t out_samples = out_frames * channels;
+
+	const uint8_t *src = _src.data;
+	uint16_t *const dest0 = buffer.GetT<uint16_t>(out_samples);
+	uint16_t *dest = dest0;
+
+	for (size_t i = 0; i < out_frames; ++i) {
+		for (size_t c = 0; c < channels; ++c)
+			*dest++ = Dsd8To16Sample(src++, channels);
+
+		src += channels;
+	}
+
+	return {dest0, out_samples};
+}

src/pcm/Dsd16.hxx

+/*
+ * Copyright 2003-2017 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_DSD_16_HXX
+#define MPD_PCM_DSD_16_HXX
+
+#include "check.h"
+
+#include <stdint.h>
+
+template<typename T> struct ConstBuffer;
+class PcmBuffer;
+
+/**
+ * Convert DSD_U8 to DSD_U16 (native endian, oldest bits in MSB).
+ */
+ConstBuffer<uint16_t>
+Dsd8To16(PcmBuffer &buffer, unsigned channels, ConstBuffer<uint8_t> src);
+
+#endif

src/pcm/PcmExport.cxx

@@ -25,6 +25,7 @@
 #include "util/ConstBuffer.hxx"
 
 #ifdef ENABLE_DSD
+#include "Dsd16.hxx"
 #include "Dsd32.hxx"
 #include "PcmDsd.hxx"
 #include "PcmDop.hxx"
@@ -42,9 +43,15 @@ PcmExport::Open(SampleFormat sample_format, unsigned _channels,
 		: SampleFormat::UNDEFINED;
 
 #ifdef ENABLE_DSD
-	assert(!params.dsd_u32 || !params.dop);
+	assert((params.dsd_u16 + params.dsd_u32 + params.dop) <= 1);
 	assert(!params.dop || audio_valid_channel_count(_channels));
 
+	dsd_u16 = params.dsd_u16 && sample_format == SampleFormat::DSD;
+	if (dsd_u16)
+		/* after the conversion to DSD_U16, the DSD samples
+		   are stuffed inside fake 16 bit samples */
+		sample_format = SampleFormat::S16;
+
 	dsd_u32 = params.dsd_u32 && sample_format == SampleFormat::DSD;
 	if (dsd_u32)
 		/* after the conversion to DSD_U32, the DSD samples
@@ -83,6 +90,9 @@ PcmExport::GetFrameSize(const AudioFormat &audio_format) const
 		return audio_format.channels * 3;
 
 #ifdef ENABLE_DSD
+	if (dsd_u16)
+		return channels * 2;
+
 	if (dsd_u32)
 		return channels * 4;
 
@@ -101,6 +111,11 @@ unsigned
 PcmExport::Params::CalcOutputSampleRate(unsigned sample_rate) const
 {
 #ifdef ENABLE_DSD
+	if (dsd_u16)
+		/* DSD_U16 combines two 8-bit "samples" in one 16-bit
+		   "sample" */
+		sample_rate /= 2;
+
 	if (dsd_u32)
 		/* DSD_U32 combines four 8-bit "samples" in one 32-bit
 		   "sample" */
@@ -119,6 +134,9 @@ unsigned
 PcmExport::Params::CalcInputSampleRate(unsigned sample_rate) const
 {
 #ifdef ENABLE_DSD
+	if (dsd_u16)
+		sample_rate *= 2;
+
 	if (dsd_u32)
 		sample_rate *= 4;
 
@@ -137,6 +155,11 @@ PcmExport::Export(ConstBuffer<void> data)
 					  alsa_channel_order, channels);
 
 #ifdef ENABLE_DSD
+	if (dsd_u16)
+		data = Dsd8To16(dop_buffer, channels,
+				ConstBuffer<uint8_t>::FromVoid(data))
+			.ToVoid();
+
 	if (dsd_u32)
 		data = Dsd8To32(dop_buffer, channels,
 				ConstBuffer<uint8_t>::FromVoid(data))

src/pcm/PcmExport.hxx

@@ -80,6 +80,11 @@ class PcmExport {
 
 #ifdef ENABLE_DSD
 	/**
+	 * Convert DSD (U8) to DSD_U16?
+	 */
+	bool dsd_u16;
+
+	/**
 	 * Convert DSD (U8) to DSD_U32?
 	 */
 	bool dsd_u32;
@@ -114,6 +119,7 @@ public:
 	struct Params {
 		bool alsa_channel_order = false;
 #ifdef ENABLE_DSD
+		bool dsd_u16 = false;
 		bool dsd_u32 = false;
 		bool dop = false;
 #endif

test/test_pcm_all.hxx

@@ -128,6 +128,7 @@ class PcmExportTest : public CppUnit::TestFixture {
 	CPPUNIT_TEST(TestPack24);
 	CPPUNIT_TEST(TestReverseEndian);
 #ifdef ENABLE_DSD
+	CPPUNIT_TEST(TestDsdU16);
 	CPPUNIT_TEST(TestDsdU32);
 	CPPUNIT_TEST(TestDop);
 #endif
@@ -139,6 +140,7 @@ public:
 	void TestPack24();
 	void TestReverseEndian();
 #ifdef ENABLE_DSD
+	void TestDsdU16();
 	void TestDsdU32();
 	void TestDop();
 #endif

test/test_pcm_export.cxx

@@ -127,6 +127,37 @@ PcmExportTest::TestReverseEndian()
 #ifdef ENABLE_DSD
 
 void
+PcmExportTest::TestDsdU16()
+{
+	static constexpr uint8_t src[] = {
+		0x01, 0x23, 0x45, 0x67,
+		0x89, 0xab, 0xcd, 0xef,
+		0x11, 0x22, 0x33, 0x44,
+		0x55, 0x66, 0x77, 0x88,
+	};
+
+	static constexpr uint16_t expected[] = {
+		0x0145, 0x2367,
+		0x89cd, 0xabef,
+		0x1133, 0x2244,
+		0x5577, 0x6688,
+	};
+
+	PcmExport::Params params;
+	params.dsd_u16 = true;
+
+	CPPUNIT_ASSERT_EQUAL(params.CalcOutputSampleRate(705600u), 352800u);
+	CPPUNIT_ASSERT_EQUAL(params.CalcInputSampleRate(352800u), 705600u);
+
+	PcmExport e;
+	e.Open(SampleFormat::DSD, 2, params);
+
+	auto dest = e.Export({src, sizeof(src)});
+	CPPUNIT_ASSERT_EQUAL(sizeof(expected), dest.size);
+	CPPUNIT_ASSERT(memcmp(dest.data, expected, dest.size) == 0);
+}
+
+void
 PcmExportTest::TestDsdU32()
 {
 	static constexpr uint8_t src[] = {