Initial community commit

1 files changed, 113 insertions, 0 deletions

diff --git a/Src/external_dependencies/openmpt-trunk/soundlib/MPEGFrame.cpp b/Src/external_dependencies/openmpt-trunk/soundlib/MPEGFrame.cpp
new file mode 100644
index 00000000..16547539
--- /dev/null
+++ b/Src/external_dependencies/openmpt-trunk/soundlib/MPEGFrame.cpp
@@ -0,0 +1,113 @@
+/*
+ * MPEGFrame.cpp
+ * -------------
+ * Purpose: Basic MPEG frame parsing functionality
+ * Notes  : (currently none)
+ * Authors: OpenMPT Devs
+ * The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
+ */
+
+
+#include "stdafx.h"
+#include "MPEGFrame.h"
+#include "../common/FileReader.h"
+
+OPENMPT_NAMESPACE_BEGIN
+
+// Samples per frame - for each MPEG version and all three layers
+static constexpr uint16 samplesPerFrame[2][3] =
+{
+	{ 384, 1152, 1152 },	// MPEG 1
+	{ 384, 1152,  576 }		// MPEG 2 / 2.5
+};
+// Bit rates for each MPEG version and all three layers
+static constexpr uint16 bitRates[2][3][15] =
+{
+	// MPEG 1
+	{
+		{ 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448 },	// Layer 1
+		{ 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256, 320, 384 },	// Layer 2
+		{ 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224, 256, 320 }	// Layer 3
+	},
+	// MPEG 2 / 2.5
+	{
+		{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256 },	// Layer 1
+		{ 0,  8, 16, 24, 32, 40, 48,  56,  64,  80,  96, 112, 128, 144, 160 },	// Layer 2
+		{ 0,  8, 16, 24, 32, 40, 48,  56,  64,  80,  96, 112, 128, 144, 160 }	// Layer 3
+	}
+};
+// Sampling rates for each MPEG version and all three layers
+static constexpr uint16 samplingRates[4][3] =
+{ 
+	{ 11025, 12000,  8000 },	// MPEG 2.5
+	{     0,     0,     0 },	// Invalid
+	{ 22050, 24000, 16000 },	// MPEG 2
+	{ 44100, 48000, 32000 }		// MPEG 1
+};
+// Samples per Frame / 8
+static constexpr uint8 mpegCoefficients[2][3] =
+{
+	{ 12, 144, 144 },	// MPEG 1
+	{ 12, 144,  72 }	// MPEG 2 / 2.5
+};
+// Side info size = Offset in frame where Xing/Info magic starts
+static constexpr uint8 sideInfoSize[2][2] =
+{
+	{ 17, 32 },	// MPEG 1
+	{  9, 17 }	// MPEG 2 / 2.5
+};
+
+
+bool MPEGFrame::IsMPEGHeader(const uint8 (&header)[3])
+{
+	return header[0] == 0xFF && (header[1] & 0xE0) == 0xE0	// Sync
+		&& (header[1] & 0x18) != 0x08	// Invalid MPEG version
+		&& (header[1] & 0x06) != 0x00	// Invalid MPEG layer
+		&& (header[2] & 0x0C) != 0x0C	// Invalid frequency
+		&& (header[2] & 0xF0) != 0xF0;	// Invalid bitrate
+}
+
+
+MPEGFrame::MPEGFrame(FileReader &file)
+	: frameSize(0)
+	, numSamples(0)
+	, isValid(false)
+	, isLAME(false)
+{
+	uint8 header[4];
+	file.ReadArray(header);
+	
+	if(!IsMPEGHeader(reinterpret_cast<const uint8(&)[3]>(header)))
+		return;
+		
+	uint8 version = (header[1] & 0x18) >> 3;
+	uint8 mpeg1 = (version == 3) ? 0 : 1;
+	uint8 layer = 3 - ((header[1] & 0x06) >> 1);
+	uint8 bitRate = (header[2] & 0xF0) >> 4;
+	uint8 sampleRate = (header[2] & 0x0C) >> 2;
+	uint8 padding = (header[2] & 0x02) >> 1;
+	bool stereo = ((header[3] & 0xC0) >> 6) != 3;
+
+	isValid = true;
+	frameSize = (((mpegCoefficients[mpeg1][layer] * (bitRates[mpeg1][layer][bitRate] * 1000) / samplingRates[version][sampleRate]) + padding)) * (layer == 0 ? 4 : 1);
+	numSamples = samplesPerFrame[mpeg1][layer];
+	if(stereo) numSamples *= 2u;
+
+	uint32 lameOffset = sideInfoSize[mpeg1][stereo ? 1 : 0];
+	if(frameSize < lameOffset + 8)
+		return;
+
+	uint8 frame[36];
+	file.ReadStructPartial(frame, lameOffset + 4);
+	// Don't check first two bytes, might be CRC
+	for(uint32 i = 2; i < lameOffset; i++)
+	{
+		if(frame[i] != 0)
+			return;
+	}
+
+	// This is all we really need to know for our purposes in the MO3 decoder.
+	isLAME = !memcmp(frame + lameOffset, "Info", 4) || !memcmp(frame + lameOffset, "Xing", 4);
+}
+
+OPENMPT_NAMESPACE_END