Initial community commit

1 files changed, 170 insertions, 0 deletions

diff --git a/Src/replicant/nsmp3/MPEGHeader.cpp b/Src/replicant/nsmp3/MPEGHeader.cpp
new file mode 100644
index 00000000..1971577e
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+++ b/Src/replicant/nsmp3/MPEGHeader.cpp
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+#include "MPEGHeader.h"
+#include <math.h>
+
+// [mpeg_version][layer][index]
+static const int bitrates[4][4][15] =
+{
+	{
+		// MPEG-2.5
+		{ 0,},
+		{  0, 8000, 16000, 24000, 32000, 40000, 48000, 56000, 64000, 80000, 96000, 112000, 128000, 144000, 160000}, // Layer 3
+		{  0, 8000, 16000, 24000, 32000, 40000, 48000, 56000, 64000, 80000, 96000, 112000, 128000, 144000, 160000}, // Layer 2
+		{  0, 32000, 48000, 56000, 64000, 80000, 96000, 112000, 128000, 144000, 160000, 176000, 192000, 224000, 256000}, // Layer 1
+	},
+
+	{
+		// invalid
+		{ 0, },
+		{ 0, },
+		{ 0, },
+		{ 0, },
+	},
+
+	{
+		// MPEG-2
+		{ 0,},
+		{  0, 8000, 16000, 24000, 32000, 40000, 48000, 56000, 64000, 80000, 96000, 112000, 128000, 144000, 160000}, // Layer 3
+		{  0, 8000, 16000, 24000, 32000, 40000, 48000, 56000, 64000, 80000, 96000, 112000, 128000, 144000, 160000}, // Layer 2
+		{  0, 32000, 48000, 56000, 64000, 80000, 96000, 112000, 128000, 144000, 160000, 176000, 192000, 224000, 256000}, // Layer 1
+	},
+
+	{
+		// MPEG-1
+		{ 0,},
+		{  0, 32000, 40000, 48000, 56000, 64000, 80000, 96000, 112000, 128000, 160000, 192000, 224000, 256000, 320000}, // Layer 3
+		{  0, 32000, 48000, 56000, 64000, 80000, 96000, 112000, 128000, 160000, 192000, 224000, 256000, 320000, 384000}, // Layer 2
+		{  0, 32000, 64000, 96000, 128000, 160000, 192000, 224000, 256000, 288000, 320000, 352000, 384000, 416000, 448000}, // Layer 1
+	},
+};
+
+// [mpeg_version][index]
+static const int sample_rates[4][4] =
+{
+	{11025, 12000,  8000, 0}, // MPEG-2.5
+	{0, },
+	{22050, 24000, 16000, 0}, // MPEG-2
+  {44100, 48000, 32000, 0}, // MPEG-1  
+};
+
+// [mpeg_version][layer]
+static const int samples_per_frame[4][4] =
+{
+	//    Layer 3, Layer 2, Layer 1
+	{  0, 576, 1152, 384}, // MPEG2.5
+	{  0, },
+	{  0, 576, 1152, 384}, // MPEG2
+	{  0, 1152, 1152, 384}, // MPEG1
+};
+
+// [layer]
+static const int bits_per_slot[4] = { 0, 8, 8, 32 };
+
+void MPEGHeader::ReadBuffer(const uint8_t *buffer)
+{
+	sync = 	((uint16_t)buffer[0] << 3) | (buffer[1] >> 5);
+	mpeg_version = (buffer[1] >> 3) & 3;
+	layer = (buffer[1] >> 1) & 3;
+	protection = (buffer[1]) & 1;
+	bitrate_index = (buffer[2] >> 4) & 0xF;
+	sample_rate_index = (buffer[2] >> 2) & 3;
+	padding_bit = (buffer[2] >> 1) & 1;
+	private_bit = buffer[2] & 1;
+	channel_mode = (buffer[3] >> 6) & 3;
+	mode_extension = (buffer[3] >> 4) & 3;
+	copyright = (buffer[3] >> 3) & 1;
+	original = (buffer[3] >> 2) & 1;
+	emphasis = (buffer[3]) & 3;
+}
+
+bool MPEGHeader::IsSync() const
+{
+	return sync == 0x07FF
+		&& layer != LayerError
+		&& mpeg_version != MPEG_Error
+		&& bitrate_index != 15
+		&& bitrate_index != 0
+		&& sample_rate_index != 3
+		&& !(mpeg_version == MPEG2 && layer != Layer3)
+		&& !(mpeg_version == MPEG2_5 && layer != Layer3);
+}
+
+int MPEGHeader::GetBitrate() const
+{
+	return bitrates[mpeg_version][layer][bitrate_index];
+}
+
+int MPEGHeader::HeaderSize() const
+{
+	if (protection == CRC)
+		return 4 + 2; // 32bits frame header, 16bits CRC
+	else
+		return 4; // 32bits frame ehader
+}
+
+int MPEGHeader::GetSampleRate() const
+{
+	return sample_rates[mpeg_version][sample_rate_index];
+}
+
+bool MPEGHeader::IsCopyright() const
+{
+	return copyright == 1;
+}
+bool MPEGHeader::IsCRC() const
+{
+	return protection == CRC;
+}
+
+bool MPEGHeader::IsOriginal() const
+{
+	return original == 1;
+}
+
+int MPEGHeader::GetSamplesPerFrame() const
+{
+	return samples_per_frame[mpeg_version][layer];
+}
+
+int MPEGHeader::FrameSize() const
+{
+	int nBitsPerSlot;
+  int nAvgSlotsPerFrame;
+
+  nBitsPerSlot     = bits_per_slot[layer];
+
+  nAvgSlotsPerFrame = (GetSamplesPerFrame() * (bitrates[mpeg_version][layer][bitrate_index] / nBitsPerSlot)) / sample_rates[mpeg_version][sample_rate_index];
+
+  return (nAvgSlotsPerFrame + padding_bit) * nBitsPerSlot / 8;
+}
+
+int MPEGHeader::GetLayer() const
+{
+	switch(layer)
+	{
+	case Layer1:
+		return 1;
+	case Layer2:
+		return 2;
+	case Layer3:
+		return 3;
+	default:
+		return 0;
+	}
+}
+
+int MPEGHeader::GetNumChannels() const
+{
+	switch(channel_mode)
+	{
+	case Stereo:
+		return 2;
+	case JointStereo:
+		return 2;
+	case DualChannel:
+		return 2;
+	case Mono:
+		return 1;
+	default:
+		return 0;
+	}
+}