1 files changed, 165 insertions, 0 deletions
diff --git a/Src/Plugins/Input/in_mp3/OFL.cpp b/Src/Plugins/Input/in_mp3/OFL.cpp
new file mode 100644
index 00000000..230fa907
--- /dev/null
+++ b/Src/Plugins/Input/in_mp3/OFL.cpp
@@ -0,0 +1,165 @@
+#include "OFL.h"
+#include "foundation/error.h"
+
+static void crcofl(unsigned short crcPoly, unsigned short crcMask, unsigned long *crc, unsigned char byte)
+{
+	int i;
+	for (i=0; i<8; i++) 
+	{
+		unsigned short flag = (*crc) & crcMask ? 1:0;
+		flag ^= (byte & 0x80 ? 1 : 0);
+		(*crc)<<=1;
+		byte <<= 1;
+		if(flag)
+			(*crc) ^= crcPoly;
+	}
+}
+
+int OFL::GetGaps(size_t *pregap, size_t *postgap)
+{
+	/* TODO: verify the postgap calculation */
+	if (codec_delay >= 529)
+	{
+		*pregap = codec_delay;
+		size_t endcut;
+		endcut = samples_per_frame - ((total_length + codec_delay) % samples_per_frame); // how many 0 samples had to be added?
+		*postgap = endcut;
+		return NErr_Success;
+	}
+	return NErr_Empty;
+}
+
+
+double OFL::GetLengthSeconds() const
+{
+	return (double)GetSamples() / (double)sample_rate;
+}
+
+uint64_t OFL::GetSamples() const
+{
+	return total_length;
+}
+
+uint32_t OFL::GetFrames() const
+{
+	uint64_t real_samples = (total_length+codec_delay)*samples_per_frame;
+	return (uint32_t) (real_samples/samples_per_frame);
+}
+
+int OFL::Read(const MPEGFrame &header, const uint8_t *buffer, size_t buffer_len)
+{
+	if (header.layer != MPEGFrame::Layer3)
+		return NErr_False;
+
+	sample_rate = header.GetSampleRate();
+	samples_per_frame = header.GetSamplesPerFrame();
+
+	if (header.channelMode == MPEGFrame::Mono)
+	{
+		if (header.mpegVersion == MPEGFrame::MPEG1)
+		{
+			// 0-9 : main_data_end
+			int16_t main_data_end = (buffer[0] << 1) | (buffer[1] >> 7);
+
+			// read the 2 part2_3_lengths out so we know how big the main data section is
+			uint16_t part2_3_length = ((buffer[2] & 0x3F) << 6) | (buffer[3]>>2); // bits 18-30
+			part2_3_length += ((buffer[9] & 0x7) << 9) | (buffer[10] << 1) | (buffer[11] >> 7) ; // bits 77-89
+
+			size_t offset = 17 + (part2_3_length+7)/8;
+			if (offset+9 < buffer_len && buffer[offset] == 0xb4)
+			{
+				unsigned long crc=255;
+				for (int i=0;i<9;i++)
+					crcofl(0x0045, 0x0080, &crc, buffer[offset+i]);
+
+				if ((crc & 0xFF) == buffer[offset+9])
+				{
+					total_length = (buffer[offset+3] << 24) | (buffer[offset+4] << 16) | (buffer[offset+5] << 8) | (buffer[offset+6]);
+					codec_delay =     (buffer[offset+1] << 8) | (buffer[offset+2]);
+					additional_delay=     (buffer[offset+7] << 8) | (buffer[offset+8]);
+					return NErr_Success;
+				}
+			}
+		}
+		else
+		{ // MPEG2 and 2.5
+			// 0-8 : main_data_end
+			uint16_t main_data_end = buffer[0];
+
+			// read the 2 part2_3_lengths out so we know how big the main data section is
+			uint16_t part2_3_length = ((buffer[1] & 0x7F) << 5) | (buffer[2]>>3); // bits 9-21
+
+			size_t offset = 9 + (part2_3_length+7)/8;
+			if (offset+9 < buffer_len && buffer[offset] == 0xb4)
+			{
+				unsigned long crc=255;
+				for (int i=0;i<9;i++)
+					crcofl(0x0045, 0x0080, &crc, buffer[offset+i]);
+
+				if ((crc & 0xFF) == buffer[offset+9])
+				{
+					total_length = (buffer[offset+3] << 24) | (buffer[offset+4] << 16) | (buffer[offset+5] << 8) | (buffer[offset+6]);
+					codec_delay =     (buffer[offset+1] << 8) | (buffer[offset+2]);
+					additional_delay=     (buffer[offset+7] << 8) | (buffer[offset+8]);
+					return NErr_Success;
+				}
+			}
+		}
+	}
+	else
+	{
+		if (header.mpegVersion == MPEGFrame::MPEG1)
+		{
+			// 0-9 : main_data_end
+			uint16_t main_data_end = (buffer[0] << 1) | (buffer[1] >> 7);
+
+			// read the 4 part2_3_lengths out so we know how big the main data section is
+			uint16_t part2_3_length = ((buffer[2] & 0xF) << 8) | buffer[3]; // bits 20-32 
+			part2_3_length += ((buffer[9] & 0x1) << 11) | (buffer[10] << 3) | (buffer[11] >> 5) ; // bits 79-91
+			part2_3_length += ((buffer[17] & 0x3F) << 6) | (buffer[18] >> 2); // bits 138-150
+			part2_3_length += ((buffer[24] & 0x7) << 9) | (buffer[25] << 1) | (buffer[26] >> 7); // bits 197-209
+
+			size_t offset = 32 + (part2_3_length+7)/8;
+			if (offset+9 < buffer_len && buffer[offset] == 0xb4)
+			{
+				unsigned long crc=255;
+				for (int i=0;i<9;i++)
+					crcofl(0x0045, 0x0080, &crc, buffer[offset+i]);
+
+				if ((crc & 0xFF) == buffer[offset+9])
+				{
+					total_length = (buffer[offset+3] << 24) | (buffer[offset+4] << 16) | (buffer[offset+5] << 8) | (buffer[offset+6]);
+					codec_delay =     (buffer[offset+1] << 8) | (buffer[offset+2]);
+					additional_delay=     (buffer[offset+7] << 8) | (buffer[offset+8]);
+					return NErr_Success;
+				}
+			}
+		}
+		else
+		{ // MPEG2 and 2.5
+			// 0-8 : main_data_end
+			uint16_t main_data_end = buffer[0];
+
+			// read the 4 part2_3_lengths out so we know how big the main data section is
+			uint16_t part2_3_length = ((buffer[1] & 0x3F) << 6) | (buffer[2] >> 2); // bits 10-22
+			part2_3_length += ((buffer[8] & 0x7) << 9) | (buffer[9] << 1) | (buffer[10] >> 7) ; // bits 69-81
+
+			size_t offset = 17 + (part2_3_length+7)/8;
+			if (offset+9 < buffer_len && buffer[offset] == 0xb4)
+			{
+				unsigned long crc=255;
+				for (int i=0;i<9;i++)
+					crcofl(0x0045, 0x0080, &crc, buffer[offset+i]);
+
+				if ((crc & 0xFF) == buffer[offset+9])
+				{
+					total_length = (buffer[offset+3] << 24) | (buffer[offset+4] << 16) | (buffer[offset+5] << 8) | (buffer[offset+6]);
+					codec_delay =     (buffer[offset+1] << 8) | (buffer[offset+2]);
+					additional_delay=     (buffer[offset+7] << 8) | (buffer[offset+8]);
+					return NErr_Success;
+				}
+			}
+		}
+	}
+	return NErr_False;
+}