Decode LFE blocks and band extension

C/band_extension.c

@@ -0,0 +1,191 @@
+#include "band_extension.h"
+#include "tables.h"
+#include "utility.h"
+#include <math.h>
+
+void ApplyBandExtension(block* block)
+{
+	if (!block->BandExtensionEnabled || !block->HasExtensionData) return;
+
+	for (int i = 0; i < block->ChannelCount; i++)
+	{
+		ApplyBandExtensionChannel(&block->Channels[i]);
+	}
+}
+
+void ApplyBandExtensionChannel(channel* channel)
+{
+	const int groupAUnit = channel->Block->QuantizationUnitCount;
+	int* scaleFactors = channel->ScaleFactors;
+	double* spectra = channel->Spectra;
+	double scales[6];
+	int* values = channel->BexValues;
+
+	const bex_group* bex_info = &BexGroupInfo[channel->Block->QuantizationUnitCount - 13];
+	const int bandCount = bex_info->band_count;
+	const int groupBUnit = bex_info->group_b_unit;
+	const int groupCUnit = bex_info->group_c_unit;
+
+	const int totalUnits = max(groupCUnit, 22);
+	const int bexQuantUnits = totalUnits - groupAUnit;
+
+	const int groupABin = QuantUnitToCoeffIndex[groupAUnit];
+	const int groupBBin = QuantUnitToCoeffIndex[groupBUnit];
+	const int groupCBin = QuantUnitToCoeffIndex[groupCUnit];
+	const int totalBins = QuantUnitToCoeffIndex[totalUnits];
+
+	FillHighFrequencies(spectra, groupABin, groupBBin, groupCBin, totalBins);
+
+	double groupAScale, groupBScale, groupCScale;
+	double rate, scale, mult;
+
+	switch (channel->BexMode)
+	{
+	case 0:
+		switch (bandCount)
+		{
+		case 3:
+			scales[0] = BexMode0Bands3[0][values[0]];
+			scales[1] = BexMode0Bands3[1][values[0]];
+			scales[2] = BexMode0Bands3[2][values[1]];
+			scales[3] = BexMode0Bands3[3][values[2]];
+			scales[4] = BexMode0Bands3[4][values[3]];
+			break;
+		case 4:
+			scales[0] = BexMode0Bands4[0][values[0]];
+			scales[1] = BexMode0Bands4[1][values[0]];
+			scales[2] = BexMode0Bands4[2][values[1]];
+			scales[3] = BexMode0Bands4[3][values[2]];
+			scales[4] = BexMode0Bands4[4][values[3]];
+			break;
+		case 5:
+			scales[0] = BexMode0Bands5[0][values[0]];
+			scales[1] = BexMode0Bands5[1][values[1]];
+			scales[2] = BexMode0Bands5[2][values[1]];
+			break;
+		}
+
+		scales[bexQuantUnits - 1] = SpectrumScale[scaleFactors[groupAUnit]];
+
+		AddNoiseToSpectrum(channel, QuantUnitToCoeffIndex[totalUnits - 1],
+			QuantUnitToCoeffCount[totalUnits - 1]);
+		ScaleBexQuantUnits(spectra, scales, groupAUnit, totalUnits);
+		break;
+	case 1:
+		for (int i = groupAUnit; i < totalUnits; i++)
+		{
+			scales[i - groupAUnit] = SpectrumScale[scaleFactors[i]];
+		}
+
+		AddNoiseToSpectrum(channel, groupABin, totalBins - groupABin);
+		ScaleBexQuantUnits(spectra, scales, groupAUnit, totalUnits);
+		break;
+	case 2:
+		groupAScale = BexMode2Scale[values[0]];
+		groupBScale = BexMode2Scale[values[1]];
+
+		for (int i = groupABin; i < groupBBin; i++)
+		{
+			spectra[i] *= groupAScale;
+		}
+
+		for (int i = groupBBin; i < groupCBin; i++)
+		{
+			spectra[i] *= groupBScale;
+		}
+		return;
+	case 3:
+		rate = pow(2, BexMode3Rate[values[1]]);
+		scale = BexMode3Initial[values[0]];
+		for (int i = groupABin; i < totalBins; i++)
+		{
+			scale *= rate;
+			spectra[i] *= scale;
+		}
+		return;
+	case 4:
+		mult = BexMode4Multiplier[values[0]];
+		groupAScale = 0.7079468 * mult;
+		groupBScale = 0.5011902 * mult;
+		groupCScale = 0.3548279 * mult;
+
+		for (int i = groupABin; i < groupBBin; i++)
+		{
+			spectra[i] *= groupAScale;
+		}
+
+		for (int i = groupBBin; i < groupCBin; i++)
+		{
+			spectra[i] *= groupBScale;
+		}
+
+		for (int i = groupCBin; i < totalBins; i++)
+		{
+			spectra[i] *= groupCScale;
+		}
+	}
+}
+
+void ScaleBexQuantUnits(double* spectra, double* scales, int startUnit, int totalUnits)
+{
+	for (int i = startUnit; i < totalUnits; i++)
+	{
+		for (int k = QuantUnitToCoeffIndex[i]; k < QuantUnitToCoeffIndex[i + 1]; k++)
+		{
+			spectra[k] *= scales[i - startUnit];
+		}
+	}
+}
+
+void FillHighFrequencies(double* spectra, int groupABin, int groupBBin, int groupCBin, int totalBins)
+{
+	for (int i = 0; i < groupBBin - groupABin; i++)
+	{
+		spectra[groupABin + i] = spectra[groupABin - i - 1];
+	}
+
+	for (int i = 0; i < groupCBin - groupBBin; i++)
+	{
+		spectra[groupBBin + i] = spectra[groupBBin - i - 1];
+	}
+
+	for (int i = 0; i < totalBins - groupCBin; i++)
+	{
+		spectra[groupCBin + i] = spectra[groupCBin - i - 1];
+	}
+}
+
+void AddNoiseToSpectrum(channel* channel, int index, int count)
+{
+	if (!channel->rng.initialized)
+	{
+		int* sf = channel->ScaleFactors;
+		const unsigned short seed = (unsigned short)(543 * (sf[8] + sf[12] + sf[15] + 1));
+		rng_init(&channel->rng, seed);
+	}
+	for (int i = 0; i < count; i++)
+	{
+		channel->Spectra[i + index] = rng_next(&channel->rng) / 65535.0 * 2.0 - 1.0;
+	}
+}
+
+void rng_init(rng_cxt* rng, unsigned short seed)
+{
+	const int startValue = 0x4D93 * (seed ^ (seed >> 14));
+
+	rng->stateA = (unsigned short)(3 - startValue);
+	rng->stateB = (unsigned short)(2 - startValue);
+	rng->stateC = (unsigned short)(1 - startValue);
+	rng->stateD = (unsigned short)(0 - startValue);
+	rng->initialized = TRUE;
+}
+
+unsigned short rng_next(rng_cxt* rng)
+{
+	const unsigned short t = (unsigned short)(rng->stateD ^ (rng->stateD << 5));
+	rng->stateD = rng->stateC;
+	rng->stateC = rng->stateB;
+	rng->stateB = rng->stateA;
+	rng->stateA = (unsigned short)(t ^ rng->stateA ^ ((t ^ (rng->stateA >> 5)) >> 4));
+	return rng->stateA;
+}

C/band_extension.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include "structures.h"
+
+void ApplyBandExtension(block* block);
+void ApplyBandExtensionChannel(channel* channel);
+
+void ScaleBexQuantUnits(double* spectra, double* scales, int startUnit, int totalUnits);
+void FillHighFrequencies(double* spectra, int groupABin, int groupBBin, int groupCBin, int totalBins);
+void AddNoiseToSpectrum(channel* channel, int index, int count);
+
+void rng_init(rng_cxt* rng, unsigned short seed);
+unsigned short rng_next(rng_cxt* rng);

C/decoder.c

@@ -1,10 +1,12 @@
+#include <string.h>
 #include "decoder.h"
 #include "unpack.h"
 #include "quantization.h"
 #include "tables.h"
 #include "imdct.h"
 #include <math.h>
 #include "utility.h"
+#include "band_extension.h"
 
 at9_status Decode(atrac9_handle* handle, const unsigned char* audio, unsigned char* pcm, int* bytesUsed)
 {
@@ -15,8 +17,8 @@ at9_status Decode(atrac9_handle* handle, const unsigned char* audio, unsigned ch
 
 	PcmFloatToShort(&handle->frame, (short*)pcm);
 
-
-	*bytesUsed = br.position / 8;
+	
+		*bytesUsed = br.position / 8;
 	return ERR_SUCCESS;
 }
 
@@ -31,6 +33,7 @@ at9_status DecodeFrame(frame* frame, bit_reader_cxt* br)
 		DequantizeSpectra(block);
 		ApplyIntensityStereo(block);
 		ScaleSpectrumBlock(block);
+		ApplyBandExtension(block);
 		ImdctBlock(block);
 	}
 
@@ -97,3 +100,16 @@ void ApplyIntensityStereo(block* block)
 		}
 	}
 }
+
+int GetCodecInfo(atrac9_handle* handle, CodecInfo * pCodecInfo)
+{
+	pCodecInfo->channels = handle->config.ChannelCount;
+	pCodecInfo->channelConfigIndex = handle->config.ChannelConfigIndex;
+	pCodecInfo->samplingRate = handle->config.SampleRate;
+	pCodecInfo->superframeSize = handle->config.SuperframeBytes;
+	pCodecInfo->framesInSuperframe = handle->config.FramesPerSuperframe;
+	pCodecInfo->frameSamples = handle->config.FrameSamples;
+	pCodecInfo->wlength = handle->wlength;
+	memcpy(pCodecInfo->configData, handle->config.ConfigData, CONFIG_DATA_SIZE);
+	return ERR_SUCCESS;
+}

C/decoder.h

@@ -7,4 +7,5 @@ at9_status Decode(atrac9_handle* handle, const unsigned char* audio, unsigned ch
 at9_status DecodeFrame(frame* frame, bit_reader_cxt* br);
 void ImdctBlock(block* block);
 void ApplyIntensityStereo(block* block);
-void PcmFloatToShort(frame* frame, short* pcmOut);
+void PcmFloatToShort(frame* frame, short* pcmOut);
+int GetCodecInfo(atrac9_handle* handle, CodecInfo* pCodecInfo);

C/error_codes.h

@@ -20,7 +20,9 @@ typedef enum at9_status
 	ERR_UNPACK_GRAD_END_UNIT_INVALID, // start_unit > end_unit
 
 	ERR_UNPACK_SCALE_FACTOR_MODE_INVALID,
-	ERR_UNPACK_SCALE_FACTOR_OOB
+	ERR_UNPACK_SCALE_FACTOR_OOB,
+
+	ERR_UNPACK_EXTENSION_DATA_INVALID
 } at9_status;
 
 #define ERROR_CHECK(x) do { \

C/libatrac9.c

@@ -5,47 +5,29 @@
 #include "decinit.h"
 #include "decoder.h"
 
-HANDLE_ATRAC9 GetHandle()
+void* Atrac9GetHandle()
 {
 	struct atrac9_handle* handle = malloc(sizeof(atrac9_handle));
 	memset(handle, 0, sizeof(atrac9_handle));
 	return handle;
 }
 
-void ReleaseHandle(HANDLE_ATRAC9 handle)
+void Atrac9ReleaseHandle(void* handle)
 {
 	free(handle);
 }
 
-int DecInit(HANDLE_ATRAC9 handle, unsigned char * pConfigData, int wlength)
+int Atrac9InitDecoder(void* handle, unsigned char * pConfigData)
 {
-	if (wlength != 16)
-	{
-		return -1;
-	}
-
-	ERROR_CHECK(init_decoder(handle, pConfigData, wlength));
-
-	return 0;
+	return init_decoder(handle, pConfigData, 16);
 }
 
-int DecDecode(HANDLE_ATRAC9 handle, const unsigned char * pStreamBuffer, int * pNByteUsed, void * pPcmBuffer)
+int Atrac9Decode(void* handle, const unsigned char *pAtrac9Buffer, short *pPcmBuffer, int *pNBytesUsed)
 {
-	at9_status status = Decode(handle, pStreamBuffer, pPcmBuffer, pNByteUsed);
-	return status;
+	return Decode(handle, pAtrac9Buffer, (unsigned char*)pPcmBuffer, pNBytesUsed);
 }
 
-int GetCodecInfo(HANDLE_ATRAC9 handle, CodecInfo * pCodecInfo)
+int Atrac9GetCodecInfo(void* handle, Atrac9CodecInfo * pCodecInfo)
 {
-	atrac9_handle* h = handle;
-
-	pCodecInfo->channels = h->config.ChannelCount;
-	pCodecInfo->channelConfigIndex = h->config.ChannelConfigIndex;
-	pCodecInfo->samplingRate = h->config.SampleRate;
-	pCodecInfo->superframeSize = h->config.SuperframeBytes;
-	pCodecInfo->framesInSuperframe = h->config.FramesPerSuperframe;
-	pCodecInfo->frameSamples = h->config.FrameSamples;
-	pCodecInfo->wlength = h->wlength;
-	memcpy(pCodecInfo->configData, h->config.ConfigData, CONFIG_DATA_SIZE);
-	return ERR_SUCCESS;
+	return GetCodecInfo(handle, (CodecInfo*)pCodecInfo);
 }

C/libatrac9.h

@@ -9,7 +9,7 @@ extern "C" {
 #define DLLEXPORT __declspec(dllimport)  
 #endif
 
-typedef void* HANDLE_ATRAC9;
+#define ATRAC9_CONFIG_DATA_SIZE 4
 
 typedef struct {
 	int channels;
@@ -19,15 +19,16 @@ typedef struct {
 	int framesInSuperframe;
 	int frameSamples;
 	int wlength;
-	unsigned char configData[4];
-} CodecInfo;
+	unsigned char configData[ATRAC9_CONFIG_DATA_SIZE];
+} Atrac9CodecInfo;
 
-DLLEXPORT HANDLE_ATRAC9 GetHandle(void);
-DLLEXPORT void ReleaseHandle(HANDLE_ATRAC9 handle);
+DLLEXPORT void* Atrac9GetHandle(void);
+DLLEXPORT void Atrac9ReleaseHandle(void* handle);
 
-DLLEXPORT int DecInit(HANDLE_ATRAC9 handle, unsigned char *pConfigData, int wlength);
-DLLEXPORT int DecDecode(HANDLE_ATRAC9 handle, const unsigned char *pStreamBuffer, int *pNByteUsed, void *pPcmBuffer);
-DLLEXPORT int GetCodecInfo(HANDLE_ATRAC9 handle, CodecInfo *pCodecInfo);
+DLLEXPORT int Atrac9InitDecoder(void* handle, unsigned char *pConfigData);
+DLLEXPORT int Atrac9Decode(void* handle, const unsigned char *pAtrac9Buffer, short *pPcmBuffer, int *pNBytesUsed);
+
+DLLEXPORT int Atrac9GetCodecInfo(void* handle, Atrac9CodecInfo *pCodecInfo);
 
 #ifdef __cplusplus
 }

C/libatrac9.vcxproj

@@ -125,6 +125,7 @@
     </Link>
   </ItemDefinitionGroup>
   <ItemGroup>
+    <ClInclude Include="band_extension.h" />
     <ClInclude Include="bit_allocation.h" />
     <ClInclude Include="bit_reader.h" />
     <ClInclude Include="decinit.h" />
@@ -141,6 +142,7 @@
     <ClInclude Include="utility.h" />
   </ItemGroup>
   <ItemGroup>
+    <ClCompile Include="band_extension.c" />
     <ClCompile Include="bit_allocation.c" />
     <ClCompile Include="bit_reader.c" />
     <ClCompile Include="decinit.c" />