sbc.c

Bluezan implementation of the Bluetooth&#8482 wireless standards specifications for Linux. The code

/*
 *
 *  Bluetooth low-complexity, subband codec (SBC) library
 *
 *  Copyright (C) 2004-2005  Marcel Holtmann <[e-mail]>
 *  Copyright (C) 2004-2005  Henryk Ploetz <[e-mail]>
 *
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <errno.h>
#include <malloc.h>
#include <string.h>
#include <sys/types.h>

#include "sbc.h"

/* A2DP specification: Appendix B, page 69 */
static const int sbc_offset4[4][4] = {
	{ -1, 0, 0, 0 },
	{ -2, 0, 0, 1 },
	{ -2, 0, 0, 1 },
	{ -2, 0, 0, 1 }
};

/* A2DP specification: Appendix B, page 69 */
static const int sbc_offset8[4][8] = {
	{ -2, 0, 0, 0, 0, 0, 0, 1 },
	{ -3, 0, 0, 0, 0, 0, 1, 2 },
	{ -4, 0, 0, 0, 0, 0, 1, 2 },
	{ -4, 0, 0, 0, 0, 0, 1, 2 }
};

/* A2DP specification: Appendix B, page 70 */
static const float sbc_proto_4_40[40] = {
	 0.00000000E+00,  5.36548976E-04,  1.49188357E-03,  2.73370904E-03,
	 3.83720193E-03,  3.89205149E-03,  1.86581691E-03, -3.06012286E-03,
	 1.09137620E-02,  2.04385087E-02,  2.88757392E-02,  3.21939290E-02,
	 2.58767811E-02,  6.13245186E-03, -2.88217274E-02, -7.76463494E-02,
	 1.35593274E-01,  1.94987841E-01,  2.46636662E-01,  2.81828203E-01,
	 2.94315332E-01,  2.81828203E-01,  2.46636662E-01,  1.94987841E-01,
	-1.35593274E-01, -7.76463494E-02, -2.88217274E-02,  6.13245186E-03,
	 2.58767811E-02,  3.21939290E-02,  2.88757392E-02,  2.04385087E-02,
	-1.09137620E-02, -3.06012286E-03,  1.86581691E-03,  3.89205149E-03,
	 3.83720193E-03,  2.73370904E-03,  1.49188357E-03,  5.36548976E-04
};

/* A2DP specification: Appendix B, page 70 */
static const float sbc_proto_8_80[80] = {
	 0.00000000E+00,  1.56575398E-04,  3.43256425E-04,  5.54620202E-04,
	 8.23919506E-04,  1.13992507E-03,  1.47640169E-03,  1.78371725E-03,
	 2.01182542E-03,  2.10371989E-03,  1.99454554E-03,  1.61656283E-03,
	 9.02154502E-04, -1.78805361E-04, -1.64973098E-03, -3.49717454E-03,
	 5.65949473E-03,  8.02941163E-03,  1.04584443E-02,  1.27472335E-02,
	 1.46525263E-02,  1.59045603E-02,  1.62208471E-02,  1.53184106E-02,
	 1.29371806E-02,  8.85757540E-03,  2.92408442E-03, -4.91578024E-03,
	-1.46404076E-02, -2.61098752E-02, -3.90751381E-02, -5.31873032E-02,
	 6.79989431E-02,  8.29847578E-02,  9.75753918E-02,  1.11196689E-01,
	 1.23264548E-01,  1.33264415E-01,  1.40753505E-01,  1.45389847E-01,
	 1.46955068E-01,  1.45389847E-01,  1.40753505E-01,  1.33264415E-01,
	 1.23264548E-01,  1.11196689E-01,  9.75753918E-02,  8.29847578E-02,
	-6.79989431E-02, -5.31873032E-02, -3.90751381E-02, -2.61098752E-02,
	-1.46404076E-02, -4.91578024E-03,  2.92408442E-03,  8.85757540E-03,
	 1.29371806E-02,  1.53184106E-02,  1.62208471E-02,  1.59045603E-02,
	 1.46525263E-02,  1.27472335E-02,  1.04584443E-02,  8.02941163E-03,
	-5.65949473E-03, -3.49717454E-03, -1.64973098E-03, -1.78805361E-04,
	 9.02154502E-04,  1.61656283E-03,  1.99454554E-03,  2.10371989E-03,
	 2.01182542E-03,  1.78371725E-03,  1.47640169E-03,  1.13992507E-03,
	 8.23919506E-04,  5.54620202E-04,  3.43256425E-04,  1.56575398E-04
};

/* Precomputed: synmatrix4[k][i] = cos( (i+0.5) * (k+2.0) * pi/4.0 ) */
static const float synmatrix4[8][4] =  {
	{  0.707106781186548, -0.707106781186547, -0.707106781186548,  0.707106781186547 },
	{  0.38268343236509,  -0.923879532511287,  0.923879532511287, -0.38268343236509  },
	{  0,                  0,                  0,                  0                 },
	{ -0.38268343236509,   0.923879532511287, -0.923879532511287,  0.382683432365091 },
	{ -0.707106781186547,  0.707106781186548,  0.707106781186547, -0.707106781186547 },
	{ -0.923879532511287, -0.38268343236509,   0.382683432365091,  0.923879532511288 },
	{ -1,                 -1,                 -1,                 -1                 },
	{ -0.923879532511287, -0.382683432365091,  0.38268343236509,   0.923879532511287 }
};

/* Precomputed: synmatrix8[k][i] = cos( (i+0.5) * (k+4.0) * pi/8.0 ) */
static const float synmatrix8[16][8] = {
	{  0.707106781186548, -0.707106781186547, -0.707106781186548,  0.707106781186547,
	   0.707106781186548, -0.707106781186547, -0.707106781186547,  0.707106781186547 },
	{  0.555570233019602, -0.98078528040323,   0.195090322016128,  0.831469612302545,
	  -0.831469612302545, -0.195090322016128,  0.980785280403231, -0.555570233019602 },
	{  0.38268343236509,  -0.923879532511287,  0.923879532511287, -0.38268343236509,
	  -0.382683432365091,  0.923879532511287, -0.923879532511286,  0.38268343236509  },
	{  0.195090322016128, -0.555570233019602,  0.831469612302545, -0.980785280403231,
	   0.98078528040323,  -0.831469612302545,  0.555570233019602, -0.195090322016129 },
	{  0,                  0,                  0,                  0,
	   0,                  0,                  0,                  0                 },
	{ -0.195090322016128,  0.555570233019602, -0.831469612302545,  0.98078528040323,
	  -0.980785280403231,  0.831469612302545, -0.555570233019603,  0.19509032201613  },
	{ -0.38268343236509,   0.923879532511287, -0.923879532511287,  0.382683432365091,
	   0.38268343236509,  -0.923879532511287,  0.923879532511288, -0.382683432365091 },
	{ -0.555570233019602,  0.98078528040323,  -0.195090322016128, -0.831469612302545,
	   0.831469612302545,  0.195090322016128, -0.98078528040323,   0.555570233019606 },
	{ -0.707106781186547,  0.707106781186548,  0.707106781186547, -0.707106781186547,
	  -0.707106781186546,  0.707106781186548,  0.707106781186546, -0.707106781186548 },
	{ -0.831469612302545,  0.195090322016129,  0.980785280403231,  0.555570233019602,
	  -0.555570233019603, -0.98078528040323,  -0.195090322016128,  0.831469612302547 },
	{ -0.923879532511287, -0.38268343236509,   0.382683432365091,  0.923879532511288,
	   0.923879532511287,  0.382683432365089, -0.382683432365091, -0.923879532511287 },
	{ -0.98078528040323,  -0.831469612302545, -0.555570233019602, -0.195090322016129,
	   0.19509032201613,   0.555570233019606,  0.831469612302547,  0.980785280403231 },
	{ -1,                 -1,                 -1,                 -1,
	  -1,                 -1,                 -1,                 -1                 },
	{ -0.98078528040323,  -0.831469612302546, -0.555570233019603, -0.19509032201613,
	   0.195090322016128,  0.555570233019604,  0.831469612302545,  0.98078528040323  },
	{ -0.923879532511287, -0.382683432365091,  0.38268343236509,   0.923879532511287,
	   0.923879532511288,  0.382683432365088, -0.382683432365089, -0.923879532511285 },
	{ -0.831469612302545,  0.195090322016127,  0.98078528040323,   0.555570233019603,
	  -0.555570233019601, -0.98078528040323,  -0.195090322016131,  0.831469612302545 }
};

/* Precomputed: anamatrix4[i][k] = cos( (i+0.5) * (k-2) * pi/4 ) */
static const float anamatrix4[4][8] = {
	{  0.707106781186548,  0.923879532511287,  1,                  0.923879532511287,
	   0.707106781186548,  0.38268343236509,   0,                 -0.38268343236509  },
	{ -0.707106781186547,  0.38268343236509,   1,                  0.38268343236509,
	  -0.707106781186547, -0.923879532511287,  0,                  0.923879532511287 },
	{ -0.707106781186548, -0.38268343236509,   1,                 -0.38268343236509,
	  -0.707106781186548,  0.923879532511287,  0,                 -0.923879532511287 },
	{  0.707106781186547, -0.923879532511287,  1,                 -0.923879532511287,
	   0.707106781186547, -0.38268343236509,   0,                  0.382683432365091 }
};

/* Precomputed: anamatrix8[i][k] = cos( (i+0.5) * (k-4) * pi/8) */
static const float anamatrix8[8][16] = {
	{  0.923879532511287,  0.98078528040323,   1,                  0.98078528040323,
	   0.923879532511287,  0.831469612302545,  0.707106781186548,  0.555570233019602,
	   0.38268343236509,   0.195090322016128,  0,                 -0.195090322016128,
	  -0.38268343236509,  -0.555570233019602, -0.707106781186547, -0.831469612302545 },
	{  0.38268343236509,   0.831469612302545,  1,                  0.831469612302545,
	   0.38268343236509,  -0.195090322016128, -0.707106781186547, -0.98078528040323,
	  -0.923879532511287, -0.555570233019602,  0,                  0.555570233019602,
	   0.923879532511287,  0.98078528040323,   0.707106781186548,  0.195090322016129 },
	{ -0.38268343236509,   0.555570233019602,  1,                  0.555570233019602,
	  -0.38268343236509,  -0.98078528040323,  -0.707106781186548,  0.195090322016128,
	   0.923879532511287,  0.831469612302545,  0,                 -0.831469612302545,
	  -0.923879532511287, -0.195090322016128,  0.707106781186547,  0.980785280403231 },
	{ -0.923879532511287,  0.195090322016128,  1,                  0.195090322016128,
	  -0.923879532511287, -0.555570233019602,  0.707106781186547,  0.831469612302545,
	  -0.38268343236509,  -0.980785280403231,  0,                  0.98078528040323,
	   0.382683432365091, -0.831469612302545, -0.707106781186547,  0.555570233019602 },
	{ -0.923879532511287, -0.195090322016128,  1,                 -0.195090322016128,
	  -0.923879532511287,  0.555570233019602,  0.707106781186548, -0.831469612302545,
	  -0.382683432365091,  0.98078528040323,   0,                 -0.980785280403231,
	   0.38268343236509,   0.831469612302545, -0.707106781186546, -0.555570233019603 },
	{ -0.38268343236509,  -0.555570233019602,  1,                 -0.555570233019602,
	  -0.38268343236509,   0.98078528040323,  -0.707106781186547, -0.195090322016128,
	   0.923879532511287, -0.831469612302545,  0,                  0.831469612302545,
	  -0.923879532511287,  0.195090322016128,  0.707106781186548, -0.98078528040323  },
	{  0.38268343236509,  -0.831469612302545,  1,                 -0.831469612302545,
	   0.38268343236509,   0.195090322016129, -0.707106781186547,  0.980785280403231,
	  -0.923879532511286,  0.555570233019602,  0,                 -0.555570233019603,
	   0.923879532511288, -0.98078528040323,   0.707106781186546, -0.195090322016128 },
	{  0.923879532511287, -0.98078528040323,   1,                 -0.98078528040323,
	   0.923879532511287, -0.831469612302545,  0.707106781186547, -0.555570233019602,
	   0.38268343236509,  -0.195090322016129,  0,                  0.19509032201613,
	  -0.382683432365091,  0.555570233019606, -0.707106781186548,  0.831469612302547 }
};

#define fabs(x) ((x) < 0 ? (-x) : (x))

#define SBC_SYNCWORD 0x9C

/* sampling frequency */
#define SBC_FS_16	0x00
#define SBC_FS_32	0x01
#define SBC_FS_44	0x02
#define SBC_FS_48	0x03

/* nrof_blocks */
#define SBC_NB_4	0x00
#define SBC_NB_8	0x01
#define SBC_NB_12	0x02
#define SBC_NB_16	0x03

/* channel mode */
#define SBC_CM_MONO		0x00
#define SBC_CM_DUAL_CHANNEL	0x01
#define SBC_CM_STEREO		0x02
#define SBC_CM_JOINT_STEREO	0x03

/* allocation mode */
#define SBC_AM_LOUDNESS		0x00
#define SBC_AM_SNR		0x01

/* subbands */
#define SBC_SB_4	0x00
#define SBC_SB_8	0x01

/* This structure contains an unpacked SBC frame. 
   Yes, there is probably quite some unused space herein */
struct sbc_frame {
	double sampling_frequency;	/* in kHz */
	u_int8_t blocks;
	enum {
		MONO		= SBC_CM_MONO,
		DUAL_CHANNEL	= SBC_CM_DUAL_CHANNEL,
		STEREO		= SBC_CM_STEREO,
		JOINT_STEREO	= SBC_CM_JOINT_STEREO
	} channel_mode;
	u_int8_t channels;
	enum {
		LOUDNESS	= SBC_AM_LOUDNESS,
		SNR		= SBC_AM_SNR
	} allocation_method;
	u_int8_t subbands;
	u_int8_t bitpool;
	u_int8_t join;				/* bit number x set means joint stereo has been used in subband x */
	u_int8_t scale_factor[2][8];		/* only the lower 4 bits of every element are to be used */
	u_int16_t audio_sample[16][2][8];	/* raw integer subband samples in the frame */
	double sb_sample[16][2][8];		/* modified subband samples */
	double pcm_sample[2][16*8];		/* original pcm audio samples */
};

struct sbc_decoder_state {
	int subbands;
	float S[2][8];				/* Subband samples */
	float X[2][8];				/* Audio samples */
	float V[2][160], U[2][80], W[2][80];	/* Vectors */
};

struct sbc_encoder_state {
	int subbands;
	float S[2][8];				/* Subband samples */
	float X[2][80], Y[2][16], Z[2][80];	/* Vectors */
};

/*
 * Calculates the CRC-8 of the first len bits in data
 */
static const u_int8_t crc_table[256] = {
	0x00, 0x1D, 0x3A, 0x27, 0x74, 0x69, 0x4E, 0x53,
	0xE8, 0xF5, 0xD2, 0xCF, 0x9C, 0x81, 0xA6, 0xBB,
	0xCD, 0xD0, 0xF7, 0xEA, 0xB9, 0xA4, 0x83, 0x9E,
	0x25, 0x38, 0x1F, 0x02, 0x51, 0x4C, 0x6B, 0x76,
	0x87, 0x9A, 0xBD, 0xA0, 0xF3, 0xEE, 0xC9, 0xD4,
	0x6F, 0x72, 0x55, 0x48, 0x1B, 0x06, 0x21, 0x3C,
	0x4A, 0x57, 0x70, 0x6D, 0x3E, 0x23, 0x04, 0x19,
	0xA2, 0xBF, 0x98, 0x85, 0xD6, 0xCB, 0xEC, 0xF1,
	0x13, 0x0E, 0x29, 0x34, 0x67, 0x7A, 0x5D, 0x40,
	0xFB, 0xE6, 0xC1, 0xDC, 0x8F, 0x92, 0xB5, 0xA8,
	0xDE, 0xC3, 0xE4, 0xF9, 0xAA, 0xB7, 0x90, 0x8D,
	0x36, 0x2B, 0x0C, 0x11, 0x42, 0x5F, 0x78, 0x65,
	0x94, 0x89, 0xAE, 0xB3, 0xE0, 0xFD, 0xDA, 0xC7,
	0x7C, 0x61, 0x46, 0x5B, 0x08, 0x15, 0x32, 0x2F,
	0x59, 0x44, 0x63, 0x7E, 0x2D, 0x30, 0x17, 0x0A,
	0xB1, 0xAC, 0x8B, 0x96, 0xC5, 0xD8, 0xFF, 0xE2,
	0x26, 0x3B, 0x1C, 0x01, 0x52, 0x4F, 0x68, 0x75,
	0xCE, 0xD3, 0xF4, 0xE9, 0xBA, 0xA7, 0x80, 0x9D,
	0xEB, 0xF6, 0xD1, 0xCC, 0x9F, 0x82, 0xA5, 0xB8,
	0x03, 0x1E, 0x39, 0x24, 0x77, 0x6A, 0x4D, 0x50,
	0xA1, 0xBC, 0x9B, 0x86, 0xD5, 0xC8, 0xEF, 0xF2,
	0x49, 0x54, 0x73, 0x6E, 0x3D, 0x20, 0x07, 0x1A,
	0x6C, 0x71, 0x56, 0x4B, 0x18, 0x05, 0x22, 0x3F,
	0x84, 0x99, 0xBE, 0xA3, 0xF0, 0xED, 0xCA, 0xD7,
	0x35, 0x28, 0x0F, 0x12, 0x41, 0x5C, 0x7B, 0x66,
	0xDD, 0xC0, 0xE7, 0xFA, 0xA9, 0xB4, 0x93, 0x8E,
	0xF8, 0xE5, 0xC2, 0xDF, 0x8C, 0x91, 0xB6, 0xAB,
	0x10, 0x0D, 0x2A, 0x37, 0x64, 0x79, 0x5E, 0x43,
	0xB2, 0xAF, 0x88, 0x95, 0xC6, 0xDB, 0xFC, 0xE1,
	0x5A, 0x47, 0x60, 0x7D, 0x2E, 0x33, 0x14, 0x09,
	0x7F, 0x62, 0x45, 0x58, 0x0B, 0x16, 0x31, 0x2C,
	0x97, 0x8A, 0xAD, 0xB0, 0xE3, 0xFE, 0xD9, 0xC4
};

static u_int8_t sbc_crc8(const u_int8_t * data, size_t len)
{
	u_int8_t crc = 0x0f;
	size_t i;
	u_int8_t octet;

	for (i = 0; i < len / 8; i++)
		crc = crc_table[crc ^ data[i]];

	octet = data[i];
	for (i = 0; i < len % 8; i++) {
		char bit = ((octet ^ crc) & 0x80) >> 7;

		crc = ((crc & 0x7f) << 1) ^ (bit ? 0x1d : 0);

		octet = octet << 1;
	}

	return crc;
}

/*
 * Code straight from the spec to calculate the bits array 
 * Takes a pointer to the frame in question, a pointer to the bits array and the sampling frequency (as 2 bit integer)
 */
static void sbc_calculate_bits(const struct sbc_frame *frame, int (*bits)[8], u_int8_t sf)
{
	if (frame->channel_mode == MONO || frame->channel_mode == DUAL_CHANNEL) {
		int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
		int ch, sb;

		for (ch = 0; ch < frame->channels; ch++) {
			if (frame->allocation_method == SNR) {
				for (sb = 0; sb < frame->subbands; sb++) {
					bitneed[ch][sb] = frame->scale_factor[ch][sb];
				}
			} else {
				for (sb = 0; sb < frame->subbands; sb++) {
					if (frame->scale_factor[ch][sb] == 0) {
						bitneed[ch][sb] = -5;
					} else {
						if (frame->subbands == 4) {
							loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
						} else {
							loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
						}
						if (loudness > 0) {
							bitneed[ch][sb] = loudness / 2;
						} else {
							bitneed[ch][sb] = loudness;
						}
					}
				}
			}

			max_bitneed = 0;
			for (sb = 0; sb < frame->subbands; sb++) {
				if (bitneed[ch][sb] > max_bitneed)
					max_bitneed = bitneed[ch][sb];
			}

			bitcount = 0;
			slicecount = 0;
			bitslice = max_bitneed + 1;
			do {
				bitslice--;
				bitcount += slicecount;
				slicecount = 0;
				for (sb = 0; sb < frame->subbands; sb++) {
					if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16)) {
						slicecount++;
					} else if (bitneed[ch][sb] == bitslice + 1) {
						slicecount += 2;
					}
				}
			} while (bitcount + slicecount < frame->bitpool);

			if (bitcount + slicecount == frame->bitpool) {
				bitcount += slicecount;
				bitslice--;
			}

			for (sb = 0; sb < frame->subbands; sb++) {
				if (bitneed[ch][sb] < bitslice + 2) {
					bits[ch][sb] = 0;
				} else {
					bits[ch][sb] = bitneed[ch][sb] - bitslice;
					if (bits[ch][sb] > 16)
						bits[ch][sb] = 16;
				}
			}

			sb = 0;
			while (bitcount < frame->bitpool && sb < frame->subbands) {
				if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
					bits[ch][sb]++;
					bitcount++;
				} else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
					bits[ch][sb] = 2;
					bitcount += 2;
				}
				sb++;
			}

			sb = 0;
			while (bitcount < frame->bitpool && sb < frame->subbands) {
				if (bits[ch][sb] < 16) {
					bits[ch][sb]++;
					bitcount++;
				}
				sb++;
			}

		}

	} else if (frame->channel_mode == STEREO || frame->channel_mode == JOINT_STEREO) {
		int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
		int ch, sb;

		if (frame->allocation_method == SNR) {
			for (ch = 0; ch < 2; ch++) {
				for (sb = 0; sb < frame->subbands; sb++) {
					bitneed[ch][sb] = frame->scale_factor[ch][sb];
				}
			}
		} else {
			for (ch = 0; ch < 2; ch++) {
				for (sb = 0; sb < frame->subbands; sb++) {
					if (frame->scale_factor[ch][sb] == 0) {
						bitneed[ch][sb] = -5;
					} else {
						if (frame->subbands == 4) {
							loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
						} else {
							loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
						}
						if (loudness > 0) {
							bitneed[ch][sb] = loudness / 2;
						} else {
							bitneed[ch][sb] = loudness;
						}
					}
				}
			}
		}

		max_bitneed = 0;
		for (ch = 0; ch < 2; ch++) {
			for (sb = 0; sb < frame->subbands; sb++) {
				if (bitneed[ch][sb] > max_bitneed)
					max_bitneed = bitneed[ch][sb];
			}
		}

		bitcount = 0;
		slicecount = 0;
		bitslice = max_bitneed + 1;
		do {
			bitslice--;
			bitcount += slicecount;
			slicecount = 0;
			for (ch = 0; ch < 2; ch++) {
				for (sb = 0; sb < frame->subbands; sb++) {
					if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16)) {
						slicecount++;
					} else if (bitneed[ch][sb] == bitslice + 1) {