New SBC analysis filter function to replace current broken code

This code is heavily based on the patch submitted by Jaska Uimonen.
Additional changes include preserving extra bits in the output of
filter function for better precision, support for both 16-bit and
32-bit fixed point implementation. Sign of some table values was
changed in order to preserve a regular code structure and have
multiply-accumulate oparations only. No additional optimizations
were applied as this code is intended to be some kind of "reference"
implementation. Platform specific optimizations may require
different tricks and can be branched off from this implementation.
Some extra information about this code can be found in linux-bluetooth
mailing list archive for December 2008.

3 files changed, 323 insertions, 244 deletions

diff --git a/sbc/sbc.c b/sbc/sbc.c
index d3dcd9a3..ce52e1ec 100644
--- a/sbc/sbc.c
+++ b/sbc/sbc.c
@@ -40,6 +40,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <sys/types.h>
+#include <limits.h>
 
 #include "sbc_math.h"
 #include "sbc_tables.h"
@@ -93,7 +94,7 @@ struct sbc_decoder_state {
 struct sbc_encoder_state {
 	int subbands;
 	int position[2];
-	int32_t X[2][160];
+	int16_t X[2][160];
 };
 
 /*
@@ -656,75 +657,47 @@ static void sbc_encoder_init(struct sbc_encoder_state *state,
 	state->position[0] = state->position[1] = 9 * frame->subbands;
 }
 
-static inline void _sbc_analyze_four(const int32_t *in, int32_t *out)
+static inline void _sbc_analyze_four(const int16_t *in, int32_t *out)
 {
-	sbc_fixed_t t[8], s[5];
-
-	t[0] = SCALE4_STAGE1( /* Q8 */
-		MULA(_sbc_proto_4[0], in[8] - in[32], /* Q18 */
-		MUL( _sbc_proto_4[1], in[16] - in[24])));
-
-	t[1] = SCALE4_STAGE1(
-		MULA(_sbc_proto_4[2], in[1],
-		MULA(_sbc_proto_4[3], in[9],
-		MULA(_sbc_proto_4[4], in[17],
-		MULA(_sbc_proto_4[5], in[25],
-		MUL( _sbc_proto_4[6], in[33]))))));
-
-	t[2] = SCALE4_STAGE1(
-		MULA(_sbc_proto_4[7], in[2],
-		MULA(_sbc_proto_4[8], in[10],
-		MULA(_sbc_proto_4[9], in[18],
-		MULA(_sbc_proto_4[10], in[26],
-		MUL( _sbc_proto_4[11], in[34]))))));
-
-	t[3] = SCALE4_STAGE1(
-		MULA(_sbc_proto_4[12], in[3],
-		MULA(_sbc_proto_4[13], in[11],
-		MULA(_sbc_proto_4[14], in[19],
-		MULA(_sbc_proto_4[15], in[27],
-		MUL( _sbc_proto_4[16], in[35]))))));
-
-	t[4] = SCALE4_STAGE1(
-		MULA(_sbc_proto_4[17], in[4] + in[36],
-		MULA(_sbc_proto_4[18], in[12] + in[28],
-		MUL( _sbc_proto_4[19], in[20]))));
-
-	t[5] = SCALE4_STAGE1(
-		MULA(_sbc_proto_4[16], in[5],
-		MULA(_sbc_proto_4[15], in[13],
-		MULA(_sbc_proto_4[14], in[21],
-		MULA(_sbc_proto_4[13], in[29],
-		MUL( _sbc_proto_4[12], in[37]))))));
-
-	/* don't compute t[6]... this term always multiplies
-	 * with cos(pi/2) = 0 */
-
-	t[7] = SCALE4_STAGE1(
-		MULA(_sbc_proto_4[6], in[7],
-		MULA(_sbc_proto_4[5], in[15],
-		MULA(_sbc_proto_4[4], in[23],
-		MULA(_sbc_proto_4[3], in[31],
-		MUL( _sbc_proto_4[2], in[39]))))));
-
-	s[0] = MUL( _anamatrix4[0], t[0] + t[4]);
-	s[1] = MUL( _anamatrix4[2], t[2]);
-	s[2] = MULA(_anamatrix4[1], t[1] + t[3],
-		MUL(_anamatrix4[3], t[5]));
-	s[3] = MULA(_anamatrix4[3], t[1] + t[3],
-		MUL(_anamatrix4[1], -t[5] + t[7]));
-	s[4] = MUL( _anamatrix4[3], t[7]);
-
-	out[0] = SCALE4_STAGE2( s[0] + s[1] + s[2] + s[4]); /* Q0 */
-	out[1] = SCALE4_STAGE2(-s[0] + s[1] + s[3]);
-	out[2] = SCALE4_STAGE2(-s[0] + s[1] - s[3]);
-	out[3] = SCALE4_STAGE2( s[0] + s[1] - s[2] - s[4]);
+	FIXED_A t1[4];
+	FIXED_T t2[4];
+	int i = 0, hop = 0;
+
+	/* rounding coefficient */
+	t1[0] = t1[1] = t1[2] = t1[3] =
+		(FIXED_A) 1 << (SBC_PROTO_FIXED4_SCALE - 1);
+
+	/* low pass polyphase filter */
+	for (hop = 0; hop < 40; hop += 8) {
+		t1[0] += (FIXED_A) in[hop] * _sbc_proto_fixed4[hop];
+		t1[1] += (FIXED_A) in[hop + 1] * _sbc_proto_fixed4[hop + 1];
+		t1[2] += (FIXED_A) in[hop + 2] * _sbc_proto_fixed4[hop + 2];
+		t1[1] += (FIXED_A) in[hop + 3] * _sbc_proto_fixed4[hop + 3];
+		t1[0] += (FIXED_A) in[hop + 4] * _sbc_proto_fixed4[hop + 4];
+		t1[3] += (FIXED_A) in[hop + 5] * _sbc_proto_fixed4[hop + 5];
+		t1[3] += (FIXED_A) in[hop + 7] * _sbc_proto_fixed4[hop + 7];
+	}
+
+	/* scaling */
+	t2[0] = t1[0] >> SBC_PROTO_FIXED4_SCALE;
+	t2[1] = t1[1] >> SBC_PROTO_FIXED4_SCALE;
+	t2[2] = t1[2] >> SBC_PROTO_FIXED4_SCALE;
+	t2[3] = t1[3] >> SBC_PROTO_FIXED4_SCALE;
+
+	/* do the cos transform */
+	for (i = 0, hop = 0; i < 4; hop += 8, i++) {
+		out[i] = ((FIXED_A) t2[0] * cos_table_fixed_4[0 + hop] +
+			  (FIXED_A) t2[1] * cos_table_fixed_4[1 + hop] +
+			  (FIXED_A) t2[2] * cos_table_fixed_4[2 + hop] +
+			  (FIXED_A) t2[3] * cos_table_fixed_4[5 + hop]) >>
+			(SBC_COS_TABLE_FIXED4_SCALE - SCALE_OUT_BITS);
+	}
 }
 
 static inline void sbc_analyze_four(struct sbc_encoder_state *state,
 				struct sbc_frame *frame, int ch, int blk)
 {
-	int32_t *x = &state->X[ch][state->position[ch]];
+	int16_t *x = &state->X[ch][state->position[ch]];
 	int16_t *pcm = &frame->pcm_sample[ch][blk * 4];
 
 	/* Input 4 Audio Samples */
@@ -740,133 +713,64 @@ static inline void sbc_analyze_four(struct sbc_encoder_state *state,
 		state->position[ch] = 36;
 }
 
-static inline void _sbc_analyze_eight(const int32_t *in, int32_t *out)
+static inline void _sbc_analyze_eight(const int16_t *in, int32_t *out)
 {
-	sbc_fixed_t t[8], s[8];
-
-	t[0] = SCALE8_STAGE1( /* Q10 */
-		MULA(_sbc_proto_8[0], (in[16] - in[64]), /* Q18 = Q18 * Q0 */
-		MULA(_sbc_proto_8[1], (in[32] - in[48]),
-		MULA(_sbc_proto_8[2], in[4],
-		MULA(_sbc_proto_8[3], in[20],
-		MULA(_sbc_proto_8[4], in[36],
-		MUL( _sbc_proto_8[5], in[52])))))));
-
-	t[1] = SCALE8_STAGE1(
-		MULA(_sbc_proto_8[6], in[2],
-		MULA(_sbc_proto_8[7], in[18],
-		MULA(_sbc_proto_8[8], in[34],
-		MULA(_sbc_proto_8[9], in[50],
-		MUL(_sbc_proto_8[10], in[66]))))));
-
-	t[2] = SCALE8_STAGE1(
-		MULA(_sbc_proto_8[11], in[1],
-		MULA(_sbc_proto_8[12], in[17],
-		MULA(_sbc_proto_8[13], in[33],
-		MULA(_sbc_proto_8[14], in[49],
-		MULA(_sbc_proto_8[15], in[65],
-		MULA(_sbc_proto_8[16], in[3],
-		MULA(_sbc_proto_8[17], in[19],
-		MULA(_sbc_proto_8[18], in[35],
-		MULA(_sbc_proto_8[19], in[51],
-		MUL( _sbc_proto_8[20], in[67])))))))))));
-
-	t[3] = SCALE8_STAGE1(
-		MULA( _sbc_proto_8[21], in[5],
-		MULA( _sbc_proto_8[22], in[21],
-		MULA( _sbc_proto_8[23], in[37],
-		MULA( _sbc_proto_8[24], in[53],
-		MULA( _sbc_proto_8[25], in[69],
-		MULA(-_sbc_proto_8[15], in[15],
-		MULA(-_sbc_proto_8[14], in[31],
-		MULA(-_sbc_proto_8[13], in[47],
-		MULA(-_sbc_proto_8[12], in[63],
-		MUL( -_sbc_proto_8[11], in[79])))))))))));
-
-	t[4] = SCALE8_STAGE1(
-		MULA( _sbc_proto_8[26], in[6],
-		MULA( _sbc_proto_8[27], in[22],
-		MULA( _sbc_proto_8[28], in[38],
-		MULA( _sbc_proto_8[29], in[54],
-		MULA( _sbc_proto_8[30], in[70],
-		MULA(-_sbc_proto_8[10], in[14],
-		MULA(-_sbc_proto_8[9], in[30],
-		MULA(-_sbc_proto_8[8], in[46],
-		MULA(-_sbc_proto_8[7], in[62],
-		MUL( -_sbc_proto_8[6], in[78])))))))))));
-
-	t[5] = SCALE8_STAGE1(
-		MULA( _sbc_proto_8[31], in[7],
-		MULA( _sbc_proto_8[32], in[23],
-		MULA( _sbc_proto_8[33], in[39],
-		MULA( _sbc_proto_8[34], in[55],
-		MULA( _sbc_proto_8[35], in[71],
-		MULA(-_sbc_proto_8[20], in[13],
-		MULA(-_sbc_proto_8[19], in[29],
-		MULA(-_sbc_proto_8[18], in[45],
-		MULA(-_sbc_proto_8[17], in[61],
-		MUL( -_sbc_proto_8[16], in[77])))))))))));
-
-	t[6] = SCALE8_STAGE1(
-		MULA( _sbc_proto_8[36], (in[8] + in[72]),
-		MULA( _sbc_proto_8[37], (in[24] + in[56]),
-		MULA( _sbc_proto_8[38], in[40],
-		MULA(-_sbc_proto_8[39], in[12],
-		MULA(-_sbc_proto_8[5], in[28],
-		MULA(-_sbc_proto_8[4], in[44],
-		MULA(-_sbc_proto_8[3], in[60],
-		MUL( -_sbc_proto_8[2], in[76])))))))));
-
-	t[7] = SCALE8_STAGE1(
-		MULA( _sbc_proto_8[35], in[9],
-		MULA( _sbc_proto_8[34], in[25],
-		MULA( _sbc_proto_8[33], in[41],
-		MULA( _sbc_proto_8[32], in[57],
-		MULA( _sbc_proto_8[31], in[73],
-		MULA(-_sbc_proto_8[25], in[11],
-		MULA(-_sbc_proto_8[24], in[27],
-		MULA(-_sbc_proto_8[23], in[43],
-		MULA(-_sbc_proto_8[22], in[59],
-		MUL( -_sbc_proto_8[21], in[75])))))))))));
-
-	s[0] = MULA(  _anamatrix8[0], t[0],
-		MUL(  _anamatrix8[1], t[6]));
-	s[1] = MUL(   _anamatrix8[7], t[1]);
-	s[2] = MULA(  _anamatrix8[2], t[2],
-		MULA( _anamatrix8[3], t[3],
-		MULA( _anamatrix8[4], t[5],
-		MUL(  _anamatrix8[5], t[7]))));
-	s[3] = MUL(   _anamatrix8[6], t[4]);
-	s[4] = MULA(  _anamatrix8[3], t[2],
-		MULA(-_anamatrix8[5], t[3],
-		MULA(-_anamatrix8[2], t[5],
-		MUL( -_anamatrix8[4], t[7]))));
-	s[5] = MULA(  _anamatrix8[4], t[2],
-		MULA(-_anamatrix8[2], t[3],
-		MULA( _anamatrix8[5], t[5],
-		MUL(  _anamatrix8[3], t[7]))));
-	s[6] = MULA(  _anamatrix8[1], t[0],
-		MUL( -_anamatrix8[0], t[6]));
-	s[7] = MULA(  _anamatrix8[5], t[2],
-		MULA(-_anamatrix8[4], t[3],
-		MULA( _anamatrix8[3], t[5],
-		MUL( -_anamatrix8[2], t[7]))));
-
-	out[0] = SCALE8_STAGE2( s[0] + s[1] + s[2] + s[3]);
-	out[1] = SCALE8_STAGE2( s[1] - s[3] + s[4] + s[6]);
-	out[2] = SCALE8_STAGE2( s[1] - s[3] + s[5] - s[6]);
-	out[3] = SCALE8_STAGE2(-s[0] + s[1] + s[3] + s[7]);
-	out[4] = SCALE8_STAGE2(-s[0] + s[1] + s[3] - s[7]);
-	out[5] = SCALE8_STAGE2( s[1] - s[3] - s[5] - s[6]);
-	out[6] = SCALE8_STAGE2( s[1] - s[3] - s[4] + s[6]);
-	out[7] = SCALE8_STAGE2( s[0] + s[1] - s[2] + s[3]);
+	FIXED_A t1[8];
+	FIXED_T t2[8];
+	int i, hop;
+
+	/* rounding coefficient */
+	t1[0] = t1[1] = t1[2] = t1[3] = t1[4] = t1[5] = t1[6] = t1[7] =
+		(FIXED_A) 1 << (SBC_PROTO_FIXED8_SCALE-1);
+
+	/* low pass polyphase filter */
+	for (hop = 0; hop < 80; hop += 16) {
+		t1[0] += (FIXED_A) in[hop] * _sbc_proto_fixed8[hop];
+		t1[1] += (FIXED_A) in[hop + 1] * _sbc_proto_fixed8[hop + 1];
+		t1[2] += (FIXED_A) in[hop + 2] * _sbc_proto_fixed8[hop + 2];
+		t1[3] += (FIXED_A) in[hop + 3] * _sbc_proto_fixed8[hop + 3];
+		t1[4] += (FIXED_A) in[hop + 4] * _sbc_proto_fixed8[hop + 4];
+		t1[3] += (FIXED_A) in[hop + 5] * _sbc_proto_fixed8[hop + 5];
+		t1[2] += (FIXED_A) in[hop + 6] * _sbc_proto_fixed8[hop + 6];
+		t1[1] += (FIXED_A) in[hop + 7] * _sbc_proto_fixed8[hop + 7];
+		t1[0] += (FIXED_A) in[hop + 8] * _sbc_proto_fixed8[hop + 8];
+		t1[5] += (FIXED_A) in[hop + 9] * _sbc_proto_fixed8[hop + 9];
+		t1[6] += (FIXED_A) in[hop + 10] * _sbc_proto_fixed8[hop + 10];
+		t1[7] += (FIXED_A) in[hop + 11] * _sbc_proto_fixed8[hop + 11];
+		t1[7] += (FIXED_A) in[hop + 13] * _sbc_proto_fixed8[hop + 13];
+		t1[6] += (FIXED_A) in[hop + 14] * _sbc_proto_fixed8[hop + 14];
+		t1[5] += (FIXED_A) in[hop + 15] * _sbc_proto_fixed8[hop + 15];
+	}
+
+	/* scaling */
+	t2[0] = t1[0] >> SBC_PROTO_FIXED8_SCALE;
+	t2[1] = t1[1] >> SBC_PROTO_FIXED8_SCALE;
+	t2[2] = t1[2] >> SBC_PROTO_FIXED8_SCALE;
+	t2[3] = t1[3] >> SBC_PROTO_FIXED8_SCALE;
+	t2[4] = t1[4] >> SBC_PROTO_FIXED8_SCALE;
+	t2[5] = t1[5] >> SBC_PROTO_FIXED8_SCALE;
+	t2[6] = t1[6] >> SBC_PROTO_FIXED8_SCALE;
+	t2[7] = t1[7] >> SBC_PROTO_FIXED8_SCALE;
+
+	/* do the cos transform */
+	for (i = 0, hop = 0; i < 8; hop += 16, i++) {
+		out[i] = ((FIXED_A) t2[0] * cos_table_fixed_8[0 + hop] +
+			  (FIXED_A) t2[1] * cos_table_fixed_8[1 + hop] +
+			  (FIXED_A) t2[2] * cos_table_fixed_8[2 + hop] +
+			  (FIXED_A) t2[3] * cos_table_fixed_8[3 + hop] +
+			  (FIXED_A) t2[4] * cos_table_fixed_8[4 + hop] +
+			  (FIXED_A) t2[5] * cos_table_fixed_8[9 + hop] +
+			  (FIXED_A) t2[6] * cos_table_fixed_8[10 + hop] +
+			  (FIXED_A) t2[7] * cos_table_fixed_8[11 + hop]) >>
+			(SBC_COS_TABLE_FIXED8_SCALE - SCALE_OUT_BITS);
+	}
 }
 
 static inline void sbc_analyze_eight(struct sbc_encoder_state *state,
 					struct sbc_frame *frame, int ch,
 					int blk)
 {
-	int32_t *x = &state->X[ch][state->position[ch]];
+	int16_t *x = &state->X[ch][state->position[ch]];
 	int16_t *pcm = &frame->pcm_sample[ch][blk * 8];
 
 	/* Input 8 Audio Samples */
@@ -1004,7 +908,7 @@ static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
 	for (ch = 0; ch < frame->channels; ch++) {
 		for (sb = 0; sb < frame->subbands; sb++) {
 			frame->scale_factor[ch][sb] = 0;
-			scalefactor[ch][sb] = 2;
+			scalefactor[ch][sb] = 2 << SCALE_OUT_BITS;
 			for (blk = 0; blk < frame->blocks; blk++) {
 				while (scalefactor[ch][sb] < fabs(frame->sb_sample_f[blk][ch][sb])) {
 					frame->scale_factor[ch][sb]++;
@@ -1026,18 +930,18 @@ static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
 
 		for (sb = 0; sb < frame->subbands - 1; sb++) {
 			scale_factor_j[0] = 0;
-			scalefactor_j[0] = 2;
+			scalefactor_j[0] = 2 << SCALE_OUT_BITS;
 			scale_factor_j[1] = 0;
-			scalefactor_j[1] = 2;
+			scalefactor_j[1] = 2 << SCALE_OUT_BITS;
 
 			for (blk = 0; blk < frame->blocks; blk++) {
 				/* Calculate joint stereo signal */
 				sb_sample_j[blk][0] =
-					(frame->sb_sample_f[blk][0][sb] +
-						frame->sb_sample_f[blk][1][sb]) >> 1;
+					ASR(frame->sb_sample_f[blk][0][sb], 1) +
+					ASR(frame->sb_sample_f[blk][1][sb], 1);
 				sb_sample_j[blk][1] =
-					(frame->sb_sample_f[blk][0][sb] -
-						frame->sb_sample_f[blk][1][sb]) >> 1;
+					ASR(frame->sb_sample_f[blk][0][sb], 1) -
+					ASR(frame->sb_sample_f[blk][1][sb], 1);
 
 				/* calculate scale_factor_j and scalefactor_j for joint case */
 				while (scalefactor_j[0] < fabs(sb_sample_j[blk][0])) {
@@ -1099,13 +1003,19 @@ static int sbc_pack_frame(uint8_t *data, struct sbc_frame *frame, size_t len)
 	for (blk = 0; blk < frame->blocks; blk++) {
 		for (ch = 0; ch < frame->channels; ch++) {
 			for (sb = 0; sb < frame->subbands; sb++) {
-				if (levels[ch][sb] > 0) {
-					audio_sample =
-						(uint16_t) (((((int64_t)frame->sb_sample_f[blk][ch][sb]*levels[ch][sb]) >>
-									(frame->scale_factor[ch][sb] + 1)) +
-								levels[ch][sb]) >> 1);
-					PUT_BITS(audio_sample & levels[ch][sb], bits[ch][sb]);
-				}
+
+				if (bits[ch][sb] == 0)
+					continue;
+
+				audio_sample = ((uint64_t) levels[ch][sb] *
+					(((uint32_t) 1 <<
+					(frame->scale_factor[ch][sb] +
+					SCALE_OUT_BITS + 1)) +
+					frame->sb_sample_f[blk][ch][sb])) >>
+						(frame->scale_factor[ch][sb] +
+						SCALE_OUT_BITS + 2);
+
+				PUT_BITS(audio_sample, bits[ch][sb]);
 			}
 		}
 	}
diff --git a/sbc/sbc_math.h b/sbc/sbc_math.h
index b3d87a62..1503d75c 100644
--- a/sbc/sbc_math.h
+++ b/sbc/sbc_math.h
@@ -29,31 +29,21 @@
 #define ASR(val, bits) ((-2 >> 1 == -1) ? \
 		 ((int32_t)(val)) >> (bits) : ((int32_t) (val)) / (1 << (bits)))
 
-#define SCALE_PROTO4_TBL	15
-#define SCALE_ANA4_TBL		17
-#define SCALE_PROTO8_TBL	16
-#define SCALE_ANA8_TBL		17
+#define SCALE_OUT_BITS 15
+
 #define SCALE_SPROTO4_TBL	12
 #define SCALE_SPROTO8_TBL	14
 #define SCALE_NPROTO4_TBL	11
 #define SCALE_NPROTO8_TBL	11
-#define SCALE4_STAGE1_BITS	15
-#define SCALE4_STAGE2_BITS	16
 #define SCALE4_STAGED1_BITS	15
 #define SCALE4_STAGED2_BITS	16
-#define SCALE8_STAGE1_BITS	15
-#define SCALE8_STAGE2_BITS	15
 #define SCALE8_STAGED1_BITS	15
 #define SCALE8_STAGED2_BITS	16
 
 typedef int32_t sbc_fixed_t;
 
-#define SCALE4_STAGE1(src)  ASR(src, SCALE4_STAGE1_BITS)
-#define SCALE4_STAGE2(src)  ASR(src, SCALE4_STAGE2_BITS)
 #define SCALE4_STAGED1(src) ASR(src, SCALE4_STAGED1_BITS)
 #define SCALE4_STAGED2(src) ASR(src, SCALE4_STAGED2_BITS)
-#define SCALE8_STAGE1(src)  ASR(src, SCALE8_STAGE1_BITS)
-#define SCALE8_STAGE2(src)  ASR(src, SCALE8_STAGE2_BITS)
 #define SCALE8_STAGED1(src) ASR(src, SCALE8_STAGED1_BITS)
 #define SCALE8_STAGED2(src) ASR(src, SCALE8_STAGED2_BITS)
 
diff --git a/sbc/sbc_tables.h b/sbc/sbc_tables.h
index f5daaa7f..8df8c1fe 100644
--- a/sbc/sbc_tables.h
+++ b/sbc/sbc_tables.h
@@ -40,40 +40,11 @@ static const int sbc_offset8[4][8] = {
 };
 
 
-#define SP4(val) (((int32_t)(val))/17658) /* Used to be #define SP4(val) ASR(val, SCALE_PROTO4_TBL) but causes wrong gain */
-#define SA4(val) ASR(val, SCALE_ANA4_TBL)
-#define SP8(val) (((int32_t)(val))/57740) /* Used to be #define SP8(val) ASR(val, SCALE_PROTO8_TBL) but causes wrong gain */
-#define SA8(val) ASR(val, SCALE_ANA8_TBL)
 #define SS4(val) ASR(val, SCALE_SPROTO4_TBL)
 #define SS8(val) ASR(val, SCALE_SPROTO8_TBL)
 #define SN4(val) ASR(val, SCALE_NPROTO4_TBL)
 #define SN8(val) ASR(val, SCALE_NPROTO8_TBL)
 
-static const int32_t _sbc_proto_4[20] = {
-	SP4(0x02cb3e8c), SP4(0x22b63dc0), SP4(0x002329cc), SP4(0x053b7548),
-	SP4(0x31eab940), SP4(0xec1f5e60), SP4(0xff3773a8), SP4(0x0061c5a7),
-	SP4(0x07646680), SP4(0x3f239480), SP4(0xf89f23a8), SP4(0x007a4737),
-	SP4(0x00b32807), SP4(0x083ddc80), SP4(0x4825e480), SP4(0x0191e578),
-	SP4(0x00ff11ca), SP4(0x00fb7991), SP4(0x069fdc58), SP4(0x4b584000)
-};
-
-static const int32_t _anamatrix4[4] = {
-	SA4(0x2d413cc0), SA4(0x3b20d780), SA4(0x40000000), SA4(0x187de2a0)
-};
-
-static const int32_t _sbc_proto_8[40] = {
-	SP8(0x02e5cd20), SP8(0x22d0c200), SP8(0x006bfe27), SP8(0x07808930),
-	SP8(0x3f1c8800), SP8(0xf8810d70), SP8(0x002cfdc6), SP8(0x055acf28),
-	SP8(0x31f566c0), SP8(0xebfe57e0), SP8(0xff27c437), SP8(0x001485cc),
-	SP8(0x041c6e58), SP8(0x2a7cfa80), SP8(0xe4c4a240), SP8(0xfe359e4c),
-	SP8(0x0048b1f8), SP8(0x0686ce30), SP8(0x38eec5c0), SP8(0xf2a1b9f0),
-	SP8(0xffe8904a), SP8(0x0095698a), SP8(0x0824a480), SP8(0x443b3c00),
-	SP8(0xfd7badc8), SP8(0x00d3e2d9), SP8(0x00c183d2), SP8(0x084e1950),
-	SP8(0x4810d800), SP8(0x017f43fe), SP8(0x01056dd8), SP8(0x00e9cb9f),
-	SP8(0x07d7d090), SP8(0x4a708980), SP8(0x0488fae8), SP8(0x0113bd20),
-	SP8(0x0107b1a8), SP8(0x069fb3c0), SP8(0x4b3db200), SP8(0x00763f48)
-};
-
 static const int32_t sbc_proto_4_40m0[] = {
 	SS4(0x00000000), SS4(0xffa6982f), SS4(0xfba93848), SS4(0x0456c7b8),
 	SS4(0x005967d1), SS4(0xfffb9ac7), SS4(0xff589157), SS4(0xf9c2a8d8),
@@ -116,11 +87,6 @@ static const int32_t sbc_proto_8_80m1[] = {
 	SS8(0x0d9daee0), SS8(0xeac182c0), SS8(0xfdf1c8d4), SS8(0xfff5bd1a)
 };
 
-static const int32_t _anamatrix8[8] = {
-	SA8(0x3b20d780), SA8(0x187de2a0), SA8(0x3ec52f80), SA8(0x3536cc40),
-	SA8(0x238e7680), SA8(0x0c7c5c20), SA8(0x2d413cc0), SA8(0x40000000)
-};
-
 static const int32_t synmatrix4[8][4] = {
 	{ SN4(0x05a82798), SN4(0xfa57d868), SN4(0xfa57d868), SN4(0x05a82798) },
 	{ SN4(0x030fbc54), SN4(0xf89be510), SN4(0x07641af0), SN4(0xfcf043ac) },
@@ -166,3 +132,216 @@ static const int32_t synmatrix8[16][8] = {
 	{ SN8(0xf9592678), SN8(0x018f8b84), SN8(0x07d8a5f0), SN8(0x0471ced0),
 	  SN8(0xfb8e3130), SN8(0xf8275a10), SN8(0xfe70747c), SN8(0x06a6d988) }
 };
+
+/* Uncomment the following line to enable high precision build of SBC encoder */
+
+/* #define SBC_HIGH_PRECISION */
+
+#ifdef SBC_HIGH_PRECISION
+#define FIXED_A int64_t /* data type for fixed point accumulator */
+#define FIXED_T int32_t /* data type for fixed point constants */
+#define SBC_FIXED_EXTRA_BITS 16
+#else
+#define FIXED_A int32_t /* data type for fixed point accumulator */
+#define FIXED_T int16_t /* data type for fixed point constants */
+#define SBC_FIXED_EXTRA_BITS 0
+#endif
+
+/* A2DP specification: Section 12.8 Tables
+ *
+ * Original values are premultiplied by 2 for better precision (that is the
+ * maximum which is possible without overflows)
+ *
+ * Note: in each block of 8 numbers sign was changed for elements 2 and 7
+ * in order to compensate the same change applied to cos_table_fixed_4
+ */
+#define SBC_PROTO_FIXED4_SCALE \
+	((sizeof(FIXED_T) * CHAR_BIT - 1) - SBC_FIXED_EXTRA_BITS + 1)
+#define F(x) (FIXED_A) ((x * 2) * \
+	((FIXED_A) 1 << (sizeof(FIXED_T) * CHAR_BIT - 1)) + 0.5)
+static const FIXED_T _sbc_proto_fixed4[40] = {
+	 F(0.00000000E+00),  F(5.36548976E-04),
+	-F(1.49188357E-03),  F(2.73370904E-03),
+	 F(3.83720193E-03),  F(3.89205149E-03),
+	 F(1.86581691E-03),  F(3.06012286E-03),
+
+	 F(1.09137620E-02),  F(2.04385087E-02),
+	-F(2.88757392E-02),  F(3.21939290E-02),
+	 F(2.58767811E-02),  F(6.13245186E-03),
+	-F(2.88217274E-02),  F(7.76463494E-02),
+
+	 F(1.35593274E-01),  F(1.94987841E-01),
+	-F(2.46636662E-01),  F(2.81828203E-01),
+	 F(2.94315332E-01),  F(2.81828203E-01),
+	 F(2.46636662E-01), -F(1.94987841E-01),
+
+	-F(1.35593274E-01), -F(7.76463494E-02),
+	 F(2.88217274E-02),  F(6.13245186E-03),
+	 F(2.58767811E-02),  F(3.21939290E-02),
+	 F(2.88757392E-02), -F(2.04385087E-02),
+
+	-F(1.09137620E-02), -F(3.06012286E-03),
+	-F(1.86581691E-03),  F(3.89205149E-03),
+	 F(3.83720193E-03),  F(2.73370904E-03),
+	 F(1.49188357E-03), -F(5.36548976E-04),
+};
+#undef F
+
+/*
+ * To produce this cosine matrix in Octave:
+ *
+ * b = zeros(4, 8);
+ * for i = 0:3
+ * for j = 0:7 b(i+1, j+1) = cos((i + 0.5) * (j - 2) * (pi/4))
+ * endfor
+ * endfor;
+ * printf("%.10f, ", b');
+ *
+ * Note: in each block of 8 numbers sign was changed for elements 2 and 7
+ *
+ * Change of sign for element 2 allows to replace constant 1.0 (not
+ * representable in Q15 format) with -1.0 (fine with Q15).
+ * Changed sign for element 7 allows to have more similar constants
+ * and simplify subband filter function code.
+ */
+#define SBC_COS_TABLE_FIXED4_SCALE \
+	((sizeof(FIXED_T) * CHAR_BIT - 1) + SBC_FIXED_EXTRA_BITS)
+#define F(x) (FIXED_A) ((x) * \
+	((FIXED_A) 1 << (sizeof(FIXED_T) * CHAR_BIT - 1)) + 0.5)
+static const FIXED_T cos_table_fixed_4[32] = {
+	 F(0.7071067812),  F(0.9238795325), -F(1.0000000000),  F(0.9238795325),
+	 F(0.7071067812),  F(0.3826834324),  F(0.0000000000),  F(0.3826834324),
+
+	-F(0.7071067812),  F(0.3826834324), -F(1.0000000000),  F(0.3826834324),
+	-F(0.7071067812), -F(0.9238795325), -F(0.0000000000), -F(0.9238795325),
+
+	-F(0.7071067812), -F(0.3826834324), -F(1.0000000000), -F(0.3826834324),
+	-F(0.7071067812),  F(0.9238795325),  F(0.0000000000),  F(0.9238795325),
+
+	 F(0.7071067812), -F(0.9238795325), -F(1.0000000000), -F(0.9238795325),
+	 F(0.7071067812), -F(0.3826834324), -F(0.0000000000), -F(0.3826834324),
+};
+#undef F
+
+/* A2DP specification: Section 12.8 Tables
+ *
+ * Original values are premultiplied by 4 for better precision (that is the
+ * maximum which is possible without overflows)
+ *
+ * Note: in each block of 16 numbers sign was changed for elements 4, 13, 14, 15
+ * in order to compensate the same change applied to cos_table_fixed_8
+ */
+#define SBC_PROTO_FIXED8_SCALE \
+	((sizeof(FIXED_T) * CHAR_BIT - 1) - SBC_FIXED_EXTRA_BITS + 2)
+#define F(x) (FIXED_A) ((x * 4) * \
+	((FIXED_A) 1 << (sizeof(FIXED_T) * CHAR_BIT - 1)) + 0.5)
+static const FIXED_T _sbc_proto_fixed8[80] = {
+	 F(0.00000000E+00),  F(1.56575398E-04),
+	 F(3.43256425E-04),  F(5.54620202E-04),
+	-F(8.23919506E-04),  F(1.13992507E-03),
+	 F(1.47640169E-03),  F(1.78371725E-03),
+	 F(2.01182542E-03),  F(2.10371989E-03),
+	 F(1.99454554E-03),  F(1.61656283E-03),
+	 F(9.02154502E-04),  F(1.78805361E-04),
+	 F(1.64973098E-03),  F(3.49717454E-03),
+
+	 F(5.65949473E-03),  F(8.02941163E-03),
+	 F(1.04584443E-02),  F(1.27472335E-02),
+	-F(1.46525263E-02),  F(1.59045603E-02),
+	 F(1.62208471E-02),  F(1.53184106E-02),
+	 F(1.29371806E-02),  F(8.85757540E-03),
+	 F(2.92408442E-03), -F(4.91578024E-03),
+	-F(1.46404076E-02),  F(2.61098752E-02),
+	 F(3.90751381E-02),  F(5.31873032E-02),
+
+	 F(6.79989431E-02),  F(8.29847578E-02),
+	 F(9.75753918E-02),  F(1.11196689E-01),
+	-F(1.23264548E-01),  F(1.33264415E-01),
+	 F(1.40753505E-01),  F(1.45389847E-01),
+	 F(1.46955068E-01),  F(1.45389847E-01),
+	 F(1.40753505E-01),  F(1.33264415E-01),
+	 F(1.23264548E-01), -F(1.11196689E-01),
+	-F(9.75753918E-02), -F(8.29847578E-02),
+
+	-F(6.79989431E-02), -F(5.31873032E-02),
+	-F(3.90751381E-02), -F(2.61098752E-02),
+	 F(1.46404076E-02), -F(4.91578024E-03),
+	 F(2.92408442E-03),  F(8.85757540E-03),
+	 F(1.29371806E-02),  F(1.53184106E-02),
+	 F(1.62208471E-02),  F(1.59045603E-02),
+	 F(1.46525263E-02), -F(1.27472335E-02),
+	-F(1.04584443E-02), -F(8.02941163E-03),
+
+	-F(5.65949473E-03), -F(3.49717454E-03),
+	-F(1.64973098E-03), -F(1.78805361E-04),
+	-F(9.02154502E-04),  F(1.61656283E-03),
+	 F(1.99454554E-03),  F(2.10371989E-03),
+	 F(2.01182542E-03),  F(1.78371725E-03),
+	 F(1.47640169E-03),  F(1.13992507E-03),
+	 F(8.23919506E-04), -F(5.54620202E-04),
+	-F(3.43256425E-04), -F(1.56575398E-04),
+};
+#undef F
+
+/*
+ * To produce this cosine matrix in Octave:
+ *
+ * b = zeros(8, 16);
+ * for i = 0:7
+ * for j = 0:15 b(i+1, j+1) = cos((i + 0.5) * (j - 4) * (pi/8))
+ * endfor endfor;
+ * printf("%.10f, ", b');
+ *
+ * Note: in each block of 16 numbers sign was changed for elements 4, 13, 14, 15
+ *
+ * Change of sign for element 4 allows to replace constant 1.0 (not
+ * representable in Q15 format) with -1.0 (fine with Q15).
+ * Changed signs for elements 13, 14, 15 allow to have more similar constants
+ * and simplify subband filter function code.
+ */
+#define SBC_COS_TABLE_FIXED8_SCALE \
+	((sizeof(FIXED_T) * CHAR_BIT - 1) + SBC_FIXED_EXTRA_BITS)
+#define F(x) (FIXED_A) ((x) * \
+	((FIXED_A) 1 << (sizeof(FIXED_T) * CHAR_BIT - 1)) + 0.5)
+static const FIXED_T cos_table_fixed_8[128] = {
+	 F(0.7071067812),  F(0.8314696123),  F(0.9238795325),  F(0.9807852804),
+	-F(1.0000000000),  F(0.9807852804),  F(0.9238795325),  F(0.8314696123),
+	 F(0.7071067812),  F(0.5555702330),  F(0.3826834324),  F(0.1950903220),
+	 F(0.0000000000),  F(0.1950903220),  F(0.3826834324),  F(0.5555702330),
+
+	-F(0.7071067812), -F(0.1950903220),  F(0.3826834324),  F(0.8314696123),
+	-F(1.0000000000),  F(0.8314696123),  F(0.3826834324), -F(0.1950903220),
+	-F(0.7071067812), -F(0.9807852804), -F(0.9238795325), -F(0.5555702330),
+	-F(0.0000000000), -F(0.5555702330), -F(0.9238795325), -F(0.9807852804),
+
+	-F(0.7071067812), -F(0.9807852804), -F(0.3826834324),  F(0.5555702330),
+	-F(1.0000000000),  F(0.5555702330), -F(0.3826834324), -F(0.9807852804),
+	-F(0.7071067812),  F(0.1950903220),  F(0.9238795325),  F(0.8314696123),
+	 F(0.0000000000),  F(0.8314696123),  F(0.9238795325),  F(0.1950903220),
+
+	 F(0.7071067812), -F(0.5555702330), -F(0.9238795325),  F(0.1950903220),
+	-F(1.0000000000),  F(0.1950903220), -F(0.9238795325), -F(0.5555702330),
+	 F(0.7071067812),  F(0.8314696123), -F(0.3826834324), -F(0.9807852804),
+	-F(0.0000000000), -F(0.9807852804), -F(0.3826834324),  F(0.8314696123),
+
+	 F(0.7071067812),  F(0.5555702330), -F(0.9238795325), -F(0.1950903220),
+	-F(1.0000000000), -F(0.1950903220), -F(0.9238795325),  F(0.5555702330),
+	 F(0.7071067812), -F(0.8314696123), -F(0.3826834324),  F(0.9807852804),
+	 F(0.0000000000),  F(0.9807852804), -F(0.3826834324), -F(0.8314696123),
+
+	-F(0.7071067812),  F(0.9807852804), -F(0.3826834324), -F(0.5555702330),
+	-F(1.0000000000), -F(0.5555702330), -F(0.3826834324),  F(0.9807852804),
+	-F(0.7071067812), -F(0.1950903220),  F(0.9238795325), -F(0.8314696123),
+	-F(0.0000000000), -F(0.8314696123),  F(0.9238795325), -F(0.1950903220),
+
+	-F(0.7071067812),  F(0.1950903220),  F(0.3826834324), -F(0.8314696123),
+	-F(1.0000000000), -F(0.8314696123),  F(0.3826834324),  F(0.1950903220),
+	-F(0.7071067812),  F(0.9807852804), -F(0.9238795325),  F(0.5555702330),
+	-F(0.0000000000),  F(0.5555702330), -F(0.9238795325),  F(0.9807852804),
+
+	 F(0.7071067812), -F(0.8314696123),  F(0.9238795325), -F(0.9807852804),
+	-F(1.0000000000), -F(0.9807852804),  F(0.9238795325), -F(0.8314696123),
+	 F(0.7071067812), -F(0.5555702330),  F(0.3826834324), -F(0.1950903220),
+	-F(0.0000000000), -F(0.1950903220),  F(0.3826834324), -F(0.5555702330),
+};
+#undef F