libavcodec/ac3dsp.c - third_party/ffmpeg - Git at Google

 /*
  * AC-3 DSP utils
  * Copyright (c) 2011 Justin Ruggles
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #include "libavutil/avassert.h"
 #include "avcodec.h"
 #include "ac3.h"
 #include "ac3dsp.h"
 #include "mathops.h"

 static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
 {
     int blk, i;

     if (!num_reuse_blocks)
         return;

     for (i = 0; i < nb_coefs; i++) {
         uint8_t min_exp = *exp;
         uint8_t *exp1 = exp + 256;
         for (blk = 0; blk < num_reuse_blocks; blk++) {
             uint8_t next_exp = *exp1;
             if (next_exp < min_exp)
                 min_exp = next_exp;
             exp1 += 256;
         }
         *exp++ = min_exp;
     }
 }

 static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)
 {
     int i, v = 0;
     for (i = 0; i < len; i++)
         v |= abs(src[i]);
     return v;
 }

 static void ac3_lshift_int16_c(int16_t *src, unsigned int len,
                                unsigned int shift)
 {
     uint32_t *src32 = (uint32_t *)src;
     const uint32_t mask = ~(((1 << shift) - 1) << 16);
     int i;
     len >>= 1;
     for (i = 0; i < len; i += 8) {
         src32[i  ] = (src32[i  ] << shift) & mask;
         src32[i+1] = (src32[i+1] << shift) & mask;
         src32[i+2] = (src32[i+2] << shift) & mask;
         src32[i+3] = (src32[i+3] << shift) & mask;
         src32[i+4] = (src32[i+4] << shift) & mask;
         src32[i+5] = (src32[i+5] << shift) & mask;
         src32[i+6] = (src32[i+6] << shift) & mask;
         src32[i+7] = (src32[i+7] << shift) & mask;
     }
 }

 static void ac3_rshift_int32_c(int32_t *src, unsigned int len,
                                unsigned int shift)
 {
     do {
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         *src++ >>= shift;
         len -= 8;
     } while (len > 0);
 }

 static void float_to_fixed24_c(int32_t *dst, const float *src, unsigned int len)
 {
     const float scale = 1 << 24;
     do {
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         *dst++ = lrintf(*src++ * scale);
         len -= 8;
     } while (len > 0);
 }

 static void ac3_bit_alloc_calc_bap_c(int16_t *mask, int16_t *psd,
                                      int start, int end,
                                      int snr_offset, int floor,
                                      const uint8_t *bap_tab, uint8_t *bap)
 {
     int bin, band, band_end;

     /* special case, if snr offset is -960, set all bap's to zero */
     if (snr_offset == -960) {
         memset(bap, 0, AC3_MAX_COEFS);
         return;
     }

     bin  = start;
     band = ff_ac3_bin_to_band_tab[start];
     do {
         int m = (FFMAX(mask[band] - snr_offset - floor, 0) & 0x1FE0) + floor;
         band_end = ff_ac3_band_start_tab[++band];
         band_end = FFMIN(band_end, end);

         for (; bin < band_end; bin++) {
             int address = av_clip((psd[bin] - m) >> 5, 0, 63);
             bap[bin] = bap_tab[address];
         }
     } while (end > band_end);
 }

 static void ac3_update_bap_counts_c(uint16_t mant_cnt[16], uint8_t *bap,
                                     int len)
 {
     while (len-- > 0)
         mant_cnt[bap[len]]++;
 }

 DECLARE_ALIGNED(16, const uint16_t, ff_ac3_bap_bits)[16] = {
     0,  0,  0,  3,  0,  4,  5,  6,  7,  8,  9, 10, 11, 12, 14, 16
 };

 static int ac3_compute_mantissa_size_c(uint16_t mant_cnt[6][16])
 {
     int blk, bap;
     int bits = 0;

     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         // bap=1 : 3 mantissas in 5 bits
         bits += (mant_cnt[blk][1] / 3) * 5;
         // bap=2 : 3 mantissas in 7 bits
         // bap=4 : 2 mantissas in 7 bits
         bits += ((mant_cnt[blk][2] / 3) + (mant_cnt[blk][4] >> 1)) * 7;
         // bap=3 : 1 mantissa in 3 bits
         bits += mant_cnt[blk][3] * 3;
         // bap=5 to 15 : get bits per mantissa from table
         for (bap = 5; bap < 16; bap++)
             bits += mant_cnt[blk][bap] * ff_ac3_bap_bits[bap];
     }
     return bits;
 }

 static void ac3_extract_exponents_c(uint8_t *exp, int32_t *coef, int nb_coefs)
 {
     int i;

     for (i = 0; i < nb_coefs; i++) {
         int v = abs(coef[i]);
         exp[i] = v ? 23 - av_log2(v) : 24;
     }
 }

 static void ac3_sum_square_butterfly_int32_c(int64_t sum[4],
                                              const int32_t *coef0,
                                              const int32_t *coef1,
                                              int len)
 {
     int i;

     sum[0] = sum[1] = sum[2] = sum[3] = 0;

     for (i = 0; i < len; i++) {
         int lt = coef0[i];
         int rt = coef1[i];
         int md = lt + rt;
         int sd = lt - rt;
         MAC64(sum[0], lt, lt);
         MAC64(sum[1], rt, rt);
         MAC64(sum[2], md, md);
         MAC64(sum[3], sd, sd);
     }
 }

 static void ac3_sum_square_butterfly_float_c(float sum[4],
                                              const float *coef0,
                                              const float *coef1,
                                              int len)
 {
     int i;

     sum[0] = sum[1] = sum[2] = sum[3] = 0;

     for (i = 0; i < len; i++) {
         float lt = coef0[i];
         float rt = coef1[i];
         float md = lt + rt;
         float sd = lt - rt;
         sum[0] += lt * lt;
         sum[1] += rt * rt;
         sum[2] += md * md;
         sum[3] += sd * sd;
     }
 }

 av_cold void ff_ac3dsp_init(AC3DSPContext *c, int bit_exact)
 {
     c->ac3_exponent_min = ac3_exponent_min_c;
     c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;
     c->ac3_lshift_int16 = ac3_lshift_int16_c;
     c->ac3_rshift_int32 = ac3_rshift_int32_c;
     c->float_to_fixed24 = float_to_fixed24_c;
     c->bit_alloc_calc_bap = ac3_bit_alloc_calc_bap_c;
     c->update_bap_counts = ac3_update_bap_counts_c;
     c->compute_mantissa_size = ac3_compute_mantissa_size_c;
     c->extract_exponents = ac3_extract_exponents_c;
     c->sum_square_butterfly_int32 = ac3_sum_square_butterfly_int32_c;
     c->sum_square_butterfly_float = ac3_sum_square_butterfly_float_c;

     if (ARCH_ARM)
         ff_ac3dsp_init_arm(c, bit_exact);
     if (HAVE_MMX)
         ff_ac3dsp_init_x86(c, bit_exact);
 }
	/*
	* AC-3 DSP utils
	* Copyright (c) 2011 Justin Ruggles
	*
	* This file is part of FFmpeg.
	*
	* FFmpeg 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.
	*
	* FFmpeg 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 FFmpeg; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	#include "libavutil/avassert.h"
	#include "avcodec.h"
	#include "ac3.h"
	#include "ac3dsp.h"
	#include "mathops.h"

	static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
	{
	int blk, i;

	if (!num_reuse_blocks)
	return;

	for (i = 0; i < nb_coefs; i++) {
	uint8_t min_exp = *exp;
	uint8_t *exp1 = exp + 256;
	for (blk = 0; blk < num_reuse_blocks; blk++) {
	uint8_t next_exp = *exp1;
	if (next_exp < min_exp)
	min_exp = next_exp;
	exp1 += 256;
	}
	*exp++ = min_exp;
	}
	}

	static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)
	{
	int i, v = 0;
	for (i = 0; i < len; i++)
	v \|= abs(src[i]);
	return v;
	}

	static void ac3_lshift_int16_c(int16_t *src, unsigned int len,
	unsigned int shift)
	{
	uint32_t src32 = (uint32_t )src;
	const uint32_t mask = ~(((1 << shift) - 1) << 16);
	int i;
	len >>= 1;
	for (i = 0; i < len; i += 8) {
	src32[i ] = (src32[i ] << shift) & mask;
	src32[i+1] = (src32[i+1] << shift) & mask;
	src32[i+2] = (src32[i+2] << shift) & mask;
	src32[i+3] = (src32[i+3] << shift) & mask;
	src32[i+4] = (src32[i+4] << shift) & mask;
	src32[i+5] = (src32[i+5] << shift) & mask;
	src32[i+6] = (src32[i+6] << shift) & mask;
	src32[i+7] = (src32[i+7] << shift) & mask;
	}
	}

	static void ac3_rshift_int32_c(int32_t *src, unsigned int len,
	unsigned int shift)
	{
	do {
	*src++ >>= shift;
	*src++ >>= shift;
	*src++ >>= shift;
	*src++ >>= shift;
	*src++ >>= shift;
	*src++ >>= shift;
	*src++ >>= shift;
	*src++ >>= shift;
	len -= 8;
	} while (len > 0);
	}

	static void float_to_fixed24_c(int32_t dst, const float src, unsigned int len)
	{
	const float scale = 1 << 24;
	do {
	dst++ = lrintf(src++ * scale);
	dst++ = lrintf(src++ * scale);
	dst++ = lrintf(src++ * scale);
	dst++ = lrintf(src++ * scale);
	dst++ = lrintf(src++ * scale);
	dst++ = lrintf(src++ * scale);
	dst++ = lrintf(src++ * scale);
	dst++ = lrintf(src++ * scale);
	len -= 8;
	} while (len > 0);
	}

	static void ac3_bit_alloc_calc_bap_c(int16_t mask, int16_t psd,
	int start, int end,
	int snr_offset, int floor,
	const uint8_t bap_tab, uint8_t bap)
	{
	int bin, band, band_end;

	/* special case, if snr offset is -960, set all bap's to zero */
	if (snr_offset == -960) {
	memset(bap, 0, AC3_MAX_COEFS);
	return;
	}

	bin = start;
	band = ff_ac3_bin_to_band_tab[start];
	do {
	int m = (FFMAX(mask[band] - snr_offset - floor, 0) & 0x1FE0) + floor;
	band_end = ff_ac3_band_start_tab[++band];
	band_end = FFMIN(band_end, end);

	for (; bin < band_end; bin++) {
	int address = av_clip((psd[bin] - m) >> 5, 0, 63);
	bap[bin] = bap_tab[address];
	}
	} while (end > band_end);
	}

	static void ac3_update_bap_counts_c(uint16_t mant_cnt[16], uint8_t *bap,
	int len)
	{
	while (len-- > 0)
	mant_cnt[bap[len]]++;
	}

	DECLARE_ALIGNED(16, const uint16_t, ff_ac3_bap_bits)[16] = {
	0, 0, 0, 3, 0, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
	};

	static int ac3_compute_mantissa_size_c(uint16_t mant_cnt[6][16])
	{
	int blk, bap;
	int bits = 0;

	for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
	// bap=1 : 3 mantissas in 5 bits
	bits += (mant_cnt[blk][1] / 3) * 5;
	// bap=2 : 3 mantissas in 7 bits
	// bap=4 : 2 mantissas in 7 bits
	bits += ((mant_cnt[blk][2] / 3) + (mant_cnt[blk][4] >> 1)) * 7;
	// bap=3 : 1 mantissa in 3 bits
	bits += mant_cnt[blk][3] * 3;
	// bap=5 to 15 : get bits per mantissa from table
	for (bap = 5; bap < 16; bap++)
	bits += mant_cnt[blk][bap] * ff_ac3_bap_bits[bap];
	}
	return bits;
	}

	static void ac3_extract_exponents_c(uint8_t exp, int32_t coef, int nb_coefs)
	{
	int i;

	for (i = 0; i < nb_coefs; i++) {
	int v = abs(coef[i]);
	exp[i] = v ? 23 - av_log2(v) : 24;
	}
	}

	static void ac3_sum_square_butterfly_int32_c(int64_t sum[4],
	const int32_t *coef0,
	const int32_t *coef1,
	int len)
	{
	int i;

	sum[0] = sum[1] = sum[2] = sum[3] = 0;

	for (i = 0; i < len; i++) {
	int lt = coef0[i];
	int rt = coef1[i];
	int md = lt + rt;
	int sd = lt - rt;
	MAC64(sum[0], lt, lt);
	MAC64(sum[1], rt, rt);
	MAC64(sum[2], md, md);
	MAC64(sum[3], sd, sd);
	}
	}

	static void ac3_sum_square_butterfly_float_c(float sum[4],
	const float *coef0,
	const float *coef1,
	int len)
	{
	int i;

	sum[0] = sum[1] = sum[2] = sum[3] = 0;

	for (i = 0; i < len; i++) {
	float lt = coef0[i];
	float rt = coef1[i];
	float md = lt + rt;
	float sd = lt - rt;
	sum[0] += lt * lt;
	sum[1] += rt * rt;
	sum[2] += md * md;
	sum[3] += sd * sd;
	}
	}

	av_cold void ff_ac3dsp_init(AC3DSPContext *c, int bit_exact)
	{
	c->ac3_exponent_min = ac3_exponent_min_c;
	c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;
	c->ac3_lshift_int16 = ac3_lshift_int16_c;
	c->ac3_rshift_int32 = ac3_rshift_int32_c;
	c->float_to_fixed24 = float_to_fixed24_c;
	c->bit_alloc_calc_bap = ac3_bit_alloc_calc_bap_c;
	c->update_bap_counts = ac3_update_bap_counts_c;
	c->compute_mantissa_size = ac3_compute_mantissa_size_c;
	c->extract_exponents = ac3_extract_exponents_c;
	c->sum_square_butterfly_int32 = ac3_sum_square_butterfly_int32_c;
	c->sum_square_butterfly_float = ac3_sum_square_butterfly_float_c;

	if (ARCH_ARM)
	ff_ac3dsp_init_arm(c, bit_exact);
	if (HAVE_MMX)
	ff_ac3dsp_init_x86(c, bit_exact);
	}