libavcodec/vorbis.c

   1 /**
   2  * @file libavcodec/vorbis.c
   3  * Common code for Vorbis I encoder and decoder
   4  * @author Denes Balatoni  ( dbalatoni programozo hu )
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #undef V_DEBUG
  24 //#define V_DEBUG
  25
  26 #define ALT_BITSTREAM_READER_LE
  27 #include "avcodec.h"
  28 #include "get_bits.h"
  29
  30 #include "vorbis.h"
  31
  32
  33 /* Helper functions */
  34
  35 // x^(1/n)
  36 unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n)
  37 {
  38     unsigned int ret = 0, i, j;
  39
  40     do {
  41         ++ret;
  42         for (i = 0, j = ret; i < n - 1; i++)
  43             j *= ret;
  44     } while (j <= x);
  45
  46     return ret - 1;
  47 }
  48
  49 // Generate vlc codes from vorbis huffman code lengths
  50
  51 // the two bits[p] > 32 checks should be redundant, all calling code should
  52 // already ensure that, but since it allows overwriting the stack it seems
  53 // reasonable to check redundantly.
  54 int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, uint_fast32_t num)
  55 {
  56     uint_fast32_t exit_at_level[33] = {
  57         404, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  58           0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
  59
  60     uint_fast8_t i, j;
  61     uint_fast32_t code, p;
  62
  63 #ifdef V_DEBUG
  64     GetBitContext gb;
  65 #endif
  66
  67     for (p = 0; (bits[p] == 0) && (p < num); ++p)
  68         ;
  69     if (p == num) {
  70 //        av_log(vc->avccontext, AV_LOG_INFO, "An empty codebook. Heh?! \n");
  71         return 0;
  72     }
  73
  74     codes[p] = 0;
  75     if (bits[p] > 32)
  76         return 1;
  77     for (i = 0; i < bits[p]; ++i)
  78         exit_at_level[i+1] = 1 << i;
  79
  80 #ifdef V_DEBUG
  81     av_log(NULL, AV_LOG_INFO, " %d. of %d code len %d code %d - ", p, num, bits[p], codes[p]);
  82     init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
  83     for (i = 0; i < bits[p]; ++i)
  84         av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
  85     av_log(NULL, AV_LOG_INFO, "\n");
  86 #endif
  87
  88     ++p;
  89
  90     for (; p < num; ++p) {
  91         if (bits[p] > 32)
  92              return 1;
  93         if (bits[p] == 0)
  94              continue;
  95         // find corresponding exit(node which the tree can grow further from)
  96         for (i = bits[p]; i > 0; --i)
  97             if (exit_at_level[i])
  98                 break;
  99         if (!i) // overspecified tree
 100              return 1;
 101         code = exit_at_level[i];
 102         exit_at_level[i] = 0;
 103         // construct code (append 0s to end) and introduce new exits
 104         for (j = i + 1 ;j <= bits[p]; ++j)
 105             exit_at_level[j] = code + (1 << (j - 1));
 106         codes[p] = code;
 107
 108 #ifdef V_DEBUG
 109         av_log(NULL, AV_LOG_INFO, " %d. code len %d code %d - ", p, bits[p], codes[p]);
 110         init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
 111         for (i = 0; i < bits[p]; ++i)
 112             av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
 113         av_log(NULL, AV_LOG_INFO, "\n");
 114 #endif
 115
 116     }
 117
 118     //no exits should be left (underspecified tree - ie. unused valid vlcs - not allowed by SPEC)
 119     for (p = 1; p < 33; p++)
 120         if (exit_at_level[p])
 121             return 1;
 122
 123     return 0;
 124 }
 125
 126 void ff_vorbis_ready_floor1_list(vorbis_floor1_entry * list, int values)
 127 {
 128     int i;
 129     list[0].sort = 0;
 130     list[1].sort = 1;
 131     for (i = 2; i < values; i++) {
 132         int j;
 133         list[i].low  = 0;
 134         list[i].high = 1;
 135         list[i].sort = i;
 136         for (j = 2; j < i; j++) {
 137             int tmp = list[j].x;
 138             if (tmp < list[i].x) {
 139                 if (tmp > list[list[i].low].x)
 140                     list[i].low  =  j;
 141             } else {
 142                 if (tmp < list[list[i].high].x)
 143                     list[i].high = j;
 144             }
 145         }
 146     }
 147     for (i = 0; i < values - 1; i++) {
 148         int j;
 149         for (j = i + 1; j < values; j++) {
 150             if (list[list[i].sort].x > list[list[j].sort].x) {
 151                 int tmp = list[i].sort;
 152                 list[i].sort = list[j].sort;
 153                 list[j].sort = tmp;
 154             }
 155         }
 156     }
 157 }
 158
 159 static inline void render_line_unrolled(intptr_t x, intptr_t y, int x1,
 160                                         intptr_t sy, int ady, int adx,
 161                                         float *buf)
 162 {
 163     int err = -adx;
 164     x -= x1 - 1;
 165     buf += x1 - 1;
 166     while (++x < 0) {
 167         err += ady;
 168         if (err >= 0) {
 169             err += ady - adx;
 170             y   += sy;
 171             buf[x++] = ff_vorbis_floor1_inverse_db_table[y];
 172         }
 173         buf[x] = ff_vorbis_floor1_inverse_db_table[y];
 174     }
 175     if (x <= 0) {
 176         if (err + ady >= 0)
 177             y += sy;
 178         buf[x] = ff_vorbis_floor1_inverse_db_table[y];
 179     }
 180 }
 181
 182 static void render_line(int x0, int y0, int x1, int y1, float *buf)
 183 {
 184     int dy  = y1 - y0;
 185     int adx = x1 - x0;
 186     int ady = FFABS(dy);
 187     int sy  = dy < 0 ? -1 : 1;
 188     buf[x0] = ff_vorbis_floor1_inverse_db_table[y0];
 189     if (ady*2 <= adx) { // optimized common case
 190         render_line_unrolled(x0, y0, x1, sy, ady, adx, buf);
 191     } else {
 192         int base = dy / adx;
 193         int x    = x0;
 194         int y    = y0;
 195         int err  = -adx;
 196         ady -= FFABS(base) * adx;
 197         while (++x < x1) {
 198             y += base;
 199             err += ady;
 200             if (err >= 0) {
 201                 err -= adx;
 202                 y   += sy;
 203             }
 204             buf[x] = ff_vorbis_floor1_inverse_db_table[y];
 205         }
 206     }
 207 }
 208
 209 void ff_vorbis_floor1_render_list(vorbis_floor1_entry * list, int values,
 210                                   uint_fast16_t *y_list, int *flag,
 211                                   int multiplier, float *out, int samples)
 212 {
 213     int lx, ly, i;
 214     lx = 0;
 215     ly = y_list[0] * multiplier;
 216     for (i = 1; i < values; i++) {
 217         int pos = list[i].sort;
 218         if (flag[pos]) {
 219             int x1 = list[pos].x;
 220             int y1 = y_list[pos] * multiplier;
 221             if (lx < samples)
 222                 render_line(lx, ly, FFMIN(x1,samples), y1, out);
 223             lx = x1;
 224             ly = y1;
 225         }
 226         if (lx >= samples)
 227             break;
 228     }
 229     if (lx < samples)
 230         render_line(lx, ly, samples, ly, out);
 231 }