libavcodec/vorbis.c

   1 /*
   2  * This file is part of Libav.
   3  *
   4  * Libav is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * Libav is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with Libav; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 /**
  20  * @file
  21  * Common code for Vorbis I encoder and decoder
  22  * @author Denes Balatoni  ( dbalatoni programozo hu )
  23  */
  24
  25 #include "libavutil/common.h"
  26
  27 #include "avcodec.h"
  28 #include "vorbis.h"
  29
  30
  31 /* Helper functions */
  32
  33 // x^(1/n)
  34 unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n)
  35 {
  36     unsigned int ret = 0, i, j;
  37
  38     do {
  39         ++ret;
  40         for (i = 0, j = ret; i < n - 1; i++)
  41             j *= ret;
  42     } while (j <= x);
  43
  44     return ret - 1;
  45 }
  46
  47 // Generate vlc codes from vorbis huffman code lengths
  48
  49 // the two bits[p] > 32 checks should be redundant, all calling code should
  50 // already ensure that, but since it allows overwriting the stack it seems
  51 // reasonable to check redundantly.
  52 int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, unsigned num)
  53 {
  54     uint32_t exit_at_level[33] = { 404 };
  55     unsigned i, j, p, code;
  56
  57     for (p = 0; (bits[p] == 0) && (p < num); ++p)
  58         ;
  59     if (p == num)
  60         return 0;
  61
  62     codes[p] = 0;
  63     if (bits[p] > 32)
  64         return 1;
  65     for (i = 0; i < bits[p]; ++i)
  66         exit_at_level[i+1] = 1 << i;
  67
  68     ++p;
  69
  70     for (; p < num; ++p) {
  71         if (bits[p] > 32)
  72              return 1;
  73         if (bits[p] == 0)
  74              continue;
  75         // find corresponding exit(node which the tree can grow further from)
  76         for (i = bits[p]; i > 0; --i)
  77             if (exit_at_level[i])
  78                 break;
  79         if (!i) // overspecified tree
  80              return 1;
  81         code = exit_at_level[i];
  82         exit_at_level[i] = 0;
  83         // construct code (append 0s to end) and introduce new exits
  84         for (j = i + 1 ;j <= bits[p]; ++j)
  85             exit_at_level[j] = code + (1 << (j - 1));
  86         codes[p] = code;
  87     }
  88
  89     //no exits should be left (underspecified tree - ie. unused valid vlcs - not allowed by SPEC)
  90     for (p = 1; p < 33; p++)
  91         if (exit_at_level[p])
  92             return 1;
  93
  94     return 0;
  95 }
  96
  97 int ff_vorbis_ready_floor1_list(AVCodecContext *avctx,
  98                                 vorbis_floor1_entry *list, int values)
  99 {
 100     int i;
 101     list[0].sort = 0;
 102     list[1].sort = 1;
 103     for (i = 2; i < values; i++) {
 104         int j;
 105         list[i].low  = 0;
 106         list[i].high = 1;
 107         list[i].sort = i;
 108         for (j = 2; j < i; j++) {
 109             int tmp = list[j].x;
 110             if (tmp < list[i].x) {
 111                 if (tmp > list[list[i].low].x)
 112                     list[i].low  =  j;
 113             } else {
 114                 if (tmp < list[list[i].high].x)
 115                     list[i].high = j;
 116             }
 117         }
 118     }
 119     for (i = 0; i < values - 1; i++) {
 120         int j;
 121         for (j = i + 1; j < values; j++) {
 122             if (list[i].x == list[j].x) {
 123                 av_log(avctx, AV_LOG_ERROR,
 124                        "Duplicate value found in floor 1 X coordinates\n");
 125                 return AVERROR_INVALIDDATA;
 126             }
 127             if (list[list[i].sort].x > list[list[j].sort].x) {
 128                 int tmp = list[i].sort;
 129                 list[i].sort = list[j].sort;
 130                 list[j].sort = tmp;
 131             }
 132         }
 133     }
 134     return 0;
 135 }
 136
 137 static inline void render_line_unrolled(intptr_t x, int y, int x1,
 138                                         intptr_t sy, int ady, int adx,
 139                                         float *buf)
 140 {
 141     int err = -adx;
 142     x -= x1 - 1;
 143     buf += x1 - 1;
 144     while (++x < 0) {
 145         err += ady;
 146         if (err >= 0) {
 147             err += ady - adx;
 148             y   += sy;
 149             buf[x++] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
 150         }
 151         buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
 152     }
 153     if (x <= 0) {
 154         if (err + ady >= 0)
 155             y += sy;
 156         buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
 157     }
 158 }
 159
 160 static void render_line(int x0, int y0, int x1, int y1, float *buf)
 161 {
 162     int dy  = y1 - y0;
 163     int adx = x1 - x0;
 164     int ady = FFABS(dy);
 165     int sy  = dy < 0 ? -1 : 1;
 166     buf[x0] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y0)];
 167     if (ady*2 <= adx) { // optimized common case
 168         render_line_unrolled(x0, y0, x1, sy, ady, adx, buf);
 169     } else {
 170         int base  = dy / adx;
 171         int x     = x0;
 172         int y     = y0;
 173         int err   = -adx;
 174         ady -= FFABS(base) * adx;
 175         while (++x < x1) {
 176             y += base;
 177             err += ady;
 178             if (err >= 0) {
 179                 err -= adx;
 180                 y   += sy;
 181             }
 182             buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
 183         }
 184     }
 185 }
 186
 187 void ff_vorbis_floor1_render_list(vorbis_floor1_entry * list, int values,
 188                                   uint16_t *y_list, int *flag,
 189                                   int multiplier, float *out, int samples)
 190 {
 191     int lx, ly, i;
 192     lx = 0;
 193     ly = y_list[0] * multiplier;
 194     for (i = 1; i < values; i++) {
 195         int pos = list[i].sort;
 196         if (flag[pos]) {
 197             int x1 = list[pos].x;
 198             int y1 = y_list[pos] * multiplier;
 199             if (lx < samples)
 200                 render_line(lx, ly, FFMIN(x1,samples), y1, out);
 201             lx = x1;
 202             ly = y1;
 203         }
 204         if (lx >= samples)
 205             break;
 206     }
 207     if (lx < samples)
 208         render_line(lx, ly, samples, ly, out);
 209 }