libavcodec/vorbis.c

   1 /**
   2  * @file 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
  24 #undef V_DEBUG
  25 //#define V_DEBUG
  26
  27 #define ALT_BITSTREAM_READER_LE
  28 #include "avcodec.h"
  29 #include "bitstream.h"
  30
  31 #include "vorbis.h"
  32
  33
  34 /* Helper functions */
  35
  36 unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n) {   // x^(1/n)
  37     unsigned int ret=0, i, j;
  38
  39     do {
  40         ++ret;
  41         for(i=0,j=ret;i<n-1;i++) j*=ret;
  42     } while (j<=x);
  43
  44     return (ret-1);
  45 }
  46
  47 // Generate vlc codes from vorbis huffman code lengths
  48
  49 int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, uint_fast32_t num) {
  50     uint_fast32_t exit_at_level[33]={404,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  51         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
  52
  53     uint_fast8_t i,j;
  54     uint_fast32_t code,p;
  55
  56 #ifdef V_DEBUG
  57     GetBitContext gb;
  58 #endif
  59
  60     for(p=0;(bits[p]==0) && (p<num);++p);
  61     if (p==num) {
  62 //        av_log(vc->avccontext, AV_LOG_INFO, "An empty codebook. Heh?! \n");
  63         return 0;
  64     }
  65
  66     codes[p]=0;
  67     for(i=0;i<bits[p];++i) {
  68         exit_at_level[i+1]=1<<i;
  69     }
  70
  71 #ifdef V_DEBUG
  72     av_log(NULL, AV_LOG_INFO, " %d. of %d code len %d code %d - ", p, num, bits[p], codes[p]);
  73     init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
  74     for(i=0;i<bits[p];++i) {
  75         av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
  76     }
  77     av_log(NULL, AV_LOG_INFO, "\n");
  78 #endif
  79
  80     ++p;
  81
  82     for(;p<num;++p) {
  83         if (bits[p]==0) continue;
  84         // find corresponding exit(node which the tree can grow further from)
  85         for(i=bits[p];i>0;--i) {
  86             if (exit_at_level[i]) break;
  87         }
  88         if (!i) return 1; // overspecified tree
  89         code=exit_at_level[i];
  90         exit_at_level[i]=0;
  91         // construct code (append 0s to end) and introduce new exits
  92         for(j=i+1;j<=bits[p];++j) {
  93             exit_at_level[j]=code+(1<<(j-1));
  94         }
  95         codes[p]=code;
  96
  97 #ifdef V_DEBUG
  98         av_log(NULL, AV_LOG_INFO, " %d. code len %d code %d - ", p, bits[p], codes[p]);
  99         init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
 100         for(i=0;i<bits[p];++i) {
 101             av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
 102         }
 103         av_log(NULL, AV_LOG_INFO, "\n");
 104 #endif
 105
 106     }
 107
 108     //no exits should be left (underspecified tree - ie. unused valid vlcs - not allowed by SPEC)
 109     for (p=1; p<33; p++)
 110         if (exit_at_level[p]) return 1;
 111
 112     return 0;
 113 }
 114
 115 void ff_vorbis_ready_floor1_list(floor1_entry_t * list, int values) {
 116     int i;
 117     list[0].sort = 0;
 118     list[1].sort = 1;
 119     for (i = 2; i < values; i++) {
 120         int j;
 121         list[i].low = 0;
 122         list[i].high = 1;
 123         list[i].sort = i;
 124         for (j = 2; j < i; j++) {
 125             int tmp = list[j].x;
 126             if (tmp < list[i].x) {
 127                 if (tmp > list[list[i].low].x) list[i].low = j;
 128             } else {
 129                 if (tmp < list[list[i].high].x) list[i].high = j;
 130             }
 131         }
 132     }
 133     for (i = 0; i < values - 1; i++) {
 134         int j;
 135         for (j = i + 1; j < values; j++) {
 136             if (list[list[i].sort].x > list[list[j].sort].x) {
 137                 int tmp = list[i].sort;
 138                 list[i].sort = list[j].sort;
 139                 list[j].sort = tmp;
 140             }
 141         }
 142     }
 143 }
 144
 145 static void render_line(int x0, int y0, int x1, int y1, float * buf, int n) {
 146     int dy = y1 - y0;
 147     int adx = x1 - x0;
 148     int ady = FFABS(dy);
 149     int base = dy / adx;
 150     int x = x0;
 151     int y = y0;
 152     int err = 0;
 153     int sy;
 154     if (dy < 0) sy = base - 1;
 155     else        sy = base + 1;
 156     ady = ady - FFABS(base) * adx;
 157     if (x >= n) return;
 158     buf[x] = ff_vorbis_floor1_inverse_db_table[y];
 159     for (x = x0 + 1; x < x1; x++) {
 160         if (x >= n) return;
 161         err += ady;
 162         if (err >= adx) {
 163             err -= adx;
 164             y += sy;
 165         } else {
 166             y += base;
 167         }
 168         buf[x] = ff_vorbis_floor1_inverse_db_table[y];
 169     }
 170 }
 171
 172 void ff_vorbis_floor1_render_list(floor1_entry_t * list, int values, uint_fast16_t * y_list, int * flag, int multiplier, float * out, int samples) {
 173     int lx, ly, i;
 174     lx = 0;
 175     ly = y_list[0] * multiplier;
 176     for (i = 1; i < values; i++) {
 177         int pos = list[i].sort;
 178         if (flag[pos]) {
 179             render_line(lx, ly, list[pos].x, y_list[pos] * multiplier, out, samples);
 180             lx = list[pos].x;
 181             ly = y_list[pos] * multiplier;
 182         }
 183         if (lx >= samples) break;
 184     }
 185     if (lx < samples) render_line(lx, ly, samples, ly, out, samples);
 186 }