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 unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n) {   // x^(1/n)
  36     unsigned int ret=0, i, j;
  37
  38     do {
  39         ++ret;
  40         for(i=0,j=ret;i<n-1;i++) j*=ret;
  41     } while (j<=x);
  42
  43     return ret - 1;
  44 }
  45
  46 // Generate vlc codes from vorbis huffman code lengths
  47
  48 // the two bits[p] > 32 checks should be redundant, all calling code should
  49 // already ensure that, but since it allows overwriting the stack it seems
  50 // reasonable to check redundantly.
  51 int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, uint_fast32_t num) {
  52     uint_fast32_t exit_at_level[33]={404,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
  53         0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
  54
  55     uint_fast8_t i,j;
  56     uint_fast32_t code,p;
  57
  58 #ifdef V_DEBUG
  59     GetBitContext gb;
  60 #endif
  61
  62     for(p=0;(bits[p]==0) && (p<num);++p);
  63     if (p==num) {
  64 //        av_log(vc->avccontext, AV_LOG_INFO, "An empty codebook. Heh?! \n");
  65         return 0;
  66     }
  67
  68     codes[p]=0;
  69     if (bits[p] > 32) return 1;
  70     for(i=0;i<bits[p];++i) {
  71         exit_at_level[i+1]=1<<i;
  72     }
  73
  74 #ifdef V_DEBUG
  75     av_log(NULL, AV_LOG_INFO, " %d. of %d code len %d code %d - ", p, num, bits[p], codes[p]);
  76     init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
  77     for(i=0;i<bits[p];++i) {
  78         av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
  79     }
  80     av_log(NULL, AV_LOG_INFO, "\n");
  81 #endif
  82
  83     ++p;
  84
  85     for(;p<num;++p) {
  86         if (bits[p] > 32) return 1;
  87         if (bits[p]==0) continue;
  88         // find corresponding exit(node which the tree can grow further from)
  89         for(i=bits[p];i>0;--i) {
  90             if (exit_at_level[i]) break;
  91         }
  92         if (!i) return 1; // overspecified tree
  93         code=exit_at_level[i];
  94         exit_at_level[i]=0;
  95         // construct code (append 0s to end) and introduce new exits
  96         for(j=i+1;j<=bits[p];++j) {
  97             exit_at_level[j]=code+(1<<(j-1));
  98         }
  99         codes[p]=code;
 100
 101 #ifdef V_DEBUG
 102         av_log(NULL, AV_LOG_INFO, " %d. code len %d code %d - ", p, bits[p], codes[p]);
 103         init_get_bits(&gb, (uint_fast8_t *)&codes[p], bits[p]);
 104         for(i=0;i<bits[p];++i) {
 105             av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
 106         }
 107         av_log(NULL, AV_LOG_INFO, "\n");
 108 #endif
 109
 110     }
 111
 112     //no exits should be left (underspecified tree - ie. unused valid vlcs - not allowed by SPEC)
 113     for (p=1; p<33; p++)
 114         if (exit_at_level[p]) return 1;
 115
 116     return 0;
 117 }
 118
 119 void ff_vorbis_ready_floor1_list(vorbis_floor1_entry * list, int values) {
 120     int i;
 121     list[0].sort = 0;
 122     list[1].sort = 1;
 123     for (i = 2; i < values; i++) {
 124         int j;
 125         list[i].low = 0;
 126         list[i].high = 1;
 127         list[i].sort = i;
 128         for (j = 2; j < i; j++) {
 129             int tmp = list[j].x;
 130             if (tmp < list[i].x) {
 131                 if (tmp > list[list[i].low].x) list[i].low = j;
 132             } else {
 133                 if (tmp < list[list[i].high].x) list[i].high = j;
 134             }
 135         }
 136     }
 137     for (i = 0; i < values - 1; i++) {
 138         int j;
 139         for (j = i + 1; j < values; j++) {
 140             if (list[list[i].sort].x > list[list[j].sort].x) {
 141                 int tmp = list[i].sort;
 142                 list[i].sort = list[j].sort;
 143                 list[j].sort = tmp;
 144             }
 145         }
 146     }
 147 }
 148
 149 static void render_line(int x0, int y0, int x1, int y1, float * buf) {
 150     int dy = y1 - y0;
 151     int adx = x1 - x0;
 152     int base = dy / adx;
 153     int ady = FFABS(dy) - FFABS(base) * adx;
 154     int x = x0;
 155     int y = y0;
 156     int err = 0;
 157     int sy = dy<0 ? -1 : 1;
 158     buf[x] = ff_vorbis_floor1_inverse_db_table[y];
 159     while (++x < x1) {
 160         err += ady;
 161         if (err >= adx) {
 162             err -= adx;
 163             y += sy;
 164         }
 165         y += base;
 166         buf[x] = ff_vorbis_floor1_inverse_db_table[y];
 167     }
 168 }
 169
 170 void ff_vorbis_floor1_render_list(vorbis_floor1_entry * list, int values, uint_fast16_t * y_list, int * flag, int multiplier, float * out, int samples) {
 171     int lx, ly, i;
 172     lx = 0;
 173     ly = y_list[0] * multiplier;
 174     for (i = 1; i < values; i++) {
 175         int pos = list[i].sort;
 176         if (flag[pos]) {
 177             int x1 = list[pos].x;
 178             int y1 = y_list[pos] * multiplier;
 179             if (lx < samples)
 180                 render_line(lx, ly, FFMIN(x1,samples), y1, out);
 181             lx = x1;
 182             ly = y1;
 183         }
 184         if (lx >= samples) break;
 185     }
 186     if (lx < samples) render_line(lx, ly, samples, ly, out);
 187 }