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libavcodec/vorbis.c

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00001 
00023 #define ALT_BITSTREAM_READER_LE
00024 #include "avcodec.h"
00025 #include "get_bits.h"
00026 
00027 #include "vorbis.h"
00028 
00029 
00030 /* Helper functions */
00031 
00032 // x^(1/n)
00033 unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n)
00034 {
00035     unsigned int ret = 0, i, j;
00036 
00037     do {
00038         ++ret;
00039         for (i = 0, j = ret; i < n - 1; i++)
00040             j *= ret;
00041     } while (j <= x);
00042 
00043     return ret - 1;
00044 }
00045 
00046 // Generate vlc codes from vorbis huffman code lengths
00047 
00048 // the two bits[p] > 32 checks should be redundant, all calling code should
00049 // already ensure that, but since it allows overwriting the stack it seems
00050 // reasonable to check redundantly.
00051 int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, unsigned num)
00052 {
00053     uint32_t exit_at_level[33] = { 404 };
00054 
00055     unsigned i, j, p, code;
00056 
00057 #ifdef DEBUG
00058     GetBitContext gb;
00059 #endif
00060 
00061     for (p = 0; (bits[p] == 0) && (p < num); ++p)
00062         ;
00063     if (p == num) {
00064 //        av_log(vc->avccontext, AV_LOG_INFO, "An empty codebook. Heh?! \n");
00065         return 0;
00066     }
00067 
00068     codes[p] = 0;
00069     if (bits[p] > 32)
00070         return 1;
00071     for (i = 0; i < bits[p]; ++i)
00072         exit_at_level[i+1] = 1 << i;
00073 
00074 #ifdef DEBUG
00075     av_log(NULL, AV_LOG_INFO, " %u. of %u code len %d code %d - ", p, num, bits[p], codes[p]);
00076     init_get_bits(&gb, (uint8_t *)&codes[p], bits[p]);
00077     for (i = 0; i < bits[p]; ++i)
00078         av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
00079     av_log(NULL, AV_LOG_INFO, "\n");
00080 #endif
00081 
00082     ++p;
00083 
00084     for (; p < num; ++p) {
00085         if (bits[p] > 32)
00086              return 1;
00087         if (bits[p] == 0)
00088              continue;
00089         // find corresponding exit(node which the tree can grow further from)
00090         for (i = bits[p]; i > 0; --i)
00091             if (exit_at_level[i])
00092                 break;
00093         if (!i) // overspecified tree
00094              return 1;
00095         code = exit_at_level[i];
00096         exit_at_level[i] = 0;
00097         // construct code (append 0s to end) and introduce new exits
00098         for (j = i + 1 ;j <= bits[p]; ++j)
00099             exit_at_level[j] = code + (1 << (j - 1));
00100         codes[p] = code;
00101 
00102 #ifdef DEBUG
00103         av_log(NULL, AV_LOG_INFO, " %d. code len %d code %d - ", p, bits[p], codes[p]);
00104         init_get_bits(&gb, (uint8_t *)&codes[p], bits[p]);
00105         for (i = 0; i < bits[p]; ++i)
00106             av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
00107         av_log(NULL, AV_LOG_INFO, "\n");
00108 #endif
00109 
00110     }
00111 
00112     //no exits should be left (underspecified tree - ie. unused valid vlcs - not allowed by SPEC)
00113     for (p = 1; p < 33; p++)
00114         if (exit_at_level[p])
00115             return 1;
00116 
00117     return 0;
00118 }
00119 
00120 void ff_vorbis_ready_floor1_list(vorbis_floor1_entry * list, int values)
00121 {
00122     int i;
00123     list[0].sort = 0;
00124     list[1].sort = 1;
00125     for (i = 2; i < values; i++) {
00126         int j;
00127         list[i].low  = 0;
00128         list[i].high = 1;
00129         list[i].sort = i;
00130         for (j = 2; j < i; j++) {
00131             int tmp = list[j].x;
00132             if (tmp < list[i].x) {
00133                 if (tmp > list[list[i].low].x)
00134                     list[i].low  =  j;
00135             } else {
00136                 if (tmp < list[list[i].high].x)
00137                     list[i].high = j;
00138             }
00139         }
00140     }
00141     for (i = 0; i < values - 1; i++) {
00142         int j;
00143         for (j = i + 1; j < values; j++) {
00144             if (list[list[i].sort].x > list[list[j].sort].x) {
00145                 int tmp = list[i].sort;
00146                 list[i].sort = list[j].sort;
00147                 list[j].sort = tmp;
00148             }
00149         }
00150     }
00151 }
00152 
00153 static inline void render_line_unrolled(intptr_t x, int y, int x1,
00154                                         intptr_t sy, int ady, int adx,
00155                                         float *buf)
00156 {
00157     int err = -adx;
00158     x -= x1 - 1;
00159     buf += x1 - 1;
00160     while (++x < 0) {
00161         err += ady;
00162         if (err >= 0) {
00163             err += ady - adx;
00164             y   += sy;
00165             buf[x++] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
00166         }
00167         buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
00168     }
00169     if (x <= 0) {
00170         if (err + ady >= 0)
00171             y += sy;
00172         buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
00173     }
00174 }
00175 
00176 static void render_line(int x0, int y0, int x1, int y1, float *buf)
00177 {
00178     int dy  = y1 - y0;
00179     int adx = x1 - x0;
00180     int ady = FFABS(dy);
00181     int sy  = dy < 0 ? -1 : 1;
00182     buf[x0] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y0)];
00183     if (ady*2 <= adx) { // optimized common case
00184         render_line_unrolled(x0, y0, x1, sy, ady, adx, buf);
00185     } else {
00186         int base  = dy / adx;
00187         int x     = x0;
00188         int y     = y0;
00189         int err   = -adx;
00190         ady -= FFABS(base) * adx;
00191         while (++x < x1) {
00192             y += base;
00193             err += ady;
00194             if (err >= 0) {
00195                 err -= adx;
00196                 y   += sy;
00197             }
00198             buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
00199         }
00200     }
00201 }
00202 
00203 void ff_vorbis_floor1_render_list(vorbis_floor1_entry * list, int values,
00204                                   uint16_t *y_list, int *flag,
00205                                   int multiplier, float *out, int samples)
00206 {
00207     int lx, ly, i;
00208     lx = 0;
00209     ly = y_list[0] * multiplier;
00210     for (i = 1; i < values; i++) {
00211         int pos = list[i].sort;
00212         if (flag[pos]) {
00213             int x1 = list[pos].x;
00214             int y1 = y_list[pos] * multiplier;
00215             if (lx < samples)
00216                 render_line(lx, ly, FFMIN(x1,samples), y1, out);
00217             lx = x1;
00218             ly = y1;
00219         }
00220         if (lx >= samples)
00221             break;
00222     }
00223     if (lx < samples)
00224         render_line(lx, ly, samples, ly, out);
00225 }

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