libavcodec/ra144.c

   1 /*
   2  * Real Audio 1.0 (14.4K)
   3  * Copyright (c) 2003 the ffmpeg project
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "avcodec.h"
  23 #include "bitstream.h"
  24 #include "ra144.h"
  25
  26 #define NBLOCKS         4       /* number of segments within a block */
  27 #define BLOCKSIZE       40      /* (quarter) block size in 16-bit words (80 bytes) */
  28 #define HALFBLOCK       20      /* BLOCKSIZE/2 */
  29 #define BUFFERSIZE      146     /* for do_output */
  30
  31
  32 /* internal globals */
  33 typedef struct {
  34     unsigned int     old_energy;
  35
  36     /* the swapped buffers */
  37     unsigned int     lpc_tables[4][10];
  38     unsigned int    *lpc_refl;          //< LPC reflection coefficients
  39     unsigned int    *lpc_coef;          //< LPC coefficients
  40     unsigned int    *lpc_refl_old;      //< previous frame LPC reflection coefs
  41     unsigned int    *lpc_coef_old;      //< previous frame LPC coefficients
  42
  43     unsigned int buffer[5];
  44     uint16_t adapt_cb[148];  //< Adaptative codebook
  45 } RA144Context;
  46
  47 static int ra144_decode_init(AVCodecContext * avctx)
  48 {
  49     RA144Context *ractx = avctx->priv_data;
  50
  51     ractx->lpc_refl     = ractx->lpc_tables[0];
  52     ractx->lpc_coef     = ractx->lpc_tables[1];
  53     ractx->lpc_refl_old = ractx->lpc_tables[2];
  54     ractx->lpc_coef_old = ractx->lpc_tables[3];
  55
  56     return 0;
  57 }
  58
  59 /* lookup square roots in table */
  60 static int t_sqrt(unsigned int x)
  61 {
  62     int s = 0;
  63     while (x > 0xfff) {
  64         s++;
  65         x = x >> 2;
  66     }
  67
  68     return (ff_sqrt(x << 20) << s) << 2;
  69 }
  70
  71 /* do 'voice' */
  72 static void do_voice(const int *a1, int *a2)
  73 {
  74     int buffer[10];
  75     int *b1 = buffer;
  76     int *b2 = a2;
  77     int x, y;
  78
  79     for (x=0; x < 10; x++) {
  80         b1[x] = a1[x] << 4;
  81
  82         for (y=0; y < x; y++)
  83             b1[y] = ((a1[x] * b2[x-y-1]) >> 12) + b2[y];
  84
  85         FFSWAP(int *, b1, b2);
  86     }
  87
  88     for (x=0; x < 10; x++)
  89         a2[x] >>= 4;
  90 }
  91
  92 /* rotate block */
  93 static void rotate_block(const int16_t *source, int16_t *target, int offset)
  94 {
  95     int i=0, k=0;
  96     source += BUFFERSIZE - offset;
  97
  98     while (i<BLOCKSIZE) {
  99         target[i++] = source[k++];
 100
 101         if (k == offset)
 102             k = 0;
 103     }
 104 }
 105
 106 /* inverse root mean square */
 107 static int irms(const int16_t *data, int factor)
 108 {
 109     unsigned int i, sum = 0;
 110
 111     for (i=0; i < BLOCKSIZE; i++)
 112         sum += data[i] * data[i];
 113
 114     if (sum == 0)
 115         return 0; /* OOPS - division by zero */
 116
 117     return (0x20000000 / (t_sqrt(sum) >> 8)) * factor;
 118 }
 119
 120 /* multiply/add wavetable */
 121 static void add_wav(int n, int skip_first, int *m, const int16_t *s1,
 122                     const int8_t *s2, const int8_t *s3, int16_t *dest)
 123 {
 124     int i;
 125     int v[3];
 126
 127     v[0] = 0;
 128     for (i=!skip_first; i<3; i++)
 129         v[i] = (wavtable1[n][i] * m[i]) >> (wavtable2[n][i] + 1);
 130
 131     for (i=0; i < BLOCKSIZE; i++)
 132         dest[i] = ((*(s1++))*v[0] + (*(s2++))*v[1] + (*(s3++))*v[2]) >> 12;
 133 }
 134
 135
 136 static void final(const int16_t *i1, const int16_t *i2,
 137                   void *out, int *statbuf, int len)
 138 {
 139     int x, i;
 140     uint16_t work[50];
 141     int16_t *ptr = work;
 142
 143     memcpy(work, statbuf,20);
 144     memcpy(work + 10, i2, len * 2);
 145
 146     for (i=0; i<len; i++) {
 147         int sum = 0;
 148         int new_val;
 149
 150         for(x=0; x<10; x++)
 151             sum += i1[9-x] * ptr[x];
 152
 153         sum >>= 12;
 154
 155         new_val = ptr[10] - sum;
 156
 157         if (new_val < -32768 || new_val > 32767) {
 158             memset(out, 0, len * 2);
 159             memset(statbuf, 0, 20);
 160             return;
 161         }
 162
 163         ptr[10] = new_val;
 164         ptr++;
 165     }
 166
 167     memcpy(out, work+10, len * 2);
 168     memcpy(statbuf, work + 40, 20);
 169 }
 170
 171 static unsigned int rms(const int *data, int f)
 172 {
 173     int x;
 174     unsigned int res = 0x10000;
 175     int b = 0;
 176
 177     for (x=0; x<10; x++) {
 178         res = (((0x1000000 - (*data) * (*data)) >> 12) * res) >> 12;
 179
 180         if (res == 0)
 181             return 0;
 182
 183         if (res > 0x10000)
 184             return 0; /* We're screwed, might as well go out with a bang. :P */
 185
 186         while (res <= 0x3fff) {
 187             b++;
 188             res <<= 2;
 189         }
 190         data++;
 191     }
 192
 193     if (res > 0)
 194         res = t_sqrt(res);
 195
 196     res >>= (b + 10);
 197     res = (res * f) >> 10;
 198     return res;
 199 }
 200
 201 /* do quarter-block output */
 202 static void do_output_subblock(RA144Context *ractx,
 203                                const uint16_t  *gsp, unsigned int gval,
 204                                int16_t *output_buffer, GetBitContext *gb)
 205 {
 206     uint16_t buffer_a[40];
 207     uint16_t *block;
 208     int a = get_bits(gb, 7);
 209     int d = get_bits(gb, 8);
 210     int b = get_bits(gb, 7);
 211     int c = get_bits(gb, 7);
 212     int m[3];
 213
 214     if (a) {
 215         a += HALFBLOCK - 1;
 216         rotate_block(ractx->adapt_cb, buffer_a, a);
 217         m[0] = irms(buffer_a, gval) >> 12;
 218     } else {
 219         m[0] = 0;
 220     }
 221
 222     m[1] = ((ftable1[b] >> 4) * gval) >> 8;
 223     m[2] = ((ftable2[c] >> 4) * gval) >> 8;
 224
 225     memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
 226             (BUFFERSIZE - BLOCKSIZE) * 2);
 227
 228     block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
 229
 230     add_wav(d, a, m, buffer_a, etable1[b], etable2[c], block);
 231
 232     final(gsp, block, output_buffer, ractx->buffer, BLOCKSIZE);
 233 }
 234
 235 static int dec1(int16_t *decsp, const int *data, const int *inp, int f)
 236 {
 237     int i;
 238
 239     for (i=0; i<30; i++)
 240         *(decsp++) = *(inp++);
 241
 242     return rms(data, f);
 243 }
 244
 245 static int eq(const int16_t *in, int *target)
 246 {
 247     int retval = 0;
 248     int b, c, i;
 249     unsigned int u;
 250     int buffer1[10];
 251     int buffer2[10];
 252     int *bp1 = buffer1;
 253     int *bp2 = buffer2;
 254
 255     for (i=0; i < 10; i++)
 256         buffer2[i] = in[i];
 257
 258     u = target[9] = bp2[9];
 259
 260     if (u + 0x1000 > 0x1fff)
 261         return 0; /* We're screwed, might as well go out with a bang. :P */
 262
 263     for (c=8; c >= 0; c--) {
 264         if (u == 0x1000)
 265             u++;
 266
 267         if (u == 0xfffff000)
 268             u--;
 269
 270         b = 0x1000-((u * u) >> 12);
 271
 272         if (b == 0)
 273             b++;
 274
 275         for (u=0; u<=c; u++)
 276             bp1[u] = ((bp2[u] - ((target[c+1] * bp2[c-u]) >> 12)) * (0x1000000 / b)) >> 12;
 277
 278         target[c] = u = bp1[c];
 279
 280         if ((u + 0x1000) > 0x1fff)
 281             retval = 1;
 282
 283         FFSWAP(int *, bp1, bp2);
 284     }
 285     return retval;
 286 }
 287
 288 static int dec2(int16_t *decsp, const int *data, const int *inp,
 289                  int f, const int *inp2, int a)
 290 {
 291     int work[10];
 292     int b = NBLOCKS - a;
 293     int x;
 294
 295     for (x=0; x<30; x++)
 296         decsp[x] = (a * inp[x] + b * inp2[x]) >> 2;
 297
 298     if (eq(decsp, work))
 299         return dec1(decsp, data, inp, f);
 300     else
 301         return rms(work, f);
 302 }
 303
 304 /* Uncompress one block (20 bytes -> 160*2 bytes) */
 305 static int ra144_decode_frame(AVCodecContext * avctx,
 306                               void *vdata, int *data_size,
 307                               const uint8_t * buf, int buf_size)
 308 {
 309     static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
 310     unsigned int gbuf1[4];
 311     uint16_t gbuf2[4][30];
 312     unsigned int a, c;
 313     int i;
 314     int16_t *data = vdata;
 315     unsigned int energy;
 316
 317     RA144Context *ractx = avctx->priv_data;
 318     GetBitContext gb;
 319
 320     if(buf_size < 20) {
 321         av_log(avctx, AV_LOG_ERROR,
 322                "Frame too small (%d bytes). Truncated file?\n", buf_size);
 323         return buf_size;
 324     }
 325     init_get_bits(&gb, buf, 20 * 8);
 326
 327     for (i=0; i<10; i++)
 328         // "<< 1"? Doesn't this make one value out of two of the table useless?
 329         ractx->lpc_refl[i] = decodetable[i][get_bits(&gb, sizes[i]) << 1];
 330
 331     do_voice(ractx->lpc_refl, ractx->lpc_coef);
 332
 333     energy = decodeval[get_bits(&gb, 5) << 1]; // Useless table entries?
 334     a = t_sqrt(energy*ractx->old_energy) >> 12;
 335
 336     gbuf1[0] = dec2(gbuf2[0], ractx->lpc_refl_old, ractx->lpc_coef_old, ractx->old_energy, ractx->lpc_coef, 3);
 337     if (ractx->old_energy < energy) {
 338         gbuf1[1] = dec2(gbuf2[1], ractx->lpc_refl, ractx->lpc_coef, a, ractx->lpc_coef_old, 2);
 339     } else {
 340         gbuf1[1] = dec2(gbuf2[1], ractx->lpc_refl_old, ractx->lpc_coef_old, a, ractx->lpc_coef, 2);
 341     }
 342     gbuf1[2] = dec2(gbuf2[2], ractx->lpc_refl, ractx->lpc_coef, energy, ractx->lpc_coef_old, 3);
 343     gbuf1[3] = dec1(gbuf2[3], ractx->lpc_refl, ractx->lpc_coef, energy);
 344
 345     /* do output */
 346     for (c=0; c<4; c++) {
 347         do_output_subblock(ractx, gbuf2[c], gbuf1[c], data, &gb);
 348
 349         for (i=0; i<BLOCKSIZE; i++) {
 350             *data = av_clip_int16(*data << 2);
 351             data++;
 352         }
 353     }
 354
 355     ractx->old_energy = energy;
 356
 357     FFSWAP(unsigned int *, ractx->lpc_refl_old, ractx->lpc_refl);
 358     FFSWAP(unsigned int *, ractx->lpc_coef_old, ractx->lpc_coef);
 359
 360     *data_size = 2*160;
 361     return 20;
 362 }
 363
 364
 365 AVCodec ra_144_decoder =
 366 {
 367     "real_144",
 368     CODEC_TYPE_AUDIO,
 369     CODEC_ID_RA_144,
 370     sizeof(RA144Context),
 371     ra144_decode_init,
 372     NULL,
 373     NULL,
 374     ra144_decode_frame,
 375     .long_name = "RealAudio 1.0 (14.4K)",
 376 };