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 "acelp_vectors.h"
  25 #include "ra144.h"
  26
  27 #define NBLOCKS         4       /* number of segments within a block */
  28 #define BLOCKSIZE       40      /* (quarter) block size in 16-bit words (80 bytes) */
  29 #define HALFBLOCK       20      /* BLOCKSIZE/2 */
  30 #define BUFFERSIZE      146     /* for do_output */
  31
  32
  33 /* internal globals */
  34 typedef struct {
  35     unsigned int     old_energy;        ///< previous frame energy
  36
  37     /* the swapped buffers */
  38     unsigned int     refl_tables[2][10];
  39     int16_t          coef_tables[2][10];
  40     unsigned int    *lpc_refl;          ///< LPC reflection coefficients
  41     int16_t         *lpc_coef;          ///< LPC coefficients
  42     unsigned int    *lpc_refl_old;      ///< previous frame LPC reflection coefs
  43     int16_t         *lpc_coef_old;      ///< previous frame LPC coefficients
  44
  45     unsigned int buffer[5];
  46     uint16_t adapt_cb[148];             ///< adaptive codebook
  47 } RA144Context;
  48
  49 static int ra144_decode_init(AVCodecContext * avctx)
  50 {
  51     RA144Context *ractx = avctx->priv_data;
  52
  53     ractx->lpc_refl     = ractx->refl_tables[0];
  54     ractx->lpc_coef     = ractx->coef_tables[0];
  55     ractx->lpc_refl_old = ractx->refl_tables[1];
  56     ractx->lpc_coef_old = ractx->coef_tables[1];
  57
  58     return 0;
  59 }
  60
  61 /**
  62  * Evaluate sqrt(x << 24). x must fit in 20 bits. This value is evaluated in an
  63  * odd way to make the output identical to the binary decoder.
  64  */
  65 static int t_sqrt(unsigned int x)
  66 {
  67     int s = 0;
  68     while (x > 0xfff) {
  69         s++;
  70         x = x >> 2;
  71     }
  72
  73     return (ff_sqrt(x << 20) << s) << 2;
  74 }
  75
  76 /* do 'voice' */
  77 static void do_voice(const int *a1, int16_t *a2)
  78 {
  79     int buffer[10];
  80     int buffer2[10];
  81     int *b1 = buffer;
  82     int *b2 = buffer2;
  83     int x, y;
  84
  85     for (x=0; x<10; x++)
  86         buffer2[x] = a2[x];
  87
  88     for (x=0; x < 10; x++) {
  89         b1[x] = a1[x] << 4;
  90
  91         for (y=0; y < x; y++)
  92             b1[y] = ((a1[x] * b2[x-y-1]) >> 12) + b2[y];
  93
  94         FFSWAP(int *, b1, b2);
  95     }
  96
  97     for (x=0; x < 10; x++)
  98         a2[x] = buffer2[x] >> 4;
  99 }
 100
 101 /* rotate block */
 102 static void rotate_block(const int16_t *source, int16_t *target, int offset)
 103 {
 104     int i=0, k=0;
 105     source += BUFFERSIZE - offset;
 106
 107     while (i<BLOCKSIZE) {
 108         target[i++] = source[k++];
 109
 110         if (k == offset)
 111             k = 0;
 112     }
 113 }
 114
 115 /* inverse root mean square */
 116 static int irms(const int16_t *data, int factor)
 117 {
 118     unsigned int i, sum = 0;
 119
 120     for (i=0; i < BLOCKSIZE; i++)
 121         sum += data[i] * data[i];
 122
 123     if (sum == 0)
 124         return 0; /* OOPS - division by zero */
 125
 126     return (0x20000000 / (t_sqrt(sum) >> 8)) * factor;
 127 }
 128
 129 /* multiply/add wavetable */
 130 static void add_wav(int n, int skip_first, int *m, const int16_t *s1,
 131                     const int8_t *s2, const int8_t *s3, int16_t *dest)
 132 {
 133     int i;
 134     int v[3];
 135
 136     v[0] = 0;
 137     for (i=!skip_first; i<3; i++)
 138         v[i] = (wavtable1[n][i] * m[i]) >> (wavtable2[n][i] + 1);
 139
 140     for (i=0; i < BLOCKSIZE; i++)
 141         dest[i] = ((*(s1++))*v[0] + (*(s2++))*v[1] + (*(s3++))*v[2]) >> 12;
 142 }
 143
 144
 145 static void final(const int16_t *i1, const int16_t *i2,
 146                   void *out, int *statbuf, int len)
 147 {
 148     int x, i;
 149     uint16_t work[50];
 150     int16_t *ptr = work;
 151
 152     memcpy(work, statbuf,20);
 153     memcpy(work + 10, i2, len * 2);
 154
 155     for (i=0; i<len; i++) {
 156         int sum = 0;
 157         int new_val;
 158
 159         for(x=0; x<10; x++)
 160             sum += i1[9-x] * ptr[x];
 161
 162         sum >>= 12;
 163
 164         new_val = ptr[10] - sum;
 165
 166         if (new_val < -32768 || new_val > 32767) {
 167             memset(out, 0, len * 2);
 168             memset(statbuf, 0, 20);
 169             return;
 170         }
 171
 172         ptr[10] = new_val;
 173         ptr++;
 174     }
 175
 176     memcpy(out, work+10, len * 2);
 177     memcpy(statbuf, work + 40, 20);
 178 }
 179
 180 static unsigned int rms(const int *data, int f)
 181 {
 182     int x;
 183     unsigned int res = 0x10000;
 184     int b = 0;
 185
 186     for (x=0; x<10; x++) {
 187         res = (((0x1000000 - (*data) * (*data)) >> 12) * res) >> 12;
 188
 189         if (res == 0)
 190             return 0;
 191
 192         if (res > 0x10000)
 193             return 0; /* We're screwed, might as well go out with a bang. :P */
 194
 195         while (res <= 0x3fff) {
 196             b++;
 197             res <<= 2;
 198         }
 199         data++;
 200     }
 201
 202     if (res > 0)
 203         res = t_sqrt(res);
 204
 205     res >>= (b + 10);
 206     res = (res * f) >> 10;
 207     return res;
 208 }
 209
 210 /* do quarter-block output */
 211 static void do_output_subblock(RA144Context *ractx,
 212                                const uint16_t  *gsp, unsigned int gval,
 213                                int16_t *output_buffer, GetBitContext *gb)
 214 {
 215     uint16_t buffer_a[40];
 216     uint16_t *block;
 217     int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
 218     int gain    = get_bits(gb, 8);
 219     int cb1_idx = get_bits(gb, 7);
 220     int cb2_idx = get_bits(gb, 7);
 221     int m[3];
 222
 223     if (cba_idx) {
 224         cba_idx += HALFBLOCK - 1;
 225         rotate_block(ractx->adapt_cb, buffer_a, cba_idx);
 226         m[0] = irms(buffer_a, gval) >> 12;
 227     } else {
 228         m[0] = 0;
 229     }
 230
 231     m[1] = ((ftable1[cb1_idx] >> 4) * gval) >> 8;
 232     m[2] = ((ftable2[cb2_idx] >> 4) * gval) >> 8;
 233
 234     memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
 235             (BUFFERSIZE - BLOCKSIZE) * 2);
 236
 237     block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
 238
 239     add_wav(gain, cba_idx, m, buffer_a, etable1[cb1_idx], etable2[cb2_idx],
 240             block);
 241
 242     final(gsp, block, output_buffer, ractx->buffer, BLOCKSIZE);
 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(RA144Context *ractx, int16_t *decsp, int block_num,
 289                 int copynew, int f)
 290 {
 291     int work[10];
 292     int a = block_num + 1;
 293     int b = NBLOCKS - a;
 294     int x;
 295
 296     // Interpolate block coefficients from the this frame forth block and
 297     // last frame forth block
 298     ff_acelp_weighted_vector_sum(decsp, ractx->lpc_coef, ractx->lpc_coef_old,
 299                                  a, b, 0, 2, 30);
 300
 301     if (eq(decsp, work)) {
 302         // The interpolated coefficients are unstable, copy either new or old
 303         // coefficients
 304         if (copynew) {
 305             memcpy(decsp, ractx->lpc_coef, 30*sizeof(*decsp));
 306             return rms(ractx->lpc_refl, f);
 307         } else {
 308             memcpy(decsp, ractx->lpc_coef_old, 30*sizeof(*decsp));
 309             return rms(ractx->lpc_refl_old, f);
 310         }
 311     } else {
 312         return rms(work, f);
 313     }
 314 }
 315
 316 /* Uncompress one block (20 bytes -> 160*2 bytes) */
 317 static int ra144_decode_frame(AVCodecContext * avctx,
 318                               void *vdata, int *data_size,
 319                               const uint8_t * buf, int buf_size)
 320 {
 321     static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
 322     RA144Context *ractx = avctx->priv_data;
 323     unsigned int gbuf1[4];
 324     uint16_t coef_table[3][30];
 325     uint16_t *gbuf2[4] =
 326         {coef_table[0], coef_table[1], coef_table[2], ractx->lpc_coef};
 327     unsigned int c;
 328     int i;
 329     int16_t *data = vdata;
 330     unsigned int energy;
 331
 332     GetBitContext gb;
 333
 334     if(buf_size < 20) {
 335         av_log(avctx, AV_LOG_ERROR,
 336                "Frame too small (%d bytes). Truncated file?\n", buf_size);
 337         return buf_size;
 338     }
 339     init_get_bits(&gb, buf, 20 * 8);
 340
 341     for (i=0; i<10; i++)
 342         // "<< 1"? Doesn't this make one value out of two of the table useless?
 343         ractx->lpc_refl[i] = decodetable[i][get_bits(&gb, sizes[i]) << 1];
 344
 345     do_voice(ractx->lpc_refl, ractx->lpc_coef);
 346
 347     energy = decodeval[get_bits(&gb, 5) << 1]; // Useless table entries?
 348
 349     gbuf1[0] = dec2(ractx, gbuf2[0], 0, 0, ractx->old_energy);
 350     gbuf1[1] = dec2(ractx, gbuf2[1], 1, energy > ractx->old_energy,
 351                     t_sqrt(energy*ractx->old_energy) >> 12);
 352     gbuf1[2] = dec2(ractx, gbuf2[2], 2, 1, energy);
 353     gbuf1[3] = rms(ractx->lpc_refl, energy);
 354
 355     /* do output */
 356     for (c=0; c<4; c++) {
 357         do_output_subblock(ractx, gbuf2[c], gbuf1[c], data, &gb);
 358
 359         for (i=0; i<BLOCKSIZE; i++) {
 360             *data = av_clip_int16(*data << 2);
 361             data++;
 362         }
 363     }
 364
 365     ractx->old_energy = energy;
 366
 367     FFSWAP(unsigned int *, ractx->lpc_refl_old, ractx->lpc_refl);
 368     FFSWAP(int16_t *     , ractx->lpc_coef_old, ractx->lpc_coef);
 369
 370     *data_size = 2*160;
 371     return 20;
 372 }
 373
 374
 375 AVCodec ra_144_decoder =
 376 {
 377     "real_144",
 378     CODEC_TYPE_AUDIO,
 379     CODEC_ID_RA_144,
 380     sizeof(RA144Context),
 381     ra144_decode_init,
 382     NULL,
 383     NULL,
 384     ra144_decode_frame,
 385     .long_name = "RealAudio 1.0 (14.4K)",
 386 };