2 * Real Audio 1.0 (14.4K)
3 * Copyright (c) 2003 the ffmpeg project
5 * This file is part of FFmpeg.
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.
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.
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
23 #include "bitstream.h"
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 */
33 unsigned int old_energy; ///< previous frame energy
35 /* the swapped buffers */
36 unsigned int lpc_tables[2][10];
37 unsigned int *lpc_coef; ///< LPC coefficients
38 unsigned int *lpc_coef_old; ///< previous frame LPC coefficients
39 unsigned int lpc_refl_rms;
40 unsigned int lpc_refl_rms_old;
42 /** the current subblock padded by the last 10 values of the previous one*/
43 int16_t curr_sblock[50];
45 uint16_t adapt_cb[148]; ///< adaptive codebook
48 static int ra144_decode_init(AVCodecContext * avctx)
50 RA144Context *ractx = avctx->priv_data;
52 ractx->lpc_coef = ractx->lpc_tables[0];
53 ractx->lpc_coef_old = ractx->lpc_tables[1];
59 * Evaluate sqrt(x << 24). x must fit in 20 bits. This value is evaluated in an
60 * odd way to make the output identical to the binary decoder.
62 static int t_sqrt(unsigned int x)
70 return ff_sqrt(x << 20) << s;
74 * Evaluate the LPC filter coefficients from the reflection coefficients.
75 * Does the inverse of the eval_refl() function.
77 static void eval_coefs(const int *refl, int *coefs)
84 for (x=0; x < 10; x++) {
88 b1[y] = ((refl[x] * b2[x-y-1]) >> 12) + b2[y];
90 FFSWAP(int *, b1, b2);
93 for (x=0; x < 10; x++)
98 * Copy the last offset values of *source to *target. If those values are not
99 * enough to fill the target buffer, fill it with another copy of those values.
101 static void copy_and_dup(const int16_t *source, int16_t *target, int offset)
103 source += BUFFERSIZE - offset;
105 if (offset > BLOCKSIZE) {
106 memcpy(target, source, BLOCKSIZE*sizeof(*target));
108 memcpy(target, source, offset*sizeof(*target));
109 memcpy(target + offset, source, (BLOCKSIZE - offset)*sizeof(*target));
113 /* inverse root mean square */
114 static int irms(const int16_t *data, int factor)
116 unsigned int i, sum = 0;
118 for (i=0; i < BLOCKSIZE; i++)
119 sum += data[i] * data[i];
122 return 0; /* OOPS - division by zero */
124 return (0x20000000 / (t_sqrt(sum) >> 8)) * factor;
127 /* multiply/add wavetable */
128 static void add_wav(int n, int skip_first, int *m, const int16_t *s1,
129 const int8_t *s2, const int8_t *s3, int16_t *dest)
135 for (i=!skip_first; i<3; i++)
136 v[i] = (gain_val_tab[n][i] * m[i]) >> (gain_exp_tab[n][i] + 1);
138 for (i=0; i < BLOCKSIZE; i++)
139 dest[i] = ((*(s1++))*v[0] + (*(s2++))*v[1] + (*(s3++))*v[2]) >> 12;
143 * LPC Filter. Each output value is predicted from the 10 previous computed
144 * ones. It overwrites the input with the output.
146 * @param in the input of the filter. It should be an array of size len + 10.
147 * The 10 first input values are used to evaluate the first filtered one.
149 static void lpc_filter(const int16_t *lpc_coefs, uint16_t *in, int len)
154 for (i=0; i<len; i++) {
159 sum += lpc_coefs[9-x] * ptr[x];
163 new_val = ptr[10] - sum;
165 if (new_val < -32768 || new_val > 32767) {
175 static unsigned int rescale_rms(int rms, int energy)
177 return (rms * energy) >> 10;
180 static unsigned int rms(const int *data)
183 unsigned int res = 0x10000;
186 for (x=0; x<10; x++) {
187 res = (((0x1000000 - (*data) * (*data)) >> 12) * res) >> 12;
192 while (res <= 0x3fff) {
206 /* do quarter-block output */
207 static void do_output_subblock(RA144Context *ractx,
208 const uint16_t *lpc_coefs, unsigned int gval,
211 uint16_t buffer_a[40];
213 int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
214 int gain = get_bits(gb, 8);
215 int cb1_idx = get_bits(gb, 7);
216 int cb2_idx = get_bits(gb, 7);
220 cba_idx += HALFBLOCK - 1;
221 copy_and_dup(ractx->adapt_cb, buffer_a, cba_idx);
222 m[0] = irms(buffer_a, gval) >> 12;
227 m[1] = ((cb1_base[cb1_idx] >> 4) * gval) >> 8;
228 m[2] = ((cb2_base[cb2_idx] >> 4) * gval) >> 8;
230 memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
231 (BUFFERSIZE - BLOCKSIZE) * 2);
233 block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
235 add_wav(gain, cba_idx, m, buffer_a, cb1_vects[cb1_idx], cb2_vects[cb2_idx],
238 memcpy(ractx->curr_sblock, ractx->curr_sblock + 40,
239 10*sizeof(*ractx->curr_sblock));
240 memcpy(ractx->curr_sblock + 10, block,
241 BLOCKSIZE*sizeof(*ractx->curr_sblock));
243 lpc_filter(lpc_coefs, ractx->curr_sblock, BLOCKSIZE);
246 static void int_to_int16(int16_t *out, const int *inp)
255 * Evaluate the reflection coefficients from the filter coefficients.
256 * Does the inverse of the eval_coefs() function.
258 * @return 1 if one of the reflection coefficients is of magnitude greater than
261 static int eval_refl(const int16_t *coefs, int *refl, RA144Context *ractx)
271 for (i=0; i < 10; i++)
272 buffer2[i] = coefs[i];
274 u = refl[9] = bp2[9];
276 if (u + 0x1000 > 0x1fff) {
277 av_log(ractx, AV_LOG_ERROR, "Overflow. Broken sample?\n");
281 for (c=8; c >= 0; c--) {
288 b = 0x1000-((u * u) >> 12);
294 bp1[u] = ((bp2[u] - ((refl[c+1] * bp2[c-u]) >> 12)) * (0x1000000 / b)) >> 12;
296 refl[c] = u = bp1[c];
298 if ((u + 0x1000) > 0x1fff)
301 FFSWAP(int *, bp1, bp2);
306 static int interp(RA144Context *ractx, int16_t *out, int block_num,
307 int copynew, int energy)
310 int a = block_num + 1;
314 // Interpolate block coefficients from the this frame forth block and
315 // last frame forth block
317 out[x] = (a * ractx->lpc_coef[x] + b * ractx->lpc_coef_old[x])>> 2;
319 if (eval_refl(out, work, ractx)) {
320 // The interpolated coefficients are unstable, copy either new or old
323 int_to_int16(out, ractx->lpc_coef);
324 return rescale_rms(ractx->lpc_refl_rms, energy);
326 int_to_int16(out, ractx->lpc_coef_old);
327 return rescale_rms(ractx->lpc_refl_rms_old, energy);
330 return rescale_rms(rms(work), energy);
334 /* Uncompress one block (20 bytes -> 160*2 bytes) */
335 static int ra144_decode_frame(AVCodecContext * avctx,
336 void *vdata, int *data_size,
337 const uint8_t * buf, int buf_size)
339 static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
340 unsigned int refl_rms[4]; // RMS of the reflection coefficients
341 uint16_t block_coefs[4][30]; // LPC coefficients of each sub-block
342 unsigned int lpc_refl[10]; // LPC reflection coefficients of the frame
344 int16_t *data = vdata;
347 RA144Context *ractx = avctx->priv_data;
351 av_log(avctx, AV_LOG_ERROR,
352 "Frame too small (%d bytes). Truncated file?\n", buf_size);
356 init_get_bits(&gb, buf, 20 * 8);
359 // "<< 1"? Doesn't this make one value out of two of the table useless?
360 lpc_refl[i] = lpc_refl_cb[i][get_bits(&gb, sizes[i]) << 1];
362 eval_coefs(lpc_refl, ractx->lpc_coef);
363 ractx->lpc_refl_rms = rms(lpc_refl);
365 energy = energy_tab[get_bits(&gb, 5) << 1]; // Useless table entries?
367 refl_rms[0] = interp(ractx, block_coefs[0], 0, 0, ractx->old_energy);
368 refl_rms[1] = interp(ractx, block_coefs[1], 1, energy > ractx->old_energy,
369 t_sqrt(energy*ractx->old_energy) >> 12);
370 refl_rms[2] = interp(ractx, block_coefs[2], 2, 1, energy);
371 refl_rms[3] = rescale_rms(ractx->lpc_refl_rms, energy);
373 int_to_int16(block_coefs[3], ractx->lpc_coef);
376 for (c=0; c<4; c++) {
377 do_output_subblock(ractx, block_coefs[c], refl_rms[c], &gb);
379 for (i=0; i<BLOCKSIZE; i++)
380 *data++ = av_clip_int16(ractx->curr_sblock[i + 10] << 2);
383 ractx->old_energy = energy;
384 ractx->lpc_refl_rms_old = ractx->lpc_refl_rms;
386 FFSWAP(unsigned int *, ractx->lpc_coef_old, ractx->lpc_coef);
392 AVCodec ra_144_decoder =
397 sizeof(RA144Context),
402 .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),