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 subblocks within a block
27 #define BLOCKSIZE 40 ///< subblock size in 16-bit words
28 #define BUFFERSIZE 146 ///< the size of the adaptive codebook
32 unsigned int old_energy; ///< previous frame energy
34 unsigned int lpc_tables[2][10];
35 unsigned int *lpc_coef; ///< LPC coefficients
36 unsigned int *lpc_coef_old; ///< previous frame LPC coefficients
37 unsigned int lpc_refl_rms;
38 unsigned int lpc_refl_rms_old;
40 /** the current subblock padded by the last 10 values of the previous one*/
41 int16_t curr_sblock[50];
43 /** adaptive codebook. Its size is two units bigger to avoid a
45 uint16_t adapt_cb[148];
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(int *coefs, const int *refl)
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(int16_t *target, const int16_t *source, 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)
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);
127 static void add_wav(int16_t *dest, int n, int skip_first, int *m,
128 const int16_t *s1, const int8_t *s2, const int8_t *s3)
134 for (i=!skip_first; i<3; i++)
135 v[i] = (gain_val_tab[n][i] * m[i]) >> (gain_exp_tab[n][i] + 1);
137 for (i=0; i < BLOCKSIZE; i++)
138 dest[i] = (s1[i]*v[0] + s2[i]*v[1] + s3[i]*v[2]) >> 12;
142 * LPC Filter. Each output value is predicted from the 10 previous computed
143 * ones. It overwrites the input with the output.
145 * @param in the input of the filter. It should be an array of size len + 10.
146 * The 10 first input values are used to evaluate the first filtered one.
148 static void lpc_filter(uint16_t *in, const int16_t *lpc_coefs, int len)
153 for (i=0; i<len; i++) {
158 sum += lpc_coefs[9-x] * ptr[x];
162 new_val = ptr[10] - sum;
164 if (new_val < -32768 || new_val > 32767) {
165 memset(in, 0, 50*sizeof(*in));
174 static unsigned int rescale_rms(unsigned int rms, unsigned int energy)
176 return (rms * energy) >> 10;
179 static unsigned int rms(const int *data)
182 unsigned int res = 0x10000;
185 for (x=0; x<10; x++) {
186 res = (((0x1000000 - data[x]*data[x]) >> 12) * res) >> 12;
191 while (res <= 0x3fff) {
203 static void do_output_subblock(RA144Context *ractx,
204 const uint16_t *lpc_coefs, int gval,
207 uint16_t buffer_a[40];
209 int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
210 int gain = get_bits(gb, 8);
211 int cb1_idx = get_bits(gb, 7);
212 int cb2_idx = get_bits(gb, 7);
216 cba_idx += BLOCKSIZE/2 - 1;
217 copy_and_dup(buffer_a, ractx->adapt_cb, cba_idx);
218 m[0] = (irms(buffer_a) * gval) >> 12;
223 m[1] = (cb1_base[cb1_idx] * gval) >> 8;
224 m[2] = (cb2_base[cb2_idx] * gval) >> 8;
226 memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
227 (BUFFERSIZE - BLOCKSIZE) * sizeof(*ractx->adapt_cb));
229 block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
231 add_wav(block, gain, cba_idx, m, buffer_a,
232 cb1_vects[cb1_idx], cb2_vects[cb2_idx]);
234 memcpy(ractx->curr_sblock, ractx->curr_sblock + 40,
235 10*sizeof(*ractx->curr_sblock));
236 memcpy(ractx->curr_sblock + 10, block,
237 BLOCKSIZE*sizeof(*ractx->curr_sblock));
239 lpc_filter(ractx->curr_sblock, lpc_coefs, BLOCKSIZE);
242 static void int_to_int16(int16_t *out, const int *inp)
251 * Evaluate the reflection coefficients from the filter coefficients.
252 * Does the inverse of the eval_coefs() function.
254 * @return 1 if one of the reflection coefficients is of magnitude greater than
257 static int eval_refl(int *refl, const int16_t *coefs, RA144Context *ractx)
267 for (i=0; i < 10; i++)
268 buffer2[i] = coefs[i];
270 u = refl[9] = bp2[9];
272 if (u + 0x1000 > 0x1fff) {
273 av_log(ractx, AV_LOG_ERROR, "Overflow. Broken sample?\n");
277 for (c=8; c >= 0; c--) {
284 b = 0x1000-((u * u) >> 12);
290 bp1[u] = ((bp2[u] - ((refl[c+1] * bp2[c-u]) >> 12)) * (0x1000000 / b)) >> 12;
292 refl[c] = u = bp1[c];
294 if ((u + 0x1000) > 0x1fff)
297 FFSWAP(int *, bp1, bp2);
302 static int interp(RA144Context *ractx, int16_t *out, int block_num,
303 int copynew, int energy)
306 int a = block_num + 1;
310 // Interpolate block coefficients from the this frame forth block and
311 // last frame forth block
313 out[x] = (a * ractx->lpc_coef[x] + b * ractx->lpc_coef_old[x])>> 2;
315 if (eval_refl(work, out, ractx)) {
316 // The interpolated coefficients are unstable, copy either new or old
319 int_to_int16(out, ractx->lpc_coef);
320 return rescale_rms(ractx->lpc_refl_rms, energy);
322 int_to_int16(out, ractx->lpc_coef_old);
323 return rescale_rms(ractx->lpc_refl_rms_old, energy);
326 return rescale_rms(rms(work), energy);
330 /* Uncompress one block (20 bytes -> 160*2 bytes) */
331 static int ra144_decode_frame(AVCodecContext * avctx,
332 void *vdata, int *data_size,
333 const uint8_t * buf, int buf_size)
335 static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
336 unsigned int refl_rms[4]; // RMS of the reflection coefficients
337 uint16_t block_coefs[4][30]; // LPC coefficients of each sub-block
338 unsigned int lpc_refl[10]; // LPC reflection coefficients of the frame
340 int16_t *data = vdata;
343 RA144Context *ractx = avctx->priv_data;
347 av_log(avctx, AV_LOG_ERROR,
348 "Frame too small (%d bytes). Truncated file?\n", buf_size);
352 init_get_bits(&gb, buf, 20 * 8);
355 // "<< 1"? Doesn't this make one value out of two of the table useless?
356 lpc_refl[i] = lpc_refl_cb[i][get_bits(&gb, sizes[i]) << 1];
358 eval_coefs(ractx->lpc_coef, lpc_refl);
359 ractx->lpc_refl_rms = rms(lpc_refl);
361 energy = energy_tab[get_bits(&gb, 5) << 1]; // Useless table entries?
363 refl_rms[0] = interp(ractx, block_coefs[0], 0, 0, ractx->old_energy);
364 refl_rms[1] = interp(ractx, block_coefs[1], 1, energy > ractx->old_energy,
365 t_sqrt(energy*ractx->old_energy) >> 12);
366 refl_rms[2] = interp(ractx, block_coefs[2], 2, 1, energy);
367 refl_rms[3] = rescale_rms(ractx->lpc_refl_rms, energy);
369 int_to_int16(block_coefs[3], ractx->lpc_coef);
371 for (c=0; c<4; c++) {
372 do_output_subblock(ractx, block_coefs[c], refl_rms[c], &gb);
374 for (i=0; i<BLOCKSIZE; i++)
375 *data++ = av_clip_int16(ractx->curr_sblock[i + 10] << 2);
378 ractx->old_energy = energy;
379 ractx->lpc_refl_rms_old = ractx->lpc_refl_rms;
381 FFSWAP(unsigned int *, ractx->lpc_coef_old, ractx->lpc_coef);
387 AVCodec ra_144_decoder =
392 sizeof(RA144Context),
397 .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),