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"
25 #include "acelp_filters.h"
27 #define NBLOCKS 4 ///< number of subblocks within a block
28 #define BLOCKSIZE 40 ///< subblock size in 16-bit words
29 #define BUFFERSIZE 146 ///< the size of the adaptive codebook
33 unsigned int old_energy; ///< previous frame energy
35 unsigned int lpc_tables[2][10];
37 /** LPC coefficients: lpc_coef[0] is the coefficients of the current frame
38 * and lpc_coef[1] of the previous one */
39 unsigned int *lpc_coef[2];
41 unsigned int lpc_refl_rms[2];
43 /** the current subblock padded by the last 10 values of the previous one*/
44 int16_t curr_sblock[50];
46 /** adaptive codebook. Its size is two units bigger to avoid a
48 uint16_t adapt_cb[148];
51 static int ra144_decode_init(AVCodecContext * avctx)
53 RA144Context *ractx = avctx->priv_data;
55 ractx->lpc_coef[0] = ractx->lpc_tables[0];
56 ractx->lpc_coef[1] = ractx->lpc_tables[1];
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.
65 static int t_sqrt(unsigned int x)
73 return ff_sqrt(x << 20) << s;
77 * Evaluate the LPC filter coefficients from the reflection coefficients.
78 * Does the inverse of the eval_refl() function.
80 static void eval_coefs(int *coefs, const int *refl)
87 for (x=0; x < 10; x++) {
91 b1[y] = ((refl[x] * b2[x-y-1]) >> 12) + b2[y];
93 FFSWAP(int *, b1, b2);
96 for (x=0; x < 10; x++)
101 * Copy the last offset values of *source to *target. If those values are not
102 * enough to fill the target buffer, fill it with another copy of those values.
104 static void copy_and_dup(int16_t *target, const int16_t *source, int offset)
106 source += BUFFERSIZE - offset;
108 if (offset > BLOCKSIZE) {
109 memcpy(target, source, BLOCKSIZE*sizeof(*target));
111 memcpy(target, source, offset*sizeof(*target));
112 memcpy(target + offset, source, (BLOCKSIZE - offset)*sizeof(*target));
116 /** inverse root mean square */
117 static int irms(const int16_t *data)
119 unsigned int i, sum = 0;
121 for (i=0; i < BLOCKSIZE; i++)
122 sum += data[i] * data[i];
125 return 0; /* OOPS - division by zero */
127 return 0x20000000 / (t_sqrt(sum) >> 8);
130 static void add_wav(int16_t *dest, int n, int skip_first, int *m,
131 const int16_t *s1, const int8_t *s2, const int8_t *s3)
137 for (i=!skip_first; i<3; i++)
138 v[i] = (gain_val_tab[n][i] * m[i]) >> (gain_exp_tab[n][i] + 1);
140 for (i=0; i < BLOCKSIZE; i++)
141 dest[i] = (s1[i]*v[0] + s2[i]*v[1] + s3[i]*v[2]) >> 12;
144 static unsigned int rescale_rms(unsigned int rms, unsigned int energy)
146 return (rms * energy) >> 10;
149 static unsigned int rms(const int *data)
152 unsigned int res = 0x10000;
155 for (x=0; x<10; x++) {
156 res = (((0x1000000 - data[x]*data[x]) >> 12) * res) >> 12;
161 while (res <= 0x3fff) {
173 static void do_output_subblock(RA144Context *ractx, const uint16_t *lpc_coefs,
174 int gval, GetBitContext *gb)
176 uint16_t buffer_a[40];
178 int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
179 int gain = get_bits(gb, 8);
180 int cb1_idx = get_bits(gb, 7);
181 int cb2_idx = get_bits(gb, 7);
185 cba_idx += BLOCKSIZE/2 - 1;
186 copy_and_dup(buffer_a, ractx->adapt_cb, cba_idx);
187 m[0] = (irms(buffer_a) * gval) >> 12;
192 m[1] = (cb1_base[cb1_idx] * gval) >> 8;
193 m[2] = (cb2_base[cb2_idx] * gval) >> 8;
195 memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
196 (BUFFERSIZE - BLOCKSIZE) * sizeof(*ractx->adapt_cb));
198 block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
200 add_wav(block, gain, cba_idx, m, buffer_a,
201 cb1_vects[cb1_idx], cb2_vects[cb2_idx]);
203 memcpy(ractx->curr_sblock, ractx->curr_sblock + 40,
204 10*sizeof(*ractx->curr_sblock));
205 memcpy(ractx->curr_sblock + 10, block,
206 BLOCKSIZE*sizeof(*ractx->curr_sblock));
208 if (ff_acelp_lp_synthesis_filter(
209 ractx->curr_sblock + 10, lpc_coefs -1,
210 ractx->curr_sblock + 10, BLOCKSIZE,
213 memset(ractx->curr_sblock, 0, 50*sizeof(*ractx->curr_sblock));
216 static void int_to_int16(int16_t *out, const int *inp)
225 * Evaluate the reflection coefficients from the filter coefficients.
226 * Does the inverse of the eval_coefs() function.
228 * @return 1 if one of the reflection coefficients is of magnitude greater than
231 static int eval_refl(int *refl, const int16_t *coefs, RA144Context *ractx)
241 for (i=0; i < 10; i++)
242 buffer2[i] = coefs[i];
244 u = refl[9] = bp2[9];
246 if (u + 0x1000 > 0x1fff) {
247 av_log(ractx, AV_LOG_ERROR, "Overflow. Broken sample?\n");
251 for (c=8; c >= 0; c--) {
258 b = 0x1000-((u * u) >> 12);
264 bp1[u] = ((bp2[u] - ((refl[c+1] * bp2[c-u]) >> 12)) * (0x1000000 / b)) >> 12;
266 refl[c] = u = bp1[c];
268 if ((u + 0x1000) > 0x1fff)
271 FFSWAP(int *, bp1, bp2);
276 static int interp(RA144Context *ractx, int16_t *out, int block_num,
277 int copyold, int energy)
280 int a = block_num + 1;
284 // Interpolate block coefficients from the this frame forth block and
285 // last frame forth block
287 out[x] = (a * ractx->lpc_coef[0][x] + b * ractx->lpc_coef[1][x])>> 2;
289 if (eval_refl(work, out, ractx)) {
290 // The interpolated coefficients are unstable, copy either new or old
292 int_to_int16(out, ractx->lpc_coef[copyold]);
293 return rescale_rms(ractx->lpc_refl_rms[copyold], energy);
295 return rescale_rms(rms(work), energy);
299 /** Uncompress one block (20 bytes -> 160*2 bytes) */
300 static int ra144_decode_frame(AVCodecContext * avctx, void *vdata,
301 int *data_size, const uint8_t *buf, int buf_size)
303 static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
304 unsigned int refl_rms[4]; // RMS of the reflection coefficients
305 uint16_t block_coefs[4][30]; // LPC coefficients of each sub-block
306 unsigned int lpc_refl[10]; // LPC reflection coefficients of the frame
308 int16_t *data = vdata;
311 RA144Context *ractx = avctx->priv_data;
315 av_log(avctx, AV_LOG_ERROR,
316 "Frame too small (%d bytes). Truncated file?\n", buf_size);
320 init_get_bits(&gb, buf, 20 * 8);
323 lpc_refl[i] = lpc_refl_cb[i][get_bits(&gb, sizes[i])];
325 eval_coefs(ractx->lpc_coef[0], lpc_refl);
326 ractx->lpc_refl_rms[0] = rms(lpc_refl);
328 energy = energy_tab[get_bits(&gb, 5)];
330 refl_rms[0] = interp(ractx, block_coefs[0], 0, 1, ractx->old_energy);
331 refl_rms[1] = interp(ractx, block_coefs[1], 1, energy <= ractx->old_energy,
332 t_sqrt(energy*ractx->old_energy) >> 12);
333 refl_rms[2] = interp(ractx, block_coefs[2], 2, 0, energy);
334 refl_rms[3] = rescale_rms(ractx->lpc_refl_rms[0], energy);
336 int_to_int16(block_coefs[3], ractx->lpc_coef[0]);
338 for (c=0; c<4; c++) {
339 do_output_subblock(ractx, block_coefs[c], refl_rms[c], &gb);
341 for (i=0; i<BLOCKSIZE; i++)
342 *data++ = av_clip_int16(ractx->curr_sblock[i + 10] << 2);
345 ractx->old_energy = energy;
346 ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
348 FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
354 AVCodec ra_144_decoder =
359 sizeof(RA144Context),
364 .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),