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  1. /*
  2. * Real Audio 1.0 (14.4K)
  3. *
  4. * Copyright (c) 2008 Vitor Sessak
  5. * Copyright (c) 2003 Nick Kurshev
  6. * Based on public domain decoder at http://www.honeypot.net/audio
  7. *
  8. * This file is part of FFmpeg.
  9. *
  10. * FFmpeg is free software; you can redistribute it and/or
  11. * modify it under the terms of the GNU Lesser General Public
  12. * License as published by the Free Software Foundation; either
  13. * version 2.1 of the License, or (at your option) any later version.
  14. *
  15. * FFmpeg is distributed in the hope that it will be useful,
  16. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18. * Lesser General Public License for more details.
  19. *
  20. * You should have received a copy of the GNU Lesser General Public
  21. * License along with FFmpeg; if not, write to the Free Software
  22. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23. */
  24. #include "libavutil/intmath.h"
  25. #include "avcodec.h"
  26. #include "get_bits.h"
  27. #include "ra144.h"
  28. #include "celp_filters.h"
  29. #define NBLOCKS 4 ///< number of subblocks within a block
  30. #define BLOCKSIZE 40 ///< subblock size in 16-bit words
  31. #define BUFFERSIZE 146 ///< the size of the adaptive codebook
  32. typedef struct {
  33. AVCodecContext *avctx;
  34. unsigned int old_energy; ///< previous frame energy
  35. unsigned int lpc_tables[2][10];
  36. /** LPC coefficients: lpc_coef[0] is the coefficients of the current frame
  37. * and lpc_coef[1] of the previous one. */
  38. unsigned int *lpc_coef[2];
  39. unsigned int lpc_refl_rms[2];
  40. /** The current subblock padded by the last 10 values of the previous one. */
  41. int16_t curr_sblock[50];
  42. /** Adaptive codebook, its size is two units bigger to avoid a
  43. * buffer overflow. */
  44. uint16_t adapt_cb[146+2];
  45. } RA144Context;
  46. static av_cold int ra144_decode_init(AVCodecContext * avctx)
  47. {
  48. RA144Context *ractx = avctx->priv_data;
  49. ractx->avctx = avctx;
  50. ractx->lpc_coef[0] = ractx->lpc_tables[0];
  51. ractx->lpc_coef[1] = ractx->lpc_tables[1];
  52. avctx->sample_fmt = SAMPLE_FMT_S16;
  53. return 0;
  54. }
  55. /**
  56. * Evaluate sqrt(x << 24). x must fit in 20 bits. This value is evaluated in an
  57. * odd way to make the output identical to the binary decoder.
  58. */
  59. static int t_sqrt(unsigned int x)
  60. {
  61. int s = 2;
  62. while (x > 0xfff) {
  63. s++;
  64. x >>= 2;
  65. }
  66. return ff_sqrt(x << 20) << s;
  67. }
  68. /**
  69. * Evaluate the LPC filter coefficients from the reflection coefficients.
  70. * Does the inverse of the eval_refl() function.
  71. */
  72. static void eval_coefs(int *coefs, const int *refl)
  73. {
  74. int buffer[10];
  75. int *b1 = buffer;
  76. int *b2 = coefs;
  77. int i, j;
  78. for (i=0; i < 10; i++) {
  79. b1[i] = refl[i] << 4;
  80. for (j=0; j < i; j++)
  81. b1[j] = ((refl[i] * b2[i-j-1]) >> 12) + b2[j];
  82. FFSWAP(int *, b1, b2);
  83. }
  84. for (i=0; i < 10; i++)
  85. coefs[i] >>= 4;
  86. }
  87. /**
  88. * Copy the last offset values of *source to *target. If those values are not
  89. * enough to fill the target buffer, fill it with another copy of those values.
  90. */
  91. static void copy_and_dup(int16_t *target, const int16_t *source, int offset)
  92. {
  93. source += BUFFERSIZE - offset;
  94. memcpy(target, source, FFMIN(BLOCKSIZE, offset)*sizeof(*target));
  95. if (offset < BLOCKSIZE)
  96. memcpy(target + offset, source, (BLOCKSIZE - offset)*sizeof(*target));
  97. }
  98. /** inverse root mean square */
  99. static int irms(const int16_t *data)
  100. {
  101. unsigned int i, sum = 0;
  102. for (i=0; i < BLOCKSIZE; i++)
  103. sum += data[i] * data[i];
  104. if (sum == 0)
  105. return 0; /* OOPS - division by zero */
  106. return 0x20000000 / (t_sqrt(sum) >> 8);
  107. }
  108. static void add_wav(int16_t *dest, int n, int skip_first, int *m,
  109. const int16_t *s1, const int8_t *s2, const int8_t *s3)
  110. {
  111. int i;
  112. int v[3];
  113. v[0] = 0;
  114. for (i=!skip_first; i<3; i++)
  115. v[i] = (gain_val_tab[n][i] * m[i]) >> gain_exp_tab[n];
  116. if (v[0]) {
  117. for (i=0; i < BLOCKSIZE; i++)
  118. dest[i] = (s1[i]*v[0] + s2[i]*v[1] + s3[i]*v[2]) >> 12;
  119. } else {
  120. for (i=0; i < BLOCKSIZE; i++)
  121. dest[i] = ( s2[i]*v[1] + s3[i]*v[2]) >> 12;
  122. }
  123. }
  124. static unsigned int rescale_rms(unsigned int rms, unsigned int energy)
  125. {
  126. return (rms * energy) >> 10;
  127. }
  128. static unsigned int rms(const int *data)
  129. {
  130. int i;
  131. unsigned int res = 0x10000;
  132. int b = 10;
  133. for (i=0; i < 10; i++) {
  134. res = (((0x1000000 - data[i]*data[i]) >> 12) * res) >> 12;
  135. if (res == 0)
  136. return 0;
  137. while (res <= 0x3fff) {
  138. b++;
  139. res <<= 2;
  140. }
  141. }
  142. return t_sqrt(res) >> b;
  143. }
  144. static void do_output_subblock(RA144Context *ractx, const uint16_t *lpc_coefs,
  145. int gval, GetBitContext *gb)
  146. {
  147. uint16_t buffer_a[40];
  148. uint16_t *block;
  149. int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
  150. int gain = get_bits(gb, 8);
  151. int cb1_idx = get_bits(gb, 7);
  152. int cb2_idx = get_bits(gb, 7);
  153. int m[3];
  154. if (cba_idx) {
  155. cba_idx += BLOCKSIZE/2 - 1;
  156. copy_and_dup(buffer_a, ractx->adapt_cb, cba_idx);
  157. m[0] = (irms(buffer_a) * gval) >> 12;
  158. } else {
  159. m[0] = 0;
  160. }
  161. m[1] = (cb1_base[cb1_idx] * gval) >> 8;
  162. m[2] = (cb2_base[cb2_idx] * gval) >> 8;
  163. memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
  164. (BUFFERSIZE - BLOCKSIZE) * sizeof(*ractx->adapt_cb));
  165. block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
  166. add_wav(block, gain, cba_idx, m, cba_idx? buffer_a: NULL,
  167. cb1_vects[cb1_idx], cb2_vects[cb2_idx]);
  168. memcpy(ractx->curr_sblock, ractx->curr_sblock + 40,
  169. 10*sizeof(*ractx->curr_sblock));
  170. if (ff_celp_lp_synthesis_filter(ractx->curr_sblock + 10, lpc_coefs,
  171. block, BLOCKSIZE, 10, 1, 0xfff))
  172. memset(ractx->curr_sblock, 0, 50*sizeof(*ractx->curr_sblock));
  173. }
  174. static void int_to_int16(int16_t *out, const int *inp)
  175. {
  176. int i;
  177. for (i=0; i < 10; i++)
  178. *out++ = *inp++;
  179. }
  180. /**
  181. * Evaluate the reflection coefficients from the filter coefficients.
  182. * Does the inverse of the eval_coefs() function.
  183. *
  184. * @return 1 if one of the reflection coefficients is greater than
  185. * 4095, 0 if not.
  186. */
  187. static int eval_refl(int *refl, const int16_t *coefs, AVCodecContext *avctx)
  188. {
  189. int b, i, j;
  190. int buffer1[10];
  191. int buffer2[10];
  192. int *bp1 = buffer1;
  193. int *bp2 = buffer2;
  194. for (i=0; i < 10; i++)
  195. buffer2[i] = coefs[i];
  196. refl[9] = bp2[9];
  197. if ((unsigned) bp2[9] + 0x1000 > 0x1fff) {
  198. av_log(avctx, AV_LOG_ERROR, "Overflow. Broken sample?\n");
  199. return 1;
  200. }
  201. for (i=8; i >= 0; i--) {
  202. b = 0x1000-((bp2[i+1] * bp2[i+1]) >> 12);
  203. if (!b)
  204. b = -2;
  205. for (j=0; j <= i; j++)
  206. bp1[j] = ((bp2[j] - ((refl[i+1] * bp2[i-j]) >> 12)) * (0x1000000 / b)) >> 12;
  207. if ((unsigned) bp1[i] + 0x1000 > 0x1fff)
  208. return 1;
  209. refl[i] = bp1[i];
  210. FFSWAP(int *, bp1, bp2);
  211. }
  212. return 0;
  213. }
  214. static int interp(RA144Context *ractx, int16_t *out, int a,
  215. int copyold, int energy)
  216. {
  217. int work[10];
  218. int b = NBLOCKS - a;
  219. int i;
  220. // Interpolate block coefficients from the this frame's forth block and
  221. // last frame's forth block.
  222. for (i=0; i<10; i++)
  223. out[i] = (a * ractx->lpc_coef[0][i] + b * ractx->lpc_coef[1][i])>> 2;
  224. if (eval_refl(work, out, ractx->avctx)) {
  225. // The interpolated coefficients are unstable, copy either new or old
  226. // coefficients.
  227. int_to_int16(out, ractx->lpc_coef[copyold]);
  228. return rescale_rms(ractx->lpc_refl_rms[copyold], energy);
  229. } else {
  230. return rescale_rms(rms(work), energy);
  231. }
  232. }
  233. /** Uncompress one block (20 bytes -> 160*2 bytes). */
  234. static int ra144_decode_frame(AVCodecContext * avctx, void *vdata,
  235. int *data_size, AVPacket *avpkt)
  236. {
  237. const uint8_t *buf = avpkt->data;
  238. int buf_size = avpkt->size;
  239. static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
  240. unsigned int refl_rms[4]; // RMS of the reflection coefficients
  241. uint16_t block_coefs[4][10]; // LPC coefficients of each sub-block
  242. unsigned int lpc_refl[10]; // LPC reflection coefficients of the frame
  243. int i, j;
  244. int16_t *data = vdata;
  245. unsigned int energy;
  246. RA144Context *ractx = avctx->priv_data;
  247. GetBitContext gb;
  248. if (*data_size < 2*160)
  249. return -1;
  250. if(buf_size < 20) {
  251. av_log(avctx, AV_LOG_ERROR,
  252. "Frame too small (%d bytes). Truncated file?\n", buf_size);
  253. *data_size = 0;
  254. return buf_size;
  255. }
  256. init_get_bits(&gb, buf, 20 * 8);
  257. for (i=0; i<10; i++)
  258. lpc_refl[i] = lpc_refl_cb[i][get_bits(&gb, sizes[i])];
  259. eval_coefs(ractx->lpc_coef[0], lpc_refl);
  260. ractx->lpc_refl_rms[0] = rms(lpc_refl);
  261. energy = energy_tab[get_bits(&gb, 5)];
  262. refl_rms[0] = interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);
  263. refl_rms[1] = interp(ractx, block_coefs[1], 2, energy <= ractx->old_energy,
  264. t_sqrt(energy*ractx->old_energy) >> 12);
  265. refl_rms[2] = interp(ractx, block_coefs[2], 3, 0, energy);
  266. refl_rms[3] = rescale_rms(ractx->lpc_refl_rms[0], energy);
  267. int_to_int16(block_coefs[3], ractx->lpc_coef[0]);
  268. for (i=0; i < 4; i++) {
  269. do_output_subblock(ractx, block_coefs[i], refl_rms[i], &gb);
  270. for (j=0; j < BLOCKSIZE; j++)
  271. *data++ = av_clip_int16(ractx->curr_sblock[j + 10] << 2);
  272. }
  273. ractx->old_energy = energy;
  274. ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
  275. FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
  276. *data_size = 2*160;
  277. return 20;
  278. }
  279. AVCodec ra_144_decoder =
  280. {
  281. "real_144",
  282. CODEC_TYPE_AUDIO,
  283. CODEC_ID_RA_144,
  284. sizeof(RA144Context),
  285. ra144_decode_init,
  286. NULL,
  287. NULL,
  288. ra144_decode_frame,
  289. .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),
  290. };