• Main Page
  • Related Pages
  • Modules
  • Data Structures
  • Files
  • File List
  • Globals

libavcodec/ra144.c

Go to the documentation of this file.
00001 /*
00002  * Real Audio 1.0 (14.4K)
00003  *
00004  * Copyright (c) 2008 Vitor Sessak
00005  * Copyright (c) 2003 Nick Kurshev
00006  *     Based on public domain decoder at http://www.honeypot.net/audio
00007  *
00008  * This file is part of FFmpeg.
00009  *
00010  * FFmpeg is free software; you can redistribute it and/or
00011  * modify it under the terms of the GNU Lesser General Public
00012  * License as published by the Free Software Foundation; either
00013  * version 2.1 of the License, or (at your option) any later version.
00014  *
00015  * FFmpeg is distributed in the hope that it will be useful,
00016  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018  * Lesser General Public License for more details.
00019  *
00020  * You should have received a copy of the GNU Lesser General Public
00021  * License along with FFmpeg; if not, write to the Free Software
00022  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00023  */
00024 
00025 #include "avcodec.h"
00026 #include "bitstream.h"
00027 #include "ra144.h"
00028 #include "celp_filters.h"
00029 
00030 #define NBLOCKS         4       ///< number of subblocks within a block
00031 #define BLOCKSIZE       40      ///< subblock size in 16-bit words
00032 #define BUFFERSIZE      146     ///< the size of the adaptive codebook
00033 
00034 
00035 typedef struct {
00036     unsigned int     old_energy;        
00037 
00038     unsigned int     lpc_tables[2][10];
00039 
00042     unsigned int    *lpc_coef[2];
00043 
00044     unsigned int     lpc_refl_rms[2];
00045 
00047     int16_t curr_sblock[50];
00048 
00051     uint16_t adapt_cb[146+2];
00052 } RA144Context;
00053 
00054 static av_cold int ra144_decode_init(AVCodecContext * avctx)
00055 {
00056     RA144Context *ractx = avctx->priv_data;
00057 
00058     ractx->lpc_coef[0] = ractx->lpc_tables[0];
00059     ractx->lpc_coef[1] = ractx->lpc_tables[1];
00060 
00061     avctx->sample_fmt = SAMPLE_FMT_S16;
00062     return 0;
00063 }
00064 
00069 static int t_sqrt(unsigned int x)
00070 {
00071     int s = 2;
00072     while (x > 0xfff) {
00073         s++;
00074         x >>= 2;
00075     }
00076 
00077     return ff_sqrt(x << 20) << s;
00078 }
00079 
00084 static void eval_coefs(int *coefs, const int *refl)
00085 {
00086     int buffer[10];
00087     int *b1 = buffer;
00088     int *b2 = coefs;
00089     int i, j;
00090 
00091     for (i=0; i < 10; i++) {
00092         b1[i] = refl[i] << 4;
00093 
00094         for (j=0; j < i; j++)
00095             b1[j] = ((refl[i] * b2[i-j-1]) >> 12) + b2[j];
00096 
00097         FFSWAP(int *, b1, b2);
00098     }
00099 
00100     for (i=0; i < 10; i++)
00101         coefs[i] >>= 4;
00102 }
00103 
00108 static void copy_and_dup(int16_t *target, const int16_t *source, int offset)
00109 {
00110     source += BUFFERSIZE - offset;
00111 
00112     memcpy(target, source, FFMIN(BLOCKSIZE, offset)*sizeof(*target));
00113     if (offset < BLOCKSIZE)
00114         memcpy(target + offset, source, (BLOCKSIZE - offset)*sizeof(*target));
00115 }
00116 
00118 static int irms(const int16_t *data)
00119 {
00120     unsigned int i, sum = 0;
00121 
00122     for (i=0; i < BLOCKSIZE; i++)
00123         sum += data[i] * data[i];
00124 
00125     if (sum == 0)
00126         return 0; /* OOPS - division by zero */
00127 
00128     return 0x20000000 / (t_sqrt(sum) >> 8);
00129 }
00130 
00131 static void add_wav(int16_t *dest, int n, int skip_first, int *m,
00132                     const int16_t *s1, const int8_t *s2, const int8_t *s3)
00133 {
00134     int i;
00135     int v[3];
00136 
00137     v[0] = 0;
00138     for (i=!skip_first; i<3; i++)
00139         v[i] = (gain_val_tab[n][i] * m[i]) >> gain_exp_tab[n];
00140 
00141     if (v[0]) {
00142         for (i=0; i < BLOCKSIZE; i++)
00143             dest[i] = (s1[i]*v[0] + s2[i]*v[1] + s3[i]*v[2]) >> 12;
00144     } else {
00145         for (i=0; i < BLOCKSIZE; i++)
00146             dest[i] = (             s2[i]*v[1] + s3[i]*v[2]) >> 12;
00147     }
00148 }
00149 
00150 static unsigned int rescale_rms(unsigned int rms, unsigned int energy)
00151 {
00152     return (rms * energy) >> 10;
00153 }
00154 
00155 static unsigned int rms(const int *data)
00156 {
00157     int i;
00158     unsigned int res = 0x10000;
00159     int b = 10;
00160 
00161     for (i=0; i < 10; i++) {
00162         res = (((0x1000000 - data[i]*data[i]) >> 12) * res) >> 12;
00163 
00164         if (res == 0)
00165             return 0;
00166 
00167         while (res <= 0x3fff) {
00168             b++;
00169             res <<= 2;
00170         }
00171     }
00172 
00173     return t_sqrt(res) >> b;
00174 }
00175 
00176 static void do_output_subblock(RA144Context *ractx, const uint16_t  *lpc_coefs,
00177                                int gval, GetBitContext *gb)
00178 {
00179     uint16_t buffer_a[40];
00180     uint16_t *block;
00181     int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
00182     int gain    = get_bits(gb, 8);
00183     int cb1_idx = get_bits(gb, 7);
00184     int cb2_idx = get_bits(gb, 7);
00185     int m[3];
00186 
00187     if (cba_idx) {
00188         cba_idx += BLOCKSIZE/2 - 1;
00189         copy_and_dup(buffer_a, ractx->adapt_cb, cba_idx);
00190         m[0] = (irms(buffer_a) * gval) >> 12;
00191     } else {
00192         m[0] = 0;
00193     }
00194 
00195     m[1] = (cb1_base[cb1_idx] * gval) >> 8;
00196     m[2] = (cb2_base[cb2_idx] * gval) >> 8;
00197 
00198     memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
00199             (BUFFERSIZE - BLOCKSIZE) * sizeof(*ractx->adapt_cb));
00200 
00201     block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
00202 
00203     add_wav(block, gain, cba_idx, m, cba_idx? buffer_a: NULL,
00204             cb1_vects[cb1_idx], cb2_vects[cb2_idx]);
00205 
00206     memcpy(ractx->curr_sblock, ractx->curr_sblock + 40,
00207            10*sizeof(*ractx->curr_sblock));
00208 
00209     if (ff_celp_lp_synthesis_filter(ractx->curr_sblock + 10, lpc_coefs,
00210                                     block, BLOCKSIZE, 10, 1, 0xfff))
00211         memset(ractx->curr_sblock, 0, 50*sizeof(*ractx->curr_sblock));
00212 }
00213 
00214 static void int_to_int16(int16_t *out, const int *inp)
00215 {
00216     int i;
00217 
00218     for (i=0; i < 30; i++)
00219         *out++ = *inp++;
00220 }
00221 
00229 static int eval_refl(int *refl, const int16_t *coefs, RA144Context *ractx)
00230 {
00231     int b, i, j;
00232     int buffer1[10];
00233     int buffer2[10];
00234     int *bp1 = buffer1;
00235     int *bp2 = buffer2;
00236 
00237     for (i=0; i < 10; i++)
00238         buffer2[i] = coefs[i];
00239 
00240     refl[9] = bp2[9];
00241 
00242     if ((unsigned) bp2[9] + 0x1000 > 0x1fff) {
00243         av_log(ractx, AV_LOG_ERROR, "Overflow. Broken sample?\n");
00244         return 1;
00245     }
00246 
00247     for (i=8; i >= 0; i--) {
00248         b = 0x1000-((bp2[i+1] * bp2[i+1]) >> 12);
00249 
00250         if (!b)
00251             b = -2;
00252 
00253         for (j=0; j <= i; j++)
00254             bp1[j] = ((bp2[j] - ((refl[i+1] * bp2[i-j]) >> 12)) * (0x1000000 / b)) >> 12;
00255 
00256         if ((unsigned) bp1[i] + 0x1000 > 0x1fff)
00257             return 1;
00258 
00259         refl[i] = bp1[i];
00260 
00261         FFSWAP(int *, bp1, bp2);
00262     }
00263     return 0;
00264 }
00265 
00266 static int interp(RA144Context *ractx, int16_t *out, int a,
00267                   int copyold, int energy)
00268 {
00269     int work[10];
00270     int b = NBLOCKS - a;
00271     int i;
00272 
00273     // Interpolate block coefficients from the this frame's forth block and
00274     // last frame's forth block.
00275     for (i=0; i<30; i++)
00276         out[i] = (a * ractx->lpc_coef[0][i] + b * ractx->lpc_coef[1][i])>> 2;
00277 
00278     if (eval_refl(work, out, ractx)) {
00279         // The interpolated coefficients are unstable, copy either new or old
00280         // coefficients.
00281         int_to_int16(out, ractx->lpc_coef[copyold]);
00282         return rescale_rms(ractx->lpc_refl_rms[copyold], energy);
00283     } else {
00284         return rescale_rms(rms(work), energy);
00285     }
00286 }
00287 
00289 static int ra144_decode_frame(AVCodecContext * avctx, void *vdata,
00290                               int *data_size, const uint8_t *buf, int buf_size)
00291 {
00292     static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
00293     unsigned int refl_rms[4];    // RMS of the reflection coefficients
00294     uint16_t block_coefs[4][30]; // LPC coefficients of each sub-block
00295     unsigned int lpc_refl[10];   // LPC reflection coefficients of the frame
00296     int i, j;
00297     int16_t *data = vdata;
00298     unsigned int energy;
00299 
00300     RA144Context *ractx = avctx->priv_data;
00301     GetBitContext gb;
00302 
00303     if (*data_size < 2*160)
00304         return -1;
00305 
00306     if(buf_size < 20) {
00307         av_log(avctx, AV_LOG_ERROR,
00308                "Frame too small (%d bytes). Truncated file?\n", buf_size);
00309         *data_size = 0;
00310         return buf_size;
00311     }
00312     init_get_bits(&gb, buf, 20 * 8);
00313 
00314     for (i=0; i<10; i++)
00315         lpc_refl[i] = lpc_refl_cb[i][get_bits(&gb, sizes[i])];
00316 
00317     eval_coefs(ractx->lpc_coef[0], lpc_refl);
00318     ractx->lpc_refl_rms[0] = rms(lpc_refl);
00319 
00320     energy = energy_tab[get_bits(&gb, 5)];
00321 
00322     refl_rms[0] = interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);
00323     refl_rms[1] = interp(ractx, block_coefs[1], 2, energy <= ractx->old_energy,
00324                     t_sqrt(energy*ractx->old_energy) >> 12);
00325     refl_rms[2] = interp(ractx, block_coefs[2], 3, 0, energy);
00326     refl_rms[3] = rescale_rms(ractx->lpc_refl_rms[0], energy);
00327 
00328     int_to_int16(block_coefs[3], ractx->lpc_coef[0]);
00329 
00330     for (i=0; i < 4; i++) {
00331         do_output_subblock(ractx, block_coefs[i], refl_rms[i], &gb);
00332 
00333         for (j=0; j < BLOCKSIZE; j++)
00334             *data++ = av_clip_int16(ractx->curr_sblock[j + 10] << 2);
00335     }
00336 
00337     ractx->old_energy = energy;
00338     ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
00339 
00340     FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
00341 
00342     *data_size = 2*160;
00343     return 20;
00344 }
00345 
00346 AVCodec ra_144_decoder =
00347 {
00348     "real_144",
00349     CODEC_TYPE_AUDIO,
00350     CODEC_ID_RA_144,
00351     sizeof(RA144Context),
00352     ra144_decode_init,
00353     NULL,
00354     NULL,
00355     ra144_decode_frame,
00356     .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),
00357 };

Generated on Tue Nov 4 2014 12:59:22 for ffmpeg by  doxygen 1.7.1