Statistics
| Branch: | Revision:

ffmpeg / libavcodec / ra144.c @ 4dc471c3

History | View | Annotate | Download (9.7 KB)

1
/*
2
 * Real Audio 1.0 (14.4K)
3
 * Copyright (c) 2003 the ffmpeg project
4
 *
5
 * This file is part of FFmpeg.
6
 *
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.
11
 *
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.
16
 *
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
20
 */
21

    
22
#include "avcodec.h"
23
#include "bitstream.h"
24
#include "ra144.h"
25

    
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 */
30

    
31

    
32
/* internal globals */
33
typedef struct {
34
    unsigned int     old_energy;        ///< previous frame energy
35

    
36
    /* the swapped buffers */
37
    unsigned int     lpc_tables[4][10];
38
    unsigned int    *lpc_refl;          ///< LPC reflection coefficients
39
    unsigned int    *lpc_coef;          ///< LPC coefficients
40
    unsigned int    *lpc_refl_old;      ///< previous frame LPC reflection coefs
41
    unsigned int    *lpc_coef_old;      ///< previous frame LPC coefficients
42

    
43
    unsigned int buffer[5];
44
    uint16_t adapt_cb[148];             ///< adaptive codebook
45
} RA144Context;
46

    
47
static int ra144_decode_init(AVCodecContext * avctx)
48
{
49
    RA144Context *ractx = avctx->priv_data;
50

    
51
    ractx->lpc_refl     = ractx->lpc_tables[0];
52
    ractx->lpc_coef     = ractx->lpc_tables[1];
53
    ractx->lpc_refl_old = ractx->lpc_tables[2];
54
    ractx->lpc_coef_old = ractx->lpc_tables[3];
55

    
56
    return 0;
57
}
58

    
59
/**
60
 * Evaluate sqrt(x << 24). x must fit in 20 bits. This value is evaluated in an
61
 * odd way to make the output identical to the binary decoder.
62
 */
63
static int t_sqrt(unsigned int x)
64
{
65
    int s = 0;
66
    while (x > 0xfff) {
67
        s++;
68
        x = x >> 2;
69
    }
70

    
71
    return (ff_sqrt(x << 20) << s) << 2;
72
}
73

    
74
/* do 'voice' */
75
static void do_voice(const int *a1, int *a2)
76
{
77
    int buffer[10];
78
    int *b1 = buffer;
79
    int *b2 = a2;
80
    int x, y;
81

    
82
    for (x=0; x < 10; x++) {
83
        b1[x] = a1[x] << 4;
84

    
85
        for (y=0; y < x; y++)
86
            b1[y] = ((a1[x] * b2[x-y-1]) >> 12) + b2[y];
87

    
88
        FFSWAP(int *, b1, b2);
89
    }
90

    
91
    for (x=0; x < 10; x++)
92
        a2[x] >>= 4;
93
}
94

    
95
/* rotate block */
96
static void rotate_block(const int16_t *source, int16_t *target, int offset)
97
{
98
    int i=0, k=0;
99
    source += BUFFERSIZE - offset;
100

    
101
    while (i<BLOCKSIZE) {
102
        target[i++] = source[k++];
103

    
104
        if (k == offset)
105
            k = 0;
106
    }
107
}
108

    
109
/* inverse root mean square */
110
static int irms(const int16_t *data, int factor)
111
{
112
    unsigned int i, sum = 0;
113

    
114
    for (i=0; i < BLOCKSIZE; i++)
115
        sum += data[i] * data[i];
116

    
117
    if (sum == 0)
118
        return 0; /* OOPS - division by zero */
119

    
120
    return (0x20000000 / (t_sqrt(sum) >> 8)) * factor;
121
}
122

    
123
/* multiply/add wavetable */
124
static void add_wav(int n, int skip_first, int *m, const int16_t *s1,
125
                    const int8_t *s2, const int8_t *s3, int16_t *dest)
126
{
127
    int i;
128
    int v[3];
129

    
130
    v[0] = 0;
131
    for (i=!skip_first; i<3; i++)
132
        v[i] = (wavtable1[n][i] * m[i]) >> (wavtable2[n][i] + 1);
133

    
134
    for (i=0; i < BLOCKSIZE; i++)
135
        dest[i] = ((*(s1++))*v[0] + (*(s2++))*v[1] + (*(s3++))*v[2]) >> 12;
136
}
137

    
138

    
139
static void final(const int16_t *i1, const int16_t *i2,
140
                  void *out, int *statbuf, int len)
141
{
142
    int x, i;
143
    uint16_t work[50];
144
    int16_t *ptr = work;
145

    
146
    memcpy(work, statbuf,20);
147
    memcpy(work + 10, i2, len * 2);
148

    
149
    for (i=0; i<len; i++) {
150
        int sum = 0;
151
        int new_val;
152

    
153
        for(x=0; x<10; x++)
154
            sum += i1[9-x] * ptr[x];
155

    
156
        sum >>= 12;
157

    
158
        new_val = ptr[10] - sum;
159

    
160
        if (new_val < -32768 || new_val > 32767) {
161
            memset(out, 0, len * 2);
162
            memset(statbuf, 0, 20);
163
            return;
164
        }
165

    
166
        ptr[10] = new_val;
167
        ptr++;
168
    }
169

    
170
    memcpy(out, work+10, len * 2);
171
    memcpy(statbuf, work + 40, 20);
172
}
173

    
174
static unsigned int rms(const int *data, int f)
175
{
176
    int x;
177
    unsigned int res = 0x10000;
178
    int b = 0;
179

    
180
    for (x=0; x<10; x++) {
181
        res = (((0x1000000 - (*data) * (*data)) >> 12) * res) >> 12;
182

    
183
        if (res == 0)
184
            return 0;
185

    
186
        if (res > 0x10000)
187
            return 0; /* We're screwed, might as well go out with a bang. :P */
188

    
189
        while (res <= 0x3fff) {
190
            b++;
191
            res <<= 2;
192
        }
193
        data++;
194
    }
195

    
196
    if (res > 0)
197
        res = t_sqrt(res);
198

    
199
    res >>= (b + 10);
200
    res = (res * f) >> 10;
201
    return res;
202
}
203

    
204
/* do quarter-block output */
205
static void do_output_subblock(RA144Context *ractx,
206
                               const uint16_t  *gsp, unsigned int gval,
207
                               int16_t *output_buffer, GetBitContext *gb)
208
{
209
    uint16_t buffer_a[40];
210
    uint16_t *block;
211
    int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
212
    int gain    = get_bits(gb, 8);
213
    int cb1_idx = get_bits(gb, 7);
214
    int cb2_idx = get_bits(gb, 7);
215
    int m[3];
216

    
217
    if (cba_idx) {
218
        cba_idx += HALFBLOCK - 1;
219
        rotate_block(ractx->adapt_cb, buffer_a, cba_idx);
220
        m[0] = irms(buffer_a, gval) >> 12;
221
    } else {
222
        m[0] = 0;
223
    }
224

    
225
    m[1] = ((ftable1[cb1_idx] >> 4) * gval) >> 8;
226
    m[2] = ((ftable2[cb2_idx] >> 4) * gval) >> 8;
227

    
228
    memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
229
            (BUFFERSIZE - BLOCKSIZE) * 2);
230

    
231
    block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
232

    
233
    add_wav(gain, cba_idx, m, buffer_a, etable1[cb1_idx], etable2[cb2_idx],
234
            block);
235

    
236
    final(gsp, block, output_buffer, ractx->buffer, BLOCKSIZE);
237
}
238

    
239
static int dec1(int16_t *decsp, const int *data, const int *inp, int f)
240
{
241
    int i;
242

    
243
    for (i=0; i<30; i++)
244
        *(decsp++) = *(inp++);
245

    
246
    return rms(data, f);
247
}
248

    
249
static int eq(const int16_t *in, int *target)
250
{
251
    int retval = 0;
252
    int b, c, i;
253
    unsigned int u;
254
    int buffer1[10];
255
    int buffer2[10];
256
    int *bp1 = buffer1;
257
    int *bp2 = buffer2;
258

    
259
    for (i=0; i < 10; i++)
260
        buffer2[i] = in[i];
261

    
262
    u = target[9] = bp2[9];
263

    
264
    if (u + 0x1000 > 0x1fff)
265
        return 0; /* We're screwed, might as well go out with a bang. :P */
266

    
267
    for (c=8; c >= 0; c--) {
268
        if (u == 0x1000)
269
            u++;
270

    
271
        if (u == 0xfffff000)
272
            u--;
273

    
274
        b = 0x1000-((u * u) >> 12);
275

    
276
        if (b == 0)
277
            b++;
278

    
279
        for (u=0; u<=c; u++)
280
            bp1[u] = ((bp2[u] - ((target[c+1] * bp2[c-u]) >> 12)) * (0x1000000 / b)) >> 12;
281

    
282
        target[c] = u = bp1[c];
283

    
284
        if ((u + 0x1000) > 0x1fff)
285
            retval = 1;
286

    
287
        FFSWAP(int *, bp1, bp2);
288
    }
289
    return retval;
290
}
291

    
292
static int dec2(RA144Context *ractx, int16_t *decsp, int block_num,
293
                int copynew, int f)
294
{
295
    int work[10];
296
    int a = block_num + 1;
297
    int b = NBLOCKS - a;
298
    int x;
299

    
300
    // Interpolate block coefficients from the this frame forth block and
301
    // last frame forth block
302
    for (x=0; x<30; x++)
303
        decsp[x] = (a * ractx->lpc_coef[x] + b * ractx->lpc_coef_old[x])>> 2;
304

    
305
    if (eq(decsp, work)) {
306
        // The interpolated coefficients are unstable, copy either new or old
307
        // coefficients
308
        if (copynew)
309
            return dec1(decsp, ractx->lpc_refl, ractx->lpc_coef, f);
310
        else
311
            return dec1(decsp, ractx->lpc_refl_old, ractx->lpc_coef_old, f);
312
    } else {
313
        return rms(work, f);
314
    }
315
}
316

    
317
/* Uncompress one block (20 bytes -> 160*2 bytes) */
318
static int ra144_decode_frame(AVCodecContext * avctx,
319
                              void *vdata, int *data_size,
320
                              const uint8_t * buf, int buf_size)
321
{
322
    static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
323
    unsigned int refl_rms[4];  // RMS of the reflection coefficients
324
    uint16_t gbuf2[4][30];
325
    int i, c;
326
    int16_t *data = vdata;
327
    unsigned int energy;
328

    
329
    RA144Context *ractx = avctx->priv_data;
330
    GetBitContext gb;
331

    
332
    if(buf_size < 20) {
333
        av_log(avctx, AV_LOG_ERROR,
334
               "Frame too small (%d bytes). Truncated file?\n", buf_size);
335
        return buf_size;
336
    }
337
    init_get_bits(&gb, buf, 20 * 8);
338

    
339
    for (i=0; i<10; i++)
340
        // "<< 1"? Doesn't this make one value out of two of the table useless?
341
        ractx->lpc_refl[i] = decodetable[i][get_bits(&gb, sizes[i]) << 1];
342

    
343
    do_voice(ractx->lpc_refl, ractx->lpc_coef);
344

    
345
    energy = decodeval[get_bits(&gb, 5) << 1]; // Useless table entries?
346

    
347
    refl_rms[0] = dec2(ractx, gbuf2[0], 0, 0, ractx->old_energy);
348
    refl_rms[1] = dec2(ractx, gbuf2[1], 1, energy > ractx->old_energy,
349
                    t_sqrt(energy*ractx->old_energy) >> 12);
350
    refl_rms[2] = dec2(ractx, gbuf2[2], 2, 1, energy);
351
    refl_rms[3] = dec1(gbuf2[3], ractx->lpc_refl, ractx->lpc_coef, energy);
352

    
353
    /* do output */
354
    for (c=0; c<4; c++) {
355
        do_output_subblock(ractx, gbuf2[c], refl_rms[c], data, &gb);
356

    
357
        for (i=0; i<BLOCKSIZE; i++) {
358
            *data = av_clip_int16(*data << 2);
359
            data++;
360
        }
361
    }
362

    
363
    ractx->old_energy = energy;
364

    
365
    FFSWAP(unsigned int *, ractx->lpc_refl_old, ractx->lpc_refl);
366
    FFSWAP(unsigned int *, ractx->lpc_coef_old, ractx->lpc_coef);
367

    
368
    *data_size = 2*160;
369
    return 20;
370
}
371

    
372

    
373
AVCodec ra_144_decoder =
374
{
375
    "real_144",
376
    CODEC_TYPE_AUDIO,
377
    CODEC_ID_RA_144,
378
    sizeof(RA144Context),
379
    ra144_decode_init,
380
    NULL,
381
    NULL,
382
    ra144_decode_frame,
383
    .long_name = "RealAudio 1.0 (14.4K)",
384
};