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
25#include "avcodec.h"
26#include "bitstream.h"
27#include "ra144.h"
28#include "celp_filters.h"
29
30#define NBLOCKS         4       ///< number of subblocks within a block
31#define BLOCKSIZE       40      ///< subblock size in 16-bit words
32#define BUFFERSIZE      146     ///< the size of the adaptive codebook
33
34
35typedef struct {
36    unsigned int     old_energy;        ///< previous frame energy
37
38    unsigned int     lpc_tables[2][10];
39
40    /** LPC coefficients: lpc_coef[0] is the coefficients of the current frame
41     *  and lpc_coef[1] of the previous one. */
42    unsigned int    *lpc_coef[2];
43
44    unsigned int     lpc_refl_rms[2];
45
46    /** The current subblock padded by the last 10 values of the previous one. */
47    int16_t curr_sblock[50];
48
49    /** Adaptive codebook, its size is two units bigger to avoid a
50     *  buffer overflow. */
51    uint16_t adapt_cb[146+2];
52} RA144Context;
53
54static av_cold int ra144_decode_init(AVCodecContext * avctx)
55{
56    RA144Context *ractx = avctx->priv_data;
57
58    ractx->lpc_coef[0] = ractx->lpc_tables[0];
59    ractx->lpc_coef[1] = ractx->lpc_tables[1];
60
61    avctx->sample_fmt = SAMPLE_FMT_S16;
62    return 0;
63}
64
65/**
66 * Evaluate sqrt(x << 24). x must fit in 20 bits. This value is evaluated in an
67 * odd way to make the output identical to the binary decoder.
68 */
69static int t_sqrt(unsigned int x)
70{
71    int s = 2;
72    while (x > 0xfff) {
73        s++;
74        x >>= 2;
75    }
76
77    return ff_sqrt(x << 20) << s;
78}
79
80/**
81 * Evaluate the LPC filter coefficients from the reflection coefficients.
82 * Does the inverse of the eval_refl() function.
83 */
84static void eval_coefs(int *coefs, const int *refl)
85{
86    int buffer[10];
87    int *b1 = buffer;
88    int *b2 = coefs;
89    int i, j;
90
91    for (i=0; i < 10; i++) {
92        b1[i] = refl[i] << 4;
93
94        for (j=0; j < i; j++)
95            b1[j] = ((refl[i] * b2[i-j-1]) >> 12) + b2[j];
96
97        FFSWAP(int *, b1, b2);
98    }
99
100    for (i=0; i < 10; i++)
101        coefs[i] >>= 4;
102}
103
104/**
105 * Copy the last offset values of *source to *target. If those values are not
106 * enough to fill the target buffer, fill it with another copy of those values.
107 */
108static void copy_and_dup(int16_t *target, const int16_t *source, int offset)
109{
110    source += BUFFERSIZE - offset;
111
112    memcpy(target, source, FFMIN(BLOCKSIZE, offset)*sizeof(*target));
113    if (offset < BLOCKSIZE)
114        memcpy(target + offset, source, (BLOCKSIZE - offset)*sizeof(*target));
115}
116
117/** inverse root mean square */
118static int irms(const int16_t *data)
119{
120    unsigned int i, sum = 0;
121
122    for (i=0; i < BLOCKSIZE; i++)
123        sum += data[i] * data[i];
124
125    if (sum == 0)
126        return 0; /* OOPS - division by zero */
127
128    return 0x20000000 / (t_sqrt(sum) >> 8);
129}
130
131static void add_wav(int16_t *dest, int n, int skip_first, int *m,
132                    const int16_t *s1, const int8_t *s2, const int8_t *s3)
133{
134    int i;
135    int v[3];
136
137    v[0] = 0;
138    for (i=!skip_first; i<3; i++)
139        v[i] = (gain_val_tab[n][i] * m[i]) >> gain_exp_tab[n];
140
141    if (v[0]) {
142        for (i=0; i < BLOCKSIZE; i++)
143            dest[i] = (s1[i]*v[0] + s2[i]*v[1] + s3[i]*v[2]) >> 12;
144    } else {
145        for (i=0; i < BLOCKSIZE; i++)
146            dest[i] = (             s2[i]*v[1] + s3[i]*v[2]) >> 12;
147    }
148}
149
150static unsigned int rescale_rms(unsigned int rms, unsigned int energy)
151{
152    return (rms * energy) >> 10;
153}
154
155static unsigned int rms(const int *data)
156{
157    int i;
158    unsigned int res = 0x10000;
159    int b = 10;
160
161    for (i=0; i < 10; i++) {
162        res = (((0x1000000 - data[i]*data[i]) >> 12) * res) >> 12;
163
164        if (res == 0)
165            return 0;
166
167        while (res <= 0x3fff) {
168            b++;
169            res <<= 2;
170        }
171    }
172
173    return t_sqrt(res) >> b;
174}
175
176static void do_output_subblock(RA144Context *ractx, const uint16_t  *lpc_coefs,
177                               int gval, GetBitContext *gb)
178{
179    uint16_t buffer_a[40];
180    uint16_t *block;
181    int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
182    int gain    = get_bits(gb, 8);
183    int cb1_idx = get_bits(gb, 7);
184    int cb2_idx = get_bits(gb, 7);
185    int m[3];
186
187    if (cba_idx) {
188        cba_idx += BLOCKSIZE/2 - 1;
189        copy_and_dup(buffer_a, ractx->adapt_cb, cba_idx);
190        m[0] = (irms(buffer_a) * gval) >> 12;
191    } else {
192        m[0] = 0;
193    }
194
195    m[1] = (cb1_base[cb1_idx] * gval) >> 8;
196    m[2] = (cb2_base[cb2_idx] * gval) >> 8;
197
198    memmove(ractx->adapt_cb, ractx->adapt_cb + BLOCKSIZE,
199            (BUFFERSIZE - BLOCKSIZE) * sizeof(*ractx->adapt_cb));
200
201    block = ractx->adapt_cb + BUFFERSIZE - BLOCKSIZE;
202
203    add_wav(block, gain, cba_idx, m, cba_idx? buffer_a: NULL,
204            cb1_vects[cb1_idx], cb2_vects[cb2_idx]);
205
206    memcpy(ractx->curr_sblock, ractx->curr_sblock + 40,
207           10*sizeof(*ractx->curr_sblock));
208
209    if (ff_celp_lp_synthesis_filter(ractx->curr_sblock + 10, lpc_coefs,
210                                    block, BLOCKSIZE, 10, 1, 0xfff))
211        memset(ractx->curr_sblock, 0, 50*sizeof(*ractx->curr_sblock));
212}
213
214static void int_to_int16(int16_t *out, const int *inp)
215{
216    int i;
217
218    for (i=0; i < 30; i++)
219        *out++ = *inp++;
220}
221
222/**
223 * Evaluate the reflection coefficients from the filter coefficients.
224 * Does the inverse of the eval_coefs() function.
225 *
226 * @return 1 if one of the reflection coefficients is greater than
227 *         4095, 0 if not.
228 */
229static int eval_refl(int *refl, const int16_t *coefs, RA144Context *ractx)
230{
231    int b, i, j;
232    int buffer1[10];
233    int buffer2[10];
234    int *bp1 = buffer1;
235    int *bp2 = buffer2;
236
237    for (i=0; i < 10; i++)
238        buffer2[i] = coefs[i];
239
240    refl[9] = bp2[9];
241
242    if ((unsigned) bp2[9] + 0x1000 > 0x1fff) {
243        av_log(ractx, AV_LOG_ERROR, "Overflow. Broken sample?\n");
244        return 1;
245    }
246
247    for (i=8; i >= 0; i--) {
248        b = 0x1000-((bp2[i+1] * bp2[i+1]) >> 12);
249
250        if (!b)
251            b = -2;
252
253        for (j=0; j <= i; j++)
254            bp1[j] = ((bp2[j] - ((refl[i+1] * bp2[i-j]) >> 12)) * (0x1000000 / b)) >> 12;
255
256        if ((unsigned) bp1[i] + 0x1000 > 0x1fff)
257            return 1;
258
259        refl[i] = bp1[i];
260
261        FFSWAP(int *, bp1, bp2);
262    }
263    return 0;
264}
265
266static int interp(RA144Context *ractx, int16_t *out, int a,
267                  int copyold, int energy)
268{
269    int work[10];
270    int b = NBLOCKS - a;
271    int i;
272
273    // Interpolate block coefficients from the this frame's forth block and
274    // last frame's forth block.
275    for (i=0; i<30; i++)
276        out[i] = (a * ractx->lpc_coef[0][i] + b * ractx->lpc_coef[1][i])>> 2;
277
278    if (eval_refl(work, out, ractx)) {
279        // The interpolated coefficients are unstable, copy either new or old
280        // coefficients.
281        int_to_int16(out, ractx->lpc_coef[copyold]);
282        return rescale_rms(ractx->lpc_refl_rms[copyold], energy);
283    } else {
284        return rescale_rms(rms(work), energy);
285    }
286}
287
288/** Uncompress one block (20 bytes -> 160*2 bytes). */
289static int ra144_decode_frame(AVCodecContext * avctx, void *vdata,
290                              int *data_size, const uint8_t *buf, int buf_size)
291{
292    static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
293    unsigned int refl_rms[4];    // RMS of the reflection coefficients
294    uint16_t block_coefs[4][30]; // LPC coefficients of each sub-block
295    unsigned int lpc_refl[10];   // LPC reflection coefficients of the frame
296    int i, j;
297    int16_t *data = vdata;
298    unsigned int energy;
299
300    RA144Context *ractx = avctx->priv_data;
301    GetBitContext gb;
302
303    if (*data_size < 2*160)
304        return -1;
305
306    if(buf_size < 20) {
307        av_log(avctx, AV_LOG_ERROR,
308               "Frame too small (%d bytes). Truncated file?\n", buf_size);
309        *data_size = 0;
310        return buf_size;
311    }
312    init_get_bits(&gb, buf, 20 * 8);
313
314    for (i=0; i<10; i++)
315        lpc_refl[i] = lpc_refl_cb[i][get_bits(&gb, sizes[i])];
316
317    eval_coefs(ractx->lpc_coef[0], lpc_refl);
318    ractx->lpc_refl_rms[0] = rms(lpc_refl);
319
320    energy = energy_tab[get_bits(&gb, 5)];
321
322    refl_rms[0] = interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);
323    refl_rms[1] = interp(ractx, block_coefs[1], 2, energy <= ractx->old_energy,
324                    t_sqrt(energy*ractx->old_energy) >> 12);
325    refl_rms[2] = interp(ractx, block_coefs[2], 3, 0, energy);
326    refl_rms[3] = rescale_rms(ractx->lpc_refl_rms[0], energy);
327
328    int_to_int16(block_coefs[3], ractx->lpc_coef[0]);
329
330    for (i=0; i < 4; i++) {
331        do_output_subblock(ractx, block_coefs[i], refl_rms[i], &gb);
332
333        for (j=0; j < BLOCKSIZE; j++)
334            *data++ = av_clip_int16(ractx->curr_sblock[j + 10] << 2);
335    }
336
337    ractx->old_energy = energy;
338    ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
339
340    FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
341
342    *data_size = 2*160;
343    return 20;
344}
345
346AVCodec ra_144_decoder =
347{
348    "real_144",
349    CODEC_TYPE_AUDIO,
350    CODEC_ID_RA_144,
351    sizeof(RA144Context),
352    ra144_decode_init,
353    NULL,
354    NULL,
355    ra144_decode_frame,
356    .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),
357};
358