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1 | /* |
2 | * G.726 ADPCM audio codec | |
3 | * Copyright (c) 2004 Roman Shaposhnik | |
4 | * | |
5 | * This is a very straightforward rendition of the G.726 | |
6 | * Section 4 "Computational Details". | |
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 <limits.h> | |
25 | ||
26 | #include "libavutil/avassert.h" | |
27 | #include "libavutil/channel_layout.h" | |
28 | #include "libavutil/opt.h" | |
29 | #include "avcodec.h" | |
30 | #include "internal.h" | |
31 | #include "get_bits.h" | |
32 | #include "put_bits.h" | |
33 | ||
34 | /** | |
35 | * G.726 11bit float. | |
36 | * G.726 Standard uses rather odd 11bit floating point arithmentic for | |
37 | * numerous occasions. It's a mystery to me why they did it this way | |
38 | * instead of simply using 32bit integer arithmetic. | |
39 | */ | |
40 | typedef struct Float11 { | |
41 | uint8_t sign; /**< 1bit sign */ | |
42 | uint8_t exp; /**< 4bit exponent */ | |
43 | uint8_t mant; /**< 6bit mantissa */ | |
44 | } Float11; | |
45 | ||
46 | static inline Float11* i2f(int i, Float11* f) | |
47 | { | |
48 | f->sign = (i < 0); | |
49 | if (f->sign) | |
50 | i = -i; | |
51 | f->exp = av_log2_16bit(i) + !!i; | |
52 | f->mant = i? (i<<6) >> f->exp : 1<<5; | |
53 | return f; | |
54 | } | |
55 | ||
56 | static inline int16_t mult(Float11* f1, Float11* f2) | |
57 | { | |
58 | int res, exp; | |
59 | ||
60 | exp = f1->exp + f2->exp; | |
61 | res = (((f1->mant * f2->mant) + 0x30) >> 4); | |
62 | res = exp > 19 ? res << (exp - 19) : res >> (19 - exp); | |
63 | return (f1->sign ^ f2->sign) ? -res : res; | |
64 | } | |
65 | ||
66 | static inline int sgn(int value) | |
67 | { | |
68 | return (value < 0) ? -1 : 1; | |
69 | } | |
70 | ||
71 | typedef struct G726Tables { | |
72 | const int* quant; /**< quantization table */ | |
73 | const int16_t* iquant; /**< inverse quantization table */ | |
74 | const int16_t* W; /**< special table #1 ;-) */ | |
75 | const uint8_t* F; /**< special table #2 */ | |
76 | } G726Tables; | |
77 | ||
78 | typedef struct G726Context { | |
79 | AVClass *class; | |
80 | G726Tables tbls; /**< static tables needed for computation */ | |
81 | ||
82 | Float11 sr[2]; /**< prev. reconstructed samples */ | |
83 | Float11 dq[6]; /**< prev. difference */ | |
84 | int a[2]; /**< second order predictor coeffs */ | |
85 | int b[6]; /**< sixth order predictor coeffs */ | |
86 | int pk[2]; /**< signs of prev. 2 sez + dq */ | |
87 | ||
88 | int ap; /**< scale factor control */ | |
89 | int yu; /**< fast scale factor */ | |
90 | int yl; /**< slow scale factor */ | |
91 | int dms; /**< short average magnitude of F[i] */ | |
92 | int dml; /**< long average magnitude of F[i] */ | |
93 | int td; /**< tone detect */ | |
94 | ||
95 | int se; /**< estimated signal for the next iteration */ | |
96 | int sez; /**< estimated second order prediction */ | |
97 | int y; /**< quantizer scaling factor for the next iteration */ | |
98 | int code_size; | |
99 | int little_endian; /**< little-endian bitstream as used in aiff and Sun AU */ | |
100 | } G726Context; | |
101 | ||
102 | static const int quant_tbl16[] = /**< 16kbit/s 2bits per sample */ | |
103 | { 260, INT_MAX }; | |
104 | static const int16_t iquant_tbl16[] = | |
105 | { 116, 365, 365, 116 }; | |
106 | static const int16_t W_tbl16[] = | |
107 | { -22, 439, 439, -22 }; | |
108 | static const uint8_t F_tbl16[] = | |
109 | { 0, 7, 7, 0 }; | |
110 | ||
111 | static const int quant_tbl24[] = /**< 24kbit/s 3bits per sample */ | |
112 | { 7, 217, 330, INT_MAX }; | |
113 | static const int16_t iquant_tbl24[] = | |
114 | { INT16_MIN, 135, 273, 373, 373, 273, 135, INT16_MIN }; | |
115 | static const int16_t W_tbl24[] = | |
116 | { -4, 30, 137, 582, 582, 137, 30, -4 }; | |
117 | static const uint8_t F_tbl24[] = | |
118 | { 0, 1, 2, 7, 7, 2, 1, 0 }; | |
119 | ||
120 | static const int quant_tbl32[] = /**< 32kbit/s 4bits per sample */ | |
121 | { -125, 79, 177, 245, 299, 348, 399, INT_MAX }; | |
122 | static const int16_t iquant_tbl32[] = | |
123 | { INT16_MIN, 4, 135, 213, 273, 323, 373, 425, | |
124 | 425, 373, 323, 273, 213, 135, 4, INT16_MIN }; | |
125 | static const int16_t W_tbl32[] = | |
126 | { -12, 18, 41, 64, 112, 198, 355, 1122, | |
127 | 1122, 355, 198, 112, 64, 41, 18, -12}; | |
128 | static const uint8_t F_tbl32[] = | |
129 | { 0, 0, 0, 1, 1, 1, 3, 7, 7, 3, 1, 1, 1, 0, 0, 0 }; | |
130 | ||
131 | static const int quant_tbl40[] = /**< 40kbit/s 5bits per sample */ | |
132 | { -122, -16, 67, 138, 197, 249, 297, 338, | |
133 | 377, 412, 444, 474, 501, 527, 552, INT_MAX }; | |
134 | static const int16_t iquant_tbl40[] = | |
135 | { INT16_MIN, -66, 28, 104, 169, 224, 274, 318, | |
136 | 358, 395, 429, 459, 488, 514, 539, 566, | |
137 | 566, 539, 514, 488, 459, 429, 395, 358, | |
138 | 318, 274, 224, 169, 104, 28, -66, INT16_MIN }; | |
139 | static const int16_t W_tbl40[] = | |
140 | { 14, 14, 24, 39, 40, 41, 58, 100, | |
141 | 141, 179, 219, 280, 358, 440, 529, 696, | |
142 | 696, 529, 440, 358, 280, 219, 179, 141, | |
143 | 100, 58, 41, 40, 39, 24, 14, 14 }; | |
144 | static const uint8_t F_tbl40[] = | |
145 | { 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 6, | |
146 | 6, 6, 5, 4, 3, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 }; | |
147 | ||
148 | static const G726Tables G726Tables_pool[] = | |
149 | {{ quant_tbl16, iquant_tbl16, W_tbl16, F_tbl16 }, | |
150 | { quant_tbl24, iquant_tbl24, W_tbl24, F_tbl24 }, | |
151 | { quant_tbl32, iquant_tbl32, W_tbl32, F_tbl32 }, | |
152 | { quant_tbl40, iquant_tbl40, W_tbl40, F_tbl40 }}; | |
153 | ||
154 | ||
155 | /** | |
156 | * Para 4.2.2 page 18: Adaptive quantizer. | |
157 | */ | |
158 | static inline uint8_t quant(G726Context* c, int d) | |
159 | { | |
160 | int sign, exp, i, dln; | |
161 | ||
162 | sign = i = 0; | |
163 | if (d < 0) { | |
164 | sign = 1; | |
165 | d = -d; | |
166 | } | |
167 | exp = av_log2_16bit(d); | |
168 | dln = ((exp<<7) + (((d<<7)>>exp)&0x7f)) - (c->y>>2); | |
169 | ||
170 | while (c->tbls.quant[i] < INT_MAX && c->tbls.quant[i] < dln) | |
171 | ++i; | |
172 | ||
173 | if (sign) | |
174 | i = ~i; | |
175 | if (c->code_size != 2 && i == 0) /* I'm not sure this is a good idea */ | |
176 | i = 0xff; | |
177 | ||
178 | return i; | |
179 | } | |
180 | ||
181 | /** | |
182 | * Para 4.2.3 page 22: Inverse adaptive quantizer. | |
183 | */ | |
184 | static inline int16_t inverse_quant(G726Context* c, int i) | |
185 | { | |
186 | int dql, dex, dqt; | |
187 | ||
188 | dql = c->tbls.iquant[i] + (c->y >> 2); | |
189 | dex = (dql>>7) & 0xf; /* 4bit exponent */ | |
190 | dqt = (1<<7) + (dql & 0x7f); /* log2 -> linear */ | |
191 | return (dql < 0) ? 0 : ((dqt<<dex) >> 7); | |
192 | } | |
193 | ||
194 | static int16_t g726_decode(G726Context* c, int I) | |
195 | { | |
196 | int dq, re_signal, pk0, fa1, i, tr, ylint, ylfrac, thr2, al, dq0; | |
197 | Float11 f; | |
198 | int I_sig= I >> (c->code_size - 1); | |
199 | ||
200 | dq = inverse_quant(c, I); | |
201 | ||
202 | /* Transition detect */ | |
203 | ylint = (c->yl >> 15); | |
204 | ylfrac = (c->yl >> 10) & 0x1f; | |
205 | thr2 = (ylint > 9) ? 0x1f << 10 : (0x20 + ylfrac) << ylint; | |
206 | tr= (c->td == 1 && dq > ((3*thr2)>>2)); | |
207 | ||
208 | if (I_sig) /* get the sign */ | |
209 | dq = -dq; | |
210 | re_signal = c->se + dq; | |
211 | ||
212 | /* Update second order predictor coefficient A2 and A1 */ | |
213 | pk0 = (c->sez + dq) ? sgn(c->sez + dq) : 0; | |
214 | dq0 = dq ? sgn(dq) : 0; | |
215 | if (tr) { | |
216 | c->a[0] = 0; | |
217 | c->a[1] = 0; | |
218 | for (i=0; i<6; i++) | |
219 | c->b[i] = 0; | |
220 | } else { | |
221 | /* This is a bit crazy, but it really is +255 not +256 */ | |
222 | fa1 = av_clip((-c->a[0]*c->pk[0]*pk0)>>5, -256, 255); | |
223 | ||
224 | c->a[1] += 128*pk0*c->pk[1] + fa1 - (c->a[1]>>7); | |
225 | c->a[1] = av_clip(c->a[1], -12288, 12288); | |
226 | c->a[0] += 64*3*pk0*c->pk[0] - (c->a[0] >> 8); | |
227 | c->a[0] = av_clip(c->a[0], -(15360 - c->a[1]), 15360 - c->a[1]); | |
228 | ||
229 | for (i=0; i<6; i++) | |
230 | c->b[i] += 128*dq0*sgn(-c->dq[i].sign) - (c->b[i]>>8); | |
231 | } | |
232 | ||
233 | /* Update Dq and Sr and Pk */ | |
234 | c->pk[1] = c->pk[0]; | |
235 | c->pk[0] = pk0 ? pk0 : 1; | |
236 | c->sr[1] = c->sr[0]; | |
237 | i2f(re_signal, &c->sr[0]); | |
238 | for (i=5; i>0; i--) | |
239 | c->dq[i] = c->dq[i-1]; | |
240 | i2f(dq, &c->dq[0]); | |
241 | c->dq[0].sign = I_sig; /* Isn't it crazy ?!?! */ | |
242 | ||
243 | c->td = c->a[1] < -11776; | |
244 | ||
245 | /* Update Ap */ | |
246 | c->dms += (c->tbls.F[I]<<4) + ((- c->dms) >> 5); | |
247 | c->dml += (c->tbls.F[I]<<4) + ((- c->dml) >> 7); | |
248 | if (tr) | |
249 | c->ap = 256; | |
250 | else { | |
251 | c->ap += (-c->ap) >> 4; | |
252 | if (c->y <= 1535 || c->td || abs((c->dms << 2) - c->dml) >= (c->dml >> 3)) | |
253 | c->ap += 0x20; | |
254 | } | |
255 | ||
256 | /* Update Yu and Yl */ | |
257 | c->yu = av_clip(c->y + c->tbls.W[I] + ((-c->y)>>5), 544, 5120); | |
258 | c->yl += c->yu + ((-c->yl)>>6); | |
259 | ||
260 | /* Next iteration for Y */ | |
261 | al = (c->ap >= 256) ? 1<<6 : c->ap >> 2; | |
262 | c->y = (c->yl + (c->yu - (c->yl>>6))*al) >> 6; | |
263 | ||
264 | /* Next iteration for SE and SEZ */ | |
265 | c->se = 0; | |
266 | for (i=0; i<6; i++) | |
267 | c->se += mult(i2f(c->b[i] >> 2, &f), &c->dq[i]); | |
268 | c->sez = c->se >> 1; | |
269 | for (i=0; i<2; i++) | |
270 | c->se += mult(i2f(c->a[i] >> 2, &f), &c->sr[i]); | |
271 | c->se >>= 1; | |
272 | ||
273 | return av_clip(re_signal << 2, -0xffff, 0xffff); | |
274 | } | |
275 | ||
276 | static av_cold int g726_reset(G726Context *c) | |
277 | { | |
278 | int i; | |
279 | ||
280 | c->tbls = G726Tables_pool[c->code_size - 2]; | |
281 | for (i=0; i<2; i++) { | |
282 | c->sr[i].mant = 1<<5; | |
283 | c->pk[i] = 1; | |
284 | } | |
285 | for (i=0; i<6; i++) { | |
286 | c->dq[i].mant = 1<<5; | |
287 | } | |
288 | c->yu = 544; | |
289 | c->yl = 34816; | |
290 | ||
291 | c->y = 544; | |
292 | ||
293 | return 0; | |
294 | } | |
295 | ||
296 | #if CONFIG_ADPCM_G726_ENCODER | |
297 | static int16_t g726_encode(G726Context* c, int16_t sig) | |
298 | { | |
299 | uint8_t i; | |
300 | ||
301 | i = quant(c, sig/4 - c->se) & ((1<<c->code_size) - 1); | |
302 | g726_decode(c, i); | |
303 | return i; | |
304 | } | |
305 | ||
306 | /* Interfacing to the libavcodec */ | |
307 | ||
308 | static av_cold int g726_encode_init(AVCodecContext *avctx) | |
309 | { | |
310 | G726Context* c = avctx->priv_data; | |
311 | ||
312 | if (avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL && | |
313 | avctx->sample_rate != 8000) { | |
314 | av_log(avctx, AV_LOG_ERROR, "Sample rates other than 8kHz are not " | |
315 | "allowed when the compliance level is higher than unofficial. " | |
316 | "Resample or reduce the compliance level.\n"); | |
317 | return AVERROR(EINVAL); | |
318 | } | |
319 | av_assert0(avctx->sample_rate > 0); | |
320 | ||
321 | if(avctx->channels != 1){ | |
322 | av_log(avctx, AV_LOG_ERROR, "Only mono is supported\n"); | |
323 | return AVERROR(EINVAL); | |
324 | } | |
325 | ||
326 | if (avctx->bit_rate) | |
327 | c->code_size = (avctx->bit_rate + avctx->sample_rate/2) / avctx->sample_rate; | |
328 | ||
329 | c->code_size = av_clip(c->code_size, 2, 5); | |
330 | avctx->bit_rate = c->code_size * avctx->sample_rate; | |
331 | avctx->bits_per_coded_sample = c->code_size; | |
332 | ||
333 | g726_reset(c); | |
334 | ||
335 | /* select a frame size that will end on a byte boundary and have a size of | |
336 | approximately 1024 bytes */ | |
337 | avctx->frame_size = ((int[]){ 4096, 2736, 2048, 1640 })[c->code_size - 2]; | |
338 | ||
339 | return 0; | |
340 | } | |
341 | ||
342 | static int g726_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, | |
343 | const AVFrame *frame, int *got_packet_ptr) | |
344 | { | |
345 | G726Context *c = avctx->priv_data; | |
346 | const int16_t *samples = (const int16_t *)frame->data[0]; | |
347 | PutBitContext pb; | |
348 | int i, ret, out_size; | |
349 | ||
350 | out_size = (frame->nb_samples * c->code_size + 7) / 8; | |
351 | if ((ret = ff_alloc_packet2(avctx, avpkt, out_size)) < 0) | |
352 | return ret; | |
353 | init_put_bits(&pb, avpkt->data, avpkt->size); | |
354 | ||
355 | for (i = 0; i < frame->nb_samples; i++) | |
356 | put_bits(&pb, c->code_size, g726_encode(c, *samples++)); | |
357 | ||
358 | flush_put_bits(&pb); | |
359 | ||
360 | avpkt->size = out_size; | |
361 | *got_packet_ptr = 1; | |
362 | return 0; | |
363 | } | |
364 | ||
365 | #define OFFSET(x) offsetof(G726Context, x) | |
366 | #define AE AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM | |
367 | static const AVOption options[] = { | |
368 | { "code_size", "Bits per code", OFFSET(code_size), AV_OPT_TYPE_INT, { .i64 = 4 }, 2, 5, AE }, | |
369 | { NULL }, | |
370 | }; | |
371 | ||
372 | static const AVClass g726_class = { | |
373 | .class_name = "g726", | |
374 | .item_name = av_default_item_name, | |
375 | .option = options, | |
376 | .version = LIBAVUTIL_VERSION_INT, | |
377 | }; | |
378 | ||
379 | static const AVCodecDefault defaults[] = { | |
380 | { "b", "0" }, | |
381 | { NULL }, | |
382 | }; | |
383 | ||
384 | AVCodec ff_adpcm_g726_encoder = { | |
385 | .name = "g726", | |
386 | .long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM"), | |
387 | .type = AVMEDIA_TYPE_AUDIO, | |
388 | .id = AV_CODEC_ID_ADPCM_G726, | |
389 | .priv_data_size = sizeof(G726Context), | |
390 | .init = g726_encode_init, | |
391 | .encode2 = g726_encode_frame, | |
392 | .capabilities = CODEC_CAP_SMALL_LAST_FRAME, | |
393 | .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, | |
394 | AV_SAMPLE_FMT_NONE }, | |
395 | .priv_class = &g726_class, | |
396 | .defaults = defaults, | |
397 | }; | |
398 | #endif | |
399 | ||
400 | #if CONFIG_ADPCM_G726_DECODER || CONFIG_ADPCM_G726LE_DECODER | |
401 | static av_cold int g726_decode_init(AVCodecContext *avctx) | |
402 | { | |
403 | G726Context* c = avctx->priv_data; | |
404 | ||
405 | if(avctx->channels > 1){ | |
406 | avpriv_request_sample(avctx, "Decoding more than one channel"); | |
407 | return AVERROR_PATCHWELCOME; | |
408 | } | |
409 | avctx->channels = 1; | |
410 | avctx->channel_layout = AV_CH_LAYOUT_MONO; | |
411 | ||
412 | c->little_endian = !strcmp(avctx->codec->name, "g726le"); | |
413 | ||
414 | c->code_size = avctx->bits_per_coded_sample; | |
415 | if (c->code_size < 2 || c->code_size > 5) { | |
416 | av_log(avctx, AV_LOG_ERROR, "Invalid number of bits %d\n", c->code_size); | |
417 | return AVERROR(EINVAL); | |
418 | } | |
419 | g726_reset(c); | |
420 | ||
421 | avctx->sample_fmt = AV_SAMPLE_FMT_S16; | |
422 | ||
423 | return 0; | |
424 | } | |
425 | ||
426 | static int g726_decode_frame(AVCodecContext *avctx, void *data, | |
427 | int *got_frame_ptr, AVPacket *avpkt) | |
428 | { | |
429 | AVFrame *frame = data; | |
430 | const uint8_t *buf = avpkt->data; | |
431 | int buf_size = avpkt->size; | |
432 | G726Context *c = avctx->priv_data; | |
433 | int16_t *samples; | |
434 | GetBitContext gb; | |
435 | int out_samples, ret; | |
436 | ||
437 | out_samples = buf_size * 8 / c->code_size; | |
438 | ||
439 | /* get output buffer */ | |
440 | frame->nb_samples = out_samples; | |
441 | if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) | |
442 | return ret; | |
443 | samples = (int16_t *)frame->data[0]; | |
444 | ||
445 | init_get_bits(&gb, buf, buf_size * 8); | |
446 | ||
447 | while (out_samples--) | |
448 | *samples++ = g726_decode(c, c->little_endian ? | |
449 | get_bits_le(&gb, c->code_size) : | |
450 | get_bits(&gb, c->code_size)); | |
451 | ||
452 | if (get_bits_left(&gb) > 0) | |
453 | av_log(avctx, AV_LOG_ERROR, "Frame invalidly split, missing parser?\n"); | |
454 | ||
455 | *got_frame_ptr = 1; | |
456 | ||
457 | return buf_size; | |
458 | } | |
459 | ||
460 | static void g726_decode_flush(AVCodecContext *avctx) | |
461 | { | |
462 | G726Context *c = avctx->priv_data; | |
463 | g726_reset(c); | |
464 | } | |
465 | #endif | |
466 | ||
467 | #if CONFIG_ADPCM_G726_DECODER | |
468 | AVCodec ff_adpcm_g726_decoder = { | |
469 | .name = "g726", | |
470 | .long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM"), | |
471 | .type = AVMEDIA_TYPE_AUDIO, | |
472 | .id = AV_CODEC_ID_ADPCM_G726, | |
473 | .priv_data_size = sizeof(G726Context), | |
474 | .init = g726_decode_init, | |
475 | .decode = g726_decode_frame, | |
476 | .flush = g726_decode_flush, | |
477 | .capabilities = CODEC_CAP_DR1, | |
478 | }; | |
479 | #endif | |
480 | ||
481 | #if CONFIG_ADPCM_G726LE_DECODER | |
482 | AVCodec ff_adpcm_g726le_decoder = { | |
483 | .name = "g726le", | |
484 | .type = AVMEDIA_TYPE_AUDIO, | |
485 | .id = AV_CODEC_ID_ADPCM_G726LE, | |
486 | .priv_data_size = sizeof(G726Context), | |
487 | .init = g726_decode_init, | |
488 | .decode = g726_decode_frame, | |
489 | .flush = g726_decode_flush, | |
490 | .capabilities = CODEC_CAP_DR1, | |
491 | .long_name = NULL_IF_CONFIG_SMALL("G.726 ADPCM little-endian"), | |
492 | }; | |
493 | #endif |