2 * Copyright (c) CMU 1993 Computer Science, Speech Group
3 * Chengxiang Lu and Alex Hauptmann
4 * Copyright (c) 2005 Steve Underwood <steveu at coppice.org>
5 * Copyright (c) 2009 Kenan Gillet
6 * Copyright (c) 2010 Martin Storsjo
8 * This file is part of Libav.
10 * Libav 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.
15 * Libav 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.
20 * You should have received a copy of the GNU Lesser General Public
21 * License along with Libav; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 * G.722 ADPCM audio encoder
33 #define FREEZE_INTERVAL 128
35 /* This is an arbitrary value. Allowing insanely large values leads to strange
36 problems, so we limit it to a reasonable value */
37 #define MAX_FRAME_SIZE 32768
39 /* We clip the value of avctx->trellis to prevent data type overflows and
40 undefined behavior. Using larger values is insanely slow anyway. */
42 #define MAX_TRELLIS 16
44 static av_cold int g722_encode_init(AVCodecContext * avctx)
46 G722Context *c = avctx->priv_data;
48 if (avctx->channels != 1) {
49 av_log(avctx, AV_LOG_ERROR, "Only mono tracks are allowed.\n");
50 return AVERROR_INVALIDDATA;
53 c->band[0].scale_factor = 8;
54 c->band[1].scale_factor = 2;
55 c->prev_samples_pos = 22;
58 int frontier = 1 << avctx->trellis;
59 int max_paths = frontier * FREEZE_INTERVAL;
61 for (i = 0; i < 2; i++) {
62 c->paths[i] = av_mallocz(max_paths * sizeof(**c->paths));
63 c->node_buf[i] = av_mallocz(2 * frontier * sizeof(**c->node_buf));
64 c->nodep_buf[i] = av_mallocz(2 * frontier * sizeof(**c->nodep_buf));
68 if (avctx->frame_size) {
69 /* validate frame size */
70 if (avctx->frame_size & 1 || avctx->frame_size > MAX_FRAME_SIZE) {
73 if (avctx->frame_size == 1)
75 else if (avctx->frame_size > MAX_FRAME_SIZE)
76 new_frame_size = MAX_FRAME_SIZE;
78 new_frame_size = avctx->frame_size - 1;
80 av_log(avctx, AV_LOG_WARNING, "Requested frame size is not "
81 "allowed. Using %d instead of %d\n", new_frame_size,
83 avctx->frame_size = new_frame_size;
86 /* This is arbitrary. We use 320 because it's 20ms @ 16kHz, which is
87 a common packet size for VoIP applications */
88 avctx->frame_size = 320;
92 /* validate trellis */
93 if (avctx->trellis < MIN_TRELLIS || avctx->trellis > MAX_TRELLIS) {
94 int new_trellis = av_clip(avctx->trellis, MIN_TRELLIS, MAX_TRELLIS);
95 av_log(avctx, AV_LOG_WARNING, "Requested trellis value is not "
96 "allowed. Using %d instead of %d\n", new_trellis,
98 avctx->trellis = new_trellis;
105 static av_cold int g722_encode_close(AVCodecContext *avctx)
107 G722Context *c = avctx->priv_data;
109 for (i = 0; i < 2; i++) {
110 av_freep(&c->paths[i]);
111 av_freep(&c->node_buf[i]);
112 av_freep(&c->nodep_buf[i]);
117 static const int16_t low_quant[33] = {
118 35, 72, 110, 150, 190, 233, 276, 323,
119 370, 422, 473, 530, 587, 650, 714, 786,
120 858, 940, 1023, 1121, 1219, 1339, 1458, 1612,
121 1765, 1980, 2195, 2557, 2919
124 static inline void filter_samples(G722Context *c, const int16_t *samples,
125 int *xlow, int *xhigh)
128 c->prev_samples[c->prev_samples_pos++] = samples[0];
129 c->prev_samples[c->prev_samples_pos++] = samples[1];
130 ff_g722_apply_qmf(c->prev_samples + c->prev_samples_pos - 24, &xout1, &xout2);
131 *xlow = xout1 + xout2 >> 13;
132 *xhigh = xout1 - xout2 >> 13;
133 if (c->prev_samples_pos >= PREV_SAMPLES_BUF_SIZE) {
134 memmove(c->prev_samples,
135 c->prev_samples + c->prev_samples_pos - 22,
136 22 * sizeof(c->prev_samples[0]));
137 c->prev_samples_pos = 22;
141 static inline int encode_high(const struct G722Band *state, int xhigh)
143 int diff = av_clip_int16(xhigh - state->s_predictor);
144 int pred = 141 * state->scale_factor >> 8;
145 /* = diff >= 0 ? (diff < pred) + 2 : diff >= -pred */
146 return ((diff ^ (diff >> (sizeof(diff)*8-1))) < pred) + 2*(diff >= 0);
149 static inline int encode_low(const struct G722Band* state, int xlow)
151 int diff = av_clip_int16(xlow - state->s_predictor);
152 /* = diff >= 0 ? diff : -(diff + 1) */
153 int limit = diff ^ (diff >> (sizeof(diff)*8-1));
155 limit = limit + 1 << 10;
156 if (limit > low_quant[8] * state->scale_factor)
158 while (i < 29 && limit > low_quant[i] * state->scale_factor)
160 return (diff < 0 ? (i < 2 ? 63 : 33) : 61) - i;
163 static void g722_encode_trellis(G722Context *c, int trellis,
164 uint8_t *dst, int nb_samples,
165 const int16_t *samples)
168 int frontier = 1 << trellis;
169 struct TrellisNode **nodes[2];
170 struct TrellisNode **nodes_next[2];
171 int pathn[2] = {0, 0}, froze = -1;
172 struct TrellisPath *p[2];
174 for (i = 0; i < 2; i++) {
175 nodes[i] = c->nodep_buf[i];
176 nodes_next[i] = c->nodep_buf[i] + frontier;
177 memset(c->nodep_buf[i], 0, 2 * frontier * sizeof(*c->nodep_buf));
178 nodes[i][0] = c->node_buf[i] + frontier;
179 nodes[i][0]->ssd = 0;
180 nodes[i][0]->path = 0;
181 nodes[i][0]->state = c->band[i];
184 for (i = 0; i < nb_samples >> 1; i++) {
186 struct TrellisNode *next[2];
187 int heap_pos[2] = {0, 0};
189 for (j = 0; j < 2; j++) {
190 next[j] = c->node_buf[j] + frontier*(i & 1);
191 memset(nodes_next[j], 0, frontier * sizeof(**nodes_next));
194 filter_samples(c, &samples[2*i], &xlow, &xhigh);
196 for (j = 0; j < frontier && nodes[0][j]; j++) {
197 /* Only k >> 2 affects the future adaptive state, therefore testing
198 * small steps that don't change k >> 2 is useless, the original
199 * value from encode_low is better than them. Since we step k
200 * in steps of 4, make sure range is a multiple of 4, so that
201 * we don't miss the original value from encode_low. */
202 int range = j < frontier/2 ? 4 : 0;
203 struct TrellisNode *cur_node = nodes[0][j];
205 int ilow = encode_low(&cur_node->state, xlow);
207 for (k = ilow - range; k <= ilow + range && k <= 63; k += 4) {
208 int decoded, dec_diff, pos;
210 struct TrellisNode* node;
215 decoded = av_clip((cur_node->state.scale_factor *
216 ff_g722_low_inv_quant6[k] >> 10)
217 + cur_node->state.s_predictor, -16384, 16383);
218 dec_diff = xlow - decoded;
220 #define STORE_NODE(index, UPDATE, VALUE)\
221 ssd = cur_node->ssd + dec_diff*dec_diff;\
222 /* Check for wraparound. Using 64 bit ssd counters would \
223 * be simpler, but is slower on x86 32 bit. */\
224 if (ssd < cur_node->ssd)\
226 if (heap_pos[index] < frontier) {\
227 pos = heap_pos[index]++;\
228 assert(pathn[index] < FREEZE_INTERVAL * frontier);\
229 node = nodes_next[index][pos] = next[index]++;\
230 node->path = pathn[index]++;\
232 /* Try to replace one of the leaf nodes with the new \
233 * one, but not always testing the same leaf position */\
234 pos = (frontier>>1) + (heap_pos[index] & ((frontier>>1) - 1));\
235 if (ssd >= nodes_next[index][pos]->ssd)\
238 node = nodes_next[index][pos];\
241 node->state = cur_node->state;\
243 c->paths[index][node->path].value = VALUE;\
244 c->paths[index][node->path].prev = cur_node->path;\
245 /* Sift the newly inserted node up in the heap to restore \
246 * the heap property */\
248 int parent = (pos - 1) >> 1;\
249 if (nodes_next[index][parent]->ssd <= ssd)\
251 FFSWAP(struct TrellisNode*, nodes_next[index][parent],\
252 nodes_next[index][pos]);\
255 STORE_NODE(0, ff_g722_update_low_predictor(&node->state, k >> 2), k);
259 for (j = 0; j < frontier && nodes[1][j]; j++) {
261 struct TrellisNode *cur_node = nodes[1][j];
263 /* We don't try to get any initial guess for ihigh via
264 * encode_high - since there's only 4 possible values, test
265 * them all. Testing all of these gives a much, much larger
266 * gain than testing a larger range around ilow. */
267 for (ihigh = 0; ihigh < 4; ihigh++) {
268 int dhigh, decoded, dec_diff, pos;
270 struct TrellisNode* node;
272 dhigh = cur_node->state.scale_factor *
273 ff_g722_high_inv_quant[ihigh] >> 10;
274 decoded = av_clip(dhigh + cur_node->state.s_predictor,
276 dec_diff = xhigh - decoded;
278 STORE_NODE(1, ff_g722_update_high_predictor(&node->state, dhigh, ihigh), ihigh);
282 for (j = 0; j < 2; j++) {
283 FFSWAP(struct TrellisNode**, nodes[j], nodes_next[j]);
285 if (nodes[j][0]->ssd > (1 << 16)) {
286 for (k = 1; k < frontier && nodes[j][k]; k++)
287 nodes[j][k]->ssd -= nodes[j][0]->ssd;
288 nodes[j][0]->ssd = 0;
292 if (i == froze + FREEZE_INTERVAL) {
293 p[0] = &c->paths[0][nodes[0][0]->path];
294 p[1] = &c->paths[1][nodes[1][0]->path];
295 for (j = i; j > froze; j--) {
296 dst[j] = p[1]->value << 6 | p[0]->value;
297 p[0] = &c->paths[0][p[0]->prev];
298 p[1] = &c->paths[1][p[1]->prev];
301 pathn[0] = pathn[1] = 0;
302 memset(nodes[0] + 1, 0, (frontier - 1)*sizeof(**nodes));
303 memset(nodes[1] + 1, 0, (frontier - 1)*sizeof(**nodes));
307 p[0] = &c->paths[0][nodes[0][0]->path];
308 p[1] = &c->paths[1][nodes[1][0]->path];
309 for (j = i; j > froze; j--) {
310 dst[j] = p[1]->value << 6 | p[0]->value;
311 p[0] = &c->paths[0][p[0]->prev];
312 p[1] = &c->paths[1][p[1]->prev];
314 c->band[0] = nodes[0][0]->state;
315 c->band[1] = nodes[1][0]->state;
318 static av_always_inline void encode_byte(G722Context *c, uint8_t *dst,
319 const int16_t *samples)
321 int xlow, xhigh, ilow, ihigh;
322 filter_samples(c, samples, &xlow, &xhigh);
323 ihigh = encode_high(&c->band[1], xhigh);
324 ilow = encode_low (&c->band[0], xlow);
325 ff_g722_update_high_predictor(&c->band[1], c->band[1].scale_factor *
326 ff_g722_high_inv_quant[ihigh] >> 10, ihigh);
327 ff_g722_update_low_predictor(&c->band[0], ilow >> 2);
328 *dst = ihigh << 6 | ilow;
331 static void g722_encode_no_trellis(G722Context *c,
332 uint8_t *dst, int nb_samples,
333 const int16_t *samples)
336 for (i = 0; i < nb_samples; i += 2)
337 encode_byte(c, dst++, &samples[i]);
340 static int g722_encode_frame(AVCodecContext *avctx,
341 uint8_t *dst, int buf_size, void *data)
343 G722Context *c = avctx->priv_data;
344 const int16_t *samples = data;
347 nb_samples = avctx->frame_size - (avctx->frame_size & 1);
350 g722_encode_trellis(c, avctx->trellis, dst, nb_samples, samples);
352 g722_encode_no_trellis(c, dst, nb_samples, samples);
354 /* handle last frame with odd frame_size */
355 if (nb_samples < avctx->frame_size) {
356 int16_t last_samples[2] = { samples[nb_samples], samples[nb_samples] };
357 encode_byte(c, &dst[nb_samples >> 1], last_samples);
360 return (avctx->frame_size + 1) >> 1;
363 AVCodec ff_adpcm_g722_encoder = {
365 .type = AVMEDIA_TYPE_AUDIO,
366 .id = CODEC_ID_ADPCM_G722,
367 .priv_data_size = sizeof(G722Context),
368 .init = g722_encode_init,
369 .close = g722_encode_close,
370 .encode = g722_encode_frame,
371 .capabilities = CODEC_CAP_SMALL_LAST_FRAME,
372 .long_name = NULL_IF_CONFIG_SMALL("G.722 ADPCM"),
373 .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},