2 * Wavesynth pseudo-codec
3 * Copyright (c) 2011 Nicolas George
5 * This file is part of FFmpeg.
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.
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.
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
22 #include "libavutil/intreadwrite.h"
23 #include "libavutil/log.h"
29 #define WS_MAX_CHANNELS 32
30 #define INF_TS 0x7FFFFFFFFFFFFFFF
35 Format of the extradata and packets
37 THIS INFORMATION IS NOT PART OF THE PUBLIC API OR ABI.
38 IT CAN CHANGE WITHOUT NOTIFICATION.
40 All numbers are in little endian.
42 The codec extradata define a set of intervals with uniform content.
43 Overlapping intervals are added together.
46 uint32 number of intervals
50 int64 start timestamp; time_base must be 1/sample_rate;
51 start timestamps must be in ascending order
55 ... additional information, depends on type
57 sine interval (type fourcc "SINE"):
58 int32 start frequency, in 1/(1<<16) Hz
60 int32 start amplitude, 1<<16 is the full amplitude
62 uint32 start phase, 0 is sin(0), 0x20000000 is sin(pi/2), etc.;
63 n | (1<<31) means to match the phase of previous channel #n
65 pink noise interval (type fourcc "NOIS"):
69 The input packets encode the time and duration of the requested segment.
77 enum ws_interval_type {
78 WS_SINE = MKTAG('S','I','N','E'),
79 WS_NOISE = MKTAG('N','O','I','S'),
83 int64_t ts_start, ts_end;
84 uint64_t phi0, dphi0, ddphi;
86 uint64_t phi, dphi, amp;
88 enum ws_interval_type type;
92 struct wavesynth_context {
96 struct ws_interval *inter;
97 uint32_t dither_state;
99 int32_t pink_pool[PINK_UNIT];
100 unsigned pink_need, pink_pos;
106 #define LCG_A 1284865837
107 #define LCG_C 4150755663
108 #define LCG_AI 849225893 /* A*AI = 1 [mod 1<<32] */
110 static uint32_t lcg_next(uint32_t *s)
112 *s = *s * LCG_A + LCG_C;
116 static void lcg_seek(uint32_t *s, uint32_t dt)
118 uint32_t a, c, t = *s;
125 c *= a + 1; /* coefficients for a double step */
132 /* Emulate pink noise by summing white noise at the sampling frequency,
133 * white noise at half the sampling frequency (each value taken twice),
134 * etc., with a total of 8 octaves.
135 * This is known as the Voss-McCartney algorithm. */
137 static void pink_fill(struct wavesynth_context *ws)
139 int32_t vt[7] = { 0 }, v = 0;
145 for (i = 0; i < PINK_UNIT; i++) {
146 for (j = 0; j < 7; j++) {
150 vt[j] = (int32_t)lcg_next(&ws->pink_state) >> 3;
153 ws->pink_pool[i] = v + ((int32_t)lcg_next(&ws->pink_state) >> 3);
155 lcg_next(&ws->pink_state); /* so we use exactly 256 steps */
159 * @return (1<<64) * a / b, without overflow, if a < b
161 static uint64_t frac64(uint64_t a, uint64_t b)
166 if (b < (uint64_t)1 << 32) { /* b small, use two 32-bits steps */
168 return ((a / b) << 32) | ((a % b) << 32) / b;
170 if (b < (uint64_t)1 << 48) { /* b medium, use four 16-bits steps */
171 for (i = 0; i < 4; i++) {
173 r = (r << 16) | (a / b);
178 for (i = 63; i >= 0; i--) {
179 if (a >= (uint64_t)1 << 63 || a << 1 >= b) {
180 r |= (uint64_t)1 << i;
189 static uint64_t phi_at(struct ws_interval *in, int64_t ts)
191 uint64_t dt = ts - in->ts_start;
192 uint64_t dt2 = dt & 1 ? /* dt * (dt - 1) / 2 without overflow */
193 dt * ((dt - 1) >> 1) : (dt >> 1) * (dt - 1);
194 return in->phi0 + dt * in->dphi0 + dt2 * in->ddphi;
197 static void wavesynth_seek(struct wavesynth_context *ws, int64_t ts)
200 struct ws_interval *in;
202 last = &ws->cur_inter;
203 for (i = 0; i < ws->nb_inter; i++) {
205 if (ts < in->ts_start)
207 if (ts >= in->ts_end)
211 in->phi = phi_at(in, ts);
212 in->dphi = in->dphi0 + (ts - in->ts_start) * in->ddphi;
213 in->amp = in->amp0 + (ts - in->ts_start) * in->damp;
216 ws->next_ts = i < ws->nb_inter ? ws->inter[i].ts_start : INF_TS;
218 lcg_seek(&ws->dither_state, (uint32_t)ts - (uint32_t)ws->cur_ts);
220 uint64_t pink_ts_cur = (ws->cur_ts + (uint64_t)PINK_UNIT - 1) & ~(PINK_UNIT - 1);
221 uint64_t pink_ts_next = ts & ~(PINK_UNIT - 1);
222 int pos = ts & (PINK_UNIT - 1);
223 lcg_seek(&ws->pink_state, (uint32_t)(pink_ts_next - pink_ts_cur) * 2);
228 ws->pink_pos = PINK_UNIT;
234 static int wavesynth_parse_extradata(AVCodecContext *avc)
236 struct wavesynth_context *ws = avc->priv_data;
237 struct ws_interval *in;
238 uint8_t *edata, *edata_end;
239 int32_t f1, f2, a1, a2;
241 int64_t dphi1, dphi2, dt, cur_ts = -0x8000000000000000;
244 if (avc->extradata_size < 4)
245 return AVERROR(EINVAL);
246 edata = avc->extradata;
247 edata_end = edata + avc->extradata_size;
248 ws->nb_inter = AV_RL32(edata);
250 if (ws->nb_inter < 0 || (edata_end - edata) / 24 < ws->nb_inter)
251 return AVERROR(EINVAL);
252 ws->inter = av_calloc(ws->nb_inter, sizeof(*ws->inter));
254 return AVERROR(ENOMEM);
255 for (i = 0; i < ws->nb_inter; i++) {
257 if (edata_end - edata < 24)
258 return AVERROR(EINVAL);
259 in->ts_start = AV_RL64(edata + 0);
260 in->ts_end = AV_RL64(edata + 8);
261 in->type = AV_RL32(edata + 16);
262 in->channels = AV_RL32(edata + 20);
264 if (in->ts_start < cur_ts ||
265 in->ts_end <= in->ts_start ||
266 (uint64_t)in->ts_end - in->ts_start > INT64_MAX
268 return AVERROR(EINVAL);
269 cur_ts = in->ts_start;
270 dt = in->ts_end - in->ts_start;
273 if (edata_end - edata < 20 || avc->sample_rate <= 0)
274 return AVERROR(EINVAL);
275 f1 = AV_RL32(edata + 0);
276 f2 = AV_RL32(edata + 4);
277 a1 = AV_RL32(edata + 8);
278 a2 = AV_RL32(edata + 12);
279 phi = AV_RL32(edata + 16);
281 dphi1 = frac64(f1, (int64_t)avc->sample_rate << 16);
282 dphi2 = frac64(f2, (int64_t)avc->sample_rate << 16);
284 in->ddphi = (int64_t)(dphi2 - (uint64_t)dphi1) / dt;
285 if (phi & 0x80000000) {
288 return AVERROR(EINVAL);
289 in->phi0 = phi_at(&ws->inter[phi], in->ts_start);
291 in->phi0 = (uint64_t)phi << 33;
295 if (edata_end - edata < 8)
296 return AVERROR(EINVAL);
297 a1 = AV_RL32(edata + 0);
298 a2 = AV_RL32(edata + 4);
302 return AVERROR(EINVAL);
304 in->amp0 = (uint64_t)a1 << 32;
305 in->damp = (int64_t)(((uint64_t)a2 << 32) - ((uint64_t)a1 << 32)) / dt;
307 if (edata != edata_end)
308 return AVERROR(EINVAL);
312 static av_cold int wavesynth_init(AVCodecContext *avc)
314 struct wavesynth_context *ws = avc->priv_data;
317 if (avc->channels > WS_MAX_CHANNELS) {
318 av_log(avc, AV_LOG_ERROR,
319 "This implementation is limited to %d channels.\n",
321 return AVERROR(EINVAL);
323 r = wavesynth_parse_extradata(avc);
325 av_log(avc, AV_LOG_ERROR, "Invalid intervals definitions.\n");
328 ws->sin = av_malloc(sizeof(*ws->sin) << SIN_BITS);
333 for (i = 0; i < 1 << SIN_BITS; i++)
334 ws->sin[i] = floor(32767 * sin(2 * M_PI * i / (1 << SIN_BITS)));
335 ws->dither_state = MKTAG('D','I','T','H');
336 for (i = 0; i < ws->nb_inter; i++)
337 ws->pink_need += ws->inter[i].type == WS_NOISE;
338 ws->pink_state = MKTAG('P','I','N','K');
339 ws->pink_pos = PINK_UNIT;
340 wavesynth_seek(ws, 0);
341 avc->sample_fmt = AV_SAMPLE_FMT_S16;
345 av_freep(&ws->inter);
350 static void wavesynth_synth_sample(struct wavesynth_context *ws, int64_t ts,
355 struct ws_interval *in;
357 uint32_t c, all_ch = 0;
360 last = &ws->cur_inter;
361 if (ws->pink_pos == PINK_UNIT)
363 pink = ws->pink_pool[ws->pink_pos++] >> 16;
367 if (ts >= in->ts_end) {
376 val = amp * ws->sin[in->phi >> (64 - SIN_BITS)];
378 in->dphi += in->ddphi;
381 val = amp * (unsigned)pink;
386 all_ch |= in->channels;
387 for (c = in->channels, cv = channels; c; c >>= 1, cv++)
389 *cv += (unsigned)val;
391 val = (int32_t)lcg_next(&ws->dither_state) >> 16;
392 for (c = all_ch, cv = channels; c; c >>= 1, cv++)
397 static void wavesynth_enter_intervals(struct wavesynth_context *ws, int64_t ts)
400 struct ws_interval *in;
402 last = &ws->cur_inter;
403 for (i = ws->cur_inter; i >= 0; i = ws->inter[i].next)
404 last = &ws->inter[i].next;
405 for (i = ws->next_inter; i < ws->nb_inter; i++) {
407 if (ts < in->ts_start)
409 if (ts >= in->ts_end)
414 in->dphi = in->dphi0;
418 ws->next_ts = i < ws->nb_inter ? ws->inter[i].ts_start : INF_TS;
422 static int wavesynth_decode(AVCodecContext *avc, void *rframe, int *rgot_frame,
425 struct wavesynth_context *ws = avc->priv_data;
426 AVFrame *frame = rframe;
431 int32_t channels[WS_MAX_CHANNELS];
434 if (packet->size != 12)
435 return AVERROR_INVALIDDATA;
436 ts = AV_RL64(packet->data);
437 if (ts != ws->cur_ts)
438 wavesynth_seek(ws, ts);
439 duration = AV_RL32(packet->data + 8);
441 return AVERROR(EINVAL);
442 frame->nb_samples = duration;
443 r = ff_get_buffer(avc, frame, 0);
446 pcm = (int16_t *)frame->data[0];
447 for (s = 0; s < duration; s++, ts+=(uint64_t)1) {
448 memset(channels, 0, avc->channels * sizeof(*channels));
449 if (ts >= ws->next_ts)
450 wavesynth_enter_intervals(ws, ts);
451 wavesynth_synth_sample(ws, ts, channels);
452 for (c = 0; c < avc->channels; c++)
453 *(pcm++) = channels[c] >> 16;
455 ws->cur_ts += (uint64_t)duration;
460 static av_cold int wavesynth_close(AVCodecContext *avc)
462 struct wavesynth_context *ws = avc->priv_data;
465 av_freep(&ws->inter);
469 AVCodec ff_ffwavesynth_decoder = {
471 .long_name = NULL_IF_CONFIG_SMALL("Wave synthesis pseudo-codec"),
472 .type = AVMEDIA_TYPE_AUDIO,
473 .id = AV_CODEC_ID_FFWAVESYNTH,
474 .priv_data_size = sizeof(struct wavesynth_context),
475 .init = wavesynth_init,
476 .close = wavesynth_close,
477 .decode = wavesynth_decode,
478 .capabilities = AV_CODEC_CAP_DR1,