479 lines
14 KiB
C
Executable file
479 lines
14 KiB
C
Executable file
/*
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* Wavesynth pseudo-codec
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* Copyright (c) 2011 Nicolas George
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/intreadwrite.h"
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#include "libavutil/log.h"
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#include "avcodec.h"
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#include "internal.h"
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#define SIN_BITS 14
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#define WS_MAX_CHANNELS 32
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#define INF_TS 0x7FFFFFFFFFFFFFFF
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#define PINK_UNIT 128
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/*
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Format of the extradata and packets
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THIS INFORMATION IS NOT PART OF THE PUBLIC API OR ABI.
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IT CAN CHANGE WITHOUT NOTIFICATION.
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All numbers are in little endian.
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The codec extradata define a set of intervals with uniform content.
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Overlapping intervals are added together.
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extradata:
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uint32 number of intervals
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... intervals
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interval:
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int64 start timestamp; time_base must be 1/sample_rate;
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start timestamps must be in ascending order
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int64 end timestamp
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uint32 type
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uint32 channels mask
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... additional information, depends on type
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sine interval (type fourcc "SINE"):
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int32 start frequency, in 1/(1<<16) Hz
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int32 end frequency
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int32 start amplitude, 1<<16 is the full amplitude
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int32 end amplitude
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uint32 start phase, 0 is sin(0), 0x20000000 is sin(pi/2), etc.;
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n | (1<<31) means to match the phase of previous channel #n
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pink noise interval (type fourcc "NOIS"):
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int32 start amplitude
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int32 end amplitude
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The input packets encode the time and duration of the requested segment.
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packet:
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int64 start timestamp
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int32 duration
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*/
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enum ws_interval_type {
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WS_SINE = MKTAG('S','I','N','E'),
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WS_NOISE = MKTAG('N','O','I','S'),
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};
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struct ws_interval {
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int64_t ts_start, ts_end;
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uint64_t phi0, dphi0, ddphi;
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uint64_t amp0, damp;
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uint64_t phi, dphi, amp;
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uint32_t channels;
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enum ws_interval_type type;
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int next;
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};
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struct wavesynth_context {
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int64_t cur_ts;
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int64_t next_ts;
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int32_t *sin;
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struct ws_interval *inter;
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uint32_t dither_state;
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uint32_t pink_state;
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int32_t pink_pool[PINK_UNIT];
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unsigned pink_need, pink_pos;
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int nb_inter;
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int cur_inter;
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int next_inter;
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};
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#define LCG_A 1284865837
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#define LCG_C 4150755663
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#define LCG_AI 849225893 /* A*AI = 1 [mod 1<<32] */
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static uint32_t lcg_next(uint32_t *s)
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{
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*s = *s * LCG_A + LCG_C;
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return *s;
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}
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static void lcg_seek(uint32_t *s, uint32_t dt)
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{
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uint32_t a, c, t = *s;
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a = LCG_A;
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c = LCG_C;
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while (dt) {
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if (dt & 1)
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t = a * t + c;
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c *= a + 1; /* coefficients for a double step */
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a *= a;
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dt >>= 1;
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}
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*s = t;
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}
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/* Emulate pink noise by summing white noise at the sampling frequency,
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* white noise at half the sampling frequency (each value taken twice),
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* etc., with a total of 8 octaves.
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* This is known as the Voss-McCartney algorithm. */
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static void pink_fill(struct wavesynth_context *ws)
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{
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int32_t vt[7] = { 0 }, v = 0;
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int i, j;
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ws->pink_pos = 0;
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if (!ws->pink_need)
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return;
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for (i = 0; i < PINK_UNIT; i++) {
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for (j = 0; j < 7; j++) {
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if ((i >> j) & 1)
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break;
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v -= vt[j];
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vt[j] = (int32_t)lcg_next(&ws->pink_state) >> 3;
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v += vt[j];
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}
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ws->pink_pool[i] = v + ((int32_t)lcg_next(&ws->pink_state) >> 3);
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}
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lcg_next(&ws->pink_state); /* so we use exactly 256 steps */
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}
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/**
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* @return (1<<64) * a / b, without overflow, if a < b
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*/
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static uint64_t frac64(uint64_t a, uint64_t b)
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{
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uint64_t r = 0;
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int i;
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if (b < (uint64_t)1 << 32) { /* b small, use two 32-bits steps */
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a <<= 32;
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return ((a / b) << 32) | ((a % b) << 32) / b;
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}
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if (b < (uint64_t)1 << 48) { /* b medium, use four 16-bits steps */
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for (i = 0; i < 4; i++) {
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a <<= 16;
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r = (r << 16) | (a / b);
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a %= b;
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}
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return r;
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}
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for (i = 63; i >= 0; i--) {
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if (a >= (uint64_t)1 << 63 || a << 1 >= b) {
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r |= (uint64_t)1 << i;
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a = (a << 1) - b;
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} else {
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a <<= 1;
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}
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}
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return r;
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}
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static uint64_t phi_at(struct ws_interval *in, int64_t ts)
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{
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uint64_t dt = ts - in->ts_start;
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uint64_t dt2 = dt & 1 ? /* dt * (dt - 1) / 2 without overflow */
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dt * ((dt - 1) >> 1) : (dt >> 1) * (dt - 1);
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return in->phi0 + dt * in->dphi0 + dt2 * in->ddphi;
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}
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static void wavesynth_seek(struct wavesynth_context *ws, int64_t ts)
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{
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int *last, i;
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struct ws_interval *in;
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last = &ws->cur_inter;
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for (i = 0; i < ws->nb_inter; i++) {
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in = &ws->inter[i];
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if (ts < in->ts_start)
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break;
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if (ts >= in->ts_end)
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continue;
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*last = i;
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last = &in->next;
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in->phi = phi_at(in, ts);
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in->dphi = in->dphi0 + (ts - in->ts_start) * in->ddphi;
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in->amp = in->amp0 + (ts - in->ts_start) * in->damp;
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}
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ws->next_inter = i;
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ws->next_ts = i < ws->nb_inter ? ws->inter[i].ts_start : INF_TS;
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*last = -1;
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lcg_seek(&ws->dither_state, (uint32_t)ts - (uint32_t)ws->cur_ts);
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if (ws->pink_need) {
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uint64_t pink_ts_cur = (ws->cur_ts + (uint64_t)PINK_UNIT - 1) & ~(PINK_UNIT - 1);
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uint64_t pink_ts_next = ts & ~(PINK_UNIT - 1);
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int pos = ts & (PINK_UNIT - 1);
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lcg_seek(&ws->pink_state, (uint32_t)(pink_ts_next - pink_ts_cur) * 2);
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if (pos) {
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pink_fill(ws);
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ws->pink_pos = pos;
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} else {
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ws->pink_pos = PINK_UNIT;
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}
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}
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ws->cur_ts = ts;
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}
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static int wavesynth_parse_extradata(AVCodecContext *avc)
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{
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struct wavesynth_context *ws = avc->priv_data;
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struct ws_interval *in;
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uint8_t *edata, *edata_end;
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int32_t f1, f2, a1, a2;
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uint32_t phi;
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int64_t dphi1, dphi2, dt, cur_ts = -0x8000000000000000;
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int i;
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if (avc->extradata_size < 4)
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return AVERROR(EINVAL);
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edata = avc->extradata;
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edata_end = edata + avc->extradata_size;
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ws->nb_inter = AV_RL32(edata);
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edata += 4;
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if (ws->nb_inter < 0 || (edata_end - edata) / 24 < ws->nb_inter)
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return AVERROR(EINVAL);
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ws->inter = av_calloc(ws->nb_inter, sizeof(*ws->inter));
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if (!ws->inter)
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return AVERROR(ENOMEM);
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for (i = 0; i < ws->nb_inter; i++) {
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in = &ws->inter[i];
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if (edata_end - edata < 24)
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return AVERROR(EINVAL);
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in->ts_start = AV_RL64(edata + 0);
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in->ts_end = AV_RL64(edata + 8);
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in->type = AV_RL32(edata + 16);
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in->channels = AV_RL32(edata + 20);
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edata += 24;
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if (in->ts_start < cur_ts ||
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in->ts_end <= in->ts_start ||
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(uint64_t)in->ts_end - in->ts_start > INT64_MAX
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)
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return AVERROR(EINVAL);
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cur_ts = in->ts_start;
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dt = in->ts_end - in->ts_start;
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switch (in->type) {
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case WS_SINE:
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if (edata_end - edata < 20 || avc->sample_rate <= 0)
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return AVERROR(EINVAL);
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f1 = AV_RL32(edata + 0);
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f2 = AV_RL32(edata + 4);
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a1 = AV_RL32(edata + 8);
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a2 = AV_RL32(edata + 12);
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phi = AV_RL32(edata + 16);
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edata += 20;
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dphi1 = frac64(f1, (int64_t)avc->sample_rate << 16);
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dphi2 = frac64(f2, (int64_t)avc->sample_rate << 16);
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in->dphi0 = dphi1;
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in->ddphi = (int64_t)(dphi2 - (uint64_t)dphi1) / dt;
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if (phi & 0x80000000) {
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phi &= ~0x80000000;
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if (phi >= i)
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return AVERROR(EINVAL);
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in->phi0 = phi_at(&ws->inter[phi], in->ts_start);
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} else {
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in->phi0 = (uint64_t)phi << 33;
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}
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break;
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case WS_NOISE:
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if (edata_end - edata < 8)
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return AVERROR(EINVAL);
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a1 = AV_RL32(edata + 0);
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a2 = AV_RL32(edata + 4);
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edata += 8;
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break;
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default:
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return AVERROR(EINVAL);
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}
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in->amp0 = (uint64_t)a1 << 32;
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in->damp = (int64_t)(((uint64_t)a2 << 32) - ((uint64_t)a1 << 32)) / dt;
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}
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if (edata != edata_end)
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return AVERROR(EINVAL);
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return 0;
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}
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static av_cold int wavesynth_init(AVCodecContext *avc)
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{
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struct wavesynth_context *ws = avc->priv_data;
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int i, r;
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if (avc->channels > WS_MAX_CHANNELS) {
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av_log(avc, AV_LOG_ERROR,
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"This implementation is limited to %d channels.\n",
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WS_MAX_CHANNELS);
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return AVERROR(EINVAL);
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}
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r = wavesynth_parse_extradata(avc);
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if (r < 0) {
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av_log(avc, AV_LOG_ERROR, "Invalid intervals definitions.\n");
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goto fail;
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}
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ws->sin = av_malloc(sizeof(*ws->sin) << SIN_BITS);
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if (!ws->sin) {
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r = AVERROR(ENOMEM);
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goto fail;
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}
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for (i = 0; i < 1 << SIN_BITS; i++)
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ws->sin[i] = floor(32767 * sin(2 * M_PI * i / (1 << SIN_BITS)));
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ws->dither_state = MKTAG('D','I','T','H');
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for (i = 0; i < ws->nb_inter; i++)
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ws->pink_need += ws->inter[i].type == WS_NOISE;
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ws->pink_state = MKTAG('P','I','N','K');
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ws->pink_pos = PINK_UNIT;
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wavesynth_seek(ws, 0);
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avc->sample_fmt = AV_SAMPLE_FMT_S16;
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return 0;
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fail:
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av_freep(&ws->inter);
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av_freep(&ws->sin);
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return r;
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}
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static void wavesynth_synth_sample(struct wavesynth_context *ws, int64_t ts,
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int32_t *channels)
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{
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int32_t amp, *cv;
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unsigned val;
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struct ws_interval *in;
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int i, *last, pink;
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uint32_t c, all_ch = 0;
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i = ws->cur_inter;
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last = &ws->cur_inter;
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if (ws->pink_pos == PINK_UNIT)
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pink_fill(ws);
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pink = ws->pink_pool[ws->pink_pos++] >> 16;
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while (i >= 0) {
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in = &ws->inter[i];
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i = in->next;
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if (ts >= in->ts_end) {
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*last = i;
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continue;
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}
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last = &in->next;
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amp = in->amp >> 32;
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in->amp += in->damp;
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switch (in->type) {
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case WS_SINE:
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val = amp * ws->sin[in->phi >> (64 - SIN_BITS)];
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in->phi += in->dphi;
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in->dphi += in->ddphi;
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break;
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case WS_NOISE:
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val = amp * (unsigned)pink;
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break;
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default:
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val = 0;
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}
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all_ch |= in->channels;
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for (c = in->channels, cv = channels; c; c >>= 1, cv++)
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if (c & 1)
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*cv += (unsigned)val;
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}
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val = (int32_t)lcg_next(&ws->dither_state) >> 16;
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for (c = all_ch, cv = channels; c; c >>= 1, cv++)
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if (c & 1)
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*cv += val;
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}
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static void wavesynth_enter_intervals(struct wavesynth_context *ws, int64_t ts)
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{
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int *last, i;
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struct ws_interval *in;
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last = &ws->cur_inter;
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for (i = ws->cur_inter; i >= 0; i = ws->inter[i].next)
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last = &ws->inter[i].next;
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for (i = ws->next_inter; i < ws->nb_inter; i++) {
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in = &ws->inter[i];
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if (ts < in->ts_start)
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break;
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if (ts >= in->ts_end)
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continue;
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*last = i;
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last = &in->next;
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in->phi = in->phi0;
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in->dphi = in->dphi0;
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in->amp = in->amp0;
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}
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ws->next_inter = i;
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ws->next_ts = i < ws->nb_inter ? ws->inter[i].ts_start : INF_TS;
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*last = -1;
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}
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static int wavesynth_decode(AVCodecContext *avc, void *rframe, int *rgot_frame,
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AVPacket *packet)
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{
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struct wavesynth_context *ws = avc->priv_data;
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AVFrame *frame = rframe;
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int64_t ts;
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int duration;
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int s, c, r;
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int16_t *pcm;
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int32_t channels[WS_MAX_CHANNELS];
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*rgot_frame = 0;
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if (packet->size != 12)
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return AVERROR_INVALIDDATA;
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ts = AV_RL64(packet->data);
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if (ts != ws->cur_ts)
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wavesynth_seek(ws, ts);
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duration = AV_RL32(packet->data + 8);
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if (duration <= 0)
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return AVERROR(EINVAL);
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frame->nb_samples = duration;
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r = ff_get_buffer(avc, frame, 0);
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if (r < 0)
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return r;
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pcm = (int16_t *)frame->data[0];
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for (s = 0; s < duration; s++, ts+=(uint64_t)1) {
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memset(channels, 0, avc->channels * sizeof(*channels));
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if (ts >= ws->next_ts)
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wavesynth_enter_intervals(ws, ts);
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wavesynth_synth_sample(ws, ts, channels);
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for (c = 0; c < avc->channels; c++)
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*(pcm++) = channels[c] >> 16;
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}
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ws->cur_ts += (uint64_t)duration;
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*rgot_frame = 1;
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return packet->size;
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}
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static av_cold int wavesynth_close(AVCodecContext *avc)
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{
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struct wavesynth_context *ws = avc->priv_data;
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av_freep(&ws->sin);
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av_freep(&ws->inter);
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return 0;
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}
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AVCodec ff_ffwavesynth_decoder = {
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.name = "wavesynth",
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.long_name = NULL_IF_CONFIG_SMALL("Wave synthesis pseudo-codec"),
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.type = AVMEDIA_TYPE_AUDIO,
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.id = AV_CODEC_ID_FFWAVESYNTH,
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.priv_data_size = sizeof(struct wavesynth_context),
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.init = wavesynth_init,
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.close = wavesynth_close,
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.decode = wavesynth_decode,
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.capabilities = AV_CODEC_CAP_DR1,
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};
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