356 lines
9.7 KiB
C
356 lines
9.7 KiB
C
/* Copyright (c) 2011 Xiph.Org Foundation, Skype Limited
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Written by Jean-Marc Valin and Koen Vos */
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "opus.h"
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#include "opus_private.h"
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#ifndef DISABLE_FLOAT_API
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OPUS_EXPORT void opus_pcm_soft_clip(float *_x, int N, int C, float *declip_mem)
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{
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int c;
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int i;
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float *x;
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if (C<1 || N<1 || !_x || !declip_mem) return;
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/* First thing: saturate everything to +/- 2 which is the highest level our
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non-linearity can handle. At the point where the signal reaches +/-2,
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the derivative will be zero anyway, so this doesn't introduce any
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discontinuity in the derivative. */
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for (i=0;i<N*C;i++)
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_x[i] = MAX16(-2.f, MIN16(2.f, _x[i]));
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for (c=0;c<C;c++)
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{
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float a;
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float x0;
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int curr;
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x = _x+c;
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a = declip_mem[c];
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/* Continue applying the non-linearity from the previous frame to avoid
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any discontinuity. */
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for (i=0;i<N;i++)
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{
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if (x[i*C]*a>=0)
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break;
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x[i*C] = x[i*C]+a*x[i*C]*x[i*C];
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}
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curr=0;
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x0 = x[0];
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while(1)
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{
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int start, end;
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float maxval;
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int special=0;
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int peak_pos;
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for (i=curr;i<N;i++)
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{
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if (x[i*C]>1 || x[i*C]<-1)
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break;
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}
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if (i==N)
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{
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a=0;
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break;
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}
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peak_pos = i;
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start=end=i;
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maxval=ABS16(x[i*C]);
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/* Look for first zero crossing before clipping */
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while (start>0 && x[i*C]*x[(start-1)*C]>=0)
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start--;
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/* Look for first zero crossing after clipping */
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while (end<N && x[i*C]*x[end*C]>=0)
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{
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/* Look for other peaks until the next zero-crossing. */
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if (ABS16(x[end*C])>maxval)
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{
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maxval = ABS16(x[end*C]);
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peak_pos = end;
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}
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end++;
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}
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/* Detect the special case where we clip before the first zero crossing */
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special = (start==0 && x[i*C]*x[0]>=0);
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/* Compute a such that maxval + a*maxval^2 = 1 */
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a=(maxval-1)/(maxval*maxval);
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/* Slightly boost "a" by 2^-22. This is just enough to ensure -ffast-math
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does not cause output values larger than +/-1, but small enough not
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to matter even for 24-bit output. */
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a += a*2.4e-7f;
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if (x[i*C]>0)
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a = -a;
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/* Apply soft clipping */
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for (i=start;i<end;i++)
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x[i*C] = x[i*C]+a*x[i*C]*x[i*C];
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if (special && peak_pos>=2)
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{
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/* Add a linear ramp from the first sample to the signal peak.
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This avoids a discontinuity at the beginning of the frame. */
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float delta;
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float offset = x0-x[0];
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delta = offset / peak_pos;
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for (i=curr;i<peak_pos;i++)
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{
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offset -= delta;
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x[i*C] += offset;
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x[i*C] = MAX16(-1.f, MIN16(1.f, x[i*C]));
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}
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}
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curr = end;
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if (curr==N)
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break;
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}
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declip_mem[c] = a;
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}
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}
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#endif
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int encode_size(int size, unsigned char *data)
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{
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if (size < 252)
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{
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data[0] = size;
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return 1;
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} else {
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data[0] = 252+(size&0x3);
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data[1] = (size-(int)data[0])>>2;
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return 2;
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}
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}
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static int parse_size(const unsigned char *data, opus_int32 len, opus_int16 *size)
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{
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if (len<1)
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{
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*size = -1;
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return -1;
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} else if (data[0]<252)
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{
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*size = data[0];
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return 1;
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} else if (len<2)
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{
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*size = -1;
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return -1;
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} else {
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*size = 4*data[1] + data[0];
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return 2;
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}
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}
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int opus_packet_get_samples_per_frame(const unsigned char *data,
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opus_int32 Fs)
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{
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int audiosize;
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if (data[0]&0x80)
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{
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audiosize = ((data[0]>>3)&0x3);
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audiosize = (Fs<<audiosize)/400;
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} else if ((data[0]&0x60) == 0x60)
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{
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audiosize = (data[0]&0x08) ? Fs/50 : Fs/100;
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} else {
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audiosize = ((data[0]>>3)&0x3);
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if (audiosize == 3)
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audiosize = Fs*60/1000;
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else
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audiosize = (Fs<<audiosize)/100;
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}
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return audiosize;
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}
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int opus_packet_parse_impl(const unsigned char *data, opus_int32 len,
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int self_delimited, unsigned char *out_toc,
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const unsigned char *frames[48], opus_int16 size[48],
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int *payload_offset, opus_int32 *packet_offset)
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{
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int i, bytes;
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int count;
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int cbr;
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unsigned char ch, toc;
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int framesize;
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opus_int32 last_size;
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opus_int32 pad = 0;
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const unsigned char *data0 = data;
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if (size==NULL || len<0)
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return OPUS_BAD_ARG;
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if (len==0)
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return OPUS_INVALID_PACKET;
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framesize = opus_packet_get_samples_per_frame(data, 48000);
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cbr = 0;
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toc = *data++;
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len--;
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last_size = len;
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switch (toc&0x3)
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{
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/* One frame */
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case 0:
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count=1;
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break;
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/* Two CBR frames */
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case 1:
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count=2;
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cbr = 1;
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if (!self_delimited)
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{
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if (len&0x1)
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return OPUS_INVALID_PACKET;
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last_size = len/2;
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/* If last_size doesn't fit in size[0], we'll catch it later */
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size[0] = (opus_int16)last_size;
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}
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break;
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/* Two VBR frames */
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case 2:
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count = 2;
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bytes = parse_size(data, len, size);
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len -= bytes;
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if (size[0]<0 || size[0] > len)
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return OPUS_INVALID_PACKET;
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data += bytes;
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last_size = len-size[0];
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break;
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/* Multiple CBR/VBR frames (from 0 to 120 ms) */
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default: /*case 3:*/
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if (len<1)
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return OPUS_INVALID_PACKET;
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/* Number of frames encoded in bits 0 to 5 */
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ch = *data++;
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count = ch&0x3F;
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if (count <= 0 || framesize*(opus_int32)count > 5760)
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return OPUS_INVALID_PACKET;
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len--;
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/* Padding flag is bit 6 */
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if (ch&0x40)
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{
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int p;
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do {
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int tmp;
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if (len<=0)
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return OPUS_INVALID_PACKET;
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p = *data++;
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len--;
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tmp = p==255 ? 254: p;
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len -= tmp;
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pad += tmp;
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} while (p==255);
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}
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if (len<0)
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return OPUS_INVALID_PACKET;
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/* VBR flag is bit 7 */
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cbr = !(ch&0x80);
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if (!cbr)
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{
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/* VBR case */
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last_size = len;
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for (i=0;i<count-1;i++)
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{
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bytes = parse_size(data, len, size+i);
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len -= bytes;
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if (size[i]<0 || size[i] > len)
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return OPUS_INVALID_PACKET;
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data += bytes;
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last_size -= bytes+size[i];
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}
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if (last_size<0)
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return OPUS_INVALID_PACKET;
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} else if (!self_delimited)
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{
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/* CBR case */
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last_size = len/count;
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if (last_size*count!=len)
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return OPUS_INVALID_PACKET;
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for (i=0;i<count-1;i++)
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size[i] = (opus_int16)last_size;
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}
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break;
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}
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/* Self-delimited framing has an extra size for the last frame. */
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if (self_delimited)
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{
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bytes = parse_size(data, len, size+count-1);
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len -= bytes;
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if (size[count-1]<0 || size[count-1] > len)
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return OPUS_INVALID_PACKET;
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data += bytes;
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/* For CBR packets, apply the size to all the frames. */
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if (cbr)
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{
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if (size[count-1]*count > len)
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return OPUS_INVALID_PACKET;
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for (i=0;i<count-1;i++)
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size[i] = size[count-1];
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} else if (bytes+size[count-1] > last_size)
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return OPUS_INVALID_PACKET;
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} else
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{
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/* Because it's not encoded explicitly, it's possible the size of the
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last packet (or all the packets, for the CBR case) is larger than
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1275. Reject them here.*/
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if (last_size > 1275)
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return OPUS_INVALID_PACKET;
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size[count-1] = (opus_int16)last_size;
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}
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if (payload_offset)
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*payload_offset = (int)(data-data0);
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for (i=0;i<count;i++)
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{
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if (frames)
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frames[i] = data;
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data += size[i];
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}
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if (packet_offset)
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*packet_offset = pad+(opus_int32)(data-data0);
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if (out_toc)
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*out_toc = toc;
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return count;
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}
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int opus_packet_parse(const unsigned char *data, opus_int32 len,
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unsigned char *out_toc, const unsigned char *frames[48],
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opus_int16 size[48], int *payload_offset)
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{
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return opus_packet_parse_impl(data, len, 0, out_toc,
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frames, size, payload_offset, NULL);
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}
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