1/* Copyright (c) 2011 Xiph.Org Foundation, Skype Limited
2   Written by Jean-Marc Valin and Koen Vos */
3/*
4   Redistribution and use in source and binary forms, with or without
5   modification, are permitted provided that the following conditions
6   are met:
7
8   - Redistributions of source code must retain the above copyright
9   notice, this list of conditions and the following disclaimer.
10
11   - Redistributions in binary form must reproduce the above copyright
12   notice, this list of conditions and the following disclaimer in the
13   documentation and/or other materials provided with the distribution.
14
15   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
18   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
19   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
22   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
23   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
24   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26*/
27
28#ifdef HAVE_CONFIG_H
29#include "config.h"
30#endif
31
32#include "opus.h"
33#include "opus_private.h"
34
35#ifndef DISABLE_FLOAT_API
36OPUS_EXPORT void opus_pcm_soft_clip(float *_x, int N, int C, float *declip_mem)
37{
38   int c;
39   int i;
40   float *x;
41
42   if (C<1 || N<1 || !_x || !declip_mem) return;
43
44   /* First thing: saturate everything to +/- 2 which is the highest level our
45      non-linearity can handle. At the point where the signal reaches +/-2,
46      the derivative will be zero anyway, so this doesn't introduce any
47      discontinuity in the derivative. */
48   for (i=0;i<N*C;i++)
49      _x[i] = MAX16(-2.f, MIN16(2.f, _x[i]));
50   for (c=0;c<C;c++)
51   {
52      float a;
53      float x0;
54      int curr;
55
56      x = _x+c;
57      a = declip_mem[c];
58      /* Continue applying the non-linearity from the previous frame to avoid
59         any discontinuity. */
60      for (i=0;i<N;i++)
61      {
62         if (x[i*C]*a>=0)
63            break;
64         x[i*C] = x[i*C]+a*x[i*C]*x[i*C];
65      }
66
67      curr=0;
68      x0 = x[0];
69      while(1)
70      {
71         int start, end;
72         float maxval;
73         int special=0;
74         int peak_pos;
75         for (i=curr;i<N;i++)
76         {
77            if (x[i*C]>1 || x[i*C]<-1)
78               break;
79         }
80         if (i==N)
81         {
82            a=0;
83            break;
84         }
85         peak_pos = i;
86         start=end=i;
87         maxval=ABS16(x[i*C]);
88         /* Look for first zero crossing before clipping */
89         while (start>0 && x[i*C]*x[(start-1)*C]>=0)
90            start--;
91         /* Look for first zero crossing after clipping */
92         while (end<N && x[i*C]*x[end*C]>=0)
93         {
94            /* Look for other peaks until the next zero-crossing. */
95            if (ABS16(x[end*C])>maxval)
96            {
97               maxval = ABS16(x[end*C]);
98               peak_pos = end;
99            }
100            end++;
101         }
102         /* Detect the special case where we clip before the first zero crossing */
103         special = (start==0 && x[i*C]*x[0]>=0);
104
105         /* Compute a such that maxval + a*maxval^2 = 1 */
106         a=(maxval-1)/(maxval*maxval);
107         if (x[i*C]>0)
108            a = -a;
109         /* Apply soft clipping */
110         for (i=start;i<end;i++)
111            x[i*C] = x[i*C]+a*x[i*C]*x[i*C];
112
113         if (special && peak_pos>=2)
114         {
115            /* Add a linear ramp from the first sample to the signal peak.
116               This avoids a discontinuity at the beginning of the frame. */
117            float delta;
118            float offset = x0-x[0];
119            delta = offset / peak_pos;
120            for (i=curr;i<peak_pos;i++)
121            {
122               offset -= delta;
123               x[i*C] += offset;
124               x[i*C] = MAX16(-1.f, MIN16(1.f, x[i*C]));
125            }
126         }
127         curr = end;
128         if (curr==N)
129            break;
130      }
131      declip_mem[c] = a;
132   }
133}
134#endif
135
136int encode_size(int size, unsigned char *data)
137{
138   if (size < 252)
139   {
140      data[0] = size;
141      return 1;
142   } else {
143      data[0] = 252+(size&0x3);
144      data[1] = (size-(int)data[0])>>2;
145      return 2;
146   }
147}
148
149static int parse_size(const unsigned char *data, opus_int32 len, opus_int16 *size)
150{
151   if (len<1)
152   {
153      *size = -1;
154      return -1;
155   } else if (data[0]<252)
156   {
157      *size = data[0];
158      return 1;
159   } else if (len<2)
160   {
161      *size = -1;
162      return -1;
163   } else {
164      *size = 4*data[1] + data[0];
165      return 2;
166   }
167}
168
169int opus_packet_parse_impl(const unsigned char *data, opus_int32 len,
170      int self_delimited, unsigned char *out_toc,
171      const unsigned char *frames[48], opus_int16 size[48],
172      int *payload_offset, opus_int32 *packet_offset)
173{
174   int i, bytes;
175   int count;
176   int cbr;
177   unsigned char ch, toc;
178   int framesize;
179   opus_int32 last_size;
180   opus_int32 pad = 0;
181   const unsigned char *data0 = data;
182
183   if (size==NULL)
184      return OPUS_BAD_ARG;
185
186   framesize = opus_packet_get_samples_per_frame(data, 48000);
187
188   cbr = 0;
189   toc = *data++;
190   len--;
191   last_size = len;
192   switch (toc&0x3)
193   {
194   /* One frame */
195   case 0:
196      count=1;
197      break;
198   /* Two CBR frames */
199   case 1:
200      count=2;
201      cbr = 1;
202      if (!self_delimited)
203      {
204         if (len&0x1)
205            return OPUS_INVALID_PACKET;
206         last_size = len/2;
207         /* If last_size doesn't fit in size[0], we'll catch it later */
208         size[0] = (opus_int16)last_size;
209      }
210      break;
211   /* Two VBR frames */
212   case 2:
213      count = 2;
214      bytes = parse_size(data, len, size);
215      len -= bytes;
216      if (size[0]<0 || size[0] > len)
217         return OPUS_INVALID_PACKET;
218      data += bytes;
219      last_size = len-size[0];
220      break;
221   /* Multiple CBR/VBR frames (from 0 to 120 ms) */
222   default: /*case 3:*/
223      if (len<1)
224         return OPUS_INVALID_PACKET;
225      /* Number of frames encoded in bits 0 to 5 */
226      ch = *data++;
227      count = ch&0x3F;
228      if (count <= 0 || framesize*count > 5760)
229         return OPUS_INVALID_PACKET;
230      len--;
231      /* Padding flag is bit 6 */
232      if (ch&0x40)
233      {
234         int p;
235         do {
236            int tmp;
237            if (len<=0)
238               return OPUS_INVALID_PACKET;
239            p = *data++;
240            len--;
241            tmp = p==255 ? 254: p;
242            len -= tmp;
243            pad += tmp;
244         } while (p==255);
245      }
246      if (len<0)
247         return OPUS_INVALID_PACKET;
248      /* VBR flag is bit 7 */
249      cbr = !(ch&0x80);
250      if (!cbr)
251      {
252         /* VBR case */
253         last_size = len;
254         for (i=0;i<count-1;i++)
255         {
256            bytes = parse_size(data, len, size+i);
257            len -= bytes;
258            if (size[i]<0 || size[i] > len)
259               return OPUS_INVALID_PACKET;
260            data += bytes;
261            last_size -= bytes+size[i];
262         }
263         if (last_size<0)
264            return OPUS_INVALID_PACKET;
265      } else if (!self_delimited)
266      {
267         /* CBR case */
268         last_size = len/count;
269         if (last_size*count!=len)
270            return OPUS_INVALID_PACKET;
271         for (i=0;i<count-1;i++)
272            size[i] = (opus_int16)last_size;
273      }
274      break;
275   }
276   /* Self-delimited framing has an extra size for the last frame. */
277   if (self_delimited)
278   {
279      bytes = parse_size(data, len, size+count-1);
280      len -= bytes;
281      if (size[count-1]<0 || size[count-1] > len)
282         return OPUS_INVALID_PACKET;
283      data += bytes;
284      /* For CBR packets, apply the size to all the frames. */
285      if (cbr)
286      {
287         if (size[count-1]*count > len)
288            return OPUS_INVALID_PACKET;
289         for (i=0;i<count-1;i++)
290            size[i] = size[count-1];
291      } else if (bytes+size[count-1] > last_size)
292         return OPUS_INVALID_PACKET;
293   } else
294   {
295      /* Because it's not encoded explicitly, it's possible the size of the
296         last packet (or all the packets, for the CBR case) is larger than
297         1275. Reject them here.*/
298      if (last_size > 1275)
299         return OPUS_INVALID_PACKET;
300      size[count-1] = (opus_int16)last_size;
301   }
302
303   if (payload_offset)
304      *payload_offset = (int)(data-data0);
305
306   for (i=0;i<count;i++)
307   {
308      if (frames)
309         frames[i] = data;
310      data += size[i];
311   }
312
313   if (packet_offset)
314      *packet_offset = pad+(opus_int32)(data-data0);
315
316   if (out_toc)
317      *out_toc = toc;
318
319   return count;
320}
321
322int opus_packet_parse(const unsigned char *data, opus_int32 len,
323      unsigned char *out_toc, const unsigned char *frames[48],
324      opus_int16 size[48], int *payload_offset)
325{
326   return opus_packet_parse_impl(data, len, 0, out_toc,
327                                 frames, size, payload_offset, NULL);
328}
329
330