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vorbis.c
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1 /**
2  * @file
3  * Common code for Vorbis I encoder and decoder
4  * @author Denes Balatoni ( dbalatoni programozo hu )
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * Common code for Vorbis I encoder and decoder
26  * @author Denes Balatoni ( dbalatoni programozo hu )
27  */
28 
29 #define BITSTREAM_READER_LE
30 #include "avcodec.h"
31 #include "get_bits.h"
32 
33 #include "vorbis.h"
34 
35 
36 /* Helper functions */
37 
38 // x^(1/n)
39 unsigned int ff_vorbis_nth_root(unsigned int x, unsigned int n)
40 {
41  unsigned int ret = 0, i, j;
42 
43  do {
44  ++ret;
45  for (i = 0, j = ret; i < n - 1; i++)
46  j *= ret;
47  } while (j <= x);
48 
49  return ret - 1;
50 }
51 
52 // Generate vlc codes from vorbis huffman code lengths
53 
54 // the two bits[p] > 32 checks should be redundant, all calling code should
55 // already ensure that, but since it allows overwriting the stack it seems
56 // reasonable to check redundantly.
57 int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, unsigned num)
58 {
59  uint32_t exit_at_level[33] = { 404 };
60 
61  unsigned i, j, p, code;
62 
63 #ifdef DEBUG
64  GetBitContext gb;
65 #endif
66 
67  for (p = 0; (bits[p] == 0) && (p < num); ++p)
68  ;
69  if (p == num)
70  return 0;
71 
72  codes[p] = 0;
73  if (bits[p] > 32)
74  return 1;
75  for (i = 0; i < bits[p]; ++i)
76  exit_at_level[i+1] = 1 << i;
77 
78 #ifdef DEBUG
79  av_log(NULL, AV_LOG_INFO, " %u. of %u code len %d code %d - ", p, num, bits[p], codes[p]);
80  init_get_bits(&gb, (uint8_t *)&codes[p], bits[p]);
81  for (i = 0; i < bits[p]; ++i)
82  av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
83  av_log(NULL, AV_LOG_INFO, "\n");
84 #endif
85 
86  ++p;
87 
88  for (; p < num; ++p) {
89  if (bits[p] > 32)
90  return 1;
91  if (bits[p] == 0)
92  continue;
93  // find corresponding exit(node which the tree can grow further from)
94  for (i = bits[p]; i > 0; --i)
95  if (exit_at_level[i])
96  break;
97  if (!i) // overspecified tree
98  return 1;
99  code = exit_at_level[i];
100  exit_at_level[i] = 0;
101  // construct code (append 0s to end) and introduce new exits
102  for (j = i + 1 ;j <= bits[p]; ++j)
103  exit_at_level[j] = code + (1 << (j - 1));
104  codes[p] = code;
105 
106 #ifdef DEBUG
107  av_log(NULL, AV_LOG_INFO, " %d. code len %d code %d - ", p, bits[p], codes[p]);
108  init_get_bits(&gb, (uint8_t *)&codes[p], bits[p]);
109  for (i = 0; i < bits[p]; ++i)
110  av_log(NULL, AV_LOG_INFO, "%s", get_bits1(&gb) ? "1" : "0");
111  av_log(NULL, AV_LOG_INFO, "\n");
112 #endif
113 
114  }
115 
116  //no exits should be left (underspecified tree - ie. unused valid vlcs - not allowed by SPEC)
117  for (p = 1; p < 33; p++)
118  if (exit_at_level[p])
119  return 1;
120 
121  return 0;
122 }
123 
125  vorbis_floor1_entry *list, int values)
126 {
127  int i;
128  list[0].sort = 0;
129  list[1].sort = 1;
130  for (i = 2; i < values; i++) {
131  int j;
132  list[i].low = 0;
133  list[i].high = 1;
134  list[i].sort = i;
135  for (j = 2; j < i; j++) {
136  int tmp = list[j].x;
137  if (tmp < list[i].x) {
138  if (tmp > list[list[i].low].x)
139  list[i].low = j;
140  } else {
141  if (tmp < list[list[i].high].x)
142  list[i].high = j;
143  }
144  }
145  }
146  for (i = 0; i < values - 1; i++) {
147  int j;
148  for (j = i + 1; j < values; j++) {
149  if (list[i].x == list[j].x) {
150  av_log(avctx, AV_LOG_ERROR,
151  "Duplicate value found in floor 1 X coordinates\n");
152  return AVERROR_INVALIDDATA;
153  }
154  if (list[list[i].sort].x > list[list[j].sort].x) {
155  int tmp = list[i].sort;
156  list[i].sort = list[j].sort;
157  list[j].sort = tmp;
158  }
159  }
160  }
161  return 0;
162 }
163 
164 static inline void render_line_unrolled(intptr_t x, int y, int x1,
165  intptr_t sy, int ady, int adx,
166  float *buf)
167 {
168  int err = -adx;
169  x -= x1 - 1;
170  buf += x1 - 1;
171  while (++x < 0) {
172  err += ady;
173  if (err >= 0) {
174  err += ady - adx;
175  y += sy;
176  buf[x++] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
177  }
178  buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
179  }
180  if (x <= 0) {
181  if (err + ady >= 0)
182  y += sy;
183  buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
184  }
185 }
186 
187 static void render_line(int x0, int y0, int x1, int y1, float *buf)
188 {
189  int dy = y1 - y0;
190  int adx = x1 - x0;
191  int ady = FFABS(dy);
192  int sy = dy < 0 ? -1 : 1;
193  buf[x0] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y0)];
194  if (ady*2 <= adx) { // optimized common case
195  render_line_unrolled(x0, y0, x1, sy, ady, adx, buf);
196  } else {
197  int base = dy / adx;
198  int x = x0;
199  int y = y0;
200  int err = -adx;
201  ady -= FFABS(base) * adx;
202  while (++x < x1) {
203  y += base;
204  err += ady;
205  if (err >= 0) {
206  err -= adx;
207  y += sy;
208  }
209  buf[x] = ff_vorbis_floor1_inverse_db_table[av_clip_uint8(y)];
210  }
211  }
212 }
213 
215  uint16_t *y_list, int *flag,
216  int multiplier, float *out, int samples)
217 {
218  int lx, ly, i;
219  lx = 0;
220  ly = y_list[0] * multiplier;
221  for (i = 1; i < values; i++) {
222  int pos = list[i].sort;
223  if (flag[pos]) {
224  int x1 = list[pos].x;
225  int y1 = y_list[pos] * multiplier;
226  if (lx < samples)
227  render_line(lx, ly, FFMIN(x1,samples), y1, out);
228  lx = x1;
229  ly = y1;
230  }
231  if (lx >= samples)
232  break;
233  }
234  if (lx < samples)
235  render_line(lx, ly, samples, ly, out);
236 }