FFmpeg
rangecoder.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include <stdint.h>
20 #include <string.h>
21 
22 #include "libavutil/lfg.h"
23 #include "libavutil/log.h"
24 
25 #include "libavcodec/rangecoder.h"
26 
27 #define SIZE 1240
28 
29 /**
30  * Check if at the current position there is a valid looking termination
31  * @param version version 0 requires the decoder to know the data size in bytes
32  * version 1 needs about 1 bit more space but does not need to
33  * carry the size from encoder to decoder
34  * @returns negative AVERROR code on error or non negative.
35  */
37 {
38  if (version == 1) {
39  RangeCoder tmp = *c;
40  get_rac(c, (uint8_t[]) { 129 });
41 
42  if (c->bytestream == tmp.bytestream && c->bytestream > c->bytestream_start)
43  tmp.low -= *--tmp.bytestream;
44  tmp.bytestream_end = tmp.bytestream;
45 
46  if (get_rac(&tmp, (uint8_t[]) { 129 }))
47  return AVERROR_INVALIDDATA;
48  } else {
49  if (c->bytestream_end != c->bytestream)
50  return AVERROR_INVALIDDATA;
51  }
52  return 0;
53 }
54 
55 int main(void)
56 {
57  RangeCoder c;
58  uint8_t b[9 * SIZE] = {0};
59  uint8_t r[9 * SIZE];
60  int i, p, actual_length, version;
61  uint8_t state[10];
62  AVLFG prng;
63 
64  av_lfg_init(&prng, 1);
65  for (version = 0; version < 2; version++) {
66  for (p = 0; p< 1024; p++) {
68  ff_build_rac_states(&c, (1LL << 32) / 20, 128 + 64 + 32 + 16);
69 
70  memset(state, 128, sizeof(state));
71 
72  for (i = 0; i < SIZE; i++)
73  r[i] = av_lfg_get(&prng) % 7;
74 
75  for (i = 0; i < SIZE; i++)
76  put_rac(&c, state, r[i] & 1);
77 
78  actual_length = ff_rac_terminate(&c, version);
79 
80  ff_init_range_decoder(&c, b, version ? SIZE : actual_length);
81 
82  memset(state, 128, sizeof(state));
83 
84  for (i = 0; i < SIZE; i++)
85  if ((r[i] & 1) != get_rac(&c, state)) {
86  av_log(NULL, AV_LOG_ERROR, "rac failure at %d pass %d version %d\n", i, p, version);
87  return 1;
88  }
89 
90  if (rac_check_termination(&c, version) < 0) {
91  av_log(NULL, AV_LOG_ERROR, "rac failure at termination pass %d version %d\n", p, version);
92  return 1;
93  }
94  if (c.bytestream - c.bytestream_start - actual_length != version) {
95  av_log(NULL, AV_LOG_ERROR, "rac failure at pass %d version %d\n", p, version);
96  return 1;
97  }
98  }
99  }
100 
101  return 0;
102 }
Context structure for the Lagged Fibonacci PRNG.
Definition: lfg.h:33
#define NULL
Definition: coverity.c:32
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
version
Definition: libkvazaar.c:320
uint32_t low
Definition: mss3.c:64
int main(void)
Definition: rangecoder.c:55
Range coder.
uint8_t * bytestream_end
Definition: rangecoder.h:44
uint8_t
static int get_rac(RangeCoder *c, uint8_t *const state)
Definition: rangecoder.h:127
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
static struct @321 state
#define av_log(a,...)
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
const char * r
Definition: vf_curves.c:116
uint8_t * bytestream
Definition: rangecoder.h:43
#define b
Definition: input.c:41
void ff_build_rac_states(RangeCoder *c, int factor, int max_p)
Definition: rangecoder.c:68
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
Definition: lfg.h:53
static int rac_check_termination(RangeCoder *c, int version)
Check if at the current position there is a valid looking termination.
Definition: rangecoder.c:36
av_cold void ff_init_range_encoder(RangeCoder *c, uint8_t *buf, int buf_size)
Definition: rangecoder.c:42
av_cold void ff_init_range_decoder(RangeCoder *c, const uint8_t *buf, int buf_size)
Definition: rangecoder.c:53
#define SIZE
Definition: rangecoder.c:27
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
Definition: lfg.c:32
int ff_rac_terminate(RangeCoder *c, int version)
Terminates the range coder.
Definition: rangecoder.c:109
#define put_rac(C, S, B)
uint8_t * bytestream_start
Definition: rangecoder.h:42
int i
Definition: input.c:407
static uint8_t tmp[11]
Definition: aes_ctr.c:27