FFmpeg  4.4
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 }
uint8_t
static struct @321 state
#define NULL
Definition: coverity.c:32
#define put_rac(C, S, B)
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
int i
Definition: input.c:407
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
Definition: lfg.c:32
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
Definition: lfg.h:53
version
Definition: libkvazaar.c:320
int ff_rac_terminate(RangeCoder *c, int version)
Terminates the range coder.
Definition: rangecoder.c:109
av_cold void ff_init_range_decoder(RangeCoder *c, const uint8_t *buf, int buf_size)
Definition: rangecoder.c:53
void ff_build_rac_states(RangeCoder *c, int factor, int max_p)
Definition: rangecoder.c:68
av_cold void ff_init_range_encoder(RangeCoder *c, uint8_t *buf, int buf_size)
Definition: rangecoder.c:42
Range coder.
static int get_rac(RangeCoder *c, uint8_t *const state)
Definition: rangecoder.h:127
Context structure for the Lagged Fibonacci PRNG.
Definition: lfg.h:33
#define av_log(a,...)
static uint8_t tmp[11]
Definition: aes_ctr.c:27
#define SIZE
Definition: rangecoder.c:27
int main(void)
Definition: rangecoder.c:55
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
const char * b
Definition: vf_curves.c:118
const char * r
Definition: vf_curves.c:116
static double c[64]