FFmpeg
mpegvideodec.c
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1 /*
2  * RAW MPEG video demuxer
3  * Copyright (c) 2002-2003 Fabrice Bellard
4  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
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 #include "avformat.h"
24 #include "rawdec.h"
25 
26 #include "libavutil/intreadwrite.h"
27 #include "libavcodec/internal.h"
28 
29 #define SEQ_START_CODE 0x000001b3
30 #define GOP_START_CODE 0x000001b8
31 #define PICTURE_START_CODE 0x00000100
32 #define SLICE_START_CODE 0x00000101
33 #define PACK_START_CODE 0x000001ba
34 #define VIDEO_ID 0x000001e0
35 #define AUDIO_ID 0x000001c0
36 
37 static int mpegvideo_probe(const AVProbeData *p)
38 {
39  uint32_t code= -1;
40  int pic=0, seq=0, slice=0, pspack=0, vpes=0, apes=0, res=0, sicle=0;
41  const uint8_t *ptr = p->buf, *end = ptr + p->buf_size;
42  uint32_t last = 0;
43  int j;
44 
45  while (ptr < end) {
46  ptr = avpriv_find_start_code(ptr, end, &code);
47  if ((code & 0xffffff00) == 0x100) {
48  switch(code){
49  case SEQ_START_CODE:
50  if (!(ptr[3 + 1 + 2] & 0x20))
51  break;
52  j = -1;
53  if (ptr[j + 8] & 2)
54  j+= 64;
55  if (j >= end - ptr)
56  break;
57  if (ptr[j + 8] & 1)
58  j+= 64;
59  if (j >= end - ptr)
60  break;
61  if (AV_RB24(ptr + j + 9) & 0xFFFFFE)
62  break;
63  seq++;
64  break;
65  case PICTURE_START_CODE: pic++; break;
66  case PACK_START_CODE: pspack++; break;
67  case 0x1b6:
68  res++; break;
69  }
70  if (code >= SLICE_START_CODE && code <= 0x1af) {
71  if (last >= SLICE_START_CODE && last <= 0x1af) {
72  if (code >= last) slice++;
73  else sicle++;
74  }else{
75  if (code == SLICE_START_CODE) slice++;
76  else sicle++;
77  }
78  }
79  if ((code & 0x1f0) == VIDEO_ID) vpes++;
80  else if((code & 0x1e0) == AUDIO_ID) apes++;
81  last = code;
82  }
83  }
84  if(seq && seq*9<=pic*10 && pic*9<=slice*10 && !pspack && !apes && !res && slice > sicle) {
85  if(vpes) return AVPROBE_SCORE_EXTENSION / 4;
86  else return pic>1 ? AVPROBE_SCORE_EXTENSION + 1 : AVPROBE_SCORE_EXTENSION / 2; // +1 for .mpg
87  }
88  return 0;
89 }
90 
#define NULL
Definition: coverity.c:32
#define FF_DEF_RAWVIDEO_DEMUXER(shortname, longname, probe, ext, id)
Definition: rawdec.h:71
#define PICTURE_START_CODE
Definition: mpegvideodec.c:31
#define AUDIO_ID
Definition: mpegvideodec.c:35
#define SEQ_START_CODE
Definition: mpegvideodec.c:29
uint8_t
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
const uint8_t * avpriv_find_start_code(const uint8_t *p, const uint8_t *end, uint32_t *state)
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:449
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
#define PACK_START_CODE
Definition: mpegvideodec.c:33
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_RB24
Definition: bytestream.h:87
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:456
This structure contains the data a format has to probe a file.
Definition: avformat.h:446
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
Main libavformat public API header.
common internal api header.
#define VIDEO_ID
Definition: mpegvideodec.c:34
static int mpegvideo_probe(const AVProbeData *p)
Definition: mpegvideodec.c:37
#define SLICE_START_CODE
Definition: mpegvideodec.c:32