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xbmdec.c
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1 /*
2  * XBM image format
3  *
4  * Copyright (c) 2012 Paul B Mahol
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 "avcodec.h"
24 #include "internal.h"
25 #include "mathops.h"
26 #include "libavutil/avstring.h"
27 
29 {
31 
32  return 0;
33 }
34 
35 static int convert(uint8_t x)
36 {
37  if (x >= 'a')
38  x -= 87;
39  else if (x >= 'A')
40  x -= 55;
41  else
42  x -= '0';
43  return x;
44 }
45 
46 static int xbm_decode_frame(AVCodecContext *avctx, void *data,
47  int *got_frame, AVPacket *avpkt)
48 {
49  AVFrame *p = data;
50  const uint8_t *end, *ptr = avpkt->data;
51  uint8_t *dst;
52  int ret, linesize, i, j;
53 
54  end = avpkt->data + avpkt->size;
55  while (!avctx->width || !avctx->height) {
56  char name[256];
57  int number, len;
58 
59  ptr += strcspn(ptr, "#");
60  if (sscanf(ptr, "#define %255s %u", name, &number) != 2) {
61  av_log(avctx, AV_LOG_ERROR, "Unexpected preprocessor directive\n");
62  return AVERROR_INVALIDDATA;
63  }
64 
65  len = strlen(name);
66  if ((len > 6) && !avctx->height && !memcmp(name + len - 7, "_height", 7)) {
67  avctx->height = number;
68  } else if ((len > 5) && !avctx->width && !memcmp(name + len - 6, "_width", 6)) {
69  avctx->width = number;
70  } else {
71  av_log(avctx, AV_LOG_ERROR, "Unknown define '%s'\n", name);
72  return AVERROR_INVALIDDATA;
73  }
74  ptr += strcspn(ptr, "\n\r") + 1;
75  }
76 
77  if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
78  return ret;
79 
80  // goto start of image data
81  ptr += strcspn(ptr, "{") + 1;
82 
83  linesize = (avctx->width + 7) / 8;
84  for (i = 0; i < avctx->height; i++) {
85  dst = p->data[0] + i * p->linesize[0];
86  for (j = 0; j < linesize; j++) {
87  uint8_t val;
88 
89  ptr += strcspn(ptr, "x") + 1;
90  if (ptr < end && av_isxdigit(*ptr)) {
91  val = convert(*ptr);
92  ptr++;
93  if (av_isxdigit(*ptr))
94  val = (val << 4) + convert(*ptr);
95  *dst++ = ff_reverse[val];
96  } else {
97  av_log(avctx, AV_LOG_ERROR, "Unexpected data at '%.8s'\n", ptr);
98  return AVERROR_INVALIDDATA;
99  }
100  }
101  }
102 
103  p->key_frame = 1;
105 
106  *got_frame = 1;
107 
108  return avpkt->size;
109 }
110 
112  .name = "xbm",
113  .type = AVMEDIA_TYPE_VIDEO,
114  .id = AV_CODEC_ID_XBM,
115  .init = xbm_decode_init,
116  .decode = xbm_decode_frame,
117  .capabilities = CODEC_CAP_DR1,
118  .long_name = NULL_IF_CONFIG_SMALL("XBM (X BitMap) image"),
119 };