FFmpeg: libavcodec/xfacedec.c Source File

FFmpeg
xfacedec.c
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1 /*
2  * Copyright (c) 1990 James Ashton - Sydney University
3  * Copyright (c) 2012 Stefano Sabatini
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * X-Face decoder, based on libcompface, by James Ashton.
25  */
26 
27 #include "libavutil/pixdesc.h"
28 #include "avcodec.h"
29 #include "bytestream.h"
30 #include "internal.h"
31 #include "xface.h"
32 
33  static int pop_integer(BigInt *b, const ProbRange *pranges)
34 {
35  uint8_t r;
36  int i;
37 
38  /* extract the last byte into r, and shift right b by 8 bits */
39  ff_big_div(b, 0, &r);
40 
41  i = 0;
42  while (r < pranges->offset || r >= pranges->range + pranges->offset) {
43  pranges++;
44  i++;
45  }
46  ff_big_mul(b, pranges->range);
47  ff_big_add(b, r - pranges->offset);
48  return i;
49 }
50 
51  static void pop_greys(BigInt *b, char *bitmap, int w, int h)
52 {
53  if (w > 3) {
54  w /= 2;
55  h /= 2;
56  pop_greys(b, bitmap, w, h);
57  pop_greys(b, bitmap + w, w, h);
58  pop_greys(b, bitmap + XFACE_WIDTH * h, w, h);
59  pop_greys(b, bitmap + XFACE_WIDTH * h + w, w, h);
60  } else {
61  w = pop_integer(b, ff_xface_probranges_2x2);
62  if (w & 1) bitmap[0] = 1;
63  if (w & 2) bitmap[1] = 1;
64  if (w & 4) bitmap[XFACE_WIDTH] = 1;
65  if (w & 8) bitmap[XFACE_WIDTH + 1] = 1;
66  }
67 }
68 
69  static void decode_block(BigInt *b, char *bitmap, int w, int h, int level)
70 {
71  switch (pop_integer(b, &ff_xface_probranges_per_level[level][0])) {
72  case XFACE_COLOR_WHITE:
73  return;
74  case XFACE_COLOR_BLACK:
75  pop_greys(b, bitmap, w, h);
76  return;
77  default:
78  w /= 2;
79  h /= 2;
80  level++;
81  decode_block(b, bitmap, w, h, level);
82  decode_block(b, bitmap + w, w, h, level);
83  decode_block(b, bitmap + h * XFACE_WIDTH, w, h, level);
84  decode_block(b, bitmap + w + h * XFACE_WIDTH, w, h, level);
85  return;
86  }
87 }
88 
89  typedef struct XFaceContext {
90   uint8_t bitmap[XFACE_PIXELS]; ///< image used internally for decoding
91 } XFaceContext;
92 
93  static av_cold int xface_decode_init(AVCodecContext *avctx)
94 {
95  if (avctx->width || avctx->height) {
96  if (avctx->width != XFACE_WIDTH || avctx->height != XFACE_HEIGHT) {
97  av_log(avctx, AV_LOG_ERROR,
98  "Size value %dx%d not supported, only accepts a size of %dx%d\n",
99  avctx->width, avctx->height, XFACE_WIDTH, XFACE_HEIGHT);
100  return AVERROR(EINVAL);
101  }
102  }
103 
104  avctx->width = XFACE_WIDTH;
105  avctx->height = XFACE_HEIGHT;
106  avctx->pix_fmt = AV_PIX_FMT_MONOWHITE;
107 
108  return 0;
109 }
110 
111  static int xface_decode_frame(AVCodecContext *avctx,
112  void *data, int *got_frame,
113  AVPacket *avpkt)
114 {
115  XFaceContext *xface = avctx->priv_data;
116  int ret, i, j, k;
117  uint8_t byte;
118  BigInt b = {0};
119  char *buf;
120  int64_t c;
121  AVFrame *frame = data;
122 
123  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
124  return ret;
125 
126  for (i = 0, k = 0; avpkt->data[i] && i < avpkt->size; i++) {
127  c = avpkt->data[i];
128 
129  /* ignore invalid digits */
130  if (c < XFACE_FIRST_PRINT || c > XFACE_LAST_PRINT)
131  continue;
132 
133  if (++k > XFACE_MAX_DIGITS) {
134  av_log(avctx, AV_LOG_WARNING,
135  "Buffer is longer than expected, truncating at byte %d\n", i);
136  break;
137  }
138  ff_big_mul(&b, XFACE_PRINTS);
139  ff_big_add(&b, c - XFACE_FIRST_PRINT);
140  }
141 
142  /* decode image and put it in bitmap */
143  memset(xface->bitmap, 0, XFACE_PIXELS);
144  buf = xface->bitmap;
145  decode_block(&b, buf, 16, 16, 0);
146  decode_block(&b, buf + 16, 16, 16, 0);
147  decode_block(&b, buf + 32, 16, 16, 0);
148  decode_block(&b, buf + XFACE_WIDTH * 16, 16, 16, 0);
149  decode_block(&b, buf + XFACE_WIDTH * 16 + 16, 16, 16, 0);
150  decode_block(&b, buf + XFACE_WIDTH * 16 + 32, 16, 16, 0);
151  decode_block(&b, buf + XFACE_WIDTH * 32 , 16, 16, 0);
152  decode_block(&b, buf + XFACE_WIDTH * 32 + 16, 16, 16, 0);
153  decode_block(&b, buf + XFACE_WIDTH * 32 + 32, 16, 16, 0);
154 
155  ff_xface_generate_face(xface->bitmap, xface->bitmap);
156 
157  /* convert image from 1=black 0=white bitmap to MONOWHITE */
158  buf = frame->data[0];
159  for (i = 0, j = 0, k = 0, byte = 0; i < XFACE_PIXELS; i++) {
160  byte += xface->bitmap[i];
161  if (k == 7) {
162  buf[j++] = byte;
163  byte = k = 0;
164  } else {
165  k++;
166  byte <<= 1;
167  }
168  if (j == XFACE_WIDTH/8) {
169  j = 0;
170  buf += frame->linesize[0];
171  }
172  }
173 
174  *got_frame = 1;
175 
176  return avpkt->size;
177 }
178 
179  AVCodec ff_xface_decoder = {
180  .name = "xface",
181  .long_name = NULL_IF_CONFIG_SMALL("X-face image"),
182  .type = AVMEDIA_TYPE_VIDEO,
183  .id = AV_CODEC_ID_XFACE,
184  .priv_data_size = sizeof(XFaceContext),
185  .init = xface_decode_init,
186  .decode = xface_decode_frame,
187  .pix_fmts = (const enum AVPixelFormat[]) { AV_PIX_FMT_MONOWHITE, AV_PIX_FMT_NONE },
188 };
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