yop.c
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1 /*
2  * Psygnosis YOP decoder
3  *
4  * Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>
5  * derived from the code by
6  * Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.com>
7  *
8  * This file is part of Libav.
9  *
10  * Libav is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU Lesser General Public
12  * License as published by the Free Software Foundation; either
13  * version 2.1 of the License, or (at your option) any later version.
14  *
15  * Libav is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18  * Lesser General Public License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public
21  * License along with Libav; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
25 #include "libavutil/intreadwrite.h"
26 #include "libavutil/imgutils.h"
27 
28 #include "avcodec.h"
29 #include "internal.h"
30 #include "get_bits.h"
31 
32 typedef struct YopDecContext {
35 
37  int first_color[2];
39  int row_pos;
40 
41  uint8_t *low_nibble;
42  uint8_t *srcptr;
43  uint8_t *dstptr;
44  uint8_t *dstbuf;
46 
47 // These tables are taken directly from:
48 // http://wiki.multimedia.cx/index.php?title=Psygnosis_YOP
49 
56 static const uint8_t paint_lut[15][4] =
57  {{1, 2, 3, 4}, {1, 2, 0, 3},
58  {1, 2, 1, 3}, {1, 2, 2, 3},
59  {1, 0, 2, 3}, {1, 0, 0, 2},
60  {1, 0, 1, 2}, {1, 1, 2, 3},
61  {0, 1, 2, 3}, {0, 1, 0, 2},
62  {1, 1, 0, 2}, {0, 1, 1, 2},
63  {0, 0, 1, 2}, {0, 0, 0, 1},
64  {1, 1, 1, 2},
65  };
66 
71 static const int8_t motion_vector[16][2] =
72  {{-4, -4}, {-2, -4},
73  { 0, -4}, { 2, -4},
74  {-4, -2}, {-4, 0},
75  {-3, -3}, {-1, -3},
76  { 1, -3}, { 3, -3},
77  {-3, -1}, {-2, -2},
78  { 0, -2}, { 2, -2},
79  { 4, -2}, {-2, 0},
80  };
81 
83 {
84  YopDecContext *s = avctx->priv_data;
85  s->avctx = avctx;
86 
87  if (avctx->width & 1 || avctx->height & 1 ||
88  av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
89  av_log(avctx, AV_LOG_ERROR, "YOP has invalid dimensions\n");
90  return -1;
91  }
92 
93  avctx->pix_fmt = PIX_FMT_PAL8;
94 
95  s->num_pal_colors = avctx->extradata[0];
96  s->first_color[0] = avctx->extradata[1];
97  s->first_color[1] = avctx->extradata[2];
98 
99  if (s->num_pal_colors + s->first_color[0] > 256 ||
100  s->num_pal_colors + s->first_color[1] > 256) {
101  av_log(avctx, AV_LOG_ERROR,
102  "YOP: palette parameters invalid, header probably corrupt\n");
103  return AVERROR_INVALIDDATA;
104  }
105 
106  return 0;
107 }
108 
110 {
111  YopDecContext *s = avctx->priv_data;
112  if (s->frame.data[0])
113  avctx->release_buffer(avctx, &s->frame);
114  return 0;
115 }
116 
122 static void yop_paint_block(YopDecContext *s, int tag)
123 {
124  s->dstptr[0] = s->srcptr[0];
125  s->dstptr[1] = s->srcptr[paint_lut[tag][0]];
126  s->dstptr[s->frame.linesize[0]] = s->srcptr[paint_lut[tag][1]];
127  s->dstptr[s->frame.linesize[0] + 1] = s->srcptr[paint_lut[tag][2]];
128 
129  // The number of src bytes consumed is in the last part of the lut entry.
130  s->srcptr += paint_lut[tag][3];
131 }
132 
137 static int yop_copy_previous_block(YopDecContext *s, int copy_tag)
138 {
139  uint8_t *bufptr;
140 
141  // Calculate position for the copy source
142  bufptr = s->dstptr + motion_vector[copy_tag][0] +
143  s->frame.linesize[0] * motion_vector[copy_tag][1];
144  if (bufptr < s->dstbuf) {
146  "YOP: cannot decode, file probably corrupt\n");
147  return AVERROR_INVALIDDATA;
148  }
149 
150  s->dstptr[0] = bufptr[0];
151  s->dstptr[1] = bufptr[1];
152  s->dstptr[s->frame.linesize[0]] = bufptr[s->frame.linesize[0]];
153  s->dstptr[s->frame.linesize[0] + 1] = bufptr[s->frame.linesize[0] + 1];
154 
155  return 0;
156 }
157 
163 {
164  int ret;
165 
166  if (s->low_nibble) {
167  ret = *s->low_nibble & 0xf;
168  s->low_nibble = NULL;
169  }else {
170  s->low_nibble = s->srcptr++;
171  ret = *s->low_nibble >> 4;
172  }
173  return ret;
174 }
175 
180 {
181  // If we are advancing to the next row of macroblocks
182  if (s->row_pos == s->frame.linesize[0] - 2) {
183  s->dstptr += s->frame.linesize[0];
184  s->row_pos = 0;
185  }else {
186  s->row_pos += 2;
187  }
188  s->dstptr += 2;
189 }
190 
191 static int yop_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
192  AVPacket *avpkt)
193 {
194  YopDecContext *s = avctx->priv_data;
195  int tag, firstcolor, is_odd_frame;
196  int ret, i;
197  uint32_t *palette;
198 
199  if (s->frame.data[0])
200  avctx->release_buffer(avctx, &s->frame);
201 
202  ret = ff_get_buffer(avctx, &s->frame);
203  if (ret < 0) {
204  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
205  return ret;
206  }
207 
208  s->frame.linesize[0] = avctx->width;
209 
210  s->dstbuf = s->frame.data[0];
211  s->dstptr = s->frame.data[0];
212  s->srcptr = avpkt->data + 4;
213  s->row_pos = 0;
214  s->low_nibble = NULL;
215 
216  is_odd_frame = avpkt->data[0];
217  firstcolor = s->first_color[is_odd_frame];
218  palette = (uint32_t *)s->frame.data[1];
219 
220  for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3)
221  palette[i + firstcolor] = (s->srcptr[0] << 18) |
222  (s->srcptr[1] << 10) |
223  (s->srcptr[2] << 2);
224 
225  s->frame.palette_has_changed = 1;
226 
227  while (s->dstptr - s->dstbuf <
228  avctx->width * avctx->height &&
229  s->srcptr - avpkt->data < avpkt->size) {
230 
231  tag = yop_get_next_nibble(s);
232 
233  if (tag != 0xf) {
234  yop_paint_block(s, tag);
235  }else {
236  tag = yop_get_next_nibble(s);
237  ret = yop_copy_previous_block(s, tag);
238  if (ret < 0) {
239  avctx->release_buffer(avctx, &s->frame);
240  return ret;
241  }
242  }
244  }
245 
246  *data_size = sizeof(AVFrame);
247  *(AVFrame *) data = s->frame;
248  return avpkt->size;
249 }
250 
252  .name = "yop",
253  .type = AVMEDIA_TYPE_VIDEO,
254  .id = CODEC_ID_YOP,
255  .priv_data_size = sizeof(YopDecContext),
259  .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Video"),
260 };