Libav
yop.c
Go to the documentation of this file.
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 "get_bits.h"
30 #include "internal.h"
31 
32 typedef struct YopDecContext {
34 
36  int first_color[2];
38 
45 
46 // These tables are taken directly from:
47 // http://wiki.multimedia.cx/index.php?title=Psygnosis_YOP
48 
55 static const uint8_t paint_lut[15][4] =
56  {{1, 2, 3, 4}, {1, 2, 0, 3},
57  {1, 2, 1, 3}, {1, 2, 2, 3},
58  {1, 0, 2, 3}, {1, 0, 0, 2},
59  {1, 0, 1, 2}, {1, 1, 2, 3},
60  {0, 1, 2, 3}, {0, 1, 0, 2},
61  {1, 1, 0, 2}, {0, 1, 1, 2},
62  {0, 0, 1, 2}, {0, 0, 0, 1},
63  {1, 1, 1, 2},
64  };
65 
70 static const int8_t motion_vector[16][2] =
71  {{-4, -4}, {-2, -4},
72  { 0, -4}, { 2, -4},
73  {-4, -2}, {-4, 0},
74  {-3, -3}, {-1, -3},
75  { 1, -3}, { 3, -3},
76  {-3, -1}, {-2, -2},
77  { 0, -2}, { 2, -2},
78  { 4, -2}, {-2, 0},
79  };
80 
82 {
83  YopDecContext *s = avctx->priv_data;
84  s->avctx = avctx;
85 
86  if (avctx->width & 1 || avctx->height & 1 ||
87  av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
88  av_log(avctx, AV_LOG_ERROR, "YOP has invalid dimensions\n");
89  return AVERROR_INVALIDDATA;
90  }
91 
92  if (avctx->extradata_size < 3) {
93  av_log(avctx, AV_LOG_ERROR, "Missing or incomplete extradata.\n");
94  return AVERROR_INVALIDDATA;
95  }
96 
97  avctx->pix_fmt = AV_PIX_FMT_PAL8;
98 
99  s->num_pal_colors = avctx->extradata[0];
100  s->first_color[0] = avctx->extradata[1];
101  s->first_color[1] = avctx->extradata[2];
102 
103  if (s->num_pal_colors + s->first_color[0] > 256 ||
104  s->num_pal_colors + s->first_color[1] > 256) {
105  av_log(avctx, AV_LOG_ERROR,
106  "YOP: palette parameters invalid, header probably corrupt\n");
107  return AVERROR_INVALIDDATA;
108  }
109 
110  return 0;
111 }
112 
118 static int yop_paint_block(YopDecContext *s, int linesize, int tag)
119 {
120  if (s->src_end - s->srcptr < paint_lut[tag][3]) {
121  av_log(s->avctx, AV_LOG_ERROR, "Packet too small.\n");
122  return AVERROR_INVALIDDATA;
123  }
124 
125  s->dstptr[0] = s->srcptr[0];
126  s->dstptr[1] = s->srcptr[paint_lut[tag][0]];
127  s->dstptr[linesize] = s->srcptr[paint_lut[tag][1]];
128  s->dstptr[linesize + 1] = s->srcptr[paint_lut[tag][2]];
129 
130  // The number of src bytes consumed is in the last part of the lut entry.
131  s->srcptr += paint_lut[tag][3];
132  return 0;
133 }
134 
139 static int yop_copy_previous_block(YopDecContext *s, int linesize, int copy_tag)
140 {
141  uint8_t *bufptr;
142 
143  // Calculate position for the copy source
144  bufptr = s->dstptr + motion_vector[copy_tag][0] +
145  linesize * motion_vector[copy_tag][1];
146  if (bufptr < s->dstbuf) {
148  "YOP: cannot decode, file probably corrupt\n");
149  return AVERROR_INVALIDDATA;
150  }
151 
152  s->dstptr[0] = bufptr[0];
153  s->dstptr[1] = bufptr[1];
154  s->dstptr[linesize] = bufptr[linesize];
155  s->dstptr[linesize + 1] = bufptr[linesize + 1];
156 
157  return 0;
158 }
159 
165 {
166  int ret;
167 
168  if (s->low_nibble) {
169  ret = *s->low_nibble & 0xf;
170  s->low_nibble = NULL;
171  }else {
172  s->low_nibble = s->srcptr++;
173  ret = *s->low_nibble >> 4;
174  }
175  return ret;
176 }
177 
178 static int yop_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
179  AVPacket *avpkt)
180 {
181  YopDecContext *s = avctx->priv_data;
182  AVFrame *frame = data;
183  int tag, firstcolor, is_odd_frame;
184  int ret, i, x, y;
185  uint32_t *palette;
186 
187  if (avpkt->size < 4 + 3 * s->num_pal_colors) {
188  av_log(avctx, AV_LOG_ERROR, "Packet too small.\n");
189  return AVERROR_INVALIDDATA;
190  }
191 
192  ret = ff_get_buffer(avctx, frame, 0);
193  if (ret < 0) {
194  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
195  return ret;
196  }
197 
198  if (!avctx->frame_number)
199  memset(frame->data[1], 0, AVPALETTE_SIZE);
200 
201  s->dstbuf = frame->data[0];
202  s->dstptr = frame->data[0];
203  s->srcptr = avpkt->data + 4;
204  s->src_end = avpkt->data + avpkt->size;
205  s->low_nibble = NULL;
206 
207  is_odd_frame = avpkt->data[0];
208  firstcolor = s->first_color[is_odd_frame];
209  palette = (uint32_t *)frame->data[1];
210 
211  for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3)
212  palette[i + firstcolor] = (s->srcptr[0] << 18) |
213  (s->srcptr[1] << 10) |
214  (s->srcptr[2] << 2);
215 
216  frame->palette_has_changed = 1;
217 
218  for (y = 0; y < avctx->height; y += 2) {
219  for (x = 0; x < avctx->width; x += 2) {
220  if (s->srcptr - avpkt->data >= avpkt->size) {
221  av_log(avctx, AV_LOG_ERROR, "Packet too small.\n");
222  return AVERROR_INVALIDDATA;
223  }
224 
225  tag = yop_get_next_nibble(s);
226 
227  if (tag != 0xf) {
228  ret = yop_paint_block(s, frame->linesize[0], tag);
229  if (ret < 0)
230  return ret;
231  } else {
232  tag = yop_get_next_nibble(s);
233  ret = yop_copy_previous_block(s, frame->linesize[0], tag);
234  if (ret < 0)
235  return ret;
236  }
237  s->dstptr += 2;
238  }
239  s->dstptr += 2*frame->linesize[0] - x;
240  }
241 
242  *got_frame = 1;
243  return avpkt->size;
244 }
245 
247  .name = "yop",
248  .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Video"),
249  .type = AVMEDIA_TYPE_VIDEO,
250  .id = AV_CODEC_ID_YOP,
251  .priv_data_size = sizeof(YopDecContext),
254  .capabilities = CODEC_CAP_DR1,
255 };