FFmpeg: libavcodec/yop.c Source File

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libavcodec

yop.c

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1 /*

2 * Psygnosis YOP decoder

3 *

5 * derived from the code by

7 *

8 * This file is part of FFmpeg.

9 *

10 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software

22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

23 */

25 #include "libavutil/intreadwrite.h"

26 #include "libavutil/imgutils.h"

28 #include "avcodec.h"

29 #include "get_bits.h"

30 #include "internal.h"

32 typedef struct YopDecContext {

33 AVCodecContext *avctx;

34 AVFrame *frame;

36 int num_pal_colors;

37 int first_color[2];

38 int frame_data_length;

40 uint8_t *low_nibble;

41 uint8_t *srcptr;

42 uint8_t *src_end;

43 uint8_t *dstptr;

44 uint8_t *dstbuf;

45 } YopDecContext;

47 // These tables are taken directly from:

48 // http://wiki.multimedia.cx/index.php?title=Psygnosis_YOP

50 /**

51 * Lookup table for painting macroblocks. Bytes 0-2 of each entry contain

52 * the macroblock positions to be painted (taken as (0, B0, B1, B2)).

53 * Byte 3 contains the number of bytes consumed on the input,

54 * equal to max(bytes 0-2) + 1.

55 */

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 };

67 /**

68 * Lookup table for copying macroblocks. Each entry contains the respective

69 * x and y pixel offset for the copy source.

70 */

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 };

82 static av_cold int yop_decode_close(AVCodecContext *avctx)

83 {

84 YopDecContext *s = avctx->priv_data;

86 av_frame_free(&s->frame);

88 return 0;

89 }

91 static av_cold int yop_decode_init(AVCodecContext *avctx)

92 {

93 YopDecContext *s = avctx->priv_data;

94 s->avctx = avctx;

96 if (avctx->width & 1 || avctx->height & 1 ||

97 av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {

98 av_log(avctx, AV_LOG_ERROR, "YOP has invalid dimensions\n");

99 return AVERROR_INVALIDDATA;

100 }

101

102 if (avctx->extradata_size < 3) {

103 av_log(avctx, AV_LOG_ERROR, "Missing or incomplete extradata.\n");

104 return AVERROR_INVALIDDATA;

105 }

106

107 avctx->pix_fmt = AV_PIX_FMT_PAL8;

108

109 s->num_pal_colors = avctx->extradata[0];

110 s->first_color[0] = avctx->extradata[1];

111 s->first_color[1] = avctx->extradata[2];

112

113 if (s->num_pal_colors + s->first_color[0] > 256 ||

114 s->num_pal_colors + s->first_color[1] > 256) {

115 av_log(avctx, AV_LOG_ERROR,

116 "Palette parameters invalid, header probably corrupt\n");

117 return AVERROR_INVALIDDATA;

118 }

119

120 s->frame = av_frame_alloc();

121

122 return 0;

123 }

124

125 /**

126 * Paint a macroblock using the pattern in paint_lut.

127 * @param s codec context

128 * @param tag the tag that was in the nibble

129 */

130 static int yop_paint_block(YopDecContext *s, int linesize, int tag)

131 {

132 if (s->src_end - s->srcptr < paint_lut[tag][3]) {

133 av_log(s->avctx, AV_LOG_ERROR, "Packet too small.\n");

134 return AVERROR_INVALIDDATA;

135 }

136

137 s->dstptr[0] = s->srcptr[0];

138 s->dstptr[1] = s->srcptr[paint_lut[tag][0]];

139 s->dstptr[linesize] = s->srcptr[paint_lut[tag][1]];

140 s->dstptr[linesize + 1] = s->srcptr[paint_lut[tag][2]];

141

142 // The number of src bytes consumed is in the last part of the lut entry.

143 s->srcptr += paint_lut[tag][3];

144 return 0;

145 }

146

147 /**

148 * Copy a previously painted macroblock to the current_block.

149 * @param copy_tag the tag that was in the nibble

150 */

151 static int yop_copy_previous_block(YopDecContext *s, int linesize, int copy_tag)

152 {

153 uint8_t *bufptr;

154

155 // Calculate position for the copy source

156 bufptr = s->dstptr + motion_vector[copy_tag][0] +

157 linesize * motion_vector[copy_tag][1];

158 if (bufptr < s->dstbuf) {

159 av_log(s->avctx, AV_LOG_ERROR, "File probably corrupt\n");

160 return AVERROR_INVALIDDATA;

161 }

162

163 s->dstptr[0] = bufptr[0];

164 s->dstptr[1] = bufptr[1];

165 s->dstptr[linesize] = bufptr[linesize];

166 s->dstptr[linesize + 1] = bufptr[linesize + 1];

167

168 return 0;

169 }

170

171 /**

172 * Return the next nibble in sequence, consuming a new byte on the input

173 * only if necessary.

174 */

175 static uint8_t yop_get_next_nibble(YopDecContext *s)

176 {

177 int ret;

178

179 if (s->low_nibble) {

180 ret = *s->low_nibble & 0xf;

181 s->low_nibble = NULL;

182 }else {

183 s->low_nibble = s->srcptr++;

184 ret = *s->low_nibble >> 4;

185 }

186 return ret;

187 }

188

189 static int yop_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

190 AVPacket *avpkt)

191 {

192 YopDecContext *s = avctx->priv_data;

193 AVFrame *frame = s->frame;

194 int tag, firstcolor, is_odd_frame;

195 int ret, i, x, y;

196 uint32_t *palette;

197

198 if (avpkt->size < 4 + 3 * s->num_pal_colors) {

199 av_log(avctx, AV_LOG_ERROR, "Packet too small.\n");

200 return AVERROR_INVALIDDATA;

201 }

202

203 if ((ret = ff_reget_buffer(avctx, frame)) < 0)

204 return ret;

205

206 if (!avctx->frame_number)

207 memset(frame->data[1], 0, AVPALETTE_SIZE);

208

209 s->dstbuf = frame->data[0];

210 s->dstptr = frame->data[0];

211 s->srcptr = avpkt->data + 4;

212 s->src_end = avpkt->data + avpkt->size;

213 s->low_nibble = NULL;

214

215 is_odd_frame = avpkt->data[0];

216 if(is_odd_frame>1){

217 av_log(avctx, AV_LOG_ERROR, "frame is too odd %d\n", is_odd_frame);

218 return AVERROR_INVALIDDATA;

219 }

220 firstcolor = s->first_color[is_odd_frame];

221 palette = (uint32_t *)frame->data[1];

222

223 for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3) {

224 palette[i + firstcolor] = (s->srcptr[0] << 18) |

225 (s->srcptr[1] << 10) |

226 (s->srcptr[2] << 2);

227 palette[i + firstcolor] |= 0xFFU << 24 |

228 (palette[i + firstcolor] >> 6) & 0x30303;

229 }

230

231 frame->palette_has_changed = 1;

232

233 for (y = 0; y < avctx->height; y += 2) {

234 for (x = 0; x < avctx->width; x += 2) {

235 if (s->srcptr - avpkt->data >= avpkt->size) {

236 av_log(avctx, AV_LOG_ERROR, "Packet too small.\n");

237 return AVERROR_INVALIDDATA;

238 }

239

240 tag = yop_get_next_nibble(s);

241

242 if (tag != 0xf) {

243 ret = yop_paint_block(s, frame->linesize[0], tag);

244 if (ret < 0)

245 return ret;

246 } else {

247 tag = yop_get_next_nibble(s);

248 ret = yop_copy_previous_block(s, frame->linesize[0], tag);

249 if (ret < 0)

250 return ret;

251 }

252 s->dstptr += 2;

253 }

254 s->dstptr += 2*frame->linesize[0] - x;

255 }

256

257 if ((ret = av_frame_ref(data, s->frame)) < 0)

258 return ret;

259

260 *got_frame = 1;

261 return avpkt->size;

262 }

263

264 AVCodec ff_yop_decoder = {

265 .name = "yop",

266 .type = AVMEDIA_TYPE_VIDEO,

267 .id = AV_CODEC_ID_YOP,

268 .priv_data_size = sizeof(YopDecContext),

269 .init = yop_decode_init,

270 .close = yop_decode_close,

271 .decode = yop_decode_frame,

272 .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Video"),

273 };

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