FFmpeg: libavcodec/vb.c Source File

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libavcodec

vb.c

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1 /*

2 * Beam Software VB decoder

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 */

22 /**

23 * @file

24 * VB Video decoder

25 */

27 #include <stdio.h>

28 #include <stdlib.h>

30 #include "avcodec.h"

31 #include "bytestream.h"

32 #include "internal.h"

34 enum VBFlags {

35 VB_HAS_GMC = 0x01,

36 VB_HAS_AUDIO = 0x04,

37 VB_HAS_VIDEO = 0x08,

38 VB_HAS_PALETTE = 0x10,

39 VB_HAS_LENGTH = 0x20

40 };

42 typedef struct VBDecContext {

43 AVCodecContext *avctx;

45 uint8_t *frame, *prev_frame;

46 uint32_t pal[AVPALETTE_COUNT];

47 GetByteContext stream;

48 } VBDecContext;

50 static const uint16_t vb_patterns[64] = {

51 0x0660, 0xFF00, 0xCCCC, 0xF000, 0x8888, 0x000F, 0x1111, 0xFEC8,

52 0x8CEF, 0x137F, 0xF731, 0xC800, 0x008C, 0x0013, 0x3100, 0xCC00,

53 0x00CC, 0x0033, 0x3300, 0x0FF0, 0x6666, 0x00F0, 0x0F00, 0x2222,

54 0x4444, 0xF600, 0x8CC8, 0x006F, 0x1331, 0x318C, 0xC813, 0x33CC,

55 0x6600, 0x0CC0, 0x0066, 0x0330, 0xF900, 0xC88C, 0x009F, 0x3113,

56 0x6000, 0x0880, 0x0006, 0x0110, 0xCC88, 0xFC00, 0x00CF, 0x88CC,

57 0x003F, 0x1133, 0x3311, 0xF300, 0x6FF6, 0x0603, 0x08C6, 0x8C63,

58 0xC631, 0x6310, 0xC060, 0x0136, 0x136C, 0x36C8, 0x6C80, 0x324C

59 };

61 static void vb_decode_palette(VBDecContext *c, int data_size)

62 {

63 int start, size, i;

65 start = bytestream2_get_byte(&c->stream);

66 size = (bytestream2_get_byte(&c->stream) - 1) & 0xFF;

67 if (start + size > 255) {

68 av_log(c->avctx, AV_LOG_ERROR, "Palette change runs beyond entry 256\n");

69 return;

70 }

71 if (size*3+2 > data_size) {

72 av_log(c->avctx, AV_LOG_ERROR, "Palette data runs beyond chunk size\n");

73 return;

74 }

75 for (i = start; i <= start + size; i++)

76 c->pal[i] = 0xFFU << 24 | bytestream2_get_be24(&c->stream);

77 }

79 static inline int check_pixel(uint8_t *buf, uint8_t *start, uint8_t *end)

80 {

81 return buf >= start && buf < end;

82 }

84 static inline int check_line(uint8_t *buf, uint8_t *start, uint8_t *end)

85 {

86 return buf >= start && (buf + 4) <= end;

87 }

89 static int vb_decode_framedata(VBDecContext *c, int offset)

90 {

91 GetByteContext g;

92 uint8_t *prev, *cur;

93 int blk, blocks, t, blk2;

94 int blocktypes = 0;

95 int x, y, a, b;

96 int pattype, pattern;

97 const int width = c->avctx->width;

98 uint8_t *pstart = c->prev_frame;

99 uint8_t *pend = c->prev_frame + width*c->avctx->height;

100

101 g = c->stream;

102

103 prev = c->prev_frame + offset;

104 cur = c->frame;

105

106 blocks = (c->avctx->width >> 2) * (c->avctx->height >> 2);

107 blk2 = 0;

108 for (blk = 0; blk < blocks; blk++) {

109 if (!(blk & 3)) {

110 blocktypes = bytestream2_get_byte(&g);

111 }

112 switch (blocktypes & 0xC0) {

113 case 0x00: //skip

114 for (y = 0; y < 4; y++)

115 if (check_line(prev + y*width, pstart, pend))

116 memcpy(cur + y*width, prev + y*width, 4);

117 else

118 memset(cur + y*width, 0, 4);

119 break;

120 case 0x40:

121 t = bytestream2_get_byte(&g);

122 if (!t) { //raw block

123 if (bytestream2_get_bytes_left(&g) < 16) {

124 av_log(c->avctx, AV_LOG_ERROR, "Insufficient data\n");

125 return AVERROR_INVALIDDATA;

126 }

127 for (y = 0; y < 4; y++)

128 bytestream2_get_buffer(&g, cur + y * width, 4);

129 } else { // motion compensation

130 x = ((t & 0xF)^8) - 8;

131 y = ((t >> 4) ^8) - 8;

132 t = x + y*width;

133 for (y = 0; y < 4; y++)

134 if (check_line(prev + t + y*width, pstart, pend))

135 memcpy(cur + y*width, prev + t + y*width, 4);

136 else

137 memset(cur + y*width, 0, 4);

138 }

139 break;

140 case 0x80: // fill

141 t = bytestream2_get_byte(&g);

142 for (y = 0; y < 4; y++)

143 memset(cur + y*width, t, 4);

144 break;

145 case 0xC0: // pattern fill

146 t = bytestream2_get_byte(&g);

147 pattype = t >> 6;

148 pattern = vb_patterns[t & 0x3F];

149 switch (pattype) {

150 case 0:

151 a = bytestream2_get_byte(&g);

152 b = bytestream2_get_byte(&g);

153 for (y = 0; y < 4; y++)

154 for (x = 0; x < 4; x++, pattern >>= 1)

155 cur[x + y*width] = (pattern & 1) ? b : a;

156 break;

157 case 1:

158 pattern = ~pattern;

159 case 2:

160 a = bytestream2_get_byte(&g);

161 for (y = 0; y < 4; y++)

162 for (x = 0; x < 4; x++, pattern >>= 1)

163 if (pattern & 1 && check_pixel(prev + x + y*width, pstart, pend))

164 cur[x + y*width] = prev[x + y*width];

165 else

166 cur[x + y*width] = a;

167 break;

168 case 3:

169 av_log(c->avctx, AV_LOG_ERROR, "Invalid opcode seen @%d\n", blk);

170 return AVERROR_INVALIDDATA;

171 }

172 break;

173 }

174 blocktypes <<= 2;

175 cur += 4;

176 prev += 4;

177 blk2++;

178 if (blk2 == (width >> 2)) {

179 blk2 = 0;

180 cur += width * 3;

181 prev += width * 3;

182 }

183 }

184 return 0;

185 }

186

187 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

188 AVPacket *avpkt)

189 {

190 VBDecContext * const c = avctx->priv_data;

191 AVFrame *frame = data;

192 uint8_t *outptr, *srcptr;

193 int i, j, ret;

194 int flags;

195 uint32_t size;

196 int offset = 0;

197

198 bytestream2_init(&c->stream, avpkt->data, avpkt->size);

199

200 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

201 return ret;

202

203 flags = bytestream2_get_le16(&c->stream);

204

205 if (flags & VB_HAS_GMC) {

206 i = (int16_t)bytestream2_get_le16(&c->stream);

207 j = (int16_t)bytestream2_get_le16(&c->stream);

208 offset = i + j * avctx->width;

209 }

210 if (flags & VB_HAS_VIDEO) {

211 size = bytestream2_get_le32(&c->stream);

212 if(size > bytestream2_get_bytes_left(&c->stream)+4 || size<4){

213 av_log(avctx, AV_LOG_ERROR, "Frame size invalid\n");

214 return -1;

215 }

216 vb_decode_framedata(c, offset);

217 bytestream2_skip(&c->stream, size - 4);

218 }

219 if (flags & VB_HAS_PALETTE) {

220 size = bytestream2_get_le32(&c->stream);

221 vb_decode_palette(c, size);

222 }

223

224 memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);

225 frame->palette_has_changed = flags & VB_HAS_PALETTE;

226

227 outptr = frame->data[0];

228 srcptr = c->frame;

229

230 for (i = 0; i < avctx->height; i++) {

231 memcpy(outptr, srcptr, avctx->width);

232 srcptr += avctx->width;

233 outptr += frame->linesize[0];

234 }

235

236 FFSWAP(uint8_t*, c->frame, c->prev_frame);

237

238 *got_frame = 1;

239

240 /* always report that the buffer was completely consumed */

241 return avpkt->size;

242 }

243

244 static av_cold int decode_init(AVCodecContext *avctx)

245 {

246 VBDecContext * const c = avctx->priv_data;

247

248 c->avctx = avctx;

249 avctx->pix_fmt = AV_PIX_FMT_PAL8;

250

251 c->frame = av_mallocz(avctx->width * avctx->height);

252 c->prev_frame = av_mallocz(avctx->width * avctx->height);

253

254 return 0;

255 }

256

257 static av_cold int decode_end(AVCodecContext *avctx)

258 {

259 VBDecContext *c = avctx->priv_data;

260

261 av_freep(&c->frame);

262 av_freep(&c->prev_frame);

263

264 return 0;

265 }

266

267 AVCodec ff_vb_decoder = {

268 .name = "vb",

269 .long_name = NULL_IF_CONFIG_SMALL("Beam Software VB"),

270 .type = AVMEDIA_TYPE_VIDEO,

271 .id = AV_CODEC_ID_VB,

272 .priv_data_size = sizeof(VBDecContext),

273 .init = decode_init,

274 .close = decode_end,

275 .decode = decode_frame,

276 .capabilities = CODEC_CAP_DR1,

277 };

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