FFmpeg: libavcodec/mmvideo.c Source File

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libavcodec

mmvideo.c

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1 /*

2 * American Laser Games MM Video 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 * American Laser Games MM Video Decoder

25 * by Peter Ross (pross@xvid.org)

26 *

27 * The MM format was used by IBM-PC ports of ALG's "arcade shooter" games,

28 * including Mad Dog McCree and Crime Patrol.

29 *

30 * Technical details here:

31 * http://wiki.multimedia.cx/index.php?title=American_Laser_Games_MM

32 */

34 #include "libavutil/intreadwrite.h"

35 #include "avcodec.h"

36 #include "bytestream.h"

37 #include "internal.h"

39 #define MM_PREAMBLE_SIZE 6

41 #define MM_TYPE_INTER 0x5

42 #define MM_TYPE_INTRA 0x8

43 #define MM_TYPE_INTRA_HH 0xc

44 #define MM_TYPE_INTER_HH 0xd

45 #define MM_TYPE_INTRA_HHV 0xe

46 #define MM_TYPE_INTER_HHV 0xf

47 #define MM_TYPE_PALETTE 0x31

49 typedef struct MmContext {

50 AVCodecContext *avctx;

51 AVFrame *frame;

52 int palette[AVPALETTE_COUNT];

53 GetByteContext gb;

54 } MmContext;

56 static av_cold int mm_decode_init(AVCodecContext *avctx)

57 {

58 MmContext *s = avctx->priv_data;

60 s->avctx = avctx;

62 avctx->pix_fmt = AV_PIX_FMT_PAL8;

64 s->frame = av_frame_alloc();

65 if (!s->frame)

66 return AVERROR(ENOMEM);

68 return 0;

69 }

71 static int mm_decode_pal(MmContext *s)

72 {

73 int i;

75 bytestream2_skip(&s->gb, 4);

76 for (i = 0; i < 128; i++) {

77 s->palette[i] = 0xFFU << 24 | bytestream2_get_be24(&s->gb);

78 s->palette[i+128] = s->palette[i]<<2;

79 }

81 return 0;

82 }

84 /**

85 * @param half_horiz Half horizontal resolution (0 or 1)

86 * @param half_vert Half vertical resolution (0 or 1)

87 */

88 static int mm_decode_intra(MmContext * s, int half_horiz, int half_vert)

89 {

90 int x = 0, y = 0;

92 while (bytestream2_get_bytes_left(&s->gb) > 0) {

93 int run_length, color;

95 if (y >= s->avctx->height)

96 return 0;

98 color = bytestream2_get_byte(&s->gb);

99 if (color & 0x80) {

100 run_length = 1;

101 }else{

102 run_length = (color & 0x7f) + 2;

103 color = bytestream2_get_byte(&s->gb);

104 }

105

106 if (half_horiz)

107 run_length *=2;

108

109 if (run_length > s->avctx->width - x)

110 return AVERROR_INVALIDDATA;

111

112 if (color) {

113 memset(s->frame->data[0] + y*s->frame->linesize[0] + x, color, run_length);

114 if (half_vert)

115 memset(s->frame->data[0] + (y+1)*s->frame->linesize[0] + x, color, run_length);

116 }

117 x+= run_length;

118

119 if (x >= s->avctx->width) {

120 x=0;

121 y += 1 + half_vert;

122 }

123 }

124

125 return 0;

126 }

127

128 /**

129 * @param half_horiz Half horizontal resolution (0 or 1)

130 * @param half_vert Half vertical resolution (0 or 1)

131 */

132 static int mm_decode_inter(MmContext * s, int half_horiz, int half_vert)

133 {

134 int data_off = bytestream2_get_le16(&s->gb);

135 int y = 0;

136 GetByteContext data_ptr;

137

138 if (bytestream2_get_bytes_left(&s->gb) < data_off)

139 return AVERROR_INVALIDDATA;

140

141 bytestream2_init(&data_ptr, s->gb.buffer + data_off, bytestream2_get_bytes_left(&s->gb) - data_off);

142 while (s->gb.buffer < data_ptr.buffer_start) {

143 int i, j;

144 int length = bytestream2_get_byte(&s->gb);

145 int x = bytestream2_get_byte(&s->gb) + ((length & 0x80) << 1);

146 length &= 0x7F;

147

148 if (length==0) {

149 y += x;

150 continue;

151 }

152

153 if (y + half_vert >= s->avctx->height)

154 return 0;

155

156 for(i=0; i<length; i++) {

157 int replace_array = bytestream2_get_byte(&s->gb);

158 for(j=0; j<8; j++) {

159 int replace = (replace_array >> (7-j)) & 1;

160 if (x + half_horiz >= s->avctx->width)

161 return AVERROR_INVALIDDATA;

162 if (replace) {

163 int color = bytestream2_get_byte(&data_ptr);

164 s->frame->data[0][y*s->frame->linesize[0] + x] = color;

165 if (half_horiz)

166 s->frame->data[0][y*s->frame->linesize[0] + x + 1] = color;

167 if (half_vert) {

168 s->frame->data[0][(y+1)*s->frame->linesize[0] + x] = color;

169 if (half_horiz)

170 s->frame->data[0][(y+1)*s->frame->linesize[0] + x + 1] = color;

171 }

172 }

173 x += 1 + half_horiz;

174 }

175 }

176

177 y += 1 + half_vert;

178 }

179

180 return 0;

181 }

182

183 static int mm_decode_frame(AVCodecContext *avctx,

184 void *data, int *got_frame,

185 AVPacket *avpkt)

186 {

187 const uint8_t *buf = avpkt->data;

188 int buf_size = avpkt->size;

189 MmContext *s = avctx->priv_data;

190 int type, res;

191

192 if (buf_size < MM_PREAMBLE_SIZE)

193 return AVERROR_INVALIDDATA;

194 type = AV_RL16(&buf[0]);

195 buf += MM_PREAMBLE_SIZE;

196 buf_size -= MM_PREAMBLE_SIZE;

197 bytestream2_init(&s->gb, buf, buf_size);

198

199 if ((res = ff_reget_buffer(avctx, s->frame)) < 0)

200 return res;

201

202 switch(type) {

203 case MM_TYPE_PALETTE : res = mm_decode_pal(s); return avpkt->size;

204 case MM_TYPE_INTRA : res = mm_decode_intra(s, 0, 0); break;

205 case MM_TYPE_INTRA_HH : res = mm_decode_intra(s, 1, 0); break;

206 case MM_TYPE_INTRA_HHV : res = mm_decode_intra(s, 1, 1); break;

207 case MM_TYPE_INTER : res = mm_decode_inter(s, 0, 0); break;

208 case MM_TYPE_INTER_HH : res = mm_decode_inter(s, 1, 0); break;

209 case MM_TYPE_INTER_HHV : res = mm_decode_inter(s, 1, 1); break;

210 default:

211 res = AVERROR_INVALIDDATA;

212 break;

213 }

214 if (res < 0)

215 return res;

216

217 memcpy(s->frame->data[1], s->palette, AVPALETTE_SIZE);

218

219 if ((res = av_frame_ref(data, s->frame)) < 0)

220 return res;

221

222 *got_frame = 1;

223

224 return avpkt->size;

225 }

226

227 static av_cold int mm_decode_end(AVCodecContext *avctx)

228 {

229 MmContext *s = avctx->priv_data;

230

231 av_frame_free(&s->frame);

232

233 return 0;

234 }

235

236 AVCodec ff_mmvideo_decoder = {

237 .name = "mmvideo",

238 .long_name = NULL_IF_CONFIG_SMALL("American Laser Games MM Video"),

239 .type = AVMEDIA_TYPE_VIDEO,

240 .id = AV_CODEC_ID_MMVIDEO,

241 .priv_data_size = sizeof(MmContext),

242 .init = mm_decode_init,

243 .close = mm_decode_end,

244 .decode = mm_decode_frame,

245 .capabilities = CODEC_CAP_DR1,

246 };

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