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 avcodec_get_frame_defaults(&s->frame);

66 return 0;

67 }

69 static int mm_decode_pal(MmContext *s)

70 {

71 int i;

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

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

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

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

77 }

79 return 0;

80 }

82 /**

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

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

85 */

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

87 {

88 int x = 0, y = 0;

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

91 int run_length, color;

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

94 return 0;

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

97 if (color & 0x80) {

98 run_length = 1;

99 }else{

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

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

102 }

103

104 if (half_horiz)

105 run_length *=2;

106

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

108 return AVERROR_INVALIDDATA;

109

110 if (color) {

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

112 if (half_vert)

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

114 }

115 x+= run_length;

116

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

118 x=0;

119 y += 1 + half_vert;

120 }

121 }

122

123 return 0;

124 }

125

126 /**

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

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

129 */

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

131 {

132 int data_off = bytestream2_get_le16(&s->gb), y = 0;

133 GetByteContext data_ptr;

134

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

136 return AVERROR_INVALIDDATA;

137

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

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

140 int i, j;

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

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

143 length &= 0x7F;

144

145 if (length==0) {

146 y += x;

147 continue;

148 }

149

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

151 return 0;

152

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

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

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

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

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

158 return AVERROR_INVALIDDATA;

159 if (replace) {

160 int color = bytestream2_get_byte(&data_ptr);

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

162 if (half_horiz)

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

164 if (half_vert) {

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

166 if (half_horiz)

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

168 }

169 }

170 x += 1 + half_horiz;

171 }

172 }

173

174 y += 1 + half_vert;

175 }

176

177 return 0;

178 }

179

180 static int mm_decode_frame(AVCodecContext *avctx,

181 void *data, int *got_frame,

182 AVPacket *avpkt)

183 {

184 const uint8_t *buf = avpkt->data;

185 int buf_size = avpkt->size;

186 MmContext *s = avctx->priv_data;

187 int type, res;

188

189 if (buf_size < MM_PREAMBLE_SIZE)

190 return AVERROR_INVALIDDATA;

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

192 buf += MM_PREAMBLE_SIZE;

193 buf_size -= MM_PREAMBLE_SIZE;

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

195

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

197 return res;

198

199 switch(type) {

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

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

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

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

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

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

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

207 default:

208 res = AVERROR_INVALIDDATA;

209 break;

210 }

211 if (res < 0)

212 return res;

213

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

215

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

217 return res;

218

219 *got_frame = 1;

220

221 return avpkt->size;

222 }

223

224 static av_cold int mm_decode_end(AVCodecContext *avctx)

225 {

226 MmContext *s = avctx->priv_data;

227

228 av_frame_unref(&s->frame);

229

230 return 0;

231 }

232

233 AVCodec ff_mmvideo_decoder = {

234 .name = "mmvideo",

235 .type = AVMEDIA_TYPE_VIDEO,

236 .id = AV_CODEC_ID_MMVIDEO,

237 .priv_data_size = sizeof(MmContext),

238 .init = mm_decode_init,

239 .close = mm_decode_end,

240 .decode = mm_decode_frame,

241 .capabilities = CODEC_CAP_DR1,

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

243 };

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