FFmpeg: libavcodec/mpeg12.c Source File

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libavcodec

mpeg12.c

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1 /*

2 * MPEG-1/2 decoder

5 *

6 * This file is part of FFmpeg.

7 *

8 * FFmpeg is free software; you can redistribute it and/or

9 * modify it under the terms of the GNU Lesser General Public

10 * License as published by the Free Software Foundation; either

11 * version 2.1 of the License, or (at your option) any later version.

12 *

13 * FFmpeg is distributed in the hope that it will be useful,

14 * but WITHOUT ANY WARRANTY; without even the implied warranty of

15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

16 * Lesser General Public License for more details.

17 *

18 * You should have received a copy of the GNU Lesser General Public

19 * License along with FFmpeg; if not, write to the Free Software

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

21 */

23 /**

24 * @file

25 * MPEG-1/2 decoder

26 */

28 #define UNCHECKED_BITSTREAM_READER 1

30 #include "libavutil/attributes.h"

31 #include "libavutil/avassert.h"

32 #include "libavutil/timecode.h"

34 #include "internal.h"

35 #include "avcodec.h"

36 #include "dsputil.h"

37 #include "mpegvideo.h"

38 #include "error_resilience.h"

39 #include "mpeg12.h"

40 #include "mpeg12data.h"

41 #include "bytestream.h"

42 #include "vdpau_internal.h"

43 #include "xvmc_internal.h"

44 #include "thread.h"

46 uint8_t ff_mpeg12_static_rl_table_store[2][2][2*MAX_RUN + MAX_LEVEL + 3];

48 static const uint8_t table_mb_ptype[7][2] = {

49 { 3, 5 }, // 0x01 MB_INTRA

50 { 1, 2 }, // 0x02 MB_PAT

51 { 1, 3 }, // 0x08 MB_FOR

52 { 1, 1 }, // 0x0A MB_FOR|MB_PAT

53 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA

54 { 1, 5 }, // 0x12 MB_QUANT|MB_PAT

55 { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT

56 };

58 static const uint8_t table_mb_btype[11][2] = {

59 { 3, 5 }, // 0x01 MB_INTRA

60 { 2, 3 }, // 0x04 MB_BACK

61 { 3, 3 }, // 0x06 MB_BACK|MB_PAT

62 { 2, 4 }, // 0x08 MB_FOR

63 { 3, 4 }, // 0x0A MB_FOR|MB_PAT

64 { 2, 2 }, // 0x0C MB_FOR|MB_BACK

65 { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT

66 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA

67 { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT

68 { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT

69 { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT

70 };

72 #define INIT_2D_VLC_RL(rl, static_size)\

73 {\

74 static RL_VLC_ELEM rl_vlc_table[static_size];\

75 INIT_VLC_STATIC(&rl.vlc, TEX_VLC_BITS, rl.n + 2,\

76 &rl.table_vlc[0][1], 4, 2,\

77 &rl.table_vlc[0][0], 4, 2, static_size);\

78 \

79 rl.rl_vlc[0] = rl_vlc_table;\

80 init_2d_vlc_rl(&rl);\

81 }

83 static av_cold void init_2d_vlc_rl(RLTable *rl)

84 {

85 int i;

87 for (i = 0; i < rl->vlc.table_size; i++) {

88 int code = rl->vlc.table[i][0];

89 int len = rl->vlc.table[i][1];

90 int level, run;

92 if (len == 0) { // illegal code

93 run = 65;

94 level = MAX_LEVEL;

95 } else if (len<0) { //more bits needed

96 run = 0;

97 level = code;

98 } else {

99 if (code == rl->n) { //esc

100 run = 65;

101 level = 0;

102 } else if (code == rl->n+1) { //eob

103 run = 0;

104 level = 127;

105 } else {

106 run = rl->table_run [code] + 1;

107 level = rl->table_level[code];

108 }

109 }

110 rl->rl_vlc[0][i].len = len;

111 rl->rl_vlc[0][i].level = level;

112 rl->rl_vlc[0][i].run = run;

113 }

114 }

115

116 av_cold void ff_mpeg12_common_init(MpegEncContext *s)

117 {

118

119 s->y_dc_scale_table =

120 s->c_dc_scale_table = ff_mpeg2_dc_scale_table[s->intra_dc_precision];

121

122 }

123

124 void ff_mpeg1_clean_buffers(MpegEncContext *s)

125 {

126 s->last_dc[0] = 1 << (7 + s->intra_dc_precision);

127 s->last_dc[1] = s->last_dc[0];

128 s->last_dc[2] = s->last_dc[0];

129 memset(s->last_mv, 0, sizeof(s->last_mv));

130 }

131

132

133 /******************************************/

134 /* decoding */

135

136 VLC ff_mv_vlc;

137

138 VLC ff_dc_lum_vlc;

139 VLC ff_dc_chroma_vlc;

140

141 VLC ff_mbincr_vlc;

142 VLC ff_mb_ptype_vlc;

143 VLC ff_mb_btype_vlc;

144 VLC ff_mb_pat_vlc;

145

146 av_cold void ff_mpeg12_init_vlcs(void)

147 {

148 static int done = 0;

149

150 if (!done) {

151 done = 1;

152

153 INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,

154 ff_mpeg12_vlc_dc_lum_bits, 1, 1,

155 ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);

156 INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,

157 ff_mpeg12_vlc_dc_chroma_bits, 1, 1,

158 ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);

159 INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,

160 &ff_mpeg12_mbMotionVectorTable[0][1], 2, 1,

161 &ff_mpeg12_mbMotionVectorTable[0][0], 2, 1, 518);

162 INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,

163 &ff_mpeg12_mbAddrIncrTable[0][1], 2, 1,

164 &ff_mpeg12_mbAddrIncrTable[0][0], 2, 1, 538);

165 INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,

166 &ff_mpeg12_mbPatTable[0][1], 2, 1,

167 &ff_mpeg12_mbPatTable[0][0], 2, 1, 512);

168

169 INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,

170 &table_mb_ptype[0][1], 2, 1,

171 &table_mb_ptype[0][0], 2, 1, 64);

172 INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,

173 &table_mb_btype[0][1], 2, 1,

174 &table_mb_btype[0][0], 2, 1, 64);

175 ff_init_rl(&ff_rl_mpeg1, ff_mpeg12_static_rl_table_store[0]);

176 ff_init_rl(&ff_rl_mpeg2, ff_mpeg12_static_rl_table_store[1]);

177

178 INIT_2D_VLC_RL(ff_rl_mpeg1, 680);

179 INIT_2D_VLC_RL(ff_rl_mpeg2, 674);

180 }

181 }

182

183 /**

184 * Find the end of the current frame in the bitstream.

185 * @return the position of the first byte of the next frame, or -1

186 */

187 int ff_mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size, AVCodecParserContext *s)

188 {

189 int i;

190 uint32_t state = pc->state;

191

192 /* EOF considered as end of frame */

193 if (buf_size == 0)

194 return 0;

195

196 /*

197 0 frame start -> 1/4

198 1 first_SEQEXT -> 0/2

199 2 first field start -> 3/0

200 3 second_SEQEXT -> 2/0

201 4 searching end

202 */

203

204 for (i = 0; i < buf_size; i++) {

205 av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);

206 if (pc->frame_start_found & 1) {

207 if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)

208 pc->frame_start_found--;

209 else if (state == EXT_START_CODE + 2) {

210 if ((buf[i] & 3) == 3)

211 pc->frame_start_found = 0;

212 else

213 pc->frame_start_found = (pc->frame_start_found + 1) & 3;

214 }

215 state++;

216 } else {

217 i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;

218 if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {

219 i++;

220 pc->frame_start_found = 4;

221 }

222 if (state == SEQ_END_CODE) {

223 pc->frame_start_found = 0;

224 pc->state=-1;

225 return i+1;

226 }

227 if (pc->frame_start_found == 2 && state == SEQ_START_CODE)

228 pc->frame_start_found = 0;

229 if (pc->frame_start_found < 4 && state == EXT_START_CODE)

230 pc->frame_start_found++;

231 if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {

232 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {

233 pc->frame_start_found = 0;

234 pc->state = -1;

235 return i - 3;

236 }

237 }

238 if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {

239 ff_fetch_timestamp(s, i - 3, 1);

240 }

241 }

242 }

243 pc->state = state;

244 return END_NOT_FOUND;

245 }

246

Generated on Sat Jan 25 2014 19:51:51 for FFmpeg by doxygen 1.8.2