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 "mpegvideo.h"

37 #include "error_resilience.h"

38 #include "mpeg12.h"

39 #include "mpeg12data.h"

40 #include "bytestream.h"

41 #include "vdpau_internal.h"

42 #include "thread.h"

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

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

47 { 3, 5 }, // 0x01 MB_INTRA

48 { 1, 2 }, // 0x02 MB_PAT

49 { 1, 3 }, // 0x08 MB_FOR

50 { 1, 1 }, // 0x0A MB_FOR|MB_PAT

51 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA

52 { 1, 5 }, // 0x12 MB_QUANT|MB_PAT

53 { 2, 5 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT

54 };

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

57 { 3, 5 }, // 0x01 MB_INTRA

58 { 2, 3 }, // 0x04 MB_BACK

59 { 3, 3 }, // 0x06 MB_BACK|MB_PAT

60 { 2, 4 }, // 0x08 MB_FOR

61 { 3, 4 }, // 0x0A MB_FOR|MB_PAT

62 { 2, 2 }, // 0x0C MB_FOR|MB_BACK

63 { 3, 2 }, // 0x0E MB_FOR|MB_BACK|MB_PAT

64 { 1, 6 }, // 0x11 MB_QUANT|MB_INTRA

65 { 2, 6 }, // 0x16 MB_QUANT|MB_BACK|MB_PAT

66 { 3, 6 }, // 0x1A MB_QUANT|MB_FOR|MB_PAT

67 { 2, 5 }, // 0x1E MB_QUANT|MB_FOR|MB_BACK|MB_PAT

68 };

70 #define INIT_2D_VLC_RL(rl, static_size)\

71 {\

72 static RL_VLC_ELEM rl_vlc_table[static_size];\

73 rl.rl_vlc[0] = rl_vlc_table;\

74 init_2d_vlc_rl(&rl, static_size);\

75 }

77 static av_cold void init_2d_vlc_rl(RLTable *rl, unsigned static_size)

78 {

79 int i;

80 VLC_TYPE table[680][2] = {{0}};

81 VLC vlc = { .table = table, .table_allocated = static_size };

82 av_assert0(static_size <= FF_ARRAY_ELEMS(table));

83 init_vlc(&vlc, TEX_VLC_BITS, rl->n + 2, &rl->table_vlc[0][1], 4, 2, &rl->table_vlc[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);

85 for (i = 0; i < vlc.table_size; i++) {

86 int code = vlc.table[i][0];

87 int len = vlc.table[i][1];

88 int level, run;

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

91 run = 65;

92 level = MAX_LEVEL;

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

94 run = 0;

95 level = code;

96 } else {

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

98 run = 65;

99 level = 0;

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

101 run = 0;

102 level = 127;

103 } else {

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

105 level = rl->table_level[code];

106 }

107 }

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

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

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

111 }

112 }

113

114 av_cold void ff_mpeg12_common_init(MpegEncContext *s)

115 {

116

117 s->y_dc_scale_table =

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

119

120 }

121

122 void ff_mpeg1_clean_buffers(MpegEncContext *s)

123 {

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

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

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

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

128 }

129

130

131 /******************************************/

132 /* decoding */

133

134 VLC ff_mv_vlc;

135

136 VLC ff_dc_lum_vlc;

137 VLC ff_dc_chroma_vlc;

138

139 VLC ff_mbincr_vlc;

140 VLC ff_mb_ptype_vlc;

141 VLC ff_mb_btype_vlc;

142 VLC ff_mb_pat_vlc;

143

144 av_cold void ff_mpeg12_init_vlcs(void)

145 {

146 static int done = 0;

147

148 if (!done) {

149 done = 1;

150

151 INIT_VLC_STATIC(&ff_dc_lum_vlc, DC_VLC_BITS, 12,

152 ff_mpeg12_vlc_dc_lum_bits, 1, 1,

153 ff_mpeg12_vlc_dc_lum_code, 2, 2, 512);

154 INIT_VLC_STATIC(&ff_dc_chroma_vlc, DC_VLC_BITS, 12,

155 ff_mpeg12_vlc_dc_chroma_bits, 1, 1,

156 ff_mpeg12_vlc_dc_chroma_code, 2, 2, 514);

157 INIT_VLC_STATIC(&ff_mv_vlc, MV_VLC_BITS, 17,

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

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

160 INIT_VLC_STATIC(&ff_mbincr_vlc, MBINCR_VLC_BITS, 36,

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

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

163 INIT_VLC_STATIC(&ff_mb_pat_vlc, MB_PAT_VLC_BITS, 64,

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

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

166

167 INIT_VLC_STATIC(&ff_mb_ptype_vlc, MB_PTYPE_VLC_BITS, 7,

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

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

170 INIT_VLC_STATIC(&ff_mb_btype_vlc, MB_BTYPE_VLC_BITS, 11,

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

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

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

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

175

176 INIT_2D_VLC_RL(ff_rl_mpeg1, 680);

177 INIT_2D_VLC_RL(ff_rl_mpeg2, 674);

178 }

179 }

180

181 /**

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

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

184 */

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

186 {

187 int i;

188 uint32_t state = pc->state;

189

190 /* EOF considered as end of frame */

191 if (buf_size == 0)

192 return 0;

193

194 /*

195 0 frame start -> 1/4

196 1 first_SEQEXT -> 0/2

197 2 first field start -> 3/0

198 3 second_SEQEXT -> 2/0

199 4 searching end

200 */

201

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

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

204 if (pc->frame_start_found & 1) {

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

206 pc->frame_start_found--;

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

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

209 pc->frame_start_found = 0;

210 else

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

212 }

213 state++;

214 } else {

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

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

217 i++;

218 pc->frame_start_found = 4;

219 }

220 if (state == SEQ_END_CODE) {

221 pc->frame_start_found = 0;

222 pc->state=-1;

223 return i+1;

224 }

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

226 pc->frame_start_found = 0;

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

228 pc->frame_start_found++;

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

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

231 pc->frame_start_found = 0;

232 pc->state = -1;

233 return i - 3;

234 }

235 }

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

237 ff_fetch_timestamp(s, i - 3, 1, i > 3);

238 }

239 }

240 }

241 pc->state = state;

242 return END_NOT_FOUND;

243 }

244

Generated on Sun Mar 8 2015 02:34:56 for FFmpeg by doxygen 1.8.2