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2ba45a60 DM |
1 | /* |
2 | * MPEG1 / MPEG2 video parser | |
3 | * Copyright (c) 2000,2001 Fabrice Bellard | |
4 | * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> | |
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 | */ | |
22 | ||
23 | #include "parser.h" | |
24 | #include "mpeg12.h" | |
25 | #include "internal.h" | |
26 | ||
27 | struct MpvParseContext { | |
28 | ParseContext pc; | |
29 | AVRational frame_rate; | |
30 | int progressive_sequence; | |
31 | int width, height; | |
32 | }; | |
33 | ||
34 | ||
35 | static void mpegvideo_extract_headers(AVCodecParserContext *s, | |
36 | AVCodecContext *avctx, | |
37 | const uint8_t *buf, int buf_size) | |
38 | { | |
39 | struct MpvParseContext *pc = s->priv_data; | |
40 | const uint8_t *buf_end = buf + buf_size; | |
41 | uint32_t start_code; | |
42 | int frame_rate_index, ext_type, bytes_left; | |
43 | int frame_rate_ext_n, frame_rate_ext_d; | |
44 | int top_field_first, repeat_first_field, progressive_frame; | |
45 | int horiz_size_ext, vert_size_ext, bit_rate_ext; | |
46 | int did_set_size=0; | |
47 | int bit_rate = 0; | |
48 | int vbv_delay = 0; | |
49 | //FIXME replace the crap with get_bits() | |
50 | s->repeat_pict = 0; | |
51 | ||
52 | while (buf < buf_end) { | |
53 | start_code= -1; | |
54 | buf= avpriv_find_start_code(buf, buf_end, &start_code); | |
55 | bytes_left = buf_end - buf; | |
56 | switch(start_code) { | |
57 | case PICTURE_START_CODE: | |
58 | if (bytes_left >= 2) { | |
59 | s->pict_type = (buf[1] >> 3) & 7; | |
60 | if (bytes_left >= 4) | |
61 | vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3] >> 3); | |
62 | } | |
63 | break; | |
64 | case SEQ_START_CODE: | |
65 | if (bytes_left >= 7) { | |
66 | pc->width = (buf[0] << 4) | (buf[1] >> 4); | |
67 | pc->height = ((buf[1] & 0x0f) << 8) | buf[2]; | |
68 | if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){ | |
69 | ff_set_dimensions(avctx, pc->width, pc->height); | |
70 | did_set_size=1; | |
71 | } | |
72 | frame_rate_index = buf[3] & 0xf; | |
73 | pc->frame_rate.den = avctx->time_base.den = ff_mpeg12_frame_rate_tab[frame_rate_index].num; | |
74 | pc->frame_rate.num = avctx->time_base.num = ff_mpeg12_frame_rate_tab[frame_rate_index].den; | |
75 | bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6); | |
76 | avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO; | |
77 | } | |
78 | break; | |
79 | case EXT_START_CODE: | |
80 | if (bytes_left >= 1) { | |
81 | ext_type = (buf[0] >> 4); | |
82 | switch(ext_type) { | |
83 | case 0x1: /* sequence extension */ | |
84 | if (bytes_left >= 6) { | |
85 | horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7); | |
86 | vert_size_ext = (buf[2] >> 5) & 3; | |
87 | bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1); | |
88 | frame_rate_ext_n = (buf[5] >> 5) & 3; | |
89 | frame_rate_ext_d = (buf[5] & 0x1f); | |
90 | pc->progressive_sequence = buf[1] & (1 << 3); | |
91 | avctx->has_b_frames= !(buf[5] >> 7); | |
92 | ||
93 | pc->width |=(horiz_size_ext << 12); | |
94 | pc->height |=( vert_size_ext << 12); | |
95 | bit_rate = (bit_rate&0x3FFFF) | (bit_rate_ext << 18); | |
96 | if(did_set_size) | |
97 | ff_set_dimensions(avctx, pc->width, pc->height); | |
98 | avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1) * 2; | |
99 | avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1); | |
100 | avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO; | |
101 | } | |
102 | break; | |
103 | case 0x8: /* picture coding extension */ | |
104 | if (bytes_left >= 5) { | |
105 | top_field_first = buf[3] & (1 << 7); | |
106 | repeat_first_field = buf[3] & (1 << 1); | |
107 | progressive_frame = buf[4] & (1 << 7); | |
108 | ||
109 | /* check if we must repeat the frame */ | |
110 | s->repeat_pict = 1; | |
111 | if (repeat_first_field) { | |
112 | if (pc->progressive_sequence) { | |
113 | if (top_field_first) | |
114 | s->repeat_pict = 5; | |
115 | else | |
116 | s->repeat_pict = 3; | |
117 | } else if (progressive_frame) { | |
118 | s->repeat_pict = 2; | |
119 | } | |
120 | } | |
121 | ||
122 | if (!pc->progressive_sequence) { | |
123 | if (top_field_first) | |
124 | s->field_order = AV_FIELD_TT; | |
125 | else | |
126 | s->field_order = AV_FIELD_BB; | |
127 | } else | |
128 | s->field_order = AV_FIELD_PROGRESSIVE; | |
129 | } | |
130 | break; | |
131 | } | |
132 | } | |
133 | break; | |
134 | case -1: | |
135 | goto the_end; | |
136 | default: | |
137 | /* we stop parsing when we encounter a slice. It ensures | |
138 | that this function takes a negligible amount of time */ | |
139 | if (start_code >= SLICE_MIN_START_CODE && | |
140 | start_code <= SLICE_MAX_START_CODE) | |
141 | goto the_end; | |
142 | break; | |
143 | } | |
144 | } | |
145 | the_end: ; | |
146 | if (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO && bit_rate) { | |
147 | avctx->rc_max_rate = 400*bit_rate; | |
148 | } | |
149 | if (bit_rate && | |
150 | ((avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate != 0x3FFFF) || vbv_delay != 0xFFFF)) { | |
151 | avctx->bit_rate = 400*bit_rate; | |
152 | } | |
153 | } | |
154 | ||
155 | static int mpegvideo_parse(AVCodecParserContext *s, | |
156 | AVCodecContext *avctx, | |
157 | const uint8_t **poutbuf, int *poutbuf_size, | |
158 | const uint8_t *buf, int buf_size) | |
159 | { | |
160 | struct MpvParseContext *pc1 = s->priv_data; | |
161 | ParseContext *pc= &pc1->pc; | |
162 | int next; | |
163 | ||
164 | if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ | |
165 | next= buf_size; | |
166 | }else{ | |
167 | next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s); | |
168 | ||
169 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { | |
170 | *poutbuf = NULL; | |
171 | *poutbuf_size = 0; | |
172 | return buf_size; | |
173 | } | |
174 | ||
175 | } | |
176 | /* we have a full frame : we just parse the first few MPEG headers | |
177 | to have the full timing information. The time take by this | |
178 | function should be negligible for uncorrupted streams */ | |
179 | mpegvideo_extract_headers(s, avctx, buf, buf_size); | |
180 | av_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n", | |
181 | s->pict_type, (double)avctx->time_base.den / avctx->time_base.num, s->repeat_pict); | |
182 | ||
183 | *poutbuf = buf; | |
184 | *poutbuf_size = buf_size; | |
185 | return next; | |
186 | } | |
187 | ||
188 | static int mpegvideo_split(AVCodecContext *avctx, | |
189 | const uint8_t *buf, int buf_size) | |
190 | { | |
191 | int i; | |
192 | uint32_t state= -1; | |
193 | int found=0; | |
194 | ||
195 | for(i=0; i<buf_size; i++){ | |
196 | state= (state<<8) | buf[i]; | |
197 | if(state == 0x1B3){ | |
198 | found=1; | |
199 | }else if(found && state != 0x1B5 && state < 0x200 && state >= 0x100) | |
200 | return i-3; | |
201 | } | |
202 | return 0; | |
203 | } | |
204 | ||
205 | static int mpegvideo_parse_init(AVCodecParserContext *s) | |
206 | { | |
207 | s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial | |
208 | return 0; | |
209 | } | |
210 | ||
211 | AVCodecParser ff_mpegvideo_parser = { | |
212 | .codec_ids = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO }, | |
213 | .priv_data_size = sizeof(struct MpvParseContext), | |
214 | .parser_init = mpegvideo_parse_init, | |
215 | .parser_parse = mpegvideo_parse, | |
216 | .parser_close = ff_parse_close, | |
217 | .split = mpegvideo_split, | |
218 | }; |