051796e0c0d445846bea454844358270808494a7
[libav.git] / libavcodec / mpegvideo_parser.c
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 Libav.
7 *
8 * Libav 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 * Libav 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 Libav; 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 "mpegvideo.h"
25
26 struct MpvParseContext {
27 ParseContext pc;
28 AVRational frame_rate;
29 int progressive_sequence;
30 int width, height;
31 };
32
33
34 static void mpegvideo_extract_headers(AVCodecParserContext *s,
35 AVCodecContext *avctx,
36 const uint8_t *buf, int buf_size)
37 {
38 struct MpvParseContext *pc = s->priv_data;
39 const uint8_t *buf_end = buf + buf_size;
40 uint32_t start_code;
41 int frame_rate_index, ext_type, bytes_left;
42 int frame_rate_ext_n, frame_rate_ext_d;
43 int top_field_first, repeat_first_field, progressive_frame;
44 int horiz_size_ext, vert_size_ext, bit_rate_ext;
45 int did_set_size=0;
46 //FIXME replace the crap with get_bits()
47 s->repeat_pict = 0;
48
49 while (buf < buf_end) {
50 start_code= -1;
51 buf= avpriv_mpv_find_start_code(buf, buf_end, &start_code);
52 bytes_left = buf_end - buf;
53 switch(start_code) {
54 case PICTURE_START_CODE:
55 if (bytes_left >= 2) {
56 s->pict_type = (buf[1] >> 3) & 7;
57 }
58 break;
59 case SEQ_START_CODE:
60 if (bytes_left >= 7) {
61 pc->width = (buf[0] << 4) | (buf[1] >> 4);
62 pc->height = ((buf[1] & 0x0f) << 8) | buf[2];
63 if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){
64 avcodec_set_dimensions(avctx, pc->width, pc->height);
65 did_set_size=1;
66 }
67 frame_rate_index = buf[3] & 0xf;
68 pc->frame_rate.den = avctx->time_base.den = ff_mpeg12_frame_rate_tab[frame_rate_index].num;
69 pc->frame_rate.num = avctx->time_base.num = ff_mpeg12_frame_rate_tab[frame_rate_index].den;
70 avctx->bit_rate = ((buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6))*400;
71 avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO;
72 }
73 break;
74 case EXT_START_CODE:
75 if (bytes_left >= 1) {
76 ext_type = (buf[0] >> 4);
77 switch(ext_type) {
78 case 0x1: /* sequence extension */
79 if (bytes_left >= 6) {
80 horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7);
81 vert_size_ext = (buf[2] >> 5) & 3;
82 bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1);
83 frame_rate_ext_n = (buf[5] >> 5) & 3;
84 frame_rate_ext_d = (buf[5] & 0x1f);
85 pc->progressive_sequence = buf[1] & (1 << 3);
86 avctx->has_b_frames= !(buf[5] >> 7);
87
88 pc->width |=(horiz_size_ext << 12);
89 pc->height |=( vert_size_ext << 12);
90 avctx->bit_rate += (bit_rate_ext << 18) * 400;
91 if(did_set_size)
92 avcodec_set_dimensions(avctx, pc->width, pc->height);
93 avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1) * 2;
94 avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1);
95 avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO;
96 }
97 break;
98 case 0x8: /* picture coding extension */
99 if (bytes_left >= 5) {
100 top_field_first = buf[3] & (1 << 7);
101 repeat_first_field = buf[3] & (1 << 1);
102 progressive_frame = buf[4] & (1 << 7);
103
104 /* check if we must repeat the frame */
105 s->repeat_pict = 1;
106 if (repeat_first_field) {
107 if (pc->progressive_sequence) {
108 if (top_field_first)
109 s->repeat_pict = 5;
110 else
111 s->repeat_pict = 3;
112 } else if (progressive_frame) {
113 s->repeat_pict = 2;
114 }
115 }
116 }
117 break;
118 }
119 }
120 break;
121 case -1:
122 goto the_end;
123 default:
124 /* we stop parsing when we encounter a slice. It ensures
125 that this function takes a negligible amount of time */
126 if (start_code >= SLICE_MIN_START_CODE &&
127 start_code <= SLICE_MAX_START_CODE)
128 goto the_end;
129 break;
130 }
131 }
132 the_end: ;
133 }
134
135 static int mpegvideo_parse(AVCodecParserContext *s,
136 AVCodecContext *avctx,
137 const uint8_t **poutbuf, int *poutbuf_size,
138 const uint8_t *buf, int buf_size)
139 {
140 struct MpvParseContext *pc1 = s->priv_data;
141 ParseContext *pc= &pc1->pc;
142 int next;
143
144 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
145 next= buf_size;
146 }else{
147 next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s);
148
149 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
150 *poutbuf = NULL;
151 *poutbuf_size = 0;
152 return buf_size;
153 }
154
155 }
156 /* we have a full frame : we just parse the first few MPEG headers
157 to have the full timing information. The time take by this
158 function should be negligible for uncorrupted streams */
159 mpegvideo_extract_headers(s, avctx, buf, buf_size);
160 av_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n",
161 s->pict_type, (double)avctx->time_base.den / avctx->time_base.num, s->repeat_pict);
162
163 *poutbuf = buf;
164 *poutbuf_size = buf_size;
165 return next;
166 }
167
168 static int mpegvideo_split(AVCodecContext *avctx,
169 const uint8_t *buf, int buf_size)
170 {
171 int i;
172 uint32_t state= -1;
173
174 for(i=0; i<buf_size; i++){
175 state= (state<<8) | buf[i];
176 if(state != 0x1B3 && state != 0x1B5 && state < 0x200 && state >= 0x100)
177 return i-3;
178 }
179 return 0;
180 }
181
182 AVCodecParser ff_mpegvideo_parser = {
183 .codec_ids = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO },
184 .priv_data_size = sizeof(struct MpvParseContext),
185 .parser_parse = mpegvideo_parse,
186 .parser_close = ff_parse_close,
187 .split = mpegvideo_split,
188 };