lavc: Rename avpriv_mpv_find_start_code after moving out from mpegvideo
[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 #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 //FIXME replace the crap with get_bits()
48 s->repeat_pict = 0;
49
50 while (buf < buf_end) {
51 start_code= -1;
52 buf= avpriv_find_start_code(buf, buf_end, &start_code);
53 bytes_left = buf_end - buf;
54 switch(start_code) {
55 case PICTURE_START_CODE:
56 if (bytes_left >= 2) {
57 s->pict_type = (buf[1] >> 3) & 7;
58 }
59 break;
60 case SEQ_START_CODE:
61 if (bytes_left >= 7) {
62 pc->width = (buf[0] << 4) | (buf[1] >> 4);
63 pc->height = ((buf[1] & 0x0f) << 8) | buf[2];
64 if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){
65 avcodec_set_dimensions(avctx, pc->width, pc->height);
66 did_set_size=1;
67 }
68 frame_rate_index = buf[3] & 0xf;
69 pc->frame_rate.den = avctx->time_base.den = ff_mpeg12_frame_rate_tab[frame_rate_index].num;
70 pc->frame_rate.num = avctx->time_base.num = ff_mpeg12_frame_rate_tab[frame_rate_index].den;
71 avctx->bit_rate = ((buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6))*400;
72 avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO;
73 }
74 break;
75 case EXT_START_CODE:
76 if (bytes_left >= 1) {
77 ext_type = (buf[0] >> 4);
78 switch(ext_type) {
79 case 0x1: /* sequence extension */
80 if (bytes_left >= 6) {
81 horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7);
82 vert_size_ext = (buf[2] >> 5) & 3;
83 bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1);
84 frame_rate_ext_n = (buf[5] >> 5) & 3;
85 frame_rate_ext_d = (buf[5] & 0x1f);
86 pc->progressive_sequence = buf[1] & (1 << 3);
87 avctx->has_b_frames= !(buf[5] >> 7);
88
89 pc->width |=(horiz_size_ext << 12);
90 pc->height |=( vert_size_ext << 12);
91 avctx->bit_rate += (bit_rate_ext << 18) * 400;
92 if(did_set_size)
93 avcodec_set_dimensions(avctx, pc->width, pc->height);
94 avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1) * 2;
95 avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1);
96 avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO;
97 }
98 break;
99 case 0x8: /* picture coding extension */
100 if (bytes_left >= 5) {
101 top_field_first = buf[3] & (1 << 7);
102 repeat_first_field = buf[3] & (1 << 1);
103 progressive_frame = buf[4] & (1 << 7);
104
105 /* check if we must repeat the frame */
106 s->repeat_pict = 1;
107 if (repeat_first_field) {
108 if (pc->progressive_sequence) {
109 if (top_field_first)
110 s->repeat_pict = 5;
111 else
112 s->repeat_pict = 3;
113 } else if (progressive_frame) {
114 s->repeat_pict = 2;
115 }
116 }
117 }
118 break;
119 }
120 }
121 break;
122 case -1:
123 goto the_end;
124 default:
125 /* we stop parsing when we encounter a slice. It ensures
126 that this function takes a negligible amount of time */
127 if (start_code >= SLICE_MIN_START_CODE &&
128 start_code <= SLICE_MAX_START_CODE)
129 goto the_end;
130 break;
131 }
132 }
133 the_end: ;
134 }
135
136 static int mpegvideo_parse(AVCodecParserContext *s,
137 AVCodecContext *avctx,
138 const uint8_t **poutbuf, int *poutbuf_size,
139 const uint8_t *buf, int buf_size)
140 {
141 struct MpvParseContext *pc1 = s->priv_data;
142 ParseContext *pc= &pc1->pc;
143 int next;
144
145 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
146 next= buf_size;
147 }else{
148 next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s);
149
150 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
151 *poutbuf = NULL;
152 *poutbuf_size = 0;
153 return buf_size;
154 }
155
156 }
157 /* we have a full frame : we just parse the first few MPEG headers
158 to have the full timing information. The time take by this
159 function should be negligible for uncorrupted streams */
160 mpegvideo_extract_headers(s, avctx, buf, buf_size);
161 av_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n",
162 s->pict_type, (double)avctx->time_base.den / avctx->time_base.num, s->repeat_pict);
163
164 *poutbuf = buf;
165 *poutbuf_size = buf_size;
166 return next;
167 }
168
169 static int mpegvideo_split(AVCodecContext *avctx,
170 const uint8_t *buf, int buf_size)
171 {
172 int i;
173 uint32_t state= -1;
174
175 for(i=0; i<buf_size; i++){
176 state= (state<<8) | buf[i];
177 if(state != 0x1B3 && state != 0x1B5 && state < 0x200 && state >= 0x100)
178 return i-3;
179 }
180 return 0;
181 }
182
183 AVCodecParser ff_mpegvideo_parser = {
184 .codec_ids = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO },
185 .priv_data_size = sizeof(struct MpvParseContext),
186 .parser_parse = mpegvideo_parse,
187 .parser_close = ff_parse_close,
188 .split = mpegvideo_split,
189 };