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 27struct MpvParseContext { 28 ParseContext pc; 29 AVRational frame_rate; 30 int progressive_sequence; 31 int width, height; 32}; 33 34 35static 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 } else if (avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate && 149 (bit_rate != 0x3FFFF || vbv_delay != 0xFFFF)) { 150 avctx->bit_rate = 400*bit_rate; 151 } 152} 153 154static int mpegvideo_parse(AVCodecParserContext *s, 155 AVCodecContext *avctx, 156 const uint8_t **poutbuf, int *poutbuf_size, 157 const uint8_t *buf, int buf_size) 158{ 159 struct MpvParseContext *pc1 = s->priv_data; 160 ParseContext *pc= &pc1->pc; 161 int next; 162 163 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ 164 next= buf_size; 165 }else{ 166 next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s); 167 168 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { 169 *poutbuf = NULL; 170 *poutbuf_size = 0; 171 return buf_size; 172 } 173 174 } 175 /* we have a full frame : we just parse the first few MPEG headers 176 to have the full timing information. The time take by this 177 function should be negligible for uncorrupted streams */ 178 mpegvideo_extract_headers(s, avctx, buf, buf_size); 179 av_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n", 180 s->pict_type, (double)avctx->time_base.den / avctx->time_base.num, s->repeat_pict); 181 182 *poutbuf = buf; 183 *poutbuf_size = buf_size; 184 return next; 185} 186 187static int mpegvideo_split(AVCodecContext *avctx, 188 const uint8_t *buf, int buf_size) 189{ 190 int i; 191 uint32_t state= -1; 192 int found=0; 193 194 for(i=0; i<buf_size; i++){ 195 state= (state<<8) | buf[i]; 196 if(state == 0x1B3){ 197 found=1; 198 }else if(found && state != 0x1B5 && state < 0x200 && state >= 0x100) 199 return i-3; 200 } 201 return 0; 202} 203 204static int mpegvideo_parse_init(AVCodecParserContext *s) 205{ 206 s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial 207 return 0; 208} 209 210AVCodecParser ff_mpegvideo_parser = { 211 .codec_ids = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO }, 212 .priv_data_size = sizeof(struct MpvParseContext), 213 .parser_init = mpegvideo_parse_init, 214 .parser_parse = mpegvideo_parse, 215 .parser_close = ff_parse_close, 216 .split = mpegvideo_split, 217}; 218