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 26static void mpegvideo_extract_headers(AVCodecParserContext *s, 27 AVCodecContext *avctx, 28 const uint8_t *buf, int buf_size) 29{ 30 ParseContext1 *pc = s->priv_data; 31 const uint8_t *buf_end = buf + buf_size; 32 uint32_t start_code; 33 int frame_rate_index, ext_type, bytes_left; 34 int frame_rate_ext_n, frame_rate_ext_d; 35 int top_field_first, repeat_first_field, progressive_frame; 36 int horiz_size_ext, vert_size_ext, bit_rate_ext; 37 int did_set_size=0; 38//FIXME replace the crap with get_bits() 39 s->repeat_pict = 0; 40 41 while (buf < buf_end) { 42 start_code= -1; 43 buf= avpriv_mpv_find_start_code(buf, buf_end, &start_code); 44 bytes_left = buf_end - buf; 45 switch(start_code) { 46 case PICTURE_START_CODE: 47 if (bytes_left >= 2) { 48 s->pict_type = (buf[1] >> 3) & 7; 49 } 50 break; 51 case SEQ_START_CODE: 52 if (bytes_left >= 7) { 53 pc->width = (buf[0] << 4) | (buf[1] >> 4); 54 pc->height = ((buf[1] & 0x0f) << 8) | buf[2]; 55 if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){ 56 avcodec_set_dimensions(avctx, pc->width, pc->height); 57 did_set_size=1; 58 } 59 frame_rate_index = buf[3] & 0xf; 60 pc->frame_rate.den = avctx->time_base.den = avpriv_frame_rate_tab[frame_rate_index].num; 61 pc->frame_rate.num = avctx->time_base.num = avpriv_frame_rate_tab[frame_rate_index].den; 62 avctx->bit_rate = ((buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6))*400; 63 avctx->codec_id = CODEC_ID_MPEG1VIDEO; 64 avctx->sub_id = 1; 65 } 66 break; 67 case EXT_START_CODE: 68 if (bytes_left >= 1) { 69 ext_type = (buf[0] >> 4); 70 switch(ext_type) { 71 case 0x1: /* sequence extension */ 72 if (bytes_left >= 6) { 73 horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7); 74 vert_size_ext = (buf[2] >> 5) & 3; 75 bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1); 76 frame_rate_ext_n = (buf[5] >> 5) & 3; 77 frame_rate_ext_d = (buf[5] & 0x1f); 78 pc->progressive_sequence = buf[1] & (1 << 3); 79 avctx->has_b_frames= !(buf[5] >> 7); 80 81 pc->width |=(horiz_size_ext << 12); 82 pc->height |=( vert_size_ext << 12); 83 avctx->bit_rate += (bit_rate_ext << 18) * 400; 84 if(did_set_size) 85 avcodec_set_dimensions(avctx, pc->width, pc->height); 86 avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1) * 2; 87 avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1); 88 avctx->codec_id = CODEC_ID_MPEG2VIDEO; 89 avctx->sub_id = 2; /* forces MPEG2 */ 90 } 91 break; 92 case 0x8: /* picture coding extension */ 93 if (bytes_left >= 5) { 94 top_field_first = buf[3] & (1 << 7); 95 repeat_first_field = buf[3] & (1 << 1); 96 progressive_frame = buf[4] & (1 << 7); 97 98 /* check if we must repeat the frame */ 99 s->repeat_pict = 1; 100 if (repeat_first_field) { 101 if (pc->progressive_sequence) { 102 if (top_field_first) 103 s->repeat_pict = 5; 104 else 105 s->repeat_pict = 3; 106 } else if (progressive_frame) { 107 s->repeat_pict = 2; 108 } 109 } 110 } 111 break; 112 } 113 } 114 break; 115 case -1: 116 goto the_end; 117 default: 118 /* we stop parsing when we encounter a slice. It ensures 119 that this function takes a negligible amount of time */ 120 if (start_code >= SLICE_MIN_START_CODE && 121 start_code <= SLICE_MAX_START_CODE) 122 goto the_end; 123 break; 124 } 125 } 126 the_end: ; 127} 128 129static int mpegvideo_parse(AVCodecParserContext *s, 130 AVCodecContext *avctx, 131 const uint8_t **poutbuf, int *poutbuf_size, 132 const uint8_t *buf, int buf_size) 133{ 134 ParseContext1 *pc1 = s->priv_data; 135 ParseContext *pc= &pc1->pc; 136 int next; 137 138 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ 139 next= buf_size; 140 }else{ 141 next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s); 142 143 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { 144 *poutbuf = NULL; 145 *poutbuf_size = 0; 146 return buf_size; 147 } 148 149 } 150 /* we have a full frame : we just parse the first few MPEG headers 151 to have the full timing information. The time take by this 152 function should be negligible for uncorrupted streams */ 153 mpegvideo_extract_headers(s, avctx, buf, buf_size); 154 av_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n", 155 s->pict_type, (double)avctx->time_base.den / avctx->time_base.num, s->repeat_pict); 156 157 *poutbuf = buf; 158 *poutbuf_size = buf_size; 159 return next; 160} 161 162static int mpegvideo_split(AVCodecContext *avctx, 163 const uint8_t *buf, int buf_size) 164{ 165 int i; 166 uint32_t state= -1; 167 168 for(i=0; i<buf_size; i++){ 169 state= (state<<8) | buf[i]; 170 if(state != 0x1B3 && state != 0x1B5 && state < 0x200 && state >= 0x100) 171 return i-3; 172 } 173 return 0; 174} 175 176AVCodecParser ff_mpegvideo_parser = { 177 .codec_ids = { CODEC_ID_MPEG1VIDEO, CODEC_ID_MPEG2VIDEO }, 178 .priv_data_size = sizeof(ParseContext1), 179 .parser_parse = mpegvideo_parse, 180 .parser_close = ff_parse1_close, 181 .split = mpegvideo_split, 182}; 183