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 "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; 32 const uint8_t *buf_start= buf; 33 uint32_t start_code; 34 int frame_rate_index, ext_type, bytes_left; 35 int frame_rate_ext_n, frame_rate_ext_d; 36 int picture_structure, top_field_first, repeat_first_field, progressive_frame; 37 int horiz_size_ext, vert_size_ext, bit_rate_ext; 38//FIXME replace the crap with get_bits() 39 s->repeat_pict = 0; 40 buf_end = buf + buf_size; 41 while (buf < buf_end) { 42 start_code= -1; 43 buf= ff_find_start_code(buf, buf_end, &start_code); 44 bytes_left = buf_end - buf; 45 switch(start_code) { 46 case PICTURE_START_CODE: 47 ff_fetch_timestamp(s, buf-buf_start-4, 1); 48 49 if (bytes_left >= 2) { 50 s->pict_type = (buf[1] >> 3) & 7; 51 } 52 break; 53 case SEQ_START_CODE: 54 if (bytes_left >= 7) { 55 pc->width = (buf[0] << 4) | (buf[1] >> 4); 56 pc->height = ((buf[1] & 0x0f) << 8) | buf[2]; 57 avcodec_set_dimensions(avctx, pc->width, pc->height); 58 frame_rate_index = buf[3] & 0xf; 59 pc->frame_rate.den = avctx->time_base.den = ff_frame_rate_tab[frame_rate_index].num; 60 pc->frame_rate.num = avctx->time_base.num = ff_frame_rate_tab[frame_rate_index].den; 61 avctx->bit_rate = ((buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6))*400; 62 avctx->codec_id = CODEC_ID_MPEG1VIDEO; 63 avctx->sub_id = 1; 64 } 65 break; 66 case EXT_START_CODE: 67 if (bytes_left >= 1) { 68 ext_type = (buf[0] >> 4); 69 switch(ext_type) { 70 case 0x1: /* sequence extension */ 71 if (bytes_left >= 6) { 72 horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7); 73 vert_size_ext = (buf[2] >> 5) & 3; 74 bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1); 75 frame_rate_ext_n = (buf[5] >> 5) & 3; 76 frame_rate_ext_d = (buf[5] & 0x1f); 77 pc->progressive_sequence = buf[1] & (1 << 3); 78 avctx->has_b_frames= !(buf[5] >> 7); 79 80 pc->width |=(horiz_size_ext << 12); 81 pc->height |=( vert_size_ext << 12); 82 avctx->bit_rate += (bit_rate_ext << 18) * 400; 83 avcodec_set_dimensions(avctx, pc->width, pc->height); 84 avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1) * 2; 85 avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1); 86 avctx->codec_id = CODEC_ID_MPEG2VIDEO; 87 avctx->sub_id = 2; /* forces MPEG2 */ 88 } 89 break; 90 case 0x8: /* picture coding extension */ 91 if (bytes_left >= 5) { 92 picture_structure = buf[2]&3; 93 top_field_first = buf[3] & (1 << 7); 94 repeat_first_field = buf[3] & (1 << 1); 95 progressive_frame = buf[4] & (1 << 7); 96 97 /* check if we must repeat the frame */ 98 s->repeat_pict = 1; 99 if (repeat_first_field) { 100 if (pc->progressive_sequence) { 101 if (top_field_first) 102 s->repeat_pict = 5; 103 else 104 s->repeat_pict = 3; 105 } else if (progressive_frame) { 106 s->repeat_pict = 2; 107 } 108 } 109 } 110 break; 111 } 112 } 113 break; 114 case -1: 115 goto the_end; 116 default: 117 /* we stop parsing when we encounter a slice. It ensures 118 that this function takes a negligible amount of time */ 119 if (start_code >= SLICE_MIN_START_CODE && 120 start_code <= SLICE_MAX_START_CODE) 121 goto the_end; 122 break; 123 } 124 } 125 the_end: ; 126} 127 128static int mpegvideo_parse(AVCodecParserContext *s, 129 AVCodecContext *avctx, 130 const uint8_t **poutbuf, int *poutbuf_size, 131 const uint8_t *buf, int buf_size) 132{ 133 ParseContext1 *pc1 = s->priv_data; 134 ParseContext *pc= &pc1->pc; 135 int next; 136 137 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ 138 next= buf_size; 139 }else{ 140 next= ff_mpeg1_find_frame_end(pc, buf, buf_size); 141 142 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { 143 *poutbuf = NULL; 144 *poutbuf_size = 0; 145 return buf_size; 146 } 147 148 } 149 /* we have a full frame : we just parse the first few MPEG headers 150 to have the full timing information. The time take by this 151 function should be negligible for uncorrupted streams */ 152 mpegvideo_extract_headers(s, avctx, buf, buf_size); 153#if 0 154 printf("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#endif 157 158 *poutbuf = buf; 159 *poutbuf_size = buf_size; 160 return next; 161} 162 163static int mpegvideo_split(AVCodecContext *avctx, 164 const uint8_t *buf, int buf_size) 165{ 166 int i; 167 uint32_t state= -1; 168 169 for(i=0; i<buf_size; i++){ 170 state= (state<<8) | buf[i]; 171 if(state != 0x1B3 && state != 0x1B5 && state < 0x200 && state >= 0x100) 172 return i-3; 173 } 174 return 0; 175} 176 177AVCodecParser mpegvideo_parser = { 178 { CODEC_ID_MPEG1VIDEO, CODEC_ID_MPEG2VIDEO }, 179 sizeof(ParseContext1), 180 NULL, 181 mpegvideo_parse, 182 ff_parse1_close, 183}; 184