1/* 2 * MPEG4 Video frame extraction 3 * Copyright (c) 2003 Fabrice Bellard 4 * Copyright (c) 2003 Michael Niedermayer 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#include "mpeg4video.h" 26#include "mpeg4video_parser.h" 27 28 29int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){ 30 int vop_found, i; 31 uint32_t state; 32 33 vop_found= pc->frame_start_found; 34 state= pc->state; 35 36 i=0; 37 if(!vop_found){ 38 for(i=0; i<buf_size; i++){ 39 state= (state<<8) | buf[i]; 40 if(state == 0x1B6){ 41 i++; 42 vop_found=1; 43 break; 44 } 45 } 46 } 47 48 if(vop_found){ 49 /* EOF considered as end of frame */ 50 if (buf_size == 0) 51 return 0; 52 for(; i<buf_size; i++){ 53 state= (state<<8) | buf[i]; 54 if((state&0xFFFFFF00) == 0x100){ 55 pc->frame_start_found=0; 56 pc->state=-1; 57 return i-3; 58 } 59 } 60 } 61 pc->frame_start_found= vop_found; 62 pc->state= state; 63 return END_NOT_FOUND; 64} 65 66/* XXX: make it use less memory */ 67static int av_mpeg4_decode_header(AVCodecParserContext *s1, 68 AVCodecContext *avctx, 69 const uint8_t *buf, int buf_size) 70{ 71 ParseContext1 *pc = s1->priv_data; 72 MpegEncContext *s = pc->enc; 73 GetBitContext gb1, *gb = &gb1; 74 int ret; 75 76 s->avctx = avctx; 77 s->current_picture_ptr = &s->current_picture; 78 79 if (avctx->extradata_size && pc->first_picture){ 80 init_get_bits(gb, avctx->extradata, avctx->extradata_size*8); 81 ret = ff_mpeg4_decode_picture_header(s, gb); 82 } 83 84 init_get_bits(gb, buf, 8 * buf_size); 85 ret = ff_mpeg4_decode_picture_header(s, gb); 86 if (s->width && (!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height)) { 87 avcodec_set_dimensions(avctx, s->width, s->height); 88 } 89 s1->pict_type= s->pict_type; 90 pc->first_picture = 0; 91 return ret; 92} 93 94static av_cold int mpeg4video_parse_init(AVCodecParserContext *s) 95{ 96 ParseContext1 *pc = s->priv_data; 97 98 pc->enc = av_mallocz(sizeof(MpegEncContext)); 99 if (!pc->enc) 100 return -1; 101 pc->first_picture = 1; 102 return 0; 103} 104 105static int mpeg4video_parse(AVCodecParserContext *s, 106 AVCodecContext *avctx, 107 const uint8_t **poutbuf, int *poutbuf_size, 108 const uint8_t *buf, int buf_size) 109{ 110 ParseContext *pc = s->priv_data; 111 int next; 112 113 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ 114 next= buf_size; 115 }else{ 116 next= ff_mpeg4_find_frame_end(pc, buf, buf_size); 117 118 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { 119 *poutbuf = NULL; 120 *poutbuf_size = 0; 121 return buf_size; 122 } 123 } 124 av_mpeg4_decode_header(s, avctx, buf, buf_size); 125 126 *poutbuf = buf; 127 *poutbuf_size = buf_size; 128 return next; 129} 130 131 132AVCodecParser mpeg4video_parser = { 133 { CODEC_ID_MPEG4 }, 134 sizeof(ParseContext1), 135 mpeg4video_parse_init, 136 mpeg4video_parse, 137 ff_parse1_close, 138 ff_mpeg4video_split, 139}; 140