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