1/* 2 * H261 parser 3 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> 4 * Copyright (c) 2004 Maarten Daniels 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/** 24 * @file 25 * h261codec. 26 */ 27 28#include "parser.h" 29 30 31static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){ 32 int vop_found, i, j; 33 uint32_t state; 34 35 vop_found= pc->frame_start_found; 36 state= pc->state; 37 38 for(i=0; i<buf_size && !vop_found; i++){ 39 state= (state<<8) | buf[i]; 40 for(j=0; j<8; j++){ 41 if(((state>>j)&0xFFFFF0) == 0x000100){ 42 vop_found=1; 43 break; 44 } 45 } 46 } 47 if(vop_found){ 48 for(; i<buf_size; i++){ 49 state= (state<<8) | buf[i]; 50 for(j=0; j<8; j++){ 51 if(((state>>j)&0xFFFFF0) == 0x000100){ 52 pc->frame_start_found=0; 53 pc->state= (state>>(3*8))+0xFF00; 54 return i-2; 55 } 56 } 57 } 58 } 59 60 pc->frame_start_found= vop_found; 61 pc->state= state; 62 return END_NOT_FOUND; 63} 64 65static int h261_parse(AVCodecParserContext *s, 66 AVCodecContext *avctx, 67 const uint8_t **poutbuf, int *poutbuf_size, 68 const uint8_t *buf, int buf_size) 69{ 70 ParseContext *pc = s->priv_data; 71 int next; 72 73 next= h261_find_frame_end(pc,avctx, buf, buf_size); 74 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { 75 *poutbuf = NULL; 76 *poutbuf_size = 0; 77 return buf_size; 78 } 79 *poutbuf = buf; 80 *poutbuf_size = buf_size; 81 return next; 82} 83 84AVCodecParser h261_parser = { 85 { CODEC_ID_H261 }, 86 sizeof(ParseContext), 87 NULL, 88 h261_parse, 89 ff_parse_close, 90}; 91