| 1 | /* |
| 2 | * H.263 parser |
| 3 | * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> |
| 4 | * |
| 5 | * This file is part of FFmpeg. |
| 6 | * |
| 7 | * FFmpeg is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * FFmpeg is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with FFmpeg; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | /** |
| 23 | * @file |
| 24 | * H.263 parser |
| 25 | */ |
| 26 | |
| 27 | #include "parser.h" |
| 28 | #include "h263_parser.h" |
| 29 | |
| 30 | int ff_h263_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){ |
| 31 | int vop_found, i; |
| 32 | uint32_t state; |
| 33 | |
| 34 | vop_found= pc->frame_start_found; |
| 35 | state= pc->state; |
| 36 | |
| 37 | i=0; |
| 38 | if(!vop_found){ |
| 39 | for(i=0; i<buf_size; i++){ |
| 40 | state= (state<<8) | buf[i]; |
| 41 | if(state>>(32-22) == 0x20){ |
| 42 | i++; |
| 43 | vop_found=1; |
| 44 | break; |
| 45 | } |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | if(vop_found){ |
| 50 | for(; i<buf_size; i++){ |
| 51 | state= (state<<8) | buf[i]; |
| 52 | if(state>>(32-22) == 0x20){ |
| 53 | pc->frame_start_found=0; |
| 54 | pc->state=-1; |
| 55 | return i-3; |
| 56 | } |
| 57 | } |
| 58 | } |
| 59 | pc->frame_start_found= vop_found; |
| 60 | pc->state= state; |
| 61 | |
| 62 | return END_NOT_FOUND; |
| 63 | } |
| 64 | |
| 65 | static int h263_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 | if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { |
| 74 | next = buf_size; |
| 75 | } else { |
| 76 | next= ff_h263_find_frame_end(pc, buf, buf_size); |
| 77 | |
| 78 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
| 79 | *poutbuf = NULL; |
| 80 | *poutbuf_size = 0; |
| 81 | return buf_size; |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | *poutbuf = buf; |
| 86 | *poutbuf_size = buf_size; |
| 87 | return next; |
| 88 | } |
| 89 | |
| 90 | AVCodecParser ff_h263_parser = { |
| 91 | .codec_ids = { AV_CODEC_ID_H263 }, |
| 92 | .priv_data_size = sizeof(ParseContext), |
| 93 | .parser_parse = h263_parse, |
| 94 | .parser_close = ff_parse_close, |
| 95 | }; |