| 1 | /* |
| 2 | * MJPEG parser |
| 3 | * Copyright (c) 2000, 2001 Fabrice Bellard |
| 4 | * Copyright (c) 2003 Alex Beregszaszi |
| 5 | * Copyright (c) 2003-2004 Michael Niedermayer |
| 6 | * |
| 7 | * This file is part of FFmpeg. |
| 8 | * |
| 9 | * FFmpeg is free software; you can redistribute it and/or |
| 10 | * modify it under the terms of the GNU Lesser General Public |
| 11 | * License as published by the Free Software Foundation; either |
| 12 | * version 2.1 of the License, or (at your option) any later version. |
| 13 | * |
| 14 | * FFmpeg is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 17 | * Lesser General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with FFmpeg; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 22 | */ |
| 23 | |
| 24 | /** |
| 25 | * @file |
| 26 | * MJPEG parser. |
| 27 | */ |
| 28 | |
| 29 | #include "parser.h" |
| 30 | |
| 31 | typedef struct MJPEGParserContext{ |
| 32 | ParseContext pc; |
| 33 | int size; |
| 34 | }MJPEGParserContext; |
| 35 | |
| 36 | /** |
| 37 | * Find the end of the current frame in the bitstream. |
| 38 | * @return the position of the first byte of the next frame, or -1 |
| 39 | */ |
| 40 | static int find_frame_end(MJPEGParserContext *m, const uint8_t *buf, int buf_size){ |
| 41 | ParseContext *pc= &m->pc; |
| 42 | int vop_found, i; |
| 43 | uint32_t state; |
| 44 | |
| 45 | vop_found= pc->frame_start_found; |
| 46 | state= pc->state; |
| 47 | |
| 48 | i=0; |
| 49 | if(!vop_found){ |
| 50 | for(i=0; i<buf_size;){ |
| 51 | state= (state<<8) | buf[i]; |
| 52 | if(state>=0xFFC00000 && state<=0xFFFEFFFF){ |
| 53 | if(state>=0xFFD80000 && state<=0xFFD8FFFF){ |
| 54 | i++; |
| 55 | vop_found=1; |
| 56 | break; |
| 57 | }else if(state<0xFFD00000 || state>0xFFD9FFFF){ |
| 58 | m->size= (state&0xFFFF)-1; |
| 59 | } |
| 60 | } |
| 61 | if(m->size>0){ |
| 62 | int size= FFMIN(buf_size-i, m->size); |
| 63 | i+=size; |
| 64 | m->size-=size; |
| 65 | state=0; |
| 66 | continue; |
| 67 | }else |
| 68 | i++; |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | if(vop_found){ |
| 73 | /* EOF considered as end of frame */ |
| 74 | if (buf_size == 0) |
| 75 | return 0; |
| 76 | for(; i<buf_size;){ |
| 77 | state= (state<<8) | buf[i]; |
| 78 | if(state>=0xFFC00000 && state<=0xFFFEFFFF){ |
| 79 | if(state>=0xFFD80000 && state<=0xFFD8FFFF){ |
| 80 | pc->frame_start_found=0; |
| 81 | pc->state=0; |
| 82 | return i-3; |
| 83 | } else if(state<0xFFD00000 || state>0xFFD9FFFF){ |
| 84 | m->size= (state&0xFFFF)-1; |
| 85 | } |
| 86 | } |
| 87 | if(m->size>0){ |
| 88 | int size= FFMIN(buf_size-i, m->size); |
| 89 | i+=size; |
| 90 | m->size-=size; |
| 91 | state=0; |
| 92 | continue; |
| 93 | }else |
| 94 | i++; |
| 95 | } |
| 96 | } |
| 97 | pc->frame_start_found= vop_found; |
| 98 | pc->state= state; |
| 99 | return END_NOT_FOUND; |
| 100 | } |
| 101 | |
| 102 | static int jpeg_parse(AVCodecParserContext *s, |
| 103 | AVCodecContext *avctx, |
| 104 | const uint8_t **poutbuf, int *poutbuf_size, |
| 105 | const uint8_t *buf, int buf_size) |
| 106 | { |
| 107 | MJPEGParserContext *m = s->priv_data; |
| 108 | ParseContext *pc = &m->pc; |
| 109 | int next; |
| 110 | |
| 111 | if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ |
| 112 | next= buf_size; |
| 113 | }else{ |
| 114 | next= find_frame_end(m, buf, buf_size); |
| 115 | |
| 116 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
| 117 | *poutbuf = NULL; |
| 118 | *poutbuf_size = 0; |
| 119 | return buf_size; |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | *poutbuf = buf; |
| 124 | *poutbuf_size = buf_size; |
| 125 | return next; |
| 126 | } |
| 127 | |
| 128 | |
| 129 | AVCodecParser ff_mjpeg_parser = { |
| 130 | .codec_ids = { AV_CODEC_ID_MJPEG }, |
| 131 | .priv_data_size = sizeof(MJPEGParserContext), |
| 132 | .parser_parse = jpeg_parse, |
| 133 | .parser_close = ff_parse_close, |
| 134 | }; |