Fix all the recent problems Justin had run into with the AC3 parser,
[ffmpeg.git] / libavcodec / aac_ac3_parser.c
1 /*
2  * Common AAC and AC-3 parser
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 "aac_ac3_parser.h"
25
26 int ff_aac_ac3_parse(AVCodecParserContext *s1,
27                      AVCodecContext *avctx,
28                      const uint8_t **poutbuf, int *poutbuf_size,
29                      const uint8_t *buf, int buf_size)
30 {
31     AACAC3ParseContext *s = s1->priv_data;
32     ParseContext *pc = &s->pc;
33     int len, i;
34     int new_frame_start;
35
36 get_next:
37     i=END_NOT_FOUND;
38     if(s->remaining_size <= buf_size){
39         if(s->remaining_size && !s->need_next_header){
40             i= s->remaining_size;
41             s->remaining_size = 0;
42         }else{ //we need a header first
43             len=0;
44             for(i=s->remaining_size; i<buf_size; i++){
45                 s->state = (s->state<<8) + buf[i];
46                 if((len=s->sync(s->state, s, &s->need_next_header, &new_frame_start)))
47                     break;
48             }
49             if(len<=0){
50                 i=END_NOT_FOUND;
51             }else{
52                 i-= s->header_size -1;
53                 s->remaining_size = len;
54                 if(!new_frame_start || pc->index+i<=0){
55                     s->remaining_size += i;
56                     goto get_next;
57                 }
58             }
59         }
60     }
61
62     if(ff_combine_frame(pc, i, &buf, &buf_size)<0){
63         s->remaining_size -= FFMIN(s->remaining_size, buf_size);
64         *poutbuf = NULL;
65         *poutbuf_size = 0;
66         return buf_size;
67     }
68
69     *poutbuf = buf;
70     *poutbuf_size = buf_size;
71
72     /* update codec info */
73     avctx->sample_rate = s->sample_rate;
74     /* allow downmixing to stereo (or mono for AC-3) */
75     if(avctx->request_channels > 0 &&
76             avctx->request_channels < s->channels &&
77             (avctx->request_channels <= 2 ||
78             (avctx->request_channels == 1 &&
79             (avctx->codec_id == CODEC_ID_AC3 ||
80              avctx->codec_id == CODEC_ID_EAC3)))) {
81         avctx->channels = avctx->request_channels;
82     } else {
83         avctx->channels = s->channels;
84     }
85     avctx->bit_rate = s->bit_rate;
86     avctx->frame_size = s->samples;
87
88     return i;
89 }