e920b7f88c272cf0241bf505b1d3596d7853b15a
[ffmpeg.git] / libavcodec / aac_ac3_parser.c
1 /*
2  * Common AAC and AC3 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
35     while(s->remaining_size <= buf_size){
36         if(s->remaining_size && !s->need_next_header){
37             i= s->remaining_size;
38             s->remaining_size = 0;
39             goto output_frame;
40         }else{ //we need a header first
41             len=0;
42             for(i=s->remaining_size; i<buf_size; i++){
43                 s->state = (s->state<<8) + buf[i];
44                 if((len=s->sync(s->state, s, &s->need_next_header, &s->new_frame_start)))
45                     break;
46             }
47             i-= s->header_size;
48             if(len>0){
49                 s->remaining_size = len + i;
50
51                 if(pc->index+i > 0 && s->new_frame_start){
52                     s->remaining_size -= i; // remaining_size=len
53 output_frame:
54                     ff_combine_frame(pc, i, &buf, &buf_size);
55                     *poutbuf = buf;
56                     *poutbuf_size = buf_size;
57
58                     /* update codec info */
59                     avctx->sample_rate = s->sample_rate;
60                     /* allow downmixing to stereo (or mono for AC3) */
61                     if(avctx->request_channels > 0 &&
62                             avctx->request_channels < s->channels &&
63                             (avctx->request_channels <= 2 ||
64                             (avctx->request_channels == 1 &&
65                             avctx->codec_id == CODEC_ID_AC3))) {
66                         avctx->channels = avctx->request_channels;
67                     } else {
68                         avctx->channels = s->channels;
69                     }
70                     avctx->bit_rate = s->bit_rate;
71                     avctx->frame_size = s->samples;
72
73                     return i;
74                 }
75             }else{
76                 break;
77             }
78         }
79     }
80
81     ff_combine_frame(pc, END_NOT_FOUND, &buf, &buf_size);
82     s->remaining_size -= FFMIN(s->remaining_size, buf_size);
83     *poutbuf = NULL;
84     *poutbuf_size = 0;
85     return buf_size;
86 }