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aac_ac3_parser.c
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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 
24 #include "libavutil/common.h"
25 #include "parser.h"
26 #include "aac_ac3_parser.h"
27 
29  AVCodecContext *avctx,
30  const uint8_t **poutbuf, int *poutbuf_size,
31  const uint8_t *buf, int buf_size)
32 {
34  ParseContext *pc = &s->pc;
35  int len, i;
36  int new_frame_start;
37  int got_frame = 0;
38 
39 get_next:
40  i=END_NOT_FOUND;
41  if(s->remaining_size <= buf_size){
42  if(s->remaining_size && !s->need_next_header){
43  i= s->remaining_size;
44  s->remaining_size = 0;
45  }else{ //we need a header first
46  len=0;
47  for(i=s->remaining_size; i<buf_size; i++){
48  s->state = (s->state<<8) + buf[i];
49  if((len=s->sync(s->state, s, &s->need_next_header, &new_frame_start)))
50  break;
51  }
52  if(len<=0){
53  i=END_NOT_FOUND;
54  }else{
55  got_frame = 1;
56  s->state=0;
57  i-= s->header_size -1;
58  s->remaining_size = len;
59  if(!new_frame_start || pc->index+i<=0){
60  s->remaining_size += i;
61  goto get_next;
62  }
63  }
64  }
65  }
66 
67  if(ff_combine_frame(pc, i, &buf, &buf_size)<0){
68  s->remaining_size -= FFMIN(s->remaining_size, buf_size);
69  *poutbuf = NULL;
70  *poutbuf_size = 0;
71  return buf_size;
72  }
73 
74  *poutbuf = buf;
75  *poutbuf_size = buf_size;
76 
77  /* update codec info */
78  if(s->codec_id)
79  avctx->codec_id = s->codec_id;
80 
81  if (got_frame) {
82  /* Due to backwards compatible HE-AAC the sample rate, channel count,
83  and total number of samples found in an AAC ADTS header are not
84  reliable. Bit rate is still accurate because the total frame
85  duration in seconds is still correct (as is the number of bits in
86  the frame). */
87  if (avctx->codec_id != AV_CODEC_ID_AAC) {
88  avctx->sample_rate = s->sample_rate;
89 
90  /* (E-)AC-3: allow downmixing to stereo or mono */
91  if (s->channels > 1 &&
93  avctx->channels = 1;
95  } else if (s->channels > 2 &&
97  avctx->channels = 2;
99  } else {
100  avctx->channels = s->channels;
101  avctx->channel_layout = s->channel_layout;
102  }
103  s1->duration = s->samples;
104  avctx->audio_service_type = s->service_type;
105  }
106 
107  avctx->bit_rate = s->bit_rate;
108  }
109 
110  return i;
111 }
#define NULL
Definition: coverity.c:32
const char * s
Definition: avisynth_c.h:631
int64_t bit_rate
the average bitrate
Definition: avcodec.h:1722
int duration
Duration of the current frame.
Definition: avcodec.h:5062
#define AV_CH_LAYOUT_STEREO
enum AVAudioServiceType audio_service_type
Type of service that the audio stream conveys.
Definition: avcodec.h:2483
uint8_t
int(* sync)(uint64_t state, struct AACAC3ParseContext *hdr_info, int *need_next_header, int *new_frame_start)
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:245
uint64_t channel_layout
Audio channel layout.
Definition: avcodec.h:2469
audio channel layout utility functions
#define FFMIN(a, b)
Definition: common.h:96
enum AVCodecID codec_id
Definition: avcodec.h:1674
int sample_rate
samples per second
Definition: avcodec.h:2418
main external API structure.
Definition: avcodec.h:1657
void * buf
Definition: avisynth_c.h:553
enum AVCodecID codec_id
#define s1
Definition: regdef.h:38
#define END_NOT_FOUND
Definition: parser.h:40
int ff_aac_ac3_parse(AVCodecParserContext *s1, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
common internal and external API header
int index
Definition: parser.h:30
int len
int channels
number of audio channels
Definition: avcodec.h:2419
#define AV_CH_LAYOUT_MONO
uint64_t request_channel_layout
Request decoder to use this channel layout if it can (0 for default)
Definition: avcodec.h:2476