FFmpeg
mpegaudio_parser.c
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1 /*
2  * MPEG Audio 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 "mpegaudiodecheader.h"
25 #include "libavutil/common.h"
26 #include "libavformat/apetag.h" // for APE tag.
27 #include "libavformat/id3v1.h" // for ID3v1_TAG_SIZE
28 
29 typedef struct MpegAudioParseContext {
32  uint32_t header;
36 
37 #define MPA_HEADER_SIZE 4
38 
39 /* header + layer + freq + lsf/mpeg25 */
40 #define SAME_HEADER_MASK \
41  (0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19))
42 
44  AVCodecContext *avctx,
45  const uint8_t **poutbuf, int *poutbuf_size,
46  const uint8_t *buf, int buf_size)
47 {
48  MpegAudioParseContext *s = s1->priv_data;
49  ParseContext *pc = &s->pc;
50  uint32_t state= pc->state;
51  int i;
52  int next= END_NOT_FOUND;
53  int flush = !buf_size;
54 
55  for(i=0; i<buf_size; ){
56  if(s->frame_size){
57  int inc= FFMIN(buf_size - i, s->frame_size);
58  i += inc;
59  s->frame_size -= inc;
60  state = 0;
61 
62  if(!s->frame_size){
63  next= i;
64  break;
65  }
66  }else{
67  while(i<buf_size){
68  int ret, sr, channels, bit_rate, frame_size;
69  enum AVCodecID codec_id = avctx->codec_id;
70 
71  state= (state<<8) + buf[i++];
72 
73  ret = ff_mpa_decode_header(state, &sr, &channels, &frame_size, &bit_rate, &codec_id);
74  if (ret < 4) {
75  if (i > 4)
76  s->header_count = -2;
77  } else {
78  int header_threshold = avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id;
79  if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
80  s->header_count= -3;
81  s->header= state;
82  s->header_count++;
83  s->frame_size = ret-4;
84 
85  if (s->header_count > header_threshold) {
86  avctx->sample_rate= sr;
89  s1->duration = frame_size;
90  avctx->codec_id = codec_id;
91  if (s->no_bitrate || !avctx->bit_rate) {
92  s->no_bitrate = 1;
93  avctx->bit_rate += (bit_rate - avctx->bit_rate) / (s->header_count - header_threshold);
94  }
95  }
96 
97  if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
98  s->frame_size = 0;
99  next = buf_size;
100  } else if (codec_id == AV_CODEC_ID_MP3ADU) {
102  "MP3ADU full parser");
103  *poutbuf = NULL;
104  *poutbuf_size = 0;
105  return buf_size; /* parsers must not return error codes */
106  }
107 
108  break;
109  }
110  }
111  }
112  }
113 
114  pc->state= state;
115  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
116  *poutbuf = NULL;
117  *poutbuf_size = 0;
118  return buf_size;
119  }
120 
121  if (flush && buf_size >= ID3v1_TAG_SIZE && memcmp(buf, "TAG", 3) == 0) {
122  *poutbuf = NULL;
123  *poutbuf_size = 0;
124  return next;
125  }
126 
127  if (flush && buf_size >= APE_TAG_FOOTER_BYTES && memcmp(buf, APE_TAG_PREAMBLE, 8) == 0) {
128  *poutbuf = NULL;
129  *poutbuf_size = 0;
130  return next;
131  }
132 
133  *poutbuf = buf;
134  *poutbuf_size = buf_size;
135  return next;
136 }
137 
138 
141  .priv_data_size = sizeof(MpegAudioParseContext),
142  .parser_parse = mpegaudio_parse,
143  .parser_close = ff_parse_close,
144 };
ID3v1_TAG_SIZE
#define ID3v1_TAG_SIZE
Definition: id3v1.h:27
AVCodecContext::sample_rate
int sample_rate
samples per second
Definition: avcodec.h:1007
apetag.h
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:284
mpegaudiodecheader.h
MpegAudioParseContext
Definition: mpegaudio_parser.c:29
id3v1.h
ParseContext::state
uint32_t state
contains the last few bytes in MSB order
Definition: parser.h:33
APE_TAG_PREAMBLE
#define APE_TAG_PREAMBLE
Definition: apetag.h:28
AV_CODEC_ID_MP3ADU
@ AV_CODEC_ID_MP3ADU
Definition: codec_id.h:448
ff_mpa_decode_header
int ff_mpa_decode_header(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate, enum AVCodecID *codec_id)
Definition: mpegaudiodecheader.c:120
ParseContext
Definition: parser.h:28
AVCodecContext::ch_layout
AVChannelLayout ch_layout
Audio channel layout.
Definition: avcodec.h:2059
AV_CODEC_ID_MP3
@ AV_CODEC_ID_MP3
preferred ID for decoding MPEG audio layer 1, 2 or 3
Definition: codec_id.h:436
s
#define s(width, name)
Definition: cbs_vp9.c:256
frame_size
int frame_size
Definition: mxfenc.c:2202
AV_CODEC_ID_MP2
@ AV_CODEC_ID_MP2
Definition: codec_id.h:435
s1
#define s1
Definition: regdef.h:38
channels
channels
Definition: aptx.h:31
codec_id
enum AVCodecID codec_id
Definition: vaapi_decode.c:388
state
static struct @344 state
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:408
NULL
#define NULL
Definition: coverity.c:32
AVCodecContext::bit_rate
int64_t bit_rate
the average bitrate
Definition: avcodec.h:448
MpegAudioParseContext::pc
ParseContext pc
Definition: mpegaudio_parser.c:30
AVCodecID
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: codec_id.h:49
MpegAudioParseContext::header_count
int header_count
Definition: mpegaudio_parser.c:33
AVCodecParser::codec_ids
int codec_ids[7]
Definition: avcodec.h:2960
avpriv_report_missing_feature
void avpriv_report_missing_feature(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
ff_mpegaudio_parser
const AVCodecParser ff_mpegaudio_parser
Definition: mpegaudio_parser.c:139
MpegAudioParseContext::no_bitrate
int no_bitrate
Definition: mpegaudio_parser.c:34
ff_combine_frame
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:199
av_channel_layout_default
void av_channel_layout_default(AVChannelLayout *ch_layout, int nb_channels)
Get the default channel layout for a given number of channels.
Definition: channel_layout.c:962
PARSER_FLAG_COMPLETE_FRAMES
#define PARSER_FLAG_COMPLETE_FRAMES
Definition: avcodec.h:2834
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:50
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
MpegAudioParseContext::frame_size
int frame_size
Definition: mpegaudio_parser.c:31
MpegAudioParseContext::header
uint32_t header
Definition: mpegaudio_parser.c:32
common.h
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
parser.h
AVCodecParserContext
Definition: avcodec.h:2800
ret
ret
Definition: filter_design.txt:187
mpegaudio_parse
static int mpegaudio_parse(AVCodecParserContext *s1, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: mpegaudio_parser.c:43
AVCodecContext
main external API structure.
Definition: avcodec.h:398
av_channel_layout_uninit
void av_channel_layout_uninit(AVChannelLayout *channel_layout)
Free any allocated data in the channel layout and reset the channel count to 0.
Definition: channel_layout.c:632
APE_TAG_FOOTER_BYTES
#define APE_TAG_FOOTER_BYTES
Definition: apetag.h:30
flush
void(* flush)(AVBSFContext *ctx)
Definition: dts2pts_bsf.c:365
SAME_HEADER_MASK
#define SAME_HEADER_MASK
Definition: mpegaudio_parser.c:40
END_NOT_FOUND
#define END_NOT_FOUND
Definition: parser.h:40
AVCodecParser
Definition: avcodec.h:2959
AV_CODEC_ID_MP1
@ AV_CODEC_ID_MP1
Definition: codec_id.h:477