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 {
30 ParseContext pc;
31 int frame_size;
32 uint32_t header;
33 int header_count;
34 int no_bitrate;
35 } MpegAudioParseContext;
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
mpegaudio_parse(AVCodecParserContext * s1,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)43 static int mpegaudio_parse(AVCodecParserContext *s1,
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;
87 avctx->channels = channels;
88 s1->duration = frame_size;
89 avctx->codec_id = codec_id;
90 if (s->no_bitrate || !avctx->bit_rate) {
91 s->no_bitrate = 1;
92 avctx->bit_rate += (bit_rate - avctx->bit_rate) / (s->header_count - header_threshold);
93 }
94 }
95
96 if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
97 s->frame_size = 0;
98 next = buf_size;
99 } else if (codec_id == AV_CODEC_ID_MP3ADU) {
100 avpriv_report_missing_feature(avctx,
101 "MP3ADU full parser");
102 *poutbuf = NULL;
103 *poutbuf_size = 0;
104 return buf_size; /* parsers must not return error codes */
105 }
106
107 break;
108 }
109 }
110 }
111 }
112
113 pc->state= state;
114 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
115 *poutbuf = NULL;
116 *poutbuf_size = 0;
117 return buf_size;
118 }
119
120 if (flush && buf_size >= ID3v1_TAG_SIZE && memcmp(buf, "TAG", 3) == 0) {
121 *poutbuf = NULL;
122 *poutbuf_size = 0;
123 return next;
124 }
125
126 if (flush && buf_size >= APE_TAG_FOOTER_BYTES && memcmp(buf, APE_TAG_PREAMBLE, 8) == 0) {
127 *poutbuf = NULL;
128 *poutbuf_size = 0;
129 return next;
130 }
131
132 *poutbuf = buf;
133 *poutbuf_size = buf_size;
134 return next;
135 }
136
137
138 AVCodecParser ff_mpegaudio_parser = {
139 .codec_ids = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3, AV_CODEC_ID_MP3ADU },
140 .priv_data_size = sizeof(MpegAudioParseContext),
141 .parser_parse = mpegaudio_parse,
142 .parser_close = ff_parse_close,
143 };
144