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
27 typedef struct MpegAudioParseContext {
28 ParseContext pc;
29 int frame_size;
30 uint32_t header;
31 int header_count;
32 int no_bitrate;
33 } MpegAudioParseContext;
34
35 #define MPA_HEADER_SIZE 4
36
37 /* header + layer + freq + lsf/mpeg25 */
38 #define SAME_HEADER_MASK \
39 (0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19))
40
mpegaudio_parse(AVCodecParserContext * s1,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)41 static int mpegaudio_parse(AVCodecParserContext *s1,
42 AVCodecContext *avctx,
43 const uint8_t **poutbuf, int *poutbuf_size,
44 const uint8_t *buf, int buf_size)
45 {
46 MpegAudioParseContext *s = s1->priv_data;
47 ParseContext *pc = &s->pc;
48 uint32_t state= pc->state;
49 int i;
50 int next= END_NOT_FOUND;
51 int flush = !buf_size;
52
53 for(i=0; i<buf_size; ){
54 if(s->frame_size){
55 int inc= FFMIN(buf_size - i, s->frame_size);
56 i += inc;
57 s->frame_size -= inc;
58 state = 0;
59
60 if(!s->frame_size){
61 next= i;
62 break;
63 }
64 }else{
65 while(i<buf_size){
66 int ret, sr, channels, bit_rate, frame_size;
67 enum AVCodecID codec_id = avctx->codec_id;
68
69 state= (state<<8) + buf[i++];
70
71 ret = ff_mpa_decode_header(state, &sr, &channels, &frame_size, &bit_rate, &codec_id);
72 if (ret < 4) {
73 if (i > 4)
74 s->header_count = -2;
75 } else {
76 int header_threshold = avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id;
77 if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
78 s->header_count= -3;
79 s->header= state;
80 s->header_count++;
81 s->frame_size = ret-4;
82
83 if (s->header_count > header_threshold) {
84 avctx->sample_rate= sr;
85 avctx->channels = channels;
86 s1->duration = frame_size;
87 avctx->codec_id = codec_id;
88 if (s->no_bitrate || !avctx->bit_rate) {
89 s->no_bitrate = 1;
90 avctx->bit_rate += (bit_rate - avctx->bit_rate) / (s->header_count - header_threshold);
91 }
92 }
93
94 if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
95 s->frame_size = 0;
96 next = buf_size;
97 } else if (codec_id == AV_CODEC_ID_MP3ADU) {
98 avpriv_report_missing_feature(avctx,
99 "MP3ADU full parser");
100 *poutbuf = NULL;
101 *poutbuf_size = 0;
102 return buf_size; /* parsers must not return error codes */
103 }
104
105 break;
106 }
107 }
108 }
109 }
110
111 pc->state= state;
112 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
113 *poutbuf = NULL;
114 *poutbuf_size = 0;
115 return buf_size;
116 }
117
118 if (flush && buf_size && !s->frame_size) {
119 av_log(avctx, AV_LOG_WARNING, "Discarding invalid trailing data from mpeg audio stream.\n");
120 *poutbuf = NULL;
121 *poutbuf_size = 0;
122 return next;
123 }
124
125 *poutbuf = buf;
126 *poutbuf_size = buf_size;
127 return next;
128 }
129
130
131 AVCodecParser ff_mpegaudio_parser = {
132 .codec_ids = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3, AV_CODEC_ID_MP3ADU },
133 .priv_data_size = sizeof(MpegAudioParseContext),
134 .parser_parse = mpegaudio_parse,
135 .parser_close = ff_parse_close,
136 };
137