path: root/libavcodec/mpegaudio_parser.c (plain)
blob: 021cba4d5ccde8fbbc5bc34d372e3d27b7eb4599

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/id3v1.h" // for ID3v1_TAG_SIZE
27
28	typedef struct MpegAudioParseContext {
29	ParseContext pc;
30	int frame_size;
31	uint32_t header;
32	int header_count;
33	int no_bitrate;
34	} MpegAudioParseContext;
35
36	#define MPA_HEADER_SIZE 4
37
38	/* header + layer + freq + lsf/mpeg25 */
39	#define SAME_HEADER_MASK \
40	(0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19))
41
42	static int mpegaudio_parse(AVCodecParserContext *s1,
43	AVCodecContext *avctx,
44	const uint8_t **poutbuf, int *poutbuf_size,
45	const uint8_t *buf, int buf_size)
46	{
47	MpegAudioParseContext *s = s1->priv_data;
48	ParseContext *pc = &s->pc;
49	uint32_t state= pc->state;
50	int i;
51	int next= END_NOT_FOUND;
52	int flush = !buf_size;
53
54	for(i=0; i<buf_size; ){
55	if(s->frame_size){
56	int inc= FFMIN(buf_size - i, s->frame_size);
57	i += inc;
58	s->frame_size -= inc;
59	state = 0;
60
61	if(!s->frame_size){
62	next= i;
63	break;
64	}
65	}else{
66	while(i<buf_size){
67	int ret, sr, channels, bit_rate, frame_size;
68	enum AVCodecID codec_id = avctx->codec_id;
69
70	state= (state<<8) + buf[i++];
71
72	ret = ff_mpa_decode_header(state, &sr, &channels, &frame_size, &bit_rate, &codec_id);
73	if (ret < 4) {
74	if (i > 4)
75	s->header_count = -2;
76	} else {
77	int header_threshold = avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id;
78	if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
79	s->header_count= -3;
80	s->header= state;
81	s->header_count++;
82	s->frame_size = ret-4;
83
84	if (s->header_count > header_threshold) {
85	avctx->sample_rate= sr;
86	avctx->channels = channels;
87	s1->duration = frame_size;
88	avctx->codec_id = codec_id;
89	if (s->no_bitrate || !avctx->bit_rate) {
90	s->no_bitrate = 1;
91	avctx->bit_rate += (bit_rate - avctx->bit_rate) / (s->header_count - header_threshold);
92	}
93	}
94	if (avctx->codec_id == AV_CODEC_ID_MP3 && codec_id == AV_CODEC_ID_MP2) {
95	avctx->codec_id = AV_CODEC_ID_MP2;
96	}
97
98	if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
99	s->frame_size = 0;
100	next = buf_size;
101	} else if (codec_id == AV_CODEC_ID_MP3ADU) {
102	avpriv_report_missing_feature(avctx,
103	"MP3ADU full parser");
104	return 0; /* 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	*poutbuf = buf;
127	*poutbuf_size = buf_size;
128	return next;
129	}
130
131
132	AVCodecParser ff_mpegaudio_parser = {
133	.codec_ids = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3, AV_CODEC_ID_MP3ADU },
134	.priv_data_size = sizeof(MpegAudioParseContext),
135	.parser_parse = mpegaudio_parse,
136	.parser_close = ff_parse_close,
137	};
138