79dbf635b40ee309395870a35f7d343612332beb
[deb_ffmpeg.git] / ffmpeg / libavcodec / mpegaudio_parser.c
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
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 + bitrate + 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
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;
68
69 state= (state<<8) + buf[i++];
70
71 ret = avpriv_mpa_decode_header2(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 break;
94 }
95 }
96 }
97 }
98
99 pc->state= state;
100 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
101 *poutbuf = NULL;
102 *poutbuf_size = 0;
103 return buf_size;
104 }
105
106 *poutbuf = buf;
107 *poutbuf_size = buf_size;
108 return next;
109 }
110
111
112 AVCodecParser ff_mpegaudio_parser = {
113 .codec_ids = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3 },
114 .priv_data_size = sizeof(MpegAudioParseContext),
115 .parser_parse = mpegaudio_parse,
116 .parser_close = ff_parse_close,
117 };