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2ba45a60 DM |
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 { | |
f6fa7814 | 76 | int header_threshold = avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id; |
2ba45a60 DM |
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 | ||
f6fa7814 | 83 | if (s->header_count > header_threshold) { |
2ba45a60 DM |
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; | |
f6fa7814 | 90 | avctx->bit_rate += (bit_rate - avctx->bit_rate) / (s->header_count - header_threshold); |
2ba45a60 DM |
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 | }; |