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
28typedef 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
42static 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                    if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
77                        s->header_count= -3;
78                    s->header= state;
79                    s->header_count++;
80                    s->frame_size = ret-4;
81
82                    if (s->header_count > 0 + (avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id)) {
83                        avctx->sample_rate= sr;
84                        avctx->channels   = channels;
85                        s1->duration      = frame_size;
86                        avctx->codec_id   = codec_id;
87                        if (s->no_bitrate || !avctx->bit_rate) {
88                            s->no_bitrate = 1;
89                            avctx->bit_rate += (bit_rate - avctx->bit_rate) / s->header_count;
90                        }
91                    }
92                    break;
93                }
94            }
95        }
96    }
97
98    pc->state= state;
99    if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
100        *poutbuf = NULL;
101        *poutbuf_size = 0;
102        return buf_size;
103    }
104
105    *poutbuf = buf;
106    *poutbuf_size = buf_size;
107    return next;
108}
109
110
111AVCodecParser ff_mpegaudio_parser = {
112    .codec_ids      = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3 },
113    .priv_data_size = sizeof(MpegAudioParseContext),
114    .parser_parse   = mpegaudio_parse,
115    .parser_close   = ff_parse_close,
116};
117