Statistics
| Branch: | Revision:

ffmpeg / libavcodec / mp3_header_decompress_bsf.c @ 2912e87a

History | View | Annotate | Download (3.12 KB)

1
/*
2
 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3
 *
4
 * This file is part of Libav.
5
 *
6
 * Libav is free software; you can redistribute it and/or
7
 * modify it under the terms of the GNU Lesser General Public
8
 * License as published by the Free Software Foundation; either
9
 * version 2.1 of the License, or (at your option) any later version.
10
 *
11
 * Libav is distributed in the hope that it will be useful,
12
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14
 * Lesser General Public License for more details.
15
 *
16
 * You should have received a copy of the GNU Lesser General Public
17
 * License along with Libav; if not, write to the Free Software
18
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19
 */
20

    
21
#include "avcodec.h"
22
#include "mpegaudio.h"
23
#include "mpegaudiodata.h"
24

    
25

    
26
static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
27
                     uint8_t **poutbuf, int *poutbuf_size,
28
                     const uint8_t *buf, int buf_size, int keyframe){
29
    uint32_t header;
30
    int sample_rate= avctx->sample_rate;
31
    int sample_rate_index=0;
32
    int lsf, mpeg25, bitrate_index, frame_size;
33

    
34
    header = AV_RB32(buf);
35
    if(ff_mpa_check_header(header) >= 0){
36
        *poutbuf= (uint8_t *) buf;
37
        *poutbuf_size= buf_size;
38

    
39
        return 0;
40
    }
41

    
42
    if(avctx->extradata_size != 15 || strcmp(avctx->extradata, "FFCMP3 0.0")){
43
        av_log(avctx, AV_LOG_ERROR, "Extradata invalid %d\n", avctx->extradata_size);
44
        return -1;
45
    }
46

    
47
    header= AV_RB32(avctx->extradata+11) & MP3_MASK;
48

    
49
    lsf     = sample_rate < (24000+32000)/2;
50
    mpeg25  = sample_rate < (12000+16000)/2;
51
    sample_rate_index= (header>>10)&3;
52
    sample_rate= ff_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off
53

    
54
    for(bitrate_index=2; bitrate_index<30; bitrate_index++){
55
        frame_size = ff_mpa_bitrate_tab[lsf][2][bitrate_index>>1];
56
        frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1);
57
        if(frame_size == buf_size + 4)
58
            break;
59
        if(frame_size == buf_size + 6)
60
            break;
61
    }
62
    if(bitrate_index == 30){
63
        av_log(avctx, AV_LOG_ERROR, "Could not find bitrate_index.\n");
64
        return -1;
65
    }
66

    
67
    header |= (bitrate_index&1)<<9;
68
    header |= (bitrate_index>>1)<<12;
69
    header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0
70

    
71
    *poutbuf_size= frame_size;
72
    *poutbuf= av_malloc(frame_size + FF_INPUT_BUFFER_PADDING_SIZE);
73
    memcpy(*poutbuf + frame_size - buf_size, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
74

    
75
    if(avctx->channels==2){
76
        uint8_t *p= *poutbuf + frame_size - buf_size;
77
        if(lsf){
78
            FFSWAP(int, p[1], p[2]);
79
            header |= (p[1] & 0xC0)>>2;
80
            p[1] &= 0x3F;
81
        }else{
82
            header |= p[1] & 0x30;
83
            p[1] &= 0xCF;
84
        }
85
    }
86

    
87
    AV_WB32(*poutbuf, header);
88

    
89
    return 1;
90
}
91

    
92
AVBitStreamFilter ff_mp3_header_decompress_bsf={
93
    "mp3decomp",
94
    0,
95
    mp3_header_decompress,
96
};