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1 | /* |
2 | * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> | |
3 | * | |
4 | * This file is part of FFmpeg. | |
5 | * | |
6 | * FFmpeg 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 | * FFmpeg 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 FFmpeg; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | */ | |
20 | ||
21 | #include "libavutil/common.h" | |
22 | #include "libavutil/intreadwrite.h" | |
23 | #include "avcodec.h" | |
24 | #include "mpegaudiodecheader.h" | |
25 | #include "mpegaudiodata.h" | |
26 | ||
27 | ||
28 | static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args, | |
29 | uint8_t **poutbuf, int *poutbuf_size, | |
30 | const uint8_t *buf, int buf_size, int keyframe){ | |
31 | uint32_t header; | |
32 | int sample_rate= avctx->sample_rate; | |
33 | int sample_rate_index=0; | |
34 | int lsf, mpeg25, bitrate_index, frame_size; | |
35 | ||
36 | header = AV_RB32(buf); | |
37 | if(ff_mpa_check_header(header) >= 0){ | |
38 | *poutbuf= (uint8_t *) buf; | |
39 | *poutbuf_size= buf_size; | |
40 | ||
41 | return 0; | |
42 | } | |
43 | ||
44 | if(avctx->extradata_size != 15 || strcmp(avctx->extradata, "FFCMP3 0.0")){ | |
45 | av_log(avctx, AV_LOG_ERROR, "Extradata invalid %d\n", avctx->extradata_size); | |
46 | return -1; | |
47 | } | |
48 | ||
49 | header= AV_RB32(avctx->extradata+11) & MP3_MASK; | |
50 | ||
51 | lsf = sample_rate < (24000+32000)/2; | |
52 | mpeg25 = sample_rate < (12000+16000)/2; | |
53 | sample_rate_index= (header>>10)&3; | |
54 | sample_rate= avpriv_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off | |
55 | ||
56 | for(bitrate_index=2; bitrate_index<30; bitrate_index++){ | |
57 | frame_size = avpriv_mpa_bitrate_tab[lsf][2][bitrate_index>>1]; | |
58 | frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1); | |
59 | if(frame_size == buf_size + 4) | |
60 | break; | |
61 | if(frame_size == buf_size + 6) | |
62 | break; | |
63 | } | |
64 | if(bitrate_index == 30){ | |
65 | av_log(avctx, AV_LOG_ERROR, "Could not find bitrate_index.\n"); | |
66 | return -1; | |
67 | } | |
68 | ||
69 | header |= (bitrate_index&1)<<9; | |
70 | header |= (bitrate_index>>1)<<12; | |
71 | header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0 | |
72 | ||
73 | *poutbuf_size= frame_size; | |
74 | *poutbuf= av_malloc(frame_size + FF_INPUT_BUFFER_PADDING_SIZE); | |
75 | memcpy(*poutbuf + frame_size - buf_size, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE); | |
76 | ||
77 | if(avctx->channels==2){ | |
78 | uint8_t *p= *poutbuf + frame_size - buf_size; | |
79 | if(lsf){ | |
80 | FFSWAP(int, p[1], p[2]); | |
81 | header |= (p[1] & 0xC0)>>2; | |
82 | p[1] &= 0x3F; | |
83 | }else{ | |
84 | header |= p[1] & 0x30; | |
85 | p[1] &= 0xCF; | |
86 | } | |
87 | } | |
88 | ||
89 | AV_WB32(*poutbuf, header); | |
90 | ||
91 | return 1; | |
92 | } | |
93 | ||
94 | AVBitStreamFilter ff_mp3_header_decompress_bsf={ | |
95 | .name = "mp3decomp", | |
96 | .filter = mp3_header_decompress, | |
97 | }; |