| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * MPEG Audio header decoder | ||
| 3 | * Copyright (c) 2001, 2002 Fabrice Bellard | ||
| 4 | * | ||
| 5 | * This file is part of FFmpeg. | ||
| 6 | * | ||
| 7 | * FFmpeg is free software; you can redistribute it and/or | ||
| 8 | * modify it under the terms of the GNU Lesser General Public | ||
| 9 | * License as published by the Free Software Foundation; either | ||
| 10 | * version 2.1 of the License, or (at your option) any later version. | ||
| 11 | * | ||
| 12 | * FFmpeg is distributed in the hope that it will be useful, | ||
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| 15 | * Lesser General Public License for more details. | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU Lesser General Public | ||
| 18 | * License along with FFmpeg; if not, write to the Free Software | ||
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | ||
| 20 | */ | ||
| 21 | |||
| 22 | /** | ||
| 23 | * @file | ||
| 24 | * MPEG Audio header decoder. | ||
| 25 | */ | ||
| 26 | |||
| 27 | #ifndef AVCODEC_MPEGAUDIODECHEADER_H | ||
| 28 | #define AVCODEC_MPEGAUDIODECHEADER_H | ||
| 29 | |||
| 30 | #include <stdint.h> | ||
| 31 | #include "codec_id.h" | ||
| 32 | |||
| 33 | #define MP3_MASK 0xFFFE0CCF | ||
| 34 | |||
| 35 | #define MPA_DECODE_HEADER \ | ||
| 36 | int frame_size; \ | ||
| 37 | int error_protection; \ | ||
| 38 | int layer; \ | ||
| 39 | int sample_rate; \ | ||
| 40 | int sample_rate_index; /* between 0 and 8 */ \ | ||
| 41 | int bit_rate; \ | ||
| 42 | int nb_channels; \ | ||
| 43 | int mode; \ | ||
| 44 | int mode_ext; \ | ||
| 45 | int lsf; | ||
| 46 | |||
| 47 | typedef struct MPADecodeHeader { | ||
| 48 | MPA_DECODE_HEADER | ||
| 49 | } MPADecodeHeader; | ||
| 50 | |||
| 51 | /* header decoding. MUST check the header before because no | ||
| 52 | consistency check is done there. Return 1 if free format found and | ||
| 53 | that the frame size must be computed externally */ | ||
| 54 | int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header); | ||
| 55 | |||
| 56 | /* useful helper to get MPEG audio stream info. Return -1 if error in | ||
| 57 | header, otherwise the coded frame size in bytes */ | ||
| 58 | int ff_mpa_decode_header(uint32_t head, int *sample_rate, | ||
| 59 | int *channels, int *frame_size, int *bitrate, enum AVCodecID *codec_id); | ||
| 60 | |||
| 61 | /* fast header check for resync */ | ||
| 62 | 341066405 | static inline int ff_mpa_check_header(uint32_t header){ | |
| 63 | /* header */ | ||
| 64 |
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341066405 | if ((header & 0xffe00000) != 0xffe00000) |
| 65 | 339914493 | return -1; | |
| 66 | /* version check */ | ||
| 67 |
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1151912 | if ((header & (3<<19)) == 1<<19) |
| 68 | 221074 | return -1; | |
| 69 | /* layer check */ | ||
| 70 |
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930838 | if ((header & (3<<17)) == 0) |
| 71 | 203810 | return -1; | |
| 72 | /* bit rate */ | ||
| 73 |
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727028 | if ((header & (0xf<<12)) == 0xf<<12) |
| 74 | 492985 | return -1; | |
| 75 | /* frequency */ | ||
| 76 |
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234043 | if ((header & (3<<10)) == 3<<10) |
| 77 | 33264 | return -1; | |
| 78 | 200779 | return 0; | |
| 79 | } | ||
| 80 | |||
| 81 | #endif /* AVCODEC_MPEGAUDIODECHEADER_H */ | ||
| 82 |