repositories / deb_ffmpeg.git / blame
| Commit | Line | Data |
|---|---|---|
| 2ba45a60 DM |
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 "avcodec.h" | |
| 31 | ||
| 32 | #define MP3_MASK 0xFFFE0CCF | |
| 33 | ||
| 34 | #define MPA_DECODE_HEADER \ | |
| 35 | int frame_size; \ | |
| 36 | int error_protection; \ | |
| 37 | int layer; \ | |
| 38 | int sample_rate; \ | |
| 39 | int sample_rate_index; /* between 0 and 8 */ \ | |
| 40 | int bit_rate; \ | |
| 41 | int nb_channels; \ | |
| 42 | int mode; \ | |
| 43 | int mode_ext; \ | |
| 44 | int lsf; | |
| 45 | ||
| 46 | typedef struct MPADecodeHeader { | |
| 47 | MPA_DECODE_HEADER | |
| 48 | } MPADecodeHeader; | |
| 49 | ||
| 50 | /* header decoding. MUST check the header before because no | |
| 51 | consistency check is done there. Return 1 if free format found and | |
| 52 | that the frame size must be computed externally */ | |
| 53 | int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header); | |
| 54 | ||
| 55 | /* useful helper to get mpeg audio stream infos. Return -1 if error in | |
| 56 | header, otherwise the coded frame size in bytes */ | |
| 57 | int avpriv_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bitrate); | |
| 58 | ||
| 59 | int avpriv_mpa_decode_header2(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bitrate, enum AVCodecID *codec_id); | |
| 60 | ||
| 61 | /* fast header check for resync */ | |
| 62 | static inline int ff_mpa_check_header(uint32_t header){ | |
| 63 | /* header */ | |
| 64 | if ((header & 0xffe00000) != 0xffe00000) | |
| 65 | return -1; | |
| 66 | /* layer check */ | |
| 67 | if ((header & (3<<17)) == 0) | |
| 68 | return -1; | |
| 69 | /* bit rate */ | |
| 70 | if ((header & (0xf<<12)) == 0xf<<12) | |
| 71 | return -1; | |
| 72 | /* frequency */ | |
| 73 | if ((header & (3<<10)) == 3<<10) | |
| 74 | return -1; | |
| 75 | return 0; | |
| 76 | } | |
| 77 | ||
| 78 | #endif /* AVCODEC_MPEGAUDIODECHEADER_H */ |