blob: 952ba174406fc734fe89e25330410511f87562f2
| 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 info. Return -1 if error in |
| 56 | header, otherwise the coded frame size in bytes */ |
| 57 | int ff_mpa_decode_header(uint32_t head, int *sample_rate, |
| 58 | int *channels, int *frame_size, int *bitrate, enum AVCodecID *codec_id); |
| 59 | |
| 60 | #if LIBAVCODEC_VERSION_MAJOR < 58 |
| 61 | int avpriv_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bitrate); |
| 62 | int avpriv_mpa_decode_header2(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bitrate, enum AVCodecID *codec_id); |
| 63 | #endif |
| 64 | |
| 65 | /* fast header check for resync */ |
| 66 | static inline int ff_mpa_check_header(uint32_t header){ |
| 67 | /* header */ |
| 68 | if ((header & 0xffe00000) != 0xffe00000) |
| 69 | return -1; |
| 70 | /* layer check */ |
| 71 | if ((header & (3<<17)) == 0) |
| 72 | return -1; |
| 73 | /* bit rate */ |
| 74 | if ((header & (0xf<<12)) == 0xf<<12) |
| 75 | return -1; |
| 76 | /* frequency */ |
| 77 | if ((header & (3<<10)) == 3<<10) |
| 78 | return -1; |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | #endif /* AVCODEC_MPEGAUDIODECHEADER_H */ |
| 83 |