| 1 | /* |
| 2 | * MPEG Audio parser |
| 3 | * Copyright (c) 2003 Fabrice Bellard |
| 4 | * Copyright (c) 2003 Michael Niedermayer |
| 5 | * |
| 6 | * This file is part of FFmpeg. |
| 7 | * |
| 8 | * FFmpeg is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * FFmpeg is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with FFmpeg; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | #include "parser.h" |
| 24 | #include "mpegaudiodecheader.h" |
| 25 | #include "libavutil/common.h" |
| 26 | |
| 27 | |
| 28 | typedef struct MpegAudioParseContext { |
| 29 | ParseContext pc; |
| 30 | int frame_size; |
| 31 | uint32_t header; |
| 32 | int header_count; |
| 33 | int no_bitrate; |
| 34 | } MpegAudioParseContext; |
| 35 | |
| 36 | #define MPA_HEADER_SIZE 4 |
| 37 | |
| 38 | /* header + layer + bitrate + freq + lsf/mpeg25 */ |
| 39 | #define SAME_HEADER_MASK \ |
| 40 | (0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19)) |
| 41 | |
| 42 | static int mpegaudio_parse(AVCodecParserContext *s1, |
| 43 | AVCodecContext *avctx, |
| 44 | const uint8_t **poutbuf, int *poutbuf_size, |
| 45 | const uint8_t *buf, int buf_size) |
| 46 | { |
| 47 | MpegAudioParseContext *s = s1->priv_data; |
| 48 | ParseContext *pc = &s->pc; |
| 49 | uint32_t state= pc->state; |
| 50 | int i; |
| 51 | int next= END_NOT_FOUND; |
| 52 | |
| 53 | for(i=0; i<buf_size; ){ |
| 54 | if(s->frame_size){ |
| 55 | int inc= FFMIN(buf_size - i, s->frame_size); |
| 56 | i += inc; |
| 57 | s->frame_size -= inc; |
| 58 | state = 0; |
| 59 | |
| 60 | if(!s->frame_size){ |
| 61 | next= i; |
| 62 | break; |
| 63 | } |
| 64 | }else{ |
| 65 | while(i<buf_size){ |
| 66 | int ret, sr, channels, bit_rate, frame_size; |
| 67 | enum AVCodecID codec_id; |
| 68 | |
| 69 | state= (state<<8) + buf[i++]; |
| 70 | |
| 71 | ret = avpriv_mpa_decode_header2(state, &sr, &channels, &frame_size, &bit_rate, &codec_id); |
| 72 | if (ret < 4) { |
| 73 | if (i > 4) |
| 74 | s->header_count = -2; |
| 75 | } else { |
| 76 | if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header) |
| 77 | s->header_count= -3; |
| 78 | s->header= state; |
| 79 | s->header_count++; |
| 80 | s->frame_size = ret-4; |
| 81 | |
| 82 | if (s->header_count > 0 + (avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id)) { |
| 83 | avctx->sample_rate= sr; |
| 84 | avctx->channels = channels; |
| 85 | s1->duration = frame_size; |
| 86 | avctx->codec_id = codec_id; |
| 87 | if (s->no_bitrate || !avctx->bit_rate) { |
| 88 | s->no_bitrate = 1; |
| 89 | avctx->bit_rate += (bit_rate - avctx->bit_rate) / s->header_count; |
| 90 | } |
| 91 | } |
| 92 | break; |
| 93 | } |
| 94 | } |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | pc->state= state; |
| 99 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
| 100 | *poutbuf = NULL; |
| 101 | *poutbuf_size = 0; |
| 102 | return buf_size; |
| 103 | } |
| 104 | |
| 105 | *poutbuf = buf; |
| 106 | *poutbuf_size = buf_size; |
| 107 | return next; |
| 108 | } |
| 109 | |
| 110 | |
| 111 | AVCodecParser ff_mpegaudio_parser = { |
| 112 | .codec_ids = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3 }, |
| 113 | .priv_data_size = sizeof(MpegAudioParseContext), |
| 114 | .parser_parse = mpegaudio_parse, |
| 115 | .parser_close = ff_parse_close, |
| 116 | }; |