git.sesse.net Git - ffmpeg/blob - libavcodec/mpegaudio_parser.c

   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 = avctx->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                     int header_threshold = avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id;
  77                     if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
  78                         s->header_count= -3;
  79                     s->header= state;
  80                     s->header_count++;
  81                     s->frame_size = ret-4;
  82
  83                     if (s->header_count > header_threshold) {
  84                         avctx->sample_rate= sr;
  85                         avctx->channels   = channels;
  86                         s1->duration      = frame_size;
  87                         avctx->codec_id   = codec_id;
  88                         if (s->no_bitrate || !avctx->bit_rate) {
  89                             s->no_bitrate = 1;
  90                             avctx->bit_rate += (bit_rate - avctx->bit_rate) / (s->header_count - header_threshold);
  91                         }
  92                     }
  93
  94                     if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
  95                         s->frame_size = 0;
  96                         next = buf_size;
  97                     } else if (codec_id == AV_CODEC_ID_MP3ADU) {
  98                         avpriv_report_missing_feature(avctx,
  99                             "MP3ADU full parser");
 100                         return AVERROR_PATCHWELCOME;
 101                     }
 102
 103                     break;
 104                 }
 105             }
 106         }
 107     }
 108
 109     pc->state= state;
 110     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 111         *poutbuf = NULL;
 112         *poutbuf_size = 0;
 113         return buf_size;
 114     }
 115
 116     *poutbuf = buf;
 117     *poutbuf_size = buf_size;
 118     return next;
 119 }
 120
 121
 122 AVCodecParser ff_mpegaudio_parser = {
 123     .codec_ids      = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3, AV_CODEC_ID_MP3ADU },
 124     .priv_data_size = sizeof(MpegAudioParseContext),
 125     .parser_parse   = mpegaudio_parse,
 126     .parser_close   = ff_parse_close,
 127 };