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 Libav.
   7  *
   8  * Libav 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  * Libav 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 Libav; 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
  59             if(!s->frame_size){
  60                 next= i;
  61                 break;
  62             }
  63         }else{
  64             while(i<buf_size){
  65                 int ret, sr, channels, bit_rate, frame_size;
  66                 enum AVCodecID codec_id = avctx->codec_id;
  67
  68                 state= (state<<8) + buf[i++];
  69
  70                 ret = ff_mpa_decode_header(avctx, state, &sr, &channels, &frame_size, &bit_rate);
  71                 if (ret < 4) {
  72                     if (i > 4)
  73                         s->header_count = -2;
  74                 } else {
  75                     if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
  76                         s->header_count= -3;
  77                     s->header= state;
  78                     s->header_count++;
  79                     s->frame_size = ret-4;
  80
  81                     if (s->header_count > 0) {
  82                         avctx->sample_rate= sr;
  83                         avctx->channels   = channels;
  84                         s1->duration      = frame_size;
  85                         if (s->no_bitrate || !avctx->bit_rate) {
  86                             s->no_bitrate = 1;
  87                             avctx->bit_rate += (bit_rate - avctx->bit_rate) / s->header_count;
  88                         }
  89                     }
  90
  91                     if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
  92                         s->frame_size = 0;
  93                         next = buf_size;
  94                     } else if (codec_id == AV_CODEC_ID_MP3ADU) {
  95                         avpriv_report_missing_feature(avctx,
  96                             "MP3ADU full parser");
  97                         return AVERROR_PATCHWELCOME;
  98                     }
  99
 100                     break;
 101                 }
 102             }
 103         }
 104     }
 105
 106     pc->state= state;
 107     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 108         *poutbuf = NULL;
 109         *poutbuf_size = 0;
 110         return buf_size;
 111     }
 112
 113     *poutbuf = buf;
 114     *poutbuf_size = buf_size;
 115     return next;
 116 }
 117
 118
 119 AVCodecParser ff_mpegaudio_parser = {
 120     .codec_ids      = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3, AV_CODEC_ID_MP3ADU },
 121     .priv_data_size = sizeof(MpegAudioParseContext),
 122     .parser_parse   = mpegaudio_parse,
 123     .parser_close   = ff_parse_close,
 124 };