/*
  * MPEG Audio parser

  * Copyright (c) 2003 Fabrice Bellard
  * Copyright (c) 2003 Michael Niedermayer

  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "parser.h"

 #include "mpegaudiodecheader.h"

 #include "libavutil/common.h"

 #include "libavformat/id3v1.h" // for ID3v1_TAG_SIZE

 
 typedef struct MpegAudioParseContext {

     ParseContext pc;

     int frame_size;
     uint32_t header;
     int header_count;

     int no_bitrate;

 } MpegAudioParseContext;
 
 #define MPA_HEADER_SIZE 4
 

 /* header + layer + freq + lsf/mpeg25 */

 #define SAME_HEADER_MASK \
    (0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19))
 
 static int mpegaudio_parse(AVCodecParserContext *s1,
                            AVCodecContext *avctx,

                            const uint8_t **poutbuf, int *poutbuf_size,

                            const uint8_t *buf, int buf_size)
 {
     MpegAudioParseContext *s = s1->priv_data;

     ParseContext *pc = &s->pc;
     uint32_t state= pc->state;
     int i;
     int next= END_NOT_FOUND;

     int flush = !buf_size;

 
     for(i=0; i<buf_size; ){
         if(s->frame_size){
             int inc= FFMIN(buf_size - i, s->frame_size);
             i += inc;
             s->frame_size -= inc;

             state = 0;

 
             if(!s->frame_size){
                 next= i;
                 break;

             }

         }else{
             while(i<buf_size){
                 int ret, sr, channels, bit_rate, frame_size;

                 enum AVCodecID codec_id = avctx->codec_id;

 
                 state= (state<<8) + buf[i++];

                 ret = ff_mpa_decode_header(state, &sr, &channels, &frame_size, &bit_rate, &codec_id);

                 if (ret < 4) {

                     if (i > 4)
                         s->header_count = -2;

                 } else {

                     int header_threshold = avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id;

                     if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)

                         s->header_count= -3;

                     s->header= state;

                     s->header_count++;

                     s->frame_size = ret-4;

                     if (s->header_count > header_threshold) {

                         avctx->sample_rate= sr;

                         avctx->channels   = channels;

                         s1->duration      = frame_size;

                         avctx->codec_id   = codec_id;

                         if (s->no_bitrate || !avctx->bit_rate) {
                             s->no_bitrate = 1;

                             avctx->bit_rate += (bit_rate - avctx->bit_rate) / (s->header_count - header_threshold);

                         }

                     }

 
                     if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
                         s->frame_size = 0;
                         next = buf_size;
                     } else if (codec_id == AV_CODEC_ID_MP3ADU) {

                         avpriv_report_missing_feature(avctx,
                             "MP3ADU full parser");

                         return 0; /* parsers must not return error codes */

                     }
 

                     break;

                 }

             }
         }

     }

     pc->state= state;
     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
         *poutbuf = NULL;
         *poutbuf_size = 0;
         return buf_size;

     }

     if (flush && buf_size >= ID3v1_TAG_SIZE && memcmp(buf, "TAG", 3) == 0) {
         *poutbuf = NULL;
         *poutbuf_size = 0;
         return next;
     }
 

     *poutbuf = buf;
     *poutbuf_size = buf_size;
     return next;

 }
 
 

 AVCodecParser ff_mpegaudio_parser = {

     .codec_ids      = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3, AV_CODEC_ID_MP3ADU },

     .priv_data_size = sizeof(MpegAudioParseContext),
     .parser_parse   = mpegaudio_parse,
     .parser_close   = ff_parse_close,

 };