/*
  * MPEG Audio header decoder

  * Copyright (c) 2001, 2002 Fabrice Bellard

  *
  * 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
  */
 
 /**

  * @file

  * MPEG Audio header decoder.
  */
 

 #include "libavutil/common.h"
 

 #include "avcodec.h"

 #include "internal.h"

 #include "mpegaudio.h"
 #include "mpegaudiodata.h"

 #include "mpegaudiodecheader.h"

 int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)

 {
     int sample_rate, frame_size, mpeg25, padding;
     int sample_rate_index, bitrate_index;

     int ret;
 
     ret = ff_mpa_check_header(header);
     if (ret < 0)
         return ret;
 

     if (header & (1<<20)) {
         s->lsf = (header & (1<<19)) ? 0 : 1;
         mpeg25 = 0;
     } else {
         s->lsf = 1;
         mpeg25 = 1;
     }
 
     s->layer = 4 - ((header >> 17) & 3);
     /* extract frequency */
     sample_rate_index = (header >> 10) & 3;

     if (sample_rate_index >= FF_ARRAY_ELEMS(avpriv_mpa_freq_tab))
         sample_rate_index = 0;

     sample_rate = avpriv_mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25);

     sample_rate_index += 3 * (s->lsf + mpeg25);
     s->sample_rate_index = sample_rate_index;
     s->error_protection = ((header >> 16) & 1) ^ 1;
     s->sample_rate = sample_rate;
 
     bitrate_index = (header >> 12) & 0xf;
     padding = (header >> 9) & 1;
     //extension = (header >> 8) & 1;
     s->mode = (header >> 6) & 3;
     s->mode_ext = (header >> 4) & 3;
     //copyright = (header >> 3) & 1;
     //original = (header >> 2) & 1;
     //emphasis = header & 3;
 
     if (s->mode == MPA_MONO)
         s->nb_channels = 1;
     else
         s->nb_channels = 2;
 
     if (bitrate_index != 0) {

         frame_size = avpriv_mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];

         s->bit_rate = frame_size * 1000;
         switch(s->layer) {
         case 1:
             frame_size = (frame_size * 12000) / sample_rate;
             frame_size = (frame_size + padding) * 4;
             break;
         case 2:
             frame_size = (frame_size * 144000) / sample_rate;
             frame_size += padding;
             break;
         default:
         case 3:
             frame_size = (frame_size * 144000) / (sample_rate << s->lsf);
             frame_size += padding;
             break;
         }
         s->frame_size = frame_size;
     } else {
         /* if no frame size computed, signal it */
         return 1;
     }
 
 #if defined(DEBUG)

     ff_dlog(NULL, "layer%d, %d Hz, %d kbits/s, ",

            s->layer, s->sample_rate, s->bit_rate);
     if (s->nb_channels == 2) {
         if (s->layer == 3) {
             if (s->mode_ext & MODE_EXT_MS_STEREO)

                 ff_dlog(NULL, "ms-");

             if (s->mode_ext & MODE_EXT_I_STEREO)

                 ff_dlog(NULL, "i-");

         }

         ff_dlog(NULL, "stereo");

     } else {

         ff_dlog(NULL, "mono");

     }

     ff_dlog(NULL, "\n");

 #endif
     return 0;
 }

 int ff_mpa_decode_header(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate, enum AVCodecID *codec_id)

 {
     MPADecodeHeader s1, *s = &s1;
 

     if (avpriv_mpegaudio_decode_header(s, head) != 0) {

         return -1;
     }
 
     switch(s->layer) {
     case 1:

         *codec_id = AV_CODEC_ID_MP1;

         *frame_size = 384;
         break;
     case 2:

         *codec_id = AV_CODEC_ID_MP2;

         *frame_size = 1152;
         break;
     default:
     case 3:

         if (*codec_id != AV_CODEC_ID_MP3ADU)
             *codec_id = AV_CODEC_ID_MP3;

         if (s->lsf)
             *frame_size = 576;
         else
             *frame_size = 1152;
         break;
     }
 
     *sample_rate = s->sample_rate;
     *channels = s->nb_channels;
     *bit_rate = s->bit_rate;
     return s->frame_size;
 }

 #if LIBAVCODEC_VERSION_MAJOR < 58
 int avpriv_mpa_decode_header2(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate, enum AVCodecID *codec_id)
 {
     return ff_mpa_decode_header(head, sample_rate, channels, frame_size, bit_rate, codec_id);
 }
 

 int avpriv_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate)
 {

     return ff_mpa_decode_header(head, sample_rate, channels, frame_size, bit_rate, &avctx->codec_id);

 }

 #endif