/*
  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
  *
  * 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 "libavutil/common.h"

 #include "libavutil/intreadwrite.h"

 #include "avcodec.h"

 #include "mpegaudiodecheader.h"

 
 
 static int mp3_header_compress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
                      uint8_t **poutbuf, int *poutbuf_size,
                      const uint8_t *buf, int buf_size, int keyframe){
     uint32_t header, extraheader;
     int mode_extension, header_size;
 
     if(avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL){
         av_log(avctx, AV_LOG_ERROR, "not standards compliant\n");
         return -1;
     }
 
     header = AV_RB32(buf);
     mode_extension= (header>>4)&3;
 
     if(ff_mpa_check_header(header) < 0 || (header&0x60000) != 0x20000){
 output_unchanged:
         *poutbuf= (uint8_t *) buf;
         *poutbuf_size= buf_size;
 
         av_log(avctx, AV_LOG_INFO, "cannot compress %08X\n", header);
         return 0;
     }
 
     if(avctx->extradata_size == 0){
         avctx->extradata_size=15;
         avctx->extradata= av_malloc(avctx->extradata_size);
         strcpy(avctx->extradata, "FFCMP3 0.0");
         memcpy(avctx->extradata+11, buf, 4);
     }
     if(avctx->extradata_size != 15){
         av_log(avctx, AV_LOG_ERROR, "Extradata invalid\n");
         return -1;
     }
     extraheader = AV_RB32(avctx->extradata+11);
     if((extraheader&MP3_MASK) != (header&MP3_MASK))
         goto output_unchanged;
 
     header_size= (header&0x10000) ? 4 : 6;
 
     *poutbuf_size= buf_size - header_size;
     *poutbuf= av_malloc(buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE);
     memcpy(*poutbuf, buf + header_size, buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE);
 
     if(avctx->channels==2){
         if((header & (3<<19)) != 3<<19){
             (*poutbuf)[1] &= 0x3F;
             (*poutbuf)[1] |= mode_extension<<6;
             FFSWAP(int, (*poutbuf)[1], (*poutbuf)[2]);
         }else{
             (*poutbuf)[1] &= 0x8F;
             (*poutbuf)[1] |= mode_extension<<4;
         }
     }
 
     return 1;
 }
 

 AVBitStreamFilter ff_mp3_header_compress_bsf={

     "mp3comp",
     0,
     mp3_header_compress,
 };