yading@10: /*
yading@10:  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #include "libavutil/common.h"
yading@10: #include "libavutil/intreadwrite.h"
yading@10: #include "avcodec.h"
yading@10: #include "mpegaudiodecheader.h"
yading@10: #include "mpegaudiodata.h"
yading@10: 
yading@10: 
yading@10: static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args,
yading@10:                      uint8_t **poutbuf, int *poutbuf_size,
yading@10:                      const uint8_t *buf, int buf_size, int keyframe){
yading@10:     uint32_t header;
yading@10:     int sample_rate= avctx->sample_rate;
yading@10:     int sample_rate_index=0;
yading@10:     int lsf, mpeg25, bitrate_index, frame_size;
yading@10: 
yading@10:     header = AV_RB32(buf);
yading@10:     if(ff_mpa_check_header(header) >= 0){
yading@10:         *poutbuf= (uint8_t *) buf;
yading@10:         *poutbuf_size= buf_size;
yading@10: 
yading@10:         return 0;
yading@10:     }
yading@10: 
yading@10:     if(avctx->extradata_size != 15 || strcmp(avctx->extradata, "FFCMP3 0.0")){
yading@10:         av_log(avctx, AV_LOG_ERROR, "Extradata invalid %d\n", avctx->extradata_size);
yading@10:         return -1;
yading@10:     }
yading@10: 
yading@10:     header= AV_RB32(avctx->extradata+11) & MP3_MASK;
yading@10: 
yading@10:     lsf     = sample_rate < (24000+32000)/2;
yading@10:     mpeg25  = sample_rate < (12000+16000)/2;
yading@10:     sample_rate_index= (header>>10)&3;
yading@10:     sample_rate= avpriv_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off
yading@10: 
yading@10:     for(bitrate_index=2; bitrate_index<30; bitrate_index++){
yading@10:         frame_size = avpriv_mpa_bitrate_tab[lsf][2][bitrate_index>>1];
yading@10:         frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1);
yading@10:         if(frame_size == buf_size + 4)
yading@10:             break;
yading@10:         if(frame_size == buf_size + 6)
yading@10:             break;
yading@10:     }
yading@10:     if(bitrate_index == 30){
yading@10:         av_log(avctx, AV_LOG_ERROR, "Could not find bitrate_index.\n");
yading@10:         return -1;
yading@10:     }
yading@10: 
yading@10:     header |= (bitrate_index&1)<<9;
yading@10:     header |= (bitrate_index>>1)<<12;
yading@10:     header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0
yading@10: 
yading@10:     *poutbuf_size= frame_size;
yading@10:     *poutbuf= av_malloc(frame_size + FF_INPUT_BUFFER_PADDING_SIZE);
yading@10:     memcpy(*poutbuf + frame_size - buf_size, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
yading@10: 
yading@10:     if(avctx->channels==2){
yading@10:         uint8_t *p= *poutbuf + frame_size - buf_size;
yading@10:         if(lsf){
yading@10:             FFSWAP(int, p[1], p[2]);
yading@10:             header |= (p[1] & 0xC0)>>2;
yading@10:             p[1] &= 0x3F;
yading@10:         }else{
yading@10:             header |= p[1] & 0x30;
yading@10:             p[1] &= 0xCF;
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     AV_WB32(*poutbuf, header);
yading@10: 
yading@10:     return 1;
yading@10: }
yading@10: 
yading@10: AVBitStreamFilter ff_mp3_header_decompress_bsf={
yading@10:     "mp3decomp",
yading@10:     0,
yading@10:     mp3_header_decompress,
yading@10: };