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: 
yading@10: 
yading@10: static int mp3_header_compress(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, extraheader;
yading@10:     int mode_extension, header_size;
yading@10: 
yading@10:     if(avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL){
yading@10:         av_log(avctx, AV_LOG_ERROR, "not standards compliant\n");
yading@10:         return -1;
yading@10:     }
yading@10: 
yading@10:     header = AV_RB32(buf);
yading@10:     mode_extension= (header>>4)&3;
yading@10: 
yading@10:     if(ff_mpa_check_header(header) < 0 || (header&0x60000) != 0x20000){
yading@10: output_unchanged:
yading@10:         *poutbuf= (uint8_t *) buf;
yading@10:         *poutbuf_size= buf_size;
yading@10: 
yading@10:         av_log(avctx, AV_LOG_INFO, "cannot compress %08X\n", header);
yading@10:         return 0;
yading@10:     }
yading@10: 
yading@10:     if(avctx->extradata_size == 0){
yading@10:         avctx->extradata_size=15;
yading@10:         avctx->extradata= av_malloc(avctx->extradata_size);
yading@10:         strcpy(avctx->extradata, "FFCMP3 0.0");
yading@10:         memcpy(avctx->extradata+11, buf, 4);
yading@10:     }
yading@10:     if(avctx->extradata_size != 15){
yading@10:         av_log(avctx, AV_LOG_ERROR, "Extradata invalid\n");
yading@10:         return -1;
yading@10:     }
yading@10:     extraheader = AV_RB32(avctx->extradata+11);
yading@10:     if((extraheader&MP3_MASK) != (header&MP3_MASK))
yading@10:         goto output_unchanged;
yading@10: 
yading@10:     header_size= (header&0x10000) ? 4 : 6;
yading@10: 
yading@10:     *poutbuf_size= buf_size - header_size;
yading@10:     *poutbuf= av_malloc(buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE);
yading@10:     memcpy(*poutbuf, buf + header_size, buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE);
yading@10: 
yading@10:     if(avctx->channels==2){
yading@10:         if((header & (3<<19)) != 3<<19){
yading@10:             (*poutbuf)[1] &= 0x3F;
yading@10:             (*poutbuf)[1] |= mode_extension<<6;
yading@10:             FFSWAP(int, (*poutbuf)[1], (*poutbuf)[2]);
yading@10:         }else{
yading@10:             (*poutbuf)[1] &= 0x8F;
yading@10:             (*poutbuf)[1] |= mode_extension<<4;
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     return 1;
yading@10: }
yading@10: 
yading@10: AVBitStreamFilter ff_mp3_header_compress_bsf={
yading@10:     "mp3comp",
yading@10:     0,
yading@10:     mp3_header_compress,
yading@10: };