1/* 2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> 3 * 4 * This file is part of Libav. 5 * 6 * Libav is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU Lesser General Public 8 * License as published by the Free Software Foundation; either 9 * version 2.1 of the License, or (at your option) any later version. 10 * 11 * Libav is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * Lesser General Public License for more details. 15 * 16 * You should have received a copy of the GNU Lesser General Public 17 * License along with Libav; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 21#include "libavutil/intreadwrite.h" 22#include "avcodec.h" 23#include "mpegaudiodecheader.h" 24 25 26static int mp3_header_compress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args, 27 uint8_t **poutbuf, int *poutbuf_size, 28 const uint8_t *buf, int buf_size, int keyframe){ 29 uint32_t header, extraheader; 30 int mode_extension, header_size; 31 32 if(avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL){ 33 av_log(avctx, AV_LOG_ERROR, "not standards compliant\n"); 34 return -1; 35 } 36 37 header = AV_RB32(buf); 38 mode_extension= (header>>4)&3; 39 40 if(ff_mpa_check_header(header) < 0 || (header&0x60000) != 0x20000){ 41output_unchanged: 42 *poutbuf= (uint8_t *) buf; 43 *poutbuf_size= buf_size; 44 45 av_log(avctx, AV_LOG_INFO, "cannot compress %08X\n", header); 46 return 0; 47 } 48 49 if(avctx->extradata_size == 0){ 50 avctx->extradata_size=15; 51 avctx->extradata= av_malloc(avctx->extradata_size); 52 strcpy(avctx->extradata, "FFCMP3 0.0"); 53 memcpy(avctx->extradata+11, buf, 4); 54 } 55 if(avctx->extradata_size != 15){ 56 av_log(avctx, AV_LOG_ERROR, "Extradata invalid\n"); 57 return -1; 58 } 59 extraheader = AV_RB32(avctx->extradata+11); 60 if((extraheader&MP3_MASK) != (header&MP3_MASK)) 61 goto output_unchanged; 62 63 header_size= (header&0x10000) ? 4 : 6; 64 65 *poutbuf_size= buf_size - header_size; 66 *poutbuf= av_malloc(buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE); 67 memcpy(*poutbuf, buf + header_size, buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE); 68 69 if(avctx->channels==2){ 70 if((header & (3<<19)) != 3<<19){ 71 (*poutbuf)[1] &= 0x3F; 72 (*poutbuf)[1] |= mode_extension<<6; 73 FFSWAP(int, (*poutbuf)[1], (*poutbuf)[2]); 74 }else{ 75 (*poutbuf)[1] &= 0x8F; 76 (*poutbuf)[1] |= mode_extension<<4; 77 } 78 } 79 80 return 1; 81} 82 83AVBitStreamFilter ff_mp3_header_compress_bsf={ 84 "mp3comp", 85 0, 86 mp3_header_compress, 87}; 88