1/* 2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> 3 * 4 * This file is part of FFmpeg. 5 * 6 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 21#include "avcodec.h" 22#include "mpegaudio.h" 23 24 25static int mp3_header_compress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args, 26 uint8_t **poutbuf, int *poutbuf_size, 27 const uint8_t *buf, int buf_size, int keyframe){ 28 uint32_t header, extraheader; 29 int mode_extension, header_size; 30 31 if(avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL){ 32 av_log(avctx, AV_LOG_ERROR, "not standards compliant\n"); 33 return -1; 34 } 35 36 header = AV_RB32(buf); 37 mode_extension= (header>>4)&3; 38 39 if(ff_mpa_check_header(header) < 0 || (header&0x60000) != 0x20000){ 40output_unchanged: 41 *poutbuf= (uint8_t *) buf; 42 *poutbuf_size= buf_size; 43 44 av_log(avctx, AV_LOG_INFO, "cannot compress %08X\n", header); 45 return 0; 46 } 47 48 if(avctx->extradata_size == 0){ 49 avctx->extradata_size=15; 50 avctx->extradata= av_malloc(avctx->extradata_size); 51 strcpy(avctx->extradata, "FFCMP3 0.0"); 52 memcpy(avctx->extradata+11, buf, 4); 53 } 54 if(avctx->extradata_size != 15){ 55 av_log(avctx, AV_LOG_ERROR, "Extradata invalid\n"); 56 return -1; 57 } 58 extraheader = AV_RB32(avctx->extradata+11); 59 if((extraheader&MP3_MASK) != (header&MP3_MASK)) 60 goto output_unchanged; 61 62 header_size= (header&0x10000) ? 4 : 6; 63 64 *poutbuf_size= buf_size - header_size; 65 *poutbuf= av_malloc(buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE); 66 memcpy(*poutbuf, buf + header_size, buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE); 67 68 if(avctx->channels==2){ 69 if((header & (3<<19)) != 3<<19){ 70 (*poutbuf)[1] &= 0x3F; 71 (*poutbuf)[1] |= mode_extension<<6; 72 FFSWAP(int, (*poutbuf)[1], (*poutbuf)[2]); 73 }else{ 74 (*poutbuf)[1] &= 0x8F; 75 (*poutbuf)[1] |= mode_extension<<4; 76 } 77 } 78 79 return 1; 80} 81 82AVBitStreamFilter mp3_header_compress_bsf={ 83 "mp3comp", 84 0, 85 mp3_header_compress, 86}; 87