Libav
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00001 /* 00002 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> 00003 * 00004 * This file is part of FFmpeg. 00005 * 00006 * FFmpeg is free software; you can redistribute it and/or 00007 * modify it under the terms of the GNU Lesser General Public 00008 * License as published by the Free Software Foundation; either 00009 * version 2.1 of the License, or (at your option) any later version. 00010 * 00011 * FFmpeg is distributed in the hope that it will be useful, 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00014 * Lesser General Public License for more details. 00015 * 00016 * You should have received a copy of the GNU Lesser General Public 00017 * License along with FFmpeg; if not, write to the Free Software 00018 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00019 */ 00020 00021 #include "avcodec.h" 00022 #include "mpegaudio.h" 00023 00024 00025 static int mp3_header_compress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args, 00026 uint8_t **poutbuf, int *poutbuf_size, 00027 const uint8_t *buf, int buf_size, int keyframe){ 00028 uint32_t header, extraheader; 00029 int mode_extension, header_size; 00030 00031 if(avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL){ 00032 av_log(avctx, AV_LOG_ERROR, "not standards compliant\n"); 00033 return -1; 00034 } 00035 00036 header = AV_RB32(buf); 00037 mode_extension= (header>>4)&3; 00038 00039 if(ff_mpa_check_header(header) < 0 || (header&0x60000) != 0x20000){ 00040 output_unchanged: 00041 *poutbuf= (uint8_t *) buf; 00042 *poutbuf_size= buf_size; 00043 00044 av_log(avctx, AV_LOG_INFO, "cannot compress %08X\n", header); 00045 return 0; 00046 } 00047 00048 if(avctx->extradata_size == 0){ 00049 avctx->extradata_size=15; 00050 avctx->extradata= av_malloc(avctx->extradata_size); 00051 strcpy(avctx->extradata, "FFCMP3 0.0"); 00052 memcpy(avctx->extradata+11, buf, 4); 00053 } 00054 if(avctx->extradata_size != 15){ 00055 av_log(avctx, AV_LOG_ERROR, "Extradata invalid\n"); 00056 return -1; 00057 } 00058 extraheader = AV_RB32(avctx->extradata+11); 00059 if((extraheader&MP3_MASK) != (header&MP3_MASK)) 00060 goto output_unchanged; 00061 00062 header_size= (header&0x10000) ? 4 : 6; 00063 00064 *poutbuf_size= buf_size - header_size; 00065 *poutbuf= av_malloc(buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE); 00066 memcpy(*poutbuf, buf + header_size, buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE); 00067 00068 if(avctx->channels==2){ 00069 if((header & (3<<19)) != 3<<19){ 00070 (*poutbuf)[1] &= 0x3F; 00071 (*poutbuf)[1] |= mode_extension<<6; 00072 FFSWAP(int, (*poutbuf)[1], (*poutbuf)[2]); 00073 }else{ 00074 (*poutbuf)[1] &= 0x8F; 00075 (*poutbuf)[1] |= mode_extension<<4; 00076 } 00077 } 00078 00079 return 1; 00080 } 00081 00082 AVBitStreamFilter mp3_header_compress_bsf={ 00083 "mp3comp", 00084 0, 00085 mp3_header_compress, 00086 };