Libav 0.7.1
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00001 /* 00002 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> 00003 * 00004 * This file is part of Libav. 00005 * 00006 * Libav 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 * Libav 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 Libav; if not, write to the Free Software 00018 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00019 */ 00020 00021 #include "libavutil/intreadwrite.h" 00022 #include "avcodec.h" 00023 #include "mpegaudiodecheader.h" 00024 00025 00026 static int mp3_header_compress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args, 00027 uint8_t **poutbuf, int *poutbuf_size, 00028 const uint8_t *buf, int buf_size, int keyframe){ 00029 uint32_t header, extraheader; 00030 int mode_extension, header_size; 00031 00032 if(avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL){ 00033 av_log(avctx, AV_LOG_ERROR, "not standards compliant\n"); 00034 return -1; 00035 } 00036 00037 header = AV_RB32(buf); 00038 mode_extension= (header>>4)&3; 00039 00040 if(ff_mpa_check_header(header) < 0 || (header&0x60000) != 0x20000){ 00041 output_unchanged: 00042 *poutbuf= (uint8_t *) buf; 00043 *poutbuf_size= buf_size; 00044 00045 av_log(avctx, AV_LOG_INFO, "cannot compress %08X\n", header); 00046 return 0; 00047 } 00048 00049 if(avctx->extradata_size == 0){ 00050 avctx->extradata_size=15; 00051 avctx->extradata= av_malloc(avctx->extradata_size); 00052 strcpy(avctx->extradata, "FFCMP3 0.0"); 00053 memcpy(avctx->extradata+11, buf, 4); 00054 } 00055 if(avctx->extradata_size != 15){ 00056 av_log(avctx, AV_LOG_ERROR, "Extradata invalid\n"); 00057 return -1; 00058 } 00059 extraheader = AV_RB32(avctx->extradata+11); 00060 if((extraheader&MP3_MASK) != (header&MP3_MASK)) 00061 goto output_unchanged; 00062 00063 header_size= (header&0x10000) ? 4 : 6; 00064 00065 *poutbuf_size= buf_size - header_size; 00066 *poutbuf= av_malloc(buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE); 00067 memcpy(*poutbuf, buf + header_size, buf_size - header_size + FF_INPUT_BUFFER_PADDING_SIZE); 00068 00069 if(avctx->channels==2){ 00070 if((header & (3<<19)) != 3<<19){ 00071 (*poutbuf)[1] &= 0x3F; 00072 (*poutbuf)[1] |= mode_extension<<6; 00073 FFSWAP(int, (*poutbuf)[1], (*poutbuf)[2]); 00074 }else{ 00075 (*poutbuf)[1] &= 0x8F; 00076 (*poutbuf)[1] |= mode_extension<<4; 00077 } 00078 } 00079 00080 return 1; 00081 } 00082 00083 AVBitStreamFilter ff_mp3_header_compress_bsf={ 00084 "mp3comp", 00085 0, 00086 mp3_header_compress, 00087 };