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#include "mpegaudiodata.h" 24 25 26static int mp3_header_decompress(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; 30 int sample_rate= avctx->sample_rate; 31 int sample_rate_index=0; 32 int lsf, mpeg25, bitrate_index, frame_size; 33 34 header = AV_RB32(buf); 35 if(ff_mpa_check_header(header) >= 0){ 36 *poutbuf= (uint8_t *) buf; 37 *poutbuf_size= buf_size; 38 39 return 0; 40 } 41 42 if(avctx->extradata_size != 15 || strcmp(avctx->extradata, "FFCMP3 0.0")){ 43 av_log(avctx, AV_LOG_ERROR, "Extradata invalid %d\n", avctx->extradata_size); 44 return -1; 45 } 46 47 header= AV_RB32(avctx->extradata+11) & MP3_MASK; 48 49 lsf = sample_rate < (24000+32000)/2; 50 mpeg25 = sample_rate < (12000+16000)/2; 51 sample_rate_index= (header>>10)&3; 52 sample_rate= ff_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off 53 54 for(bitrate_index=2; bitrate_index<30; bitrate_index++){ 55 frame_size = ff_mpa_bitrate_tab[lsf][2][bitrate_index>>1]; 56 frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1); 57 if(frame_size == buf_size + 4) 58 break; 59 if(frame_size == buf_size + 6) 60 break; 61 } 62 if(bitrate_index == 30){ 63 av_log(avctx, AV_LOG_ERROR, "Could not find bitrate_index.\n"); 64 return -1; 65 } 66 67 header |= (bitrate_index&1)<<9; 68 header |= (bitrate_index>>1)<<12; 69 header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0 70 71 *poutbuf_size= frame_size; 72 *poutbuf= av_malloc(frame_size + FF_INPUT_BUFFER_PADDING_SIZE); 73 memcpy(*poutbuf + frame_size - buf_size, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE); 74 75 if(avctx->channels==2){ 76 uint8_t *p= *poutbuf + frame_size - buf_size; 77 if(lsf){ 78 FFSWAP(int, p[1], p[2]); 79 header |= (p[1] & 0xC0)>>2; 80 p[1] &= 0x3F; 81 }else{ 82 header |= p[1] & 0x30; 83 p[1] &= 0xCF; 84 } 85 } 86 87 AV_WB32(*poutbuf, header); 88 89 return 1; 90} 91 92AVBitStreamFilter mp3_header_decompress_bsf={ 93 "mp3decomp", 94 0, 95 mp3_header_decompress, 96}; 97