static int mp3_header_decompress(AVBitStreamFilterContext *bsfc, AVCodecContext *avctx, const char *args, uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size, int keyframe){ uint32_t header; int sample_rate= avctx->sample_rate; int sample_rate_index=0; int lsf, mpeg25, bitrate_index, frame_size; header = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3]; if(ff_mpa_check_header(header) >= 0){ *poutbuf= (uint8_t *) buf; *poutbuf_size= buf_size; return 0; } header= 0xFFE00000 | ((4-3)<<17) | (1<<16); //FIXME simplify lsf = sample_rate < (24000+32000)/2; mpeg25 = sample_rate < (12000+16000)/2; header |= (!mpeg25)<<20; header |= (!lsf )<<19; if(sample_rate<<(lsf+mpeg25) < (44100+32000)/2) sample_rate_index |= 2; else if(sample_rate<<(lsf+mpeg25) > (44100+48000)/2) sample_rate_index |= 1; header |= sample_rate_index<<10; sample_rate= mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off for(bitrate_index=2; bitrate_index<30; bitrate_index++){ frame_size = mpa_bitrate_tab[lsf][2][bitrate_index>>1]; frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1); if(frame_size == buf_size + 4) break; } if(bitrate_index == 30){ av_log(avctx, AV_LOG_ERROR, "couldnt find bitrate_index\n"); return -1; } header |= (bitrate_index&1)<<9; header |= (bitrate_index>>1)<<12; header |= (avctx->channels==1 ? MPA_MONO : MPA_JSTEREO)<<6; *poutbuf_size= buf_size + 4; *poutbuf= av_malloc(buf_size + 4 + FF_INPUT_BUFFER_PADDING_SIZE); memcpy(*poutbuf + 4, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE); if(avctx->channels==2){ if(lsf){ FFSWAP(int, (*poutbuf)[5], (*poutbuf)[6]); header |= ((*poutbuf)[5] & 0xC0)>>2; }else{ header |= (*poutbuf)[5] & 0x30; } } (*poutbuf)[0]= header>>24; (*poutbuf)[1]= header>>16; (*poutbuf)[2]= header>> 8; (*poutbuf)[3]= header ; return 1; }