static int decodeChannelSoundUnit (ATRAC3Context *q, GetBitContext *gb, channel_unit *pSnd, float *pOut, int channelNum, int codingMode) { int band, result=0, numSubbands, lastTonal, numBands; if (codingMode == JOINT_STEREO && channelNum == 1) { if (get_bits(gb,2) != 3) { av_log(NULL,AV_LOG_ERROR,"JS mono Sound Unit id != 3.\n"); return -1; } } else { if (get_bits(gb,6) != 0x28) { av_log(NULL,AV_LOG_ERROR,"Sound Unit id != 0x28.\n"); return -1; } } /* number of coded QMF bands */ pSnd->bandsCoded = get_bits(gb,2); result = decodeGainControl (gb, &(pSnd->gainBlock[pSnd->gcBlkSwitch]), pSnd->bandsCoded); if (result) return result; pSnd->numComponents = decodeTonalComponents (gb, pSnd->components, pSnd->bandsCoded); if (pSnd->numComponents == -1) return -1; numSubbands = decodeSpectrum (gb, pSnd->spectrum); /* Merge the decoded spectrum and tonal components. */ lastTonal = addTonalComponents (pSnd->spectrum, pSnd->numComponents, pSnd->components); /* calculate number of used MLT/QMF bands according to the amount of coded spectral lines */ numBands = (subbandTab[numSubbands] - 1) >> 8; if (lastTonal >= 0) numBands = FFMAX((lastTonal + 256) >> 8, numBands); /* Reconstruct time domain samples. */ for (band=0; band<4; band++) { /* Perform the IMDCT step without overlapping. */ if (band <= numBands) { IMLT(&(pSnd->spectrum[band*256]), pSnd->IMDCT_buf, band&1); } else memset(pSnd->IMDCT_buf, 0, 512 * sizeof(float)); /* gain compensation and overlapping */ gainCompensateAndOverlap (pSnd->IMDCT_buf, &(pSnd->prevFrame[band*256]), &(pOut[band*256]), &((pSnd->gainBlock[1 - (pSnd->gcBlkSwitch)]).gBlock[band]), &((pSnd->gainBlock[pSnd->gcBlkSwitch]).gBlock[band])); } /* Swap the gain control buffers for the next frame. */ pSnd->gcBlkSwitch ^= 1; return 0; }