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Diffstat (limited to '')
| -rw-r--r-- | circuitpython/lib/mp3/src/subband.c | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/circuitpython/lib/mp3/src/subband.c b/circuitpython/lib/mp3/src/subband.c new file mode 100644 index 0000000..c18a77b --- /dev/null +++ b/circuitpython/lib/mp3/src/subband.c @@ -0,0 +1,94 @@ +/* ***** BEGIN LICENSE BLOCK ***** + * Version: RCSL 1.0/RPSL 1.0 + * + * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. + * + * The contents of this file, and the files included with this file, are + * subject to the current version of the RealNetworks Public Source License + * Version 1.0 (the "RPSL") available at + * http://www.helixcommunity.org/content/rpsl unless you have licensed + * the file under the RealNetworks Community Source License Version 1.0 + * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, + * in which case the RCSL will apply. You may also obtain the license terms + * directly from RealNetworks. You may not use this file except in + * compliance with the RPSL or, if you have a valid RCSL with RealNetworks + * applicable to this file, the RCSL. Please see the applicable RPSL or + * RCSL for the rights, obligations and limitations governing use of the + * contents of the file. + * + * This file is part of the Helix DNA Technology. RealNetworks is the + * developer of the Original Code and owns the copyrights in the portions + * it created. + * + * This file, and the files included with this file, is distributed and made + * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER + * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES, + * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS + * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. + * + * Technology Compatibility Kit Test Suite(s) Location: + * http://www.helixcommunity.org/content/tck + * + * Contributor(s): + * + * ***** END LICENSE BLOCK ***** */ + +/************************************************************************************** + * Fixed-point MP3 decoder + * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com) + * June 2003 + * + * subband.c - subband transform (synthesis filterbank implemented via 32-point DCT + * followed by polyphase filter) + **************************************************************************************/ + +#include "coder.h" +#include "assembly.h" + +/************************************************************************************** + * Function: Subband + * + * Description: do subband transform on all the blocks in one granule, all channels + * + * Inputs: filled MP3DecInfo structure, after calling IMDCT for all channels + * vbuf[ch] and vindex[ch] must be preserved between calls + * + * Outputs: decoded PCM data, interleaved LRLRLR... if stereo + * + * Return: 0 on success, -1 if null input pointers + **************************************************************************************/ +int Subband(MP3DecInfo *mp3DecInfo, short *pcmBuf) +{ + int b; + IMDCTInfo *mi; + SubbandInfo *sbi; + + /* validate pointers */ + if (!mp3DecInfo || !mp3DecInfo->HuffmanInfoPS || !mp3DecInfo->IMDCTInfoPS || !mp3DecInfo->SubbandInfoPS) + return -1; + + mi = (IMDCTInfo *)(mp3DecInfo->IMDCTInfoPS); + sbi = (SubbandInfo*)(mp3DecInfo->SubbandInfoPS); + + if (mp3DecInfo->nChans == 2) { + /* stereo */ + for (b = 0; b < BLOCK_SIZE; b++) { + FDCT32(mi->outBuf[0][b], sbi->vbuf + 0*32, sbi->vindex, (b & 0x01), mi->gb[0]); + FDCT32(mi->outBuf[1][b], sbi->vbuf + 1*32, sbi->vindex, (b & 0x01), mi->gb[1]); + PolyphaseStereo(pcmBuf, sbi->vbuf + sbi->vindex + VBUF_LENGTH * (b & 0x01), polyCoef); + sbi->vindex = (sbi->vindex - (b & 0x01)) & 7; + pcmBuf += (2 * NBANDS); + } + } else { + /* mono */ + for (b = 0; b < BLOCK_SIZE; b++) { + FDCT32(mi->outBuf[0][b], sbi->vbuf + 0*32, sbi->vindex, (b & 0x01), mi->gb[0]); + PolyphaseMono(pcmBuf, sbi->vbuf + sbi->vindex + VBUF_LENGTH * (b & 0x01), polyCoef); + sbi->vindex = (sbi->vindex - (b & 0x01)) & 7; + pcmBuf += NBANDS; + } + } + + return 0; +} + |