afc96087f8
Emulates the basic "Meier" crossfeed (2 capacitors, 3 resistors) as discussed in http://www.meier-audio.homepage.t-online.de/passivefilter.htm This crossfeed blends a bit of low-pass filtered L signal into the R signal (and vice versa) while adding about 300 us delay to the crossfed-signal. A difference with the crossfeed already present in rockbox, is that this algorithm keeps the total spectrum flat (the one currently in rockbox accentuates low-frequency signals, making it sound a bit muffled). This implementation is quite lightweight, just 3 multiplies per left-right pair of samples. Has a default C implementation and optimized assembly versions for ARM and Coldfire. The crossfeed effect is quite subtle and is noticeable mostly one albums that have very strong left-right separation (e.g. one instrument only on the left, another only on the right). In the user interface, the new crossfeed option appears as "Meier" and is not configureable. The existing crossfeed is renamed to "Custom" as it allows itself to be customised. There is no entry for the user manual yet. Change-Id: Iaa100616fe0fcd7e16f08cdb9a7f41501973eee1
35 lines
1.3 KiB
C
35 lines
1.3 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2006 Thom Johansen
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#ifndef CROSSFEED_H
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#define CROSSFEED_H
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enum crossfeed_type
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{
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CROSSFEED_TYPE_NONE,
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CROSSFEED_TYPE_MEIER,
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CROSSFEED_TYPE_CUSTOM,
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};
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void dsp_set_crossfeed_type(int type);
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void dsp_set_crossfeed_direct_gain(int gain);
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void dsp_set_crossfeed_cross_params(long lf_gain, long hf_gain, long cutoff);
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#endif /* CROSSFEED_H */
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