diff options
Diffstat (limited to 'libPCMutils/include')
| -rw-r--r-- | libPCMutils/include/limiter.h | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/libPCMutils/include/limiter.h b/libPCMutils/include/limiter.h new file mode 100644 index 0000000..0d3d701 --- /dev/null +++ b/libPCMutils/include/limiter.h @@ -0,0 +1,233 @@ + +/* ----------------------------------------------------------------------------------------------------------- +Software License for The Fraunhofer FDK AAC Codec Library for Android + +© Copyright 1995 - 2013 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. + All rights reserved. + + 1. INTRODUCTION +The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements +the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio. +This FDK AAC Codec software is intended to be used on a wide variety of Android devices. + +AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual +audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by +independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part +of the MPEG specifications. + +Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer) +may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners +individually for the purpose of encoding or decoding bit streams in products that are compliant with +the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license +these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec +software may already be covered under those patent licenses when it is used for those licensed purposes only. + +Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality, +are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional +applications information and documentation. + +2. COPYRIGHT LICENSE + +Redistribution and use in source and binary forms, with or without modification, are permitted without +payment of copyright license fees provided that you satisfy the following conditions: + +You must retain the complete text of this software license in redistributions of the FDK AAC Codec or +your modifications thereto in source code form. + +You must retain the complete text of this software license in the documentation and/or other materials +provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form. +You must make available free of charge copies of the complete source code of the FDK AAC Codec and your +modifications thereto to recipients of copies in binary form. + +The name of Fraunhofer may not be used to endorse or promote products derived from this library without +prior written permission. + +You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec +software or your modifications thereto. + +Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software +and the date of any change. For modified versions of the FDK AAC Codec, the term +"Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term +"Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android." + +3. NO PATENT LICENSE + +NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer, +ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with +respect to this software. + +You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized +by appropriate patent licenses. + +4. DISCLAIMER + +This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors +"AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties +of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR +CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages, +including but not limited to procurement of substitute goods or services; loss of use, data, or profits, +or business interruption, however caused and on any theory of liability, whether in contract, strict +liability, or tort (including negligence), arising in any way out of the use of this software, even if +advised of the possibility of such damage. + +5. CONTACT INFORMATION + +Fraunhofer Institute for Integrated Circuits IIS +Attention: Audio and Multimedia Departments - FDK AAC LL +Am Wolfsmantel 33 +91058 Erlangen, Germany + +www.iis.fraunhofer.de/amm +amm-info@iis.fraunhofer.de +----------------------------------------------------------------------------------------------------------- */ + +/************************ FDK PCM postprocessor module ********************* + + Author(s): Matthias Neusinger + Description: Hard limiter for clipping prevention + +*******************************************************************************/ + +#ifndef _LIMITER_H_ +#define _LIMITER_H_ + + +#include "common_fix.h" + +#define TDL_ATTACK_DEFAULT_MS (15) /* default attack time in ms */ +#define TDL_RELEASE_DEFAULT_MS (50) /* default release time in ms */ + +#define TDL_GAIN_SCALING (15) /* scaling of gain value. */ + + +#ifdef __cplusplus +extern "C" { +#endif + + +typedef enum { + TDLIMIT_OK = 0, + + __error_codes_start = -100, + + TDLIMIT_INVALID_HANDLE, + TDLIMIT_INVALID_PARAMETER, + + __error_codes_end +} TDLIMITER_ERROR; + +struct TDLimiter; +typedef struct TDLimiter* TDLimiterPtr; + +/****************************************************************************** +* createLimiter * +* maxAttackMs: maximum and initial attack/lookahead time in milliseconds * +* releaseMs: release time in milliseconds (90% time constant) * +* threshold: limiting threshold * +* maxChannels: maximum and initial number of channels * +* maxSampleRate: maximum and initial sampling rate in Hz * +* returns: limiter handle * +******************************************************************************/ +TDLimiterPtr createLimiter(unsigned int maxAttackMs, + unsigned int releaseMs, + INT_PCM threshold, + unsigned int maxChannels, + unsigned int maxSampleRate); + + +/****************************************************************************** +* resetLimiter * +* limiter: limiter handle * +* returns: error code * +******************************************************************************/ +TDLIMITER_ERROR resetLimiter(TDLimiterPtr limiter); + + +/****************************************************************************** +* destroyLimiter * +* limiter: limiter handle * +* returns: error code * +******************************************************************************/ +TDLIMITER_ERROR destroyLimiter(TDLimiterPtr limiter); + +/****************************************************************************** +* applyLimiter * +* limiter: limiter handle * +* pGain : pointer to gains to be applied to the signal before limiting, * +* which are downscaled by TDL_GAIN_SCALING bit. * +* These gains are delayed by gain_delay, and smoothed. * +* Smoothing is done by a butterworth lowpass filter with a cutoff * +* frequency which is fixed with respect to the sampling rate. * +* It is a substitute for the smoothing due to windowing and * +* overlap/add, if a gain is applied in frequency domain. * +* gain_scale: pointer to scaling exponents to be applied to the signal before * +* limiting, without delay and without smoothing * +* gain_size: number of elements in pGain, currently restricted to 1 * +* gain_delay: delay [samples] with which the gains in pGain shall be applied * +* gain_delay <= nSamples * +* samples: input/output buffer containing interleaved samples * +* precision of output will be DFRACT_BITS-TDL_GAIN_SCALING bits * +* nSamples: number of samples per channel * +* returns: error code * +******************************************************************************/ +TDLIMITER_ERROR applyLimiter(TDLimiterPtr limiter, + INT_PCM* samples, + FIXP_DBL* pGain, + const INT* gain_scale, + const UINT gain_size, + const UINT gain_delay, + const UINT nSamples); + +/****************************************************************************** +* getLimiterDelay * +* limiter: limiter handle * +* returns: exact delay caused by the limiter in samples * +******************************************************************************/ +unsigned int getLimiterDelay(TDLimiterPtr limiter); + +/****************************************************************************** +* setLimiterNChannels * +* limiter: limiter handle * +* nChannels: number of channels ( <= maxChannels specified on create) * +* returns: error code * +******************************************************************************/ +TDLIMITER_ERROR setLimiterNChannels(TDLimiterPtr limiter, unsigned int nChannels); + +/****************************************************************************** +* setLimiterSampleRate * +* limiter: limiter handle * +* sampleRate: sampling rate in Hz ( <= maxSampleRate specified on create) * +* returns: error code * +******************************************************************************/ +TDLIMITER_ERROR setLimiterSampleRate(TDLimiterPtr limiter, unsigned int sampleRate); + +/****************************************************************************** +* setLimiterAttack * +* limiter: limiter handle * +* attackMs: attack time in ms ( <= maxAttackMs specified on create) * +* returns: error code * +******************************************************************************/ +TDLIMITER_ERROR setLimiterAttack(TDLimiterPtr limiter, unsigned int attackMs); + +/****************************************************************************** +* setLimiterRelease * +* limiter: limiter handle * +* releaseMs: release time in ms * +* returns: error code * +******************************************************************************/ +TDLIMITER_ERROR setLimiterRelease(TDLimiterPtr limiter, unsigned int releaseMs); + +/****************************************************************************** +* setLimiterThreshold * +* limiter: limiter handle * +* threshold: limiter threshold * +* returns: error code * +******************************************************************************/ +TDLIMITER_ERROR setLimiterThreshold(TDLimiterPtr limiter, INT_PCM threshold); + +#ifdef __cplusplus +} +#endif + + +#endif //#ifndef _LIMITER_H_ |