libFDK/include/mdct.h

   1
   2 /* -----------------------------------------------------------------------------------------------------------
   3 Software License for The Fraunhofer FDK AAC Codec Library for Android
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   5 © Copyright  1995 - 2013 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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   8  1.    INTRODUCTION
   9 The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements
  10 the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio.
  11 This FDK AAC Codec software is intended to be used on a wide variety of Android devices.
  12
  13 AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual
  14 audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by
  15 independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part
  16 of the MPEG specifications.
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  18 Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
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  20 individually for the purpose of encoding or decoding bit streams in products that are compliant with
  21 the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license
  22 these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec
  23 software may already be covered under those patent licenses when it is used for those licensed purposes only.
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  29 2.    COPYRIGHT LICENSE
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  56 ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with
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  64 This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors
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  73 5.    CONTACT INFORMATION
  74
  75 Fraunhofer Institute for Integrated Circuits IIS
  76 Attention: Audio and Multimedia Departments - FDK AAC LL
  77 Am Wolfsmantel 33
  78 91058 Erlangen, Germany
  79
  80 www.iis.fraunhofer.de/amm
  81 amm-info@iis.fraunhofer.de
  82 ----------------------------------------------------------------------------------------------------------- */
  83
  84 /***************************  Fraunhofer IIS FDK Tools  **********************
  85
  86    Author(s):   Manuel Jander, Josef Hoepfl
  87    Description: MDCT routines
  88
  89 ******************************************************************************/
  90
  91 #ifndef __MDCT_H__
  92 #define __MDCT_H__
  93
  94
  95
  96 #include "common_fix.h"
  97
  98 #define MDCT_OUT_HEADROOM     2 /* Output additional headroom */
  99 #define MDCT_OUTPUT_SCALE    (DFRACT_BITS-SAMPLE_BITS-MDCT_OUT_HEADROOM)
 100 /* Refer to "Output word length" in ISO/IEC 14496-3:2008(E) 23.2.3.6 */
 101 #define MDCT_OUTPUT_GAIN      16
 102
 103 #if (SAMPLE_BITS == DFRACT_BITS)
 104 #define IMDCT_SCALE(x) (INT_PCM)SATURATE_LEFT_SHIFT(x, -MDCT_OUTPUT_SCALE, SAMPLE_BITS)
 105 #else
 106 #define IMDCT_SCALE(x) (INT_PCM)SATURATE_RIGHT_SHIFT(x, MDCT_OUTPUT_SCALE, SAMPLE_BITS)
 107 #endif
 108 #define IMDCT_SCALE_DBL(x) (FIXP_DBL)(x)
 109
 110 /**
 111  * \brief MDCT persistent data
 112  */
 113 typedef struct {
 114   union {
 115     FIXP_DBL *freq;
 116     FIXP_DBL *time;
 117   } overlap;                       /**< Pointer to overlap memory */
 118
 119   const FIXP_WTP *prev_wrs;        /**< pointer to previous right window slope  */
 120   int prev_tl;                     /**< previous tranform length */
 121   int prev_nr;                     /**< previous right window offset */
 122   int prev_fr;                     /**< previous right window slope length */
 123   int ov_offset;                   /**< overlap time data fill level */
 124   int ov_size;                     /**< Overlap buffer size in words */
 125
 126 } mdct_t;
 127
 128 typedef mdct_t* H_MDCT;
 129
 130 /**
 131  * \brief Initialize as valid MDCT handle
 132  *
 133  * \param hMdct handle of an allocated MDCT handle.
 134  * \param overlap pointer to FIXP_DBL overlap buffer.
 135  * \param overlapBufferSize size in FIXP_DBLs of the given overlap buffer.
 136  * \return void
 137  */
 138 void mdct_init( H_MDCT hMdct,
 139                 FIXP_DBL *overlap,
 140                 INT overlapBufferSize );
 141
 142 /**
 143  * \brief perform MDCT transform (time domain to frequency domain) with given parameters.
 144  *
 145  * \param hMdct handle of an allocated MDCT handle.
 146  * \param spectrum pointer to where the resulting MDCT spectrum will be stored into.
 147  * \param scalefactor pointer to the input scale shift value. Updated accordingly on return.
 148  * \param input pointer to input time domain signal
 149  * \param tl transformation length.
 150  * \param nr right window slope offset (amount of window coefficients assumed to be 1.0)
 151  * \param fr right overlap window slope length
 152  * \param wrs pointer to the right side overlap window coefficients.
 153  * \return number of input samples processed.
 154  */
 155 INT  mdct_block(
 156         H_MDCT hMdct,
 157         FIXP_DBL *spectrum,
 158         INT *scalefactor,
 159         INT_PCM *input,
 160         INT tl,
 161         INT nr,
 162         INT fr,
 163         const FIXP_WTB *wrs );
 164
 165
 166 /**
 167  * \brief add/multiply 2/N transform gain and MPEG4 part 3 defined output gain (see definition
 168  *        of MDCT_OUTPUT_GAIN) to given mantissa factor and exponent.
 169  * \param pGain pointer to the mantissa of a gain factor to be applied to IMDCT data.
 170  * \param pExponent pointer to the exponent of a gain factor to be applied to IMDCT data.
 171  * \param tl length of the IMDCT where the gain *pGain * (2 ^ *pExponent) will be applied to.
 172  */
 173 void imdct_gain(
 174         FIXP_DBL *pGain,
 175         int *pExponent,
 176         int tl
 177         );
 178
 179 /**
 180  * \brief drain buffered output samples into given buffer. Changes the MDCT state.
 181  */
 182 INT imdct_drain(
 183         H_MDCT hMdct,
 184         FIXP_DBL * pTimeData,
 185         INT nrSamplesRoom
 186         );
 187
 188
 189 /**
 190  * \brief Copy overlap time domain data to given buffer. Does not change the MDCT state.
 191  * \return number of actually copied samples (ov + nr).
 192  */
 193 INT imdct_copy_ov_and_nr(
 194         H_MDCT hMdct,
 195         FIXP_DBL * pTimeData,
 196         INT nrSamples
 197         );
 198
 199 /**
 200  * \brief Adapt MDCT parameters for non-matching window slopes.
 201  * \param hMdct handle of an allocated MDCT handle.
 202  * \param pfl pointer to left overlap window side length.
 203  * \param pnl pointer to length of the left n part of the window.
 204  * \param tl transform length.
 205  * \param wls pointer to the left side overlap window coefficients.
 206  * \param noOutSamples desired number of output samples.
 207  */
 208 void imdct_adapt_parameters(H_MDCT hMdct, int *pfl, int *pnl, int tl, const FIXP_WTP *wls, int noOutSamples);
 209
 210 /**
 211  * \brief perform several inverse MDCT transforms (frequency domain to time domain) with given parameters.
 212  *
 213  * \param hMdct handle of an allocated MDCT handle.
 214  * \param output pointer to where the output time domain signal will be stored into.
 215  * \param stride the stride factor for accessing time domain samples in output.
 216  * \param spectrum pointer to the input MDCT spectra.
 217  * \param scalefactors scale shift values of the input spectrum.
 218  * \param nSpec number of MDCT spectrums.
 219  * \param noOutSamples desired number of output samples.
 220  * \param tl transform length.
 221  * \param wls pointer to the left side overlap window coefficients.
 222  * \param fl left overlap window side length.
 223  * \param wrs pointer to the right side overlap window coefficients of all individual IMDCTs.
 224  * \param fr right overlap window side length of all individual IMDCTs.
 225  * \param gain factor to apply to output samples (if != 0).
 226  * \return number of output samples returned.
 227  */
 228 INT  imdct_block(
 229         H_MDCT hMdct,
 230         FIXP_DBL *output,
 231         FIXP_DBL *spectrum,
 232         const SHORT scalefactor[],
 233         const INT nSpec,
 234         const INT noOutSamples,
 235         const INT tl,
 236         const FIXP_WTP *wls,
 237         INT fl,
 238         const FIXP_WTP *wrs,
 239         const INT fr,
 240         FIXP_DBL gain );
 241
 242
 243 #endif /* __MDCT_H__ */