/*
  * audio encoder psychoacoustic model
  * Copyright (C) 2008 Konstantin Shishkov
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #ifndef AVCODEC_PSYMODEL_H
 #define AVCODEC_PSYMODEL_H
 
 #include "avcodec.h"
 
 /** maximum possible number of bands */
 #define PSY_MAX_BANDS 128

 /** maximum number of channels */
 #define PSY_MAX_CHANS 20

 #define AAC_CUTOFF(s) (s->bit_rate ? FFMIN3(4000 + s->bit_rate/8, 12000 + s->bit_rate/32, s->sample_rate / 2) : (s->sample_rate / 2))
 

 /**
  * single band psychoacoustic information
  */

 typedef struct FFPsyBand {

     int   bits;
     float energy;
     float threshold;
     float distortion;
     float perceptual_weight;

 } FFPsyBand;

 
 /**

  * single channel psychoacoustic information
  */
 typedef struct FFPsyChannel {
     FFPsyBand psy_bands[PSY_MAX_BANDS]; ///< channel bands information
     float     entropy;                  ///< total PE for this channel
 } FFPsyChannel;
 
 /**
  * psychoacoustic information for an arbitrary group of channels
  */
 typedef struct FFPsyChannelGroup {
     FFPsyChannel *ch[PSY_MAX_CHANS];  ///< pointers to the individual channels in the group
     uint8_t num_ch;                   ///< number of channels in this group
     uint8_t coupling[PSY_MAX_BANDS];  ///< allow coupling for this band in the group
 } FFPsyChannelGroup;
 
 /**

  * windowing related information
  */

 typedef struct FFPsyWindowInfo {

     int window_type[3];               ///< window type (short/long/transitional, etc.) - current, previous and next
     int window_shape;                 ///< window shape (sine/KBD/whatever)
     int num_windows;                  ///< number of windows in a frame
     int grouping[8];                  ///< window grouping (for e.g. AAC)
     int *window_sizes;                ///< sequence of window sizes inside one frame (for eg. WMA)

 } FFPsyWindowInfo;

 
 /**
  * context used by psychoacoustic model
  */

 typedef struct FFPsyContext {

     AVCodecContext *avctx;            ///< encoder context
     const struct FFPsyModel *model;   ///< encoder-specific model functions
 

     FFPsyChannel      *ch;            ///< single channel information
     FFPsyChannelGroup *group;         ///< channel group information
     int num_groups;                   ///< number of channel groups

 
     uint8_t **bands;                  ///< scalefactor band sizes for possible frame sizes
     int     *num_bands;               ///< number of scalefactor bands for possible frame sizes
     int num_lens;                     ///< number of scalefactor band sets
 

     struct {
         int size;                     ///< size of the bitresevoir in bits
         int bits;                     ///< number of bits used in the bitresevoir
     } bitres;
 

     void* model_priv_data;            ///< psychoacoustic model implementation private data

 } FFPsyContext;

 
 /**
  * codec-specific psychoacoustic model implementation
  */
 typedef struct FFPsyModel {
     const char *name;
     int  (*init)   (FFPsyContext *apc);

 
     /**
      * Suggest window sequence for channel.
      *
      * @param ctx       model context
      * @param audio     samples for the current frame
      * @param la        lookahead samples (NULL when unavailable)
      * @param channel   number of channel element to analyze
      * @param prev_type previous window type
      *
      * @return suggested window information in a structure
      */

     FFPsyWindowInfo (*window)(FFPsyContext *ctx, const float *audio, const float *la, int channel, int prev_type);

 
     /**

      * Perform psychoacoustic analysis and set band info (threshold, energy) for a group of channels.

      *

      * @param ctx      model context
      * @param channel  channel number of the first channel in the group to perform analysis on
      * @param coeffs   array of pointers to the transformed coefficients
      * @param wi       window information for the channels in the group

      */

     void (*analyze)(FFPsyContext *ctx, int channel, const float **coeffs, const FFPsyWindowInfo *wi);

     void (*end)    (FFPsyContext *apc);

 } FFPsyModel;

 
 /**
  * Initialize psychoacoustic model.
  *
  * @param ctx        model context
  * @param avctx      codec context
  * @param num_lens   number of possible frame lengths
  * @param bands      scalefactor band lengths for all frame lengths
  * @param num_bands  number of scalefactor bands for all frame lengths

  * @param num_groups number of channel groups
  * @param group_map  array with # of channels in group - 1, for each group

  *
  * @return zero if successful, a negative value if not
  */

 int ff_psy_init(FFPsyContext *ctx, AVCodecContext *avctx, int num_lens,
                 const uint8_t **bands, const int *num_bands,
                 int num_groups, const uint8_t *group_map);

 
 /**
  * Determine what group a channel belongs to.
  *
  * @param ctx     psymodel context
  * @param channel channel to locate the group for
  *
  * @return pointer to the FFPsyChannelGroup this channel belongs to
  */
 FFPsyChannelGroup *ff_psy_find_group(FFPsyContext *ctx, int channel);

 
 /**
  * Cleanup model context at the end.
  *
  * @param ctx model context
  */

 void ff_psy_end(FFPsyContext *ctx);

 
 
 /**************************************************************************
  *                       Audio preprocessing stuff.                       *
  *       This should be moved into some audio filter eventually.          *
  **************************************************************************/
 struct FFPsyPreprocessContext;
 
 /**
  * psychoacoustic model audio preprocessing initialization
  */

 struct FFPsyPreprocessContext *ff_psy_preprocess_init(AVCodecContext *avctx);

 
 /**
  * Preprocess several channel in audio frame in order to compress it better.
  *
  * @param ctx      preprocessing context

  * @param audio    samples to be filtered (in place)
  * @param channels number of channel to preprocess

  */

 void ff_psy_preprocess(struct FFPsyPreprocessContext *ctx, float **audio, int channels);

 
 /**
  * Cleanup audio preprocessing module.
  */

 void ff_psy_preprocess_end(struct FFPsyPreprocessContext *ctx);

 
 #endif /* AVCODEC_PSYMODEL_H */