psymodel.h

/*
 * 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"

#define PSY_MAX_BANDS 128

#define PSY_MAX_CHANS 20

/* cutoff for VBR is purposely increased, since LP filtering actually
 * hinders VBR performance rather than the opposite
 */
#define AAC_CUTOFF_FROM_BITRATE(bit_rate,channels,sample_rate) (bit_rate ? FFMIN3(FFMIN3( \
    FFMAX(bit_rate/channels/5, bit_rate/channels*15/32 - 5500), \
    3000 + bit_rate/channels/4, \
    12000 + bit_rate/channels/16), \
    22000, \
    sample_rate / 2): (sample_rate / 2))
#define AAC_CUTOFF(s) ( \
    (s->flags & AV_CODEC_FLAG_QSCALE) \
    ? s->sample_rate / 2 \
    : AAC_CUTOFF_FROM_BITRATE(s->bit_rate, s->channels, s->sample_rate) \
)

typedef struct FFPsyBand {
    int   bits;
    float energy;
    float threshold;
    float spread;    /* Energy spread over the band */
} FFPsyBand;

typedef struct FFPsyChannel {
    FFPsyBand psy_bands[PSY_MAX_BANDS]; 
    float     entropy;                  
} FFPsyChannel;

typedef struct FFPsyChannelGroup {
    FFPsyChannel *ch[PSY_MAX_CHANS];  
    uint8_t num_ch;                   
    uint8_t coupling[PSY_MAX_BANDS];  
} FFPsyChannelGroup;

typedef struct FFPsyWindowInfo {
    int window_type[3];               
    int window_shape;                 
    int num_windows;                  
    int grouping[8];                  
    float clipping[8];                
    int *window_sizes;                
} FFPsyWindowInfo;

typedef struct FFPsyContext {
    AVCodecContext *avctx;            
    const struct FFPsyModel *model;   

    FFPsyChannel      *ch;            
    FFPsyChannelGroup *group;         
    int num_groups;                   
    int cutoff;                       

    uint8_t **bands;                  
    int     *num_bands;               
    int num_lens;                     

    struct {
        int size;                     
        int bits;                     
        int alloc;                    
    } bitres;

    void* model_priv_data;            
} FFPsyContext;

typedef struct FFPsyModel {
    const char *name;
    int  (*init)   (FFPsyContext *apc);

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

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

    void (*end)    (FFPsyContext *apc);
} FFPsyModel;

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);

FFPsyChannelGroup *ff_psy_find_group(FFPsyContext *ctx, int channel);

void ff_psy_end(FFPsyContext *ctx);


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

struct FFPsyPreprocessContext *ff_psy_preprocess_init(AVCodecContext *avctx);

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

void ff_psy_preprocess_end(struct FFPsyPreprocessContext *ctx);

#endif /* AVCODEC_PSYMODEL_H */