libavcodec/psymodel.h - manifest_repos/ffmpeg - Git at Google

 /*
  * 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

 /* 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) \
 )

 /**
  * single band psychoacoustic information
  */
 typedef struct FFPsyBand {
     int   bits;
     float energy;
     float threshold;
     float spread;    /* Energy spread over the band */
 } 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)
     float clipping[8];                ///< maximum absolute normalized intensity in the given window for clip avoidance
     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
     int cutoff;                       ///< lowpass frequency cutoff for analysis

     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
         int alloc;                    ///< number of bits allocated by the psy, or -1 if no allocation was done
     } 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 */
	/*
	* 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

	/* 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) \
	)

	/**
	* single band psychoacoustic information
	*/
	typedef struct FFPsyBand {
	int bits;
	float energy;
	float threshold;
	float spread; /* Energy spread over the band */
	} 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)
	float clipping[8]; ///< maximum absolute normalized intensity in the given window for clip avoidance
	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
	int cutoff; ///< lowpass frequency cutoff for analysis

	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
	int alloc; ///< number of bits allocated by the psy, or -1 if no allocation was done
	} 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 */