libavcodec/aacpsy.c File Reference

AAC encoder psychoacoustic model. More...

#include "avcodec.h"
#include "aactab.h"
#include "psymodel.h"

Go to the source code of this file.

Data Structures
struct	Psy3gppBand
	information for single band used by 3GPP TS26.403-inspired psychoacoustic model More...
struct	Psy3gppChannel
	single/pair channel context for psychoacoustic model More...
struct	Psy3gppCoeffs
	psychoacoustic model frame type-dependent coefficients More...
struct	Psy3gppContext
	3GPP TS26.403-inspired psychoacoustic model specific data More...
Defines
#define	ATH_ADD   4
#define	PSY_3GPP_SPREAD_LOW   1.5f
	constants for 3GPP AAC psychoacoustic model
#define	PSY_3GPP_SPREAD_HI   3.0f
#define	PSY_3GPP_RPEMIN   0.01f
#define	PSY_3GPP_RPELEV   2.0f
Functions
static av_cold float	calc_bark (float f)
	Calculate Bark value for given line.
static av_cold float	ath (float f, float add)
	Calculate ATH value for given frequency.
static av_cold int	psy_3gpp_init (FFPsyContext *ctx)
static float	iir_filter (int in, float state[2])
	IIR filter used in block switching decision.
static FFPsyWindowInfo	psy_3gpp_window (FFPsyContext *ctx, const int16_t *audio, const int16_t *la, int channel, int prev_type)
	Tell encoder which window types to use.
static void	psy_3gpp_analyze (FFPsyContext *ctx, int channel, const float *coefs, FFPsyWindowInfo *wi)
	Calculate band thresholds as suggested in 3GPP TS26.403.
static av_cold void	psy_3gpp_end (FFPsyContext *apc)
Variables
static const uint8_t	window_grouping [9]
	window grouping information stored as bits (0 - new group, 1 - group continues)
const FFPsyModel	ff_aac_psy_model

---

Detailed Description

AAC encoder psychoacoustic model.

Definition in file aacpsy.c.

---

Define Documentation

#define ATH_ADD   4

Definition at line 101 of file aacpsy.c.

Referenced by psy_3gpp_init().

#define PSY_3GPP_RPELEV   2.0f

Definition at line 46 of file aacpsy.c.

Referenced by psy_3gpp_analyze().

#define PSY_3GPP_RPEMIN   0.01f

Definition at line 45 of file aacpsy.c.

Referenced by psy_3gpp_analyze().

#define PSY_3GPP_SPREAD_HI   3.0f

Definition at line 43 of file aacpsy.c.

Referenced by psy_3gpp_init().

#define PSY_3GPP_SPREAD_LOW   1.5f

constants for 3GPP AAC psychoacoustic model

Definition at line 42 of file aacpsy.c.

Referenced by psy_3gpp_init().

---

Function Documentation

static av_cold float ath	(	float	f,
		float	add
	)			[static]

Calculate ATH value for given frequency.

Borrowed from Lame.

Definition at line 106 of file aacpsy.c.

Referenced by psy_3gpp_init().

static av_cold float calc_bark

(

float

f

)

[static]

Calculate Bark value for given line.

Definition at line 96 of file aacpsy.c.

Referenced by psy_3gpp_init().

static float iir_filter	(	int	in,
		float	state[2]
	)			[static]

IIR filter used in block switching decision.

Definition at line 157 of file aacpsy.c.

Referenced by psy_3gpp_window().

static void psy_3gpp_analyze	(	FFPsyContext *	ctx,
		int	channel,
		const float *	coefs,
		FFPsyWindowInfo *	wi
	)			[static]

Calculate band thresholds as suggested in 3GPP TS26.403.

Definition at line 257 of file aacpsy.c.

static av_cold void psy_3gpp_end

(

FFPsyContext *

apc

)

[static]

Definition at line 303 of file aacpsy.c.

static av_cold int psy_3gpp_init

(

FFPsyContext *

ctx

)

[static]

Definition at line 115 of file aacpsy.c.

static FFPsyWindowInfo psy_3gpp_window	(	FFPsyContext *	ctx,
		const int16_t *	audio,
		const int16_t *	la,
		int	channel,
		int	prev_type
	)			[static]

Tell encoder which window types to use.

See also:

3GPP TS26.403 5.4.1 "Blockswitching"

Definition at line 178 of file aacpsy.c.

---

Variable Documentation

const FFPsyModel ff_aac_psy_model

Initial value:

{
    .name    = "3GPP TS 26.403-inspired model",
    .init    = psy_3gpp_init,
    .window  = psy_3gpp_window,
    .analyze = psy_3gpp_analyze,
    .end     = psy_3gpp_end,
}

Definition at line 311 of file aacpsy.c.

const uint8_t window_grouping[9] [static]

Initial value:

 {
    0xB6, 0x6C, 0xD8, 0xB2, 0x66, 0xC6, 0x96, 0x36, 0x36
}

window grouping information stored as bits (0 - new group, 1 - group continues)

Definition at line 170 of file aacpsy.c.

Referenced by psy_3gpp_window().