g729postfilter.c File Reference

#include <inttypes.h>
#include <limits.h>
#include "avcodec.h"
#include "g729.h"
#include "acelp_pitch_delay.h"
#include "g729postfilter.h"
#include "celp_math.h"
#include "acelp_filters.h"
#include "acelp_vectors.h"
#include "celp_filters.h"
#include "mathops.h"

Go to the source code of this file.

Macros
#define	FRAC_BITS   15

Functions
static void	residual_filter (int16_t *out, const int16_t *filter_coeffs, const int16_t *in, int subframe_size)
	Residual signal calculation (4.2.1 if G.729)
static int16_t	long_term_filter (DSPContext *dsp, int pitch_delay_int, const int16_t *residual, int16_t *residual_filt, int subframe_size)
	long-term postfilter (4.2.1)
static int16_t	get_tilt_comp (DSPContext *dsp, int16_t *lp_gn, const int16_t *lp_gd, int16_t *speech, int subframe_size)
	Calculate reflection coefficient for tilt compensation filter (4.2.3).
static int16_t	apply_tilt_comp (int16_t *out, int16_t *res_pst, int refl_coeff, int subframe_size, int16_t ht_prev_data)
	Apply tilt compensation filter (4.2.3).
void	ff_g729_postfilter (DSPContext *dsp, int16_t *ht_prev_data, int *voicing, const int16_t *lp_filter_coeffs, int pitch_delay_int, int16_t *residual, int16_t *res_filter_data, int16_t *pos_filter_data, int16_t *speech, int subframe_size)
	Signal postfiltering (4.2)
int16_t	ff_g729_adaptive_gain_control (int gain_before, int gain_after, int16_t *speech, int subframe_size, int16_t gain_prev)
	Adaptive gain control (4.2.4)

Variables
static const int16_t	ff_g729_interp_filt_short [(ANALYZED_FRAC_DELAYS+1)*SHORT_INT_FILT_LEN]
	short interpolation filter (of length 33, according to spec) for computing signal with non-integer delay
static const int16_t	ff_g729_interp_filt_long [(ANALYZED_FRAC_DELAYS+1)*LONG_INT_FILT_LEN]
	long interpolation filter (of length 129, according to spec) for computing signal with non-integer delay
static const int16_t	formant_pp_factor_num_pow [10]
	formant_pp_factor_num_pow[i] = FORMANT_PP_FACTOR_NUM^(i+1)
static const int16_t	formant_pp_factor_den_pow [10]
	formant_pp_factor_den_pow[i] = FORMANT_PP_FACTOR_DEN^(i+1)

Macro Definition Documentation

#define FRAC_BITS   15

Definition at line 33 of file g729postfilter.c.

Referenced by compute_stereo(), decode_frame(), decode_init_static(), encode_frame(), ff_mpa_synth_init_TMPL(), ff_snow_inner_add_yblock(), get_block_rd(), get_dc(), imdct36(), long_term_filter(), and predict_slice_buffered().

Function Documentation

static void residual_filter ( int16_t *  out, const int16_t *  filter_coeffs, const int16_t *  in, int  subframe_size  )

static

Residual signal calculation (4.2.1 if G.729)

Parameters

out	[out] output data filtered through A(z/FORMANT_PP_FACTOR_NUM)
filter_coeffs	(3.12) A(z/FORMANT_PP_FACTOR_NUM) filter coefficients
in	input speech data to process
subframe_size	size of one subframe

Note

in buffer must contain 10 items of previous speech data before top of the buffer

Remarks

It is safe to pass the same buffer for input and output.

Definition at line 86 of file g729postfilter.c.

Referenced by ff_g729_postfilter().

static int16_t long_term_filter ( DSPContext *  dsp, int  pitch_delay_int, const int16_t *  residual, int16_t *  residual_filt, int  subframe_size  )

static

long-term postfilter (4.2.1)

Parameters

dsp	initialized DSP context
pitch_delay_int	integer part of the pitch delay in the first subframe
residual	filtering input data
residual_filt	[out] speech signal with applied A(z/FORMANT_PP_FACTOR_NUM) filter
subframe_size	size of subframe

Returns

0 if long-term prediction gain is less than 3dB, 1 - otherwise

Definition at line 110 of file g729postfilter.c.

Referenced by ff_g729_postfilter().

static int16_t get_tilt_comp ( DSPContext *  dsp, int16_t *  lp_gn, const int16_t *  lp_gd, int16_t *  speech, int  subframe_size  )

static

Calculate reflection coefficient for tilt compensation filter (4.2.3).

Parameters

dsp	initialized DSP context
lp_gn	(3.12) coefficients of A(z/FORMANT_PP_FACTOR_NUM) filter
lp_gd	(3.12) coefficients of A(z/FORMANT_PP_FACTOR_DEN) filter
speech	speech to update
subframe_size	size of subframe

Returns

(3.12) reflection coefficient

Remarks

The routine also calculates the gain term for the short-term filter (gf) and multiplies the speech data by 1/gf.

Note

All members of lp_gn, except 10-19 must be equal to zero.

Definition at line 424 of file g729postfilter.c.

Referenced by ff_g729_postfilter().

static int16_t apply_tilt_comp ( int16_t *  out, int16_t *  res_pst, int  refl_coeff, int  subframe_size, int16_t  ht_prev_data  )

static

Apply tilt compensation filter (4.2.3).

Parameters

res_pst	[in/out] residual signal (partially filtered)
k1	(3.12) reflection coefficient
subframe_size	size of subframe
ht_prev_data	previous data for 4.2.3, equation 86

Returns

new value for ht_prev_data

Definition at line 476 of file g729postfilter.c.

Referenced by ff_g729_postfilter().

void ff_g729_postfilter	(	DSPContext *	dsp,
		int16_t *	ht_prev_data,
		int *	voicing,
		const int16_t *	lp_filter_coeffs,
		int	pitch_delay_int,
		int16_t *	residual,
		int16_t *	res_filter_data,
		int16_t *	pos_filter_data,
		int16_t *	speech,
		int	subframe_size
	)

Signal postfiltering (4.2)

Parameters

dsp	initialized DSP context
ht_prev_data	[in/out] (Q12) pointer to variable receiving tilt compensation filter data from previous subframe
voicing	[in/out] (Q0) pointer to variable receiving voicing decision
lp_filter_coeffs	(Q12) LP filter coefficients
pitch_delay_int	integer part of the pitch delay
residual	[in/out] (Q0) residual signal buffer (used in long-term postfilter)
res_filter_data	[in/out] (Q0) speech data of previous subframe
pos_filter_data	[in/out] (Q0) previous speech data for short-term postfilter
speech	[in/out] (Q0) signal buffer
subframe_size	size of subframe

Filtering has the following stages: Long-term postfilter (4.2.1) Short-term postfilter (4.2.2). Tilt-compensation (4.2.3)

Definition at line 514 of file g729postfilter.c.

Referenced by decode_frame().

int16_t ff_g729_adaptive_gain_control	(	int	gain_before,
		int	gain_after,
		int16_t *	speech,
		int	subframe_size,
		int16_t	gain_prev
	)

Adaptive gain control (4.2.4)

Parameters

gain_before	gain of speech before applying postfilters
gain_after	gain of speech after applying postfilters
speech	[in/out] signal buffer
subframe_size	length of subframe
gain_prev	(3.12) previous value of gain coefficient

Returns

(3.12) last value of gain coefficient

Definition at line 574 of file g729postfilter.c.

Referenced by decode_frame().

Variable Documentation

const int16_t ff_g729_interp_filt_short[(ANALYZED_FRAC_DELAYS+1)*SHORT_INT_FILT_LEN]

static

Initial value:

= {
      0, 31650, 28469, 23705, 18050, 12266,  7041,  2873,
      0, -1597, -2147, -1992, -1492,  -933,  -484,  -188,
}

short interpolation filter (of length 33, according to spec) for computing signal with non-integer delay

Definition at line 40 of file g729postfilter.c.

Referenced by long_term_filter().

const int16_t ff_g729_interp_filt_long[(ANALYZED_FRAC_DELAYS+1)*LONG_INT_FILT_LEN]

static

Initial value:

= {
   0, 31915, 29436, 25569, 20676, 15206,  9639,  4439,
   0, -3390, -5579, -6549, -6414, -5392, -3773, -1874,
   0,  1595,  2727,  3303,  3319,  2850,  2030,  1023,
   0,  -887, -1527, -1860, -1876, -1614, -1150,  -579,
   0,   501,   859,  1041,  1044,   892,   631,   315,
   0,  -266,  -453,  -543,  -538,  -455,  -317,  -156,
   0,   130,   218,   258,   253,   212,   147,    72,
   0,   -59,  -101,  -122,  -123,  -106,   -77,   -40,
}

long interpolation filter (of length 129, according to spec) for computing signal with non-integer delay

Definition at line 49 of file g729postfilter.c.

Referenced by long_term_filter().

const int16_t formant_pp_factor_num_pow[10]

static

Initial value:

= {
  
  18022, 9912, 5451, 2998, 1649, 907, 499, 274, 151, 83
}

formant_pp_factor_num_pow[i] = FORMANT_PP_FACTOR_NUM^(i+1)

Definition at line 63 of file g729postfilter.c.

Referenced by ff_g729_postfilter().

const int16_t formant_pp_factor_den_pow[10]

static

Initial value:

= {
  
  22938, 16057, 11240, 7868, 5508, 3856, 2699, 1889, 1322, 925
}

formant_pp_factor_den_pow[i] = FORMANT_PP_FACTOR_DEN^(i+1)

Definition at line 71 of file g729postfilter.c.

Referenced by ff_g729_postfilter().