lsp.c File Reference

#include <math.h>
#include "config.h"
#include "libavutil/macros.h"
#include "mathops.h"
#include "lsp.h"
#include "libavutil/avassert.h"

Go to the source code of this file.

Macros
#define	FRAC_BITS   14

Functions
void	ff_acelp_reorder_lsf (int16_t *lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order)
	(I.F) means fixed-point value with F fractional and I integer bits More...
void	ff_set_min_dist_lsf (float *lsf, double min_spacing, int size)
	Adjust the quantized LSFs so they are increasing and not too close. More...
static int16_t	ff_cos (uint16_t arg)
void	ff_acelp_lsf2lsp (int16_t *lsp, const int16_t *lsf, int lp_order)
	Convert LSF to LSP. More...
void	ff_acelp_lsf2lspd (double *lsp, const float *lsf, int lp_order)
	Floating point version of ff_acelp_lsf2lsp() More...
static void	lsp2poly (int *f, const int16_t *lsp, int lp_half_order)
	decodes polynomial coefficients from LSP More...
static void	lsp2polyf (const double *lsp, double *f, int lp_half_order)
	Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients needed for LSP to LPC conversion. More...
void	ff_acelp_lsp2lpc (int16_t *lp, const int16_t *lsp, int lp_half_order)
	LSP to LP conversion (3.2.6 of G.729) More...
void	ff_amrwb_lsp2lpc (const double *lsp, float *lp, int lp_order)
	LSP to LP conversion (5.2.4 of AMR-WB) More...
void	ff_acelp_lp_decode (int16_t *lp_1st, int16_t *lp_2nd, const int16_t *lsp_2nd, const int16_t *lsp_prev, int lp_order)
	Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729) More...
void	ff_acelp_lspd2lpc (const double *lsp, float *lpc, int lp_half_order)
	Reconstruct LPC coefficients from the line spectral pair frequencies. More...
void	ff_sort_nearly_sorted_floats (float *vals, int len)
	Sort values in ascending order. More...

Variables
static const int16_t	tab_cos [65]

Macro Definition Documentation

FRAC_BITS

#define FRAC_BITS   14

Definition at line 28 of file lsp.c.

Function Documentation

ff_acelp_reorder_lsf()

void ff_acelp_reorder_lsf	(	int16_t *	lsfq,
		int	lsfq_min_distance,
		int	lsfq_min,
		int	lsfq_max,
		int	lp_order
	)

(I.F) means fixed-point value with F fractional and I integer bits

ensure a minimum distance between LSFs

Parameters

[in,out]	lsfq	LSF to check and adjust
	lsfq_min_distance	minimum distance between LSFs
	lsfq_min	minimum allowed LSF value
	lsfq_max	maximum allowed LSF value
	lp_order	LP filter order

Definition at line 37 of file lsp.c.

Referenced by lsf_decode().

ff_set_min_dist_lsf()

void ff_set_min_dist_lsf	(	float *	lsf,
		double	min_spacing,
		int	size
	)

Adjust the quantized LSFs so they are increasing and not too close.

This step is not mentioned in the AMR spec but is in the reference C decoder. Omitting this step creates audible distortion on the sinusoidal sweep test vectors in 3GPP TS 26.074.

Parameters

[in,out]	lsf	LSFs in Hertz
	min_spacing	minimum distance between two consecutive lsf values
	size	size of the lsf vector

Definition at line 55 of file lsp.c.

Referenced by amrwb_decode_frame(), ff_sipr_decode_frame_16k(), lsf2lsp_3(), lsf2lsp_for_mode12k2(), and lsf_decode_fp().

ff_cos()

static int16_t ff_cos ( uint16_t  arg )

static

Definition at line 77 of file lsp.c.

Referenced by ff_acelp_lsf2lsp().

ff_acelp_lsf2lsp()

void ff_acelp_lsf2lsp	(	int16_t *	lsp,
		const int16_t *	lsf,
		int	lp_order
	)

Convert LSF to LSP.

Parameters

[out]	lsp	LSP coefficients (-0x8000 <= (0.15) < 0x8000)
	lsf	normalized LSF coefficients (0 <= (2.13) < 0x2000 * PI)
	lp_order	LP filter order

Remarks

It is safe to pass the same array into the lsf and lsp parameters.

Definition at line 87 of file lsp.c.

Referenced by decode_frame().

ff_acelp_lsf2lspd()

void ff_acelp_lsf2lspd	(	double *	lsp,
		const float *	lsf,
		int	lp_order
	)

Floating point version of ff_acelp_lsf2lsp()

Definition at line 97 of file lsp.c.

Referenced by amrwb_decode_frame(), decode_predictor_coeffs(), hb_synthesis(), lsf2lsp_3(), and lsf2lsp_for_mode12k2().

lsp2poly()

static void lsp2poly ( int *  f, const int16_t *  lsp, int  lp_half_order  )

static

decodes polynomial coefficients from LSP

Parameters

[out]	f	decoded polynomial coefficients (-0x20000000 <= (3.22) <= 0x1fffffff)
	lsp	LSP coefficients (-0x8000 <= (0.15) <= 0x7fff)

Definition at line 110 of file lsp.c.

Referenced by ff_acelp_lsp2lpc().

lsp2polyf()

static void lsp2polyf ( const double *  lsp, double *  f, int  lp_half_order  )

static

Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients needed for LSP to LPC conversion.

We only need to calculate the 6 first elements of the polynomial.

Parameters

	lsp	line spectral pairs in cosine domain
[out]	f	polynomial input/output as a vector

TIA/EIA/IS-733 2.4.3.3.5-1/2

Definition at line 138 of file lsp.c.

Referenced by ff_acelp_lspd2lpc(), and ff_amrwb_lsp2lpc().

ff_acelp_lsp2lpc()

void ff_acelp_lsp2lpc	(	int16_t *	lp,
		const int16_t *	lsp,
		int	lp_half_order
	)

LSP to LP conversion (3.2.6 of G.729)

Parameters

[out]	lp	decoded LP coefficients (-0x8000 <= (3.12) < 0x8000)
	lsp	LSP coefficients (-0x8000 <= (0.15) < 0x8000)
	lp_half_order	LP filter order, divided by 2

Definition at line 153 of file lsp.c.

Referenced by ff_acelp_lp_decode().

ff_amrwb_lsp2lpc()

void ff_amrwb_lsp2lpc	(	const double *	lsp,
		float *	lp,
		int	lp_order
	)

LSP to LP conversion (5.2.4 of AMR-WB)

Definition at line 175 of file lsp.c.

Referenced by amrwb_decode_frame(), hb_synthesis(), and sipr_decode_lp().

ff_acelp_lp_decode()

void ff_acelp_lp_decode	(	int16_t *	lp_1st,
		int16_t *	lp_2nd,
		const int16_t *	lsp_2nd,
		const int16_t *	lsp_prev,
		int	lp_order
	)

Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729)

Parameters

[out]	lp_1st	decoded LP coefficients for first subframe (-0x8000 <= (3.12) < 0x8000)
[out]	lp_2nd	decoded LP coefficients for second subframe (-0x8000 <= (3.12) < 0x8000)
	lsp_2nd	LSP coefficients of the second subframe (-0x8000 <= (0.15) < 0x8000)
	lsp_prev	LSP coefficients from the second subframe of the previous frame (-0x8000 <= (0.15) < 0x8000)
	lp_order	LP filter order

Definition at line 201 of file lsp.c.

Referenced by decode_frame().

ff_acelp_lspd2lpc()

void ff_acelp_lspd2lpc	(	const double *	lsp,
		float *	lpc,
		int	lp_half_order
	)

Reconstruct LPC coefficients from the line spectral pair frequencies.

Parameters

lsp	line spectral pairs in cosine domain
lpc	linear predictive coding coefficients
lp_half_order	half the number of the amount of LPCs to be reconstructed, need to be smaller or equal to MAX_LP_HALF_ORDER

Note

buffers should have a minimum size of 2*lp_half_order elements.

TIA/EIA/IS-733 2.4.3.3.5

Definition at line 220 of file lsp.c.

Referenced by acelp_lp_decodef(), amrnb_decode_frame(), lspf2lpc(), synth_block(), and synth_frame().

ff_sort_nearly_sorted_floats()

void ff_sort_nearly_sorted_floats	(	float *	vals,
		int	len
	)

Sort values in ascending order.

Note

O(n) if data already sorted, O(n^2) - otherwise

Definition at line 239 of file lsp.c.

Referenced by decode_lsp(), and lsf_decode_fp().

Variable Documentation

tab_cos

const int16_t tab_cos[65]

static

Initial value:

=
{
  32767,  32738,  32617,  32421,  32145,  31793,  31364,  30860,
  30280,  29629,  28905,  28113,  27252,  26326,  25336,  24285,
  23176,  22011,  20793,  19525,  18210,  16851,  15451,  14014,
  12543,  11043,   9515,   7965,   6395,   4810,   3214,   1609,
      1,  -1607,  -3211,  -4808,  -6393,  -7962,  -9513, -11040,
 -12541, -14012, -15449, -16848, -18207, -19523, -20791, -22009,
 -23174, -24283, -25334, -26324, -27250, -28111, -28904, -29627,
 -30279, -30858, -31363, -31792, -32144, -32419, -32616, -32736, -32768,
}

Definition at line 65 of file lsp.c.

Referenced by ff_cos().