AMR pre-processing functions

Functions
static void	apply_ir_filter (float *out, const AMRFixed *in, const float *filter)
	Circularly convolve a sparse fixed vector with a phase dispersion impulse response filter (D.6.2 of G.729 and 6.1.5 of AMR).
static const float *	anti_sparseness (AMRContext *p, AMRFixed *fixed_sparse, const float *fixed_vector, float fixed_gain, float *out)
	Reduce fixed vector sparseness by smoothing with one of three IR filters.

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Function Documentation

static const float* anti_sparseness	(	AMRContext *	p,
		AMRFixed *	fixed_sparse,
		const float *	fixed_vector,
		float	fixed_gain,
		float *	out
	)			[static]

Reduce fixed vector sparseness by smoothing with one of three IR filters.

Also know as "adaptive phase dispersion".

This implements 3GPP TS 26.090 section 6.1(5).

Parameters:

	p	the context
	fixed_sparse	algebraic codebook vector
	fixed_vector	unfiltered fixed vector
	fixed_gain	smoothed gain
	out	space for modified vector if necessary

Definition at line 724 of file amrnbdec.c.

Referenced by amrnb_decode_frame().

static void apply_ir_filter	(	float *	out,
		const AMRFixed *	in,
		const float *	filter
	)			[static]

Circularly convolve a sparse fixed vector with a phase dispersion impulse response filter (D.6.2 of G.729 and 6.1.5 of AMR).

Parameters:

	out	vector with filter applied
	in	source vector
	filter	phase filter coefficients

out[n] = sum(i,0,len-1){ in[i] * filter[(len + n - i)len] }

< filters at pitch lag*1 and *2

Definition at line 677 of file amrnbdec.c.

Referenced by anti_sparseness().