Reduction of complexity for phase only correlation in stereo downmix for EVS. (9786a7a7) · Commits · IVAS Codec Public Collaboration / IVAS Codec

lib_com/options.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -151,6 +151,10 @@
		#define FIX_I2_BWD /* Issue 2: BWD fix to more quickly react to WB -> SWB/FB change */



		/* NTT switches */
		#define NTT_REDUC_COMP_POC /* Contribution : Complexity reduction of phase spectrum in stereo downmix */

		/* ################## End DEVELOPMENT switches ######################### */
		/* clang-format on */
		#endif

lib_enc/ivas_stereo_dmx_evs.c

+324 −1

Original line number	Diff line number	Diff line
		@@ -155,7 +155,15 @@ static void calc_poc(
		const float *s;
		float *P;
		float tmp1, tmp2, Lr, Li, Rr, Ri, gamma, igamma, iN;

		#ifdef NTT_REDUC_COMP_POC
		float specPOr[L_FRAME48k / 2 + 1], specPOi[L_FRAME48k / 2]; /real and imaginary part of spectrum/
		float aR, aI; /real and imaginary values for searching phase angle/
		int16_t j;
		#else
		float specPOr[L_FRAME48k], specPOi[L_FRAME48k];
		#endif

		float tmpPOC1[L_FRAME48k], tmpPOC2[L_FRAME48k];
		float rfft_buf[L_FRAME48k];
		int16_t step, bias;
		@@ -200,6 +208,320 @@ static void calc_poc(
		cos_max = n0;
		}

		#ifdef NTT_REDUC_COMP_POC
		/apploximation of phase angle on an unit circle without using sqrt()/
		for ( i = 1; i < n0 / 2; i++ )
		{
		Lr = specLr[i];
		Li = specLi[i];
		Rr = specRr[i];
		Ri = specRi[i];

		i_for = i * cos_step;
		eps_cos = s[cos_max - i_for] * EPS;
		eps_sin = s[i_for] * EPS;
		Lr += ( specRr[i] * eps_cos + specRi[i] * eps_sin );
		Li += ( -specRr[i] * eps_sin + specRi[i] * eps_cos );
		Rr += ( specLr[i] * eps_cos + specLi[i] * eps_sin );
		Ri += ( -specLr[i] * eps_sin + specLi[i] * eps_cos );

		specPOr[i] = ( Lr * Rr + Li * Ri );
		specPOi[i] = ( Lr * Ri - Li * Rr );

		j = n0 - i;
		Lr = specLr[j];
		Li = specLi[j];
		Rr = specRr[j];
		Ri = specRi[j];
		Lr += ( -specRr[j] * eps_cos + specRi[j] * eps_sin );
		Li += ( -specRr[j] * eps_sin - specRi[j] * eps_cos );
		Rr += ( -specLr[j] * eps_cos + specLi[j] * eps_sin );
		Ri += ( -specLr[j] * eps_sin - specLi[j] * eps_cos );

		specPOr[j] = ( Lr * Rr + Li * Ri );
		specPOi[j] = ( Lr * Ri - Li * Rr );
		}
		{
		i = n0 / 2;
		Lr = specLr[i] + specRi[i] * EPS;
		Li = specLi[i] - specRr[i] * EPS;
		Rr = specRr[i] + specLi[i] * EPS;
		Ri = specRi[i] - specLr[i] * EPS;

		specPOr[i] = ( Lr * Rr + Li * Ri );
		specPOi[i] = ( Lr * Ri - Li * Rr );
		}
		/* complex spectrum (specPOr[i], specPOi[i]) are placed on an unit circle without using srqt()*/
		for ( i = 1; i < 10; i++ ) /search from 4 angles /
		{
		specPOr[i] = sign( specPOr[i] ) * 0.866f; /* low angles are more frequent for low frequency */
		specPOi[i] = sign( specPOi[i] ) * 0.5f;
		}
		for ( i = 10; i<n0>> 4; i++ ) /search from 4 angles /
		{
		specPOr[i] = sign( specPOr[i] ) * 0.7071f; /* low accuracy is adequate for low frequency */
		specPOi[i] = sign( specPOi[i] ) * 0.7071f;
		}
		for ( i = n0 >> 4; i<n0>> 3; i++ ) /* binary search from 8 angles */
		{
		aR = fabsf( specPOr[i] );
		aI = fabsf( specPOi[i] );
		if ( aR > aI )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.92388f; /* (wnd[n0>>2]+wnd[(n0>>2)-1])0.5f) /
		specPOi[i] = sign( specPOi[i] ) * 0.382683f; /* (wnd[n0>>2]+wnd[(n0>>2)-1])0.5f) /
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.382683f; /* (wnd[n0>>2]+wnd[(n0>>2)-1])0.5f) /
		specPOi[i] = sign( specPOi[i] ) * 0.92388f; /* (wnd[(n0>>2)3]+wnd[((n0>>2)3)-1])0.5f) /
		}
		}
		for ( i = n0 >> 3; i<n0>> 2; i++ ) /* binary search from 16 angles */
		{
		aR = fabsf( specPOr[i] );
		aI = fabsf( specPOi[i] );
		if ( aR > aI )
		{
		if ( aR * 0.414213f /tanf(PI/8)/ > aI )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.980785f; /* (wnd[(n0>>3)7]+wnd[((n0>>3)7)-1])0.5f /
		specPOi[i] = sign( specPOi[i] ) * 0.19509f; /* (wnd[n0>>3]+wnd[(n0>>3)-1])0.5f) /
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.83147f; /* (wnd[(n0>>3)5]+wnd[((n0>>3)5)-1])0.5f /
		specPOi[i] = sign( specPOi[i] ) * 0.55557f; /* (wnd[(n0>>3)3]+wnd[(n0>>3)3-1])0.5f /
		}
		}
		else
		{
		if ( aR > aI * 0.41421356f /tanf(PI/8)/ )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.55557f;
		specPOi[i] = sign( specPOi[i] ) * 0.83147f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.19509f;
		specPOi[i] = sign( specPOi[i] ) * 0.980785f;
		}
		}
		}

		for ( i = n0 >> 2; i<n0>> 1; i++ ) /* binary search from 32 angles */
		{
		aR = fabsf( specPOr[i] );
		aI = fabsf( specPOi[i] );

		if ( aR > aI )
		{
		if ( aR * 0.4142136f /tanf(PI/8)/ > aI )
		{
		if ( aR * 0.19891f /tanf(PI/16)/ > aI )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.995185f;
		specPOi[i] = sign( specPOi[i] ) * 0.098017f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.95694f;
		specPOi[i] = sign( specPOi[i] ) * 0.290285f;
		}
		}
		else
		{
		if ( aR * 0.66818f /tanf(PI3/16)*/ > aI )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.881921f;
		specPOi[i] = sign( specPOi[i] ) * 0.471397f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.77301f;
		specPOi[i] = sign( specPOi[i] ) * 0.634393f;
		}
		}
		}
		else
		{
		if ( aR > aI * 0.4142136f /tanf(PI/8)/ )
		{
		if ( aR > aI * 0.668179f /tanf(PI3/16)*/ )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.634393f;
		specPOi[i] = sign( specPOi[i] ) * 0.77301f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.471397f;
		specPOi[i] = sign( specPOi[i] ) * 0.881921f;
		}
		}
		else
		{
		if ( aR > aI * 0.198912f /tanf(PI/16)/ )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.290285f;
		specPOi[i] = sign( specPOi[i] ) * 0.95694f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.098017f;
		specPOi[i] = sign( specPOi[i] ) * 0.995158f;
		}
		}
		}
		}

		for ( i = n0 >> 1; i < min( n0, 320 ); i++ ) /* binary search from 64 angles */
		{
		aR = fabsf( specPOr[i] );
		aI = fabsf( specPOi[i] );

		if ( aR > aI )
		{
		if ( aR * 0.414213f /tanf(PI/8)/ > aI )
		{
		if ( aR * 0.19891f /tanf(PI/16)/ > aI )
		{
		if ( aR * 0.0984914f /tanf(PI/32)/ > aI )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.99879f;
		specPOi[i] = sign( specPOi[i] ) * 0.04907f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.98918f;
		specPOi[i] = sign( specPOi[i] ) * 0.14763f;
		}
		}
		else
		{
		if ( aR * 0.303347f /tanf(PI3/32)*/ > aI )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.970031f;
		specPOi[i] = sign( specPOi[i] ) * 0.24298f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.941544f;
		specPOi[i] = sign( specPOi[i] ) * 0.33689f;
		}
		}
		}
		else
		{
		if ( aR * 0.66818f /tanf(PI3/16)*/ > aI )
		{
		if ( aR * 0.534511f /tanf(PI5/32)*/ > aI )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.903989f;
		specPOi[i] = sign( specPOi[i] ) * 0.427555f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.857729f;
		specPOi[i] = sign( specPOi[i] ) * 0.514103f;
		}
		}
		else
		{
		if ( aR * 0.8206788f /tanf(PI7/32)*/ > aI )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.803208f;
		specPOi[i] = sign( specPOi[i] ) * 0.595699f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.740951f;
		specPOi[i] = sign( specPOi[i] ) * 0.671559f;
		}
		}
		}
		}
		else
		{
		if ( aR > aI * 0.4142136f /tanf(PI/8)/ )
		{
		if ( aR > aI * 0.6681767f /tanf(PI3/16)*/ )
		{
		if ( aR > aI * 0.820681f /tanf(PI7/32)*/ )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.671559f;
		specPOi[i] = sign( specPOi[i] ) * 0.740951f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.595699f;
		specPOi[i] = sign( specPOi[i] ) * 0.803208f;
		}
		}
		else
		{
		if ( aR > aI * 0.5345111f /tanf(PI5/32)*/ )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.514103f;
		specPOi[i] = sign( specPOi[i] ) * 0.857729f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.427555f;
		specPOi[i] = sign( specPOi[i] ) * 0.903989f;
		}
		}
		}
		else
		{
		if ( aR > aI * 0.1989124f /tanf(PI/16)/ )
		{
		if ( aR > aI * 0.3033467f /tanf(PI3/32)*/ )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.33689f;
		specPOi[i] = sign( specPOi[i] ) * 0.941544f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.24298f;
		specPOi[i] = sign( specPOi[i] ) * 0.970031f;
		}
		}
		else
		{
		if ( aR > aI * 0.098491f /tanf(PI/32)/ )
		{
		specPOr[i] = sign( specPOr[i] ) * 0.14673f;
		specPOi[i] = sign( specPOi[i] ) * 0.989177f;
		}
		else
		{
		specPOr[i] = sign( specPOr[i] ) * 0.049068f;
		specPOi[i] = sign( specPOi[i] ) * 0.998795f;
		}
		}
		}
		}
		}
		for ( i = 1; i < min( n0, 320 ); i++ ) /neglect highest frequency bins when 48 kHz samplng/
		{
		tmp1 = wnd[i * step + bias] * gamma;
		specPOr[i] *= tmp1;
		specPOi[i] *= tmp1;
		gamma -= igamma;
		}
		if ( i < n0 )
		{
		gamma -= igamma * ( n0 - 320 );
		}
		for ( /* i = min(n0, 320) /; i < n0; i++ ) /neglect higher frequency bins when 48 kHz samplng*/
		{
		specPOr[i] = 0.f;
		specPOi[i] = 0.f;
		}
		specPOr[n0] = sign( specLr[n0] ) * sign( specRr[n0] ) * wnd[i * step + bias] * gamma;

		#else

		for ( i = 1; i < n0 / 2; i++ )
		{
		Lr = specLr[i];
		@@ -245,6 +567,7 @@ static void calc_poc(
		}

		specPOr[n0] = sign( specLr[i] ) * sign( specRr[i] ) * wnd[i * step + bias] * gamma;
		#endif

		rfft_buf[0] = specPOr[0];
		rfft_buf[1] = specPOr[n0];

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