Fixes issue 1139 to prevent sound coloration artefacts at very low reverberation times (b815bed5) · Commits · IVAS Codec Public Collaboration / IVAS Codec

lib_com/options.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -181,6 +181,8 @@

		#define NONBE_FIX_1174_MCMASA_LBR_LOOP_ERROR /* Nokia: Fix issue 1174 by removing the unnecessary inner loop causing problems. */

		#define FIX_1139_PARAM_REV_COLORATION_SHORT_T60 /* Nokia: Fix issue 1139, prevent sound coloration artefacts at very low reverberation times */

		/* ##################### End NON-BE switches ########################### */

		/* ################## End DEVELOPMENT switches ######################### */

lib_rend/ivas_dirac_dec_binaural_functions.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -235,7 +235,19 @@ ivas_error ivas_dirac_dec_init_binaural_data(

		if ( hDiracDecBin->hReverb == NULL && pos_idx == 0 ) /* open reverb only for the main direction */
		{
		#ifdef FIX_1139_PARAM_REV_COLORATION_SHORT_T60
		if ( ( error = ivas_binaural_reverb_init_for_parambin( &hDiracDecBin->hReverb,
		st_ivas->hHrtfStatistics,
		nBins,
		CLDFB_NO_COL_MAX / MAX_PARAM_SPATIAL_SUBFRAMES,
		&( st_ivas->hRenderConfig->roomAcoustics ),
		output_Fs,
		( *phHrtfParambin )->parametricReverberationTimes,
		( *phHrtfParambin )->parametricReverberationEneCorrections,
		hDiracDecBin->earlyPartEneCorrection ) ) != IVAS_ERR_OK )
		#else
		if ( ( error = ivas_binaural_reverb_init( &hDiracDecBin->hReverb, st_ivas->hHrtfStatistics, nBins, CLDFB_NO_COL_MAX / MAX_PARAM_SPATIAL_SUBFRAMES, &( st_ivas->hRenderConfig->roomAcoustics ), output_Fs, ( phHrtfParambin )->parametricReverberationTimes, ( phHrtfParambin )->parametricReverberationEneCorrections ) ) != IVAS_ERR_OK )
		#endif
		{
		return error;
		}

lib_rend/ivas_prot_rend.h

+13 −0

Original line number	Diff line number	Diff line
		@@ -940,6 +940,19 @@ ivas_error ivas_binaural_reverb_init(
		const float defaultEne / i : default reverberation energies */
		);

		#ifdef FIX_1139_PARAM_REV_COLORATION_SHORT_T60
		ivas_error ivas_binaural_reverb_init_for_parambin(
		REVERB_STRUCT_HANDLE hReverbPr, / i/o: binaural reverb handle */
		const HRTFS_STATISTICS_HANDLE hHrtfStatistics, /* i : HRTF statistics handle */
		const int16_t numBins, /* i : number of CLDFB bins */
		const int16_t numCldfbSlotsPerFrame, /* i : number of CLDFB slots per frame */
		const IVAS_ROOM_ACOUSTICS_CONFIG_DATA roomAcoustics, / i/o: room acoustics parameters */
		const int32_t sampling_rate, /* i : sampling rate */
		const float defaultTimes, / i : default reverberation times */
		const float defaultEne, / i : default reverberation energies */
		float earlyEne / i/o: early part energies to be modified */
		);
		#endif

		void ivas_binaural_reverb_close(
		REVERB_STRUCT_HANDLE hReverb / i/o: binaural reverb handle */

lib_rend/ivas_reverb.c

+89 −0

Original line number	Diff line number	Diff line
		@@ -254,6 +254,19 @@ static void ivas_binaural_reverb_setReverbTimes(
		}
		currentEnergy *= attenuationFactorPerSampleSq;
		}
		#ifdef FIX_1139_PARAM_REV_COLORATION_SHORT_T60
		/* In some configurations with small T60s it is possible the number of taps randomizes to zero.
		Ensure at least 1 filter tap. */
		if (tap == 0)
		{
		hReverb->tapPhaseShiftType[bin][ch][0] = (int16_t) ( binRend_rand( hReverb ) % 4 );
		hReverb->tapPointersReal[bin][ch][0] = &( hReverb->loopBufReal[bin][0] );
		hReverb->tapPointersImag[bin][ch][0] = &( hReverb->loopBufImag[bin][0] );
		tap = 1;
		actualizedEnergy = 1;
		}
		#endif

		hReverb->taps[bin][ch] = tap; /* Number of taps determined at the above random procedure */
		}

		@@ -1896,6 +1909,82 @@ ivas_error ivas_binaural_reverb_init(
		return error;
		}

		#ifdef FIX_1139_PARAM_REV_COLORATION_SHORT_T60
		/*-------------------------------------------------------------------------
		* ivas_binaural_reverb_init_for_parambin()
		*
		* Allocate and initialize binaural room reverberator handle
		* for parametric binaural renderer, using room effect parameter adjustment
		------------------------------------------------------------------------/
		ivas_error ivas_binaural_reverb_init_for_parambin(
		REVERB_STRUCT_HANDLE hReverbPr, / i/o: binaural reverb handle */
		const HRTFS_STATISTICS_HANDLE hHrtfStatistics, /* i : HRTF statistics handle */
		const int16_t numBins, /* i : number of CLDFB bins */
		const int16_t numCldfbSlotsPerFrame, /* i : number of CLDFB slots per frame */
		const IVAS_ROOM_ACOUSTICS_CONFIG_DATA roomAcoustics, / i/o: room acoustics parameters */
		const int32_t sampling_rate, /* i : sampling rate */
		const float defaultTimes, / i : default reverberation times */
		const float defaultEne, / i : default reverberation energies */
		float earlyEne / i/o: Early part energies to be modified */
		)
		{
		ivas_error error;
		float revTimes[CLDFB_NO_CHANNELS_MAX];
		float revEne[CLDFB_NO_CHANNELS_MAX];
		int16_t preDelay, bin;

		error = IVAS_ERR_OK;

		if ( ( roomAcoustics != NULL ) && roomAcoustics->override )
		{
		if ( ( error = ivas_reverb_prepare_cldfb_params( roomAcoustics, hHrtfStatistics, sampling_rate, revTimes, revEne ) ) != IVAS_ERR_OK )
		{
		return error;
		}
		preDelay = (int16_t) roundf( 48000.0f * roomAcoustics->acousticPreDelay / CLDFB_NO_CHANNELS_MAX );
		}
		else
		{
		for ( bin = 0; bin < CLDFB_NO_CHANNELS_MAX; bin++ )
		{
		revTimes[bin] = defaultTimes[bin];
		revEne[bin] = defaultEne[bin];
		}
		preDelay = 10;
		}
		for ( bin = 0; bin < 60; bin++ )
		{
		/* Adjust the room effect parameters when the reverberation time is less than a threshold value, to avoid
		spectral artefacts with the synthetic reverberator. */
		const float revTimeThreshold = 0.2f;
		if ( revTimes[bin] < revTimeThreshold )
		{
		float adjustedEarlyEne, adjustedLateEne, adjustedRevTime;
		float revTimeModifier, energyModifier;

		/* Adjust reverberation times, higher towards a threshold */
		revTimeModifier = fmaxf( 0.0f, 1.0f - ( revTimes[bin] / revTimeThreshold ) );
		adjustedRevTime = ( 1.0f - revTimeModifier ) * revTimes[bin];
		adjustedRevTime += revTimeModifier * ( revTimes[bin] + revTimeThreshold ) * 0.5f;
		energyModifier = ( adjustedRevTime - revTimes[bin] ) / adjustedRevTime;

		/* Adjust early and late energies, by moving late energy to early energy */
		adjustedEarlyEne = earlyEne[bin] + revEne[bin] * energyModifier;
		adjustedLateEne = revEne[bin] * ( 1.0f - energyModifier );

		/* Store adjusted room effect parameters to be used in reverb processing */
		revTimes[bin] = adjustedRevTime;
		revEne[bin] = adjustedLateEne;
		earlyEne[bin] = adjustedEarlyEne;
		}
		}

		error = ivas_binaural_reverb_open( hReverbPr, numBins, numCldfbSlotsPerFrame, sampling_rate, revTimes, revEne, preDelay );

		return error;
		}
		#endif

		/*-------------------------------------------------------------------------
		* ivas_binaural_reverb_close()
		*