PPS (Home Audio) Loudness component Linear_Gain parameter

Ito-san,

Both PPS Loudness components seem to have a similar frequency response. However, I think that the difference is in the PCM5142 and TLV320AIC3254 Volume gains. I recommend to verify if both devices have the same volume gain. Otherwise, the frequency response will be different in both cases.

Best regards,
Luis Fernando Rodríguez S.

Luis-san,

'TLV320AIC3254 Loudness Compensation Frequency Response' was measured by Audio Precision  when a TLV320AIC3254EVM-K ran on the PPS(Portable Audio) in AIC3254App8x4x Framework, as shown below.

And 'PCM3070A Loudness Compensation Frequency Response' was measured  when the same TLV320AIC3254EVM-K ran on the PPS(Home Audio) in PCM3070App8x4x Framework, as shown below. Because, we know PCM3070 is a TLV320AIC3254 spin off device. PCM3070 DAC block may be same as it of TLV320AIC3254.

Therefore, the difference of frequency response does not depend on the kind of device, but on the kind of PPS.

We have already found a workaround, which Linear_Gain of AIC3254 doubles it of PCM5142. We hope TI to accept this workaround is correct.

Best regards,

Akio Ito

Hello, Luis-san,

I show below the response calculation of default Loudness component.
Default settings of both Biquad filters are Shelves filter as follows;

Low frequency gain of shelves filter approaches the DC gain, and high frequency gain approaches the gain of Nyquist Frequency.

The transfer function of PPS Biquad Filter is;
(B0 + 2*B1*z^-1 + B2*z^-2)/(1 -2*A1*z^-1 -A2*z^-2)

in frequency domain
z^-n -> cos(-n*omega*T) +j*sin(-n*omega*T)
omega = 2*pi*f, T=1/fs

at DC
z^-n = cos(0) +j*sin(0) =1
DC gain is calculated as follows;
(B0 +2*B1 +B2)/(1 -2*A1 -A2)
DC gain of respective Biquad Filter are;
BQ1_DC_GAIN = (BQ1B0 +2*BQ1B1 +BQ1B2)/(1 -2*BQ1A1 -BQ1A2) =1.9901 (=5.9774 dB)
BQ2_DC_GAIN = (BQ2B0 +2*BQ2B1 +BQ2B2)/(1 -2*BQ2A1 -BQ2A2) =0.50000 (=-6.0206 dB)

at Nyquist frequency
z^-n = cos(-n*pi) +j*sin(-n*pi)
z^-1 = -1
z^-2 = 1
Nyquist frequency gain is calculated as follows;
(B0 -2*B1 +B2)/(1 +2*A1 -A2)
DC gain of respective Biquad Filter are;
BQ1_NQ_GAIN = (BQ1B0 -2*BQ1B1 +BQ1B2)/(1 +2*BQ1A1 -BQ1A2) =0.50000 (=-6.0206 dB)
BQ2_NQ_GAIN = (BQ2B0 -2*BQ2B1 +BQ2B2)/(1 +2*BQ2A1 -BQ2A2) =0.99763 (=-0.0206 dB)

Low frequency total Biquad Filter gain is;
BQ1_DC_GAIN * BQ2_DC_GAIN =0.99504 (=-0.04316 dB)
Mid range frequency total Biquad Filter gain is;
BQ1_DC_GAIN * BQ2_NQ_GAIN =0.25000 (=-12.041 dB)
High frequency total Biquad Filter gain is;
BQ1_NQ_GAIN * BQ2_NQ_GAIN =0.49882 (=-6.0412 dB)

according to Loudness Help,
The loudness gain g is expressed as:
g = f(volume) = [(volume)^Log_Gain x 2^Log_Offset x Linear_Gain] + Linear_Offset

if Log_Offset =0, Linear_Offset =0, the results correspond with PPS(Portable Audio).
g = f(volume) = (volume)^Log_Gain x Linear_Gain
f(0dB) =(10^(0/20))^Log_Gain x Linear_Gain =1.0000
f(-10dB) =(10^(-10/20))^Log_Gain x Linear_Gain =1.5849
f(-20dB) =(10^(-20/20))^Log_Gain x Linear_Gain =2.5119
Phase can be ignored because of d(gain)/d(omega) is nearly equal to zero.
at low frequency
20*log10(f(-20dB)*BQ1_DC_GAIN * BQ2_DC_GAIN +1) =10.88 dB
20*log10(f(-10dB)*BQ1_DC_GAIN * BQ2_DC_GAIN +1) =8.22 dB
20*log10(f(0dB)*BQ1_DC_GAIN * BQ2_DC_GAIN +1) =6.00 dB
at mid range frequency
20*log10(f(-20dB)*BQ1_NQ_GAIN * BQ2_DC_GAIN +1) =4.23 dB
20*log10(f(-10dB)*BQ1_NQ_GAIN * BQ2_DC_GAIN +1) =2.90 dB
20*log10(f(0dB)*BQ1_NQ_GAIN * BQ2_DC_GAIN +1) = 1.94 dB
at high frequency
20*log10(f(-20dB)*BQ1_NQ_GAIN * BQ2_NQ_GAIN +1) =7.06 dB
20*log10(f(-10dB)*BQ1_NQ_GAIN * BQ2_NQ_GAIN +1) =5.06 dB
20*log10(f(0dB)*BQ1_NQ_GAIN * BQ2_NQ_GAIN +1) =3.52 dB

if Log_Offset =1, Linear_Offset =0, the results correspond with PPS(Home Audio).
g = f(volume) = (volume)^Log_Gain x 2 x Linear_Gain
f(0dB) =(10^(0/20))^Log_Gain x 2 x Linear_Gain =2.0000
f(-10dB) =(10^(-10/20))^Log_Gain x 2 x Linear_Gain =3.1698
f(-20dB) =(10^(-20/20))^Log_Gain x 2 x Linear_Gain =5.0238

at low frequency
20*log10(f(-20dB)*BQ1_DC_GAIN * BQ2_DC_GAIN +1) =15.56 dB
20*log10(f(-10dB)*BQ1_DC_GAIN * BQ2_DC_GAIN +1) =12.37 dB
20*log10(f(0dB)*BQ1_DC_GAIN * BQ2_DC_GAIN +1) =9.51 dB
at mid range frequency
20*log10(f(-20dB)*BQ1_NQ_GAIN * BQ2_DC_GAIN +1) =7.07 dB
20*log10(f(-10dB)*BQ1_NQ_GAIN * BQ2_DC_GAIN +1) =5.07 dB
20*log10(f(0dB)*BQ1_NQ_GAIN * BQ2_DC_GAIN +1) = 3.52 dB
at high frequency
20*log10(f(-20dB)*BQ1_NQ_GAIN * BQ2_NQ_GAIN +1) =10.90 dB
20*log10(f(-10dB)*BQ1_NQ_GAIN * BQ2_NQ_GAIN +1) =8.24 dB
20*log10(f(0dB)*BQ1_NQ_GAIN * BQ2_NQ_GAIN +1) =6.01 dB

Best regards,

Akio Ito

Ito-san,

Could you provide the process flows to have a better approach to this issue? I mean, could you provide the .pfw files that you are using with PPS Home version and Portable version?

Thank you.

Best regards,
Luis Fernando Rodríguez S.

Luis-san,

I cannot send the customer's process flow, because it is their product itself.
But I upload PPS(Portable Audio) and PPS(Home Audio) process flow file for TLV320AIC3254EVM-K.

PCM3070Loudness.zip

AIC3254Loudness.zip

Best regards,

Akio Ito

Luis-san,

Thank you for measurement of my .pfw files. So I can tell the customer that TI has confirmed our workaround.

Best regards,

Akio Ito