How actually Audirvana works

[goldsdad]

Hello Jud,

Let's try to make things more clear:

1. I cannot see any possibility to choose 88.2kHz neither in Audio Midi nor A+ drop down menus in Custom settings.

2. I am using TOSLINK, so as it was said it is normal that I cannot see what actually my DAC can support natively. I know for sure it can handle up to 96kHz, but WM8716 documentation does not specify if 88.2kHz is supported by this chipset. Potentially it could be.

 

I expect 88.2 is unavailable for the simple reason that your Mac is one of the older (possibly 2008 or 2009) models which do only 44.1, 48 and 96 kHz optical input and output.

 

BTW, upsampling from 88.2 to 96 is not so nice - at least mathematically…

 

You said earlier that upsampling from 88.2 to 96 sounds good, so I recommend you stop worrying about the mathematics and just enjoy the music.

[mwheelerk]

Okay maybe I am not clearing understanding this. Under Audio Filters there is both Sample Rate Conversion and Forced Upsampling. I earlier mistakenly referred to the None selection in relationship to iZotope functions.

 

My assumption here is that you will always be engaging the Sample Rate Conversion selecting either iZotope or Apple Core and then either the default settings or customize settings (steepness etc). Next you have the Forced Upsampling with the option for None and other settings.

 

I was was thinking the one way to verify what is happening to the 88.2 file is to first play it with None selected and in the interface of Audivrana it will show on the lower left corner the bit and sample rate of their coming file and on the right the bit and sample rate of what has been "processed" and sent to your DAC

 

For example with None selected on Forced Upsampling and sending it a 16/44.1 file the readout on both sides of the Audivrana UI screen should show 16/44.1. If Power of 2 is selected I would expect to see 16/44.1 and 24/88.2.

 

Since 88.2 is not supported in the OP system I am curious what would be shown in the Audivrana interface as the incoming and outgoing rate with None selected and with Power of two selected. I am assuming that something is occurring to re-sample that file to a rate supported by the Mac OS (or what else would be doing it and where would it occur)

[mkrzych]

I expect 88.2 is unavailable for the simple reason that your Mac is one of the older (possibly 2008 or 2009) models which do only 44.1, 48 and 96 kHz optical input and output.

 

 

 

You said earlier that upsampling from 88.2 to 96 sounds good, so I recommend you stop worrying about the mathematics and just enjoy the music.

 

My Mac is late 2008 and I cannot find 88.2kHz in any options. So if it is not supported by the system at all and cannot be natively sent over the Toslink it's better to upsample it to 96kHz and sent to my DAC. So can I leave Forced Upsampling to None and be sure that in that case iZotope will work as well upsampling 88.2 to 96kHz?

 

BTW, for redbook when I play it in A+ on the left I see 16/44, but on the right always 24/44, why 24?

[Jud]

My Mac is late 2008 and I cannot find 88.2kHz in any options. So if it is not supported by the system at all and cannot be natively sent over the Toslink it's better to upsample it to 96kHz and sent to my DAC. So can I leave Forced Upsampling to None and be sure that in that case iZotope will work as well upsampling 88.2 to 96kHz?

 

BTW, for redbook when I play it in A+ on the left I see 16/44, but on the right always 24/44, why 24?

 

You can leave forced upsampling to None and iZotope should change 88.2 to another rate that your DAC will handle. As I mentioned, if it doesn't work, you will know instantly since you won't hear anything! In that case, set custom upsampling for 88.2, or just set it to forced upsampling to maximum rate. The reason for 24/44 is because your DAC uses internal 24-bit processing, so A+ sends a "zero padded" file with 24 instead of 16 bits, adding 8 zeroes in the least significant bits (17th through 24th) positions. This changes absolutely nothing about the sound. It is the same as writing "1.00000000" - the eight zeroes don't change the quantity at all.

[mkrzych]

Thanks to all of you for explanations! I will do Force upsampling set to None being sure that all resampling is done by iZotope.

 

Btw, in this case all the advanced parameters for ringing, Nyquist etc. do really matter as well right?

[goldsdad]

Btw, in this case all the advanced parameters for ringing, Nyquist etc. do really matter as well right?

 

The parameters matter if you hear changes when you adjust them. Don't be afraid to experiment - discover the settings which sound best to you.

 

[mwheelerk]

I obviously have some confusion or misunderstanding how these two things work together.

 

I always have the iZotope 64-bit SRC selected and normally have the Forced Sampling set to Custom with the conversions set to 44.1/88.2, 48/96, 88.2/88.2, 96/96, 176.4/88.2 and 192/96. My DAC via USB only supports up to 24/96.

 

I selected a 24/192 file (one of two I have). With Forced Sampling set to None the Audivrana screen showed AIFF 24/192 on the left and DAC 24/96 on the right. Setting Forced Upsampling to Custom for this file the same information is displayed.

 

I then selected a 16/44.1 file with Forced Upsampling at None. The screen read AIFF 16/44.1 and DAC 24/44.1. Changing to Custom the readings were AIFF 16/44.1 and DAC 24/88.2.

 

So it appears that iZotope is doing a down sampling of the sample rate (192) or I would assume for 176.2 or any rate my DAC Doesn't support regardless of the Custom Setting or None being activated.

 

This is has no bearing on my enjoyment and listening but curious minds (and those who don't understand - me) want to know.

[Musicophile]

I obviously have some confusion or misunderstanding how these two things work together.

 

I always have the iZotope 64-bit SRC selected and normally have the Forced Sampling set to Custom with the conversions set to 44.1/88.2, 48/96, 88.2/88.2, 96/96, 176.4/88.2 and 192/96. My DAC via USB only supports up to 24/96.

 

I selected a 24/192 file (one of two I have). With Forced Sampling set to None the Audivrana screen showed AIFF 24/192 on the left and DAC 24/96 on the right. Setting Forced Upsampling to Custom for this file the same information is displayed.

 

I then selected a 16/44.1 file with Forced Upsampling at None. The screen read AIFF 16/44.1 and DAC 24/44.1. Changing to Custom the readings were AIFF 16/44.1 and DAC 24/88.2.

 

So it appears that iZotope is doing a down sampling of the sample rate (192) or I would assume for 176.2 or any rate my DAC Doesn't support regardless of the Custom Setting or None being activated.

 

This is has no bearing on my enjoyment and listening but curious minds (and those who don't understand - me) want to know.

Isn't it very simple: whenever Audirvana displays a different sample right between left (source file) and right (output), resampling is ongoing. Thi resampling is done by either isotope or Core Audio, depending on what you select in Audirvana's drop downer

[mwheelerk]

Isn't it very simple: whenever Audirvana displays a different sample right between left (source file) and right (output), resampling is ongoing. Thi resampling is done by either isotope or Core Audio, depending on what you select in Audirvana's drop downer

 

Do you see the Sample Rate Conversion (iZotope or Core) and Forced Upsampling as interconnected functions or separate. I was of the thought that with iZotope/Core they were applying the Steepness and other factors selected below but that Upsampling only occurred when Forced Sampling was selected. Obviously some down sampling occurs regardless of the selection in Forced Upsampling.

 

Please don't misunderstand me I am not trying to be difficult or argumentative I think I have just thought so much about this during this thread I have confused myself. I think I will just leave well enough alone. There are a lot of thinks in life that I don't fully understand how they work yet they work just fine and I guess this is another for me.

[Musicophile]

Isn't it very simple: whenever Audirvana displays a different sample right between left (source file) and right (output), resampling is ongoing. Thi resampling is done by either isotope or Core Audio, depending on what you select in Audirvana's drop downer

 

Do you see the Sample Rate Conversion (iZotope or Core) and Forced Upsampling as interconnected functions or separate. I was of the thought that with iZotope/Core they were applying the Steepness and other factors selected below but that Upsampling only occurred when Forced Sampling was selected. Obviously some down sampling occurs regardless of the selection in Forced Upsampling.

 

Please don't misunderstand me I am not trying to be difficult or argumentative I think I have just thought so much about this during this thread I have confused myself. I think I will just leave well enough alone. There are a lot of thinks in life that I don't fully understand how they work yet they work just fine and I guess this is another for me.

As said in the quote from the manual some posts above, resampling occurs either forced or when the DAC does not play a sample rate natively.

[Jud]

Thanks to all of you for explanations! I will do Force upsampling set to None being sure that all resampling is done by iZotope.

 

Btw, in this case all the advanced parameters for ringing, Nyquist etc. do really matter as well right?

 

The parameters may matter, but you will also hear your DAC's filters. Your DAC will take the sample rate given it and upsample *that* to 352.8 or 384. So both the iZotope filtering (governed by the parameter settings) and your DAC chip's internal filtering play a part.

[mkrzych]

I leave iZotope all the time, don't want to use CoreAudio. In my case it seems that I prefer to set up Forced Upsampling to None and allow iZotope to do al resampling according to what it seems to know about my DAC. Because my DAC can do its job up to 96kHz, it will do nothing for 44.1kHz and 48kHz, but everything else will be resampled to 96kHz.

 

I guess that this 96kHz stream will be upsampled internally according to WM8716 specs.