DSD Convolution

[Daverich4]

When I've had Home Audio Fidelity create Convolution Filters for me I get a set of .wav files at various frequencies up to 384,000 that I zip together for use in Roon. Recently I've been experimenting with Focus Fidelity to create Convolution Filters myself and get the same sets of .wav files. I understand how the various files are used with PCM but what happens with DSD files? Are one of the .wav frequencies used or perhaps Convolution doesn't work with DSD?

 

[DVDdoug]

You can't really "process" DSD.

 

[Daverich4]

You can't really "process" DSD.

Does that mean Convolution filters don't work with DSD files? I can't use DSP to improve the sound if the source is a DSD file?

 

[Sokel]

You can't really "process" DSD.

You can, but it needs special gear.
@Scytales has some amazing posts about it along with the history.

 

[Sokel]

Does that mean Convolution filters don't work with DSD files? I can't use DSP to improve the sound if the source is a DSD file?

No, you can't with normal gear. Even volume control is difficult, only previously half-solved by commercial gear.

You have to convert it to PCM.

 

[OCA]

Does that mean Convolution filters don't work with DSD files? I can't use DSP to improve the sound if the source is a DSD file?

Roon will force convert them to PCM if you use convolution filters and play DSD files. Adds some latency but filter will do what it's supposed to do. ALthough I must admit, my NUC 5th gen was stuttering with higher than DSD64. Nuc i7 13th gen can cope with DSD512 where my DAC maxes out.

PS Don't produce any .wav filters with sample rates other than 48kHz and let Roon re-sample them as necessary. All these tools you use work natively at 48kHz and Roon re-sampling algorithms are state of art and better than any other tools'.

 

[voodooless]

According to this post, Roon should handle convolution of DSD files just fine:

Native DSD processing

Unlike with PCM, processing 1-bit DSD signals in their original form is not practical because 1-bit signals do not have enough dynamic range to perform common operations like volume adjustment, eq, mixing, or convolution directly on the 1-bit representation. So when DSD IS processed, the input...

community.roonlabs.com

Basic scheme:

DSD -> 64 bit high rate PCM -> DSP -> modulate back to 1 bit DSD

If the convolution file for the specific sample rate is missing, it should also create it automatically.

 

[Daverich4]

Roon will force convert them to PCM if you use convolution filters and play DSD files. Adds some latency but filter will do what it's supposed to do. ALthough I must admit, my NUC 5th gen was stuttering with higher than DSD64. Nuc i7 13th gen can cope with DSD512 where my DAC maxes out.

PS Don't produce any .wav filters with sample rates other than 48kHz and let Roon re-sample them as necessary. All these tools you use work natively at 48kHz and Roon re-sampling algorithms are state of art and better than any other tools'.

If that’s true about converting them to PCM Roon isn’t being very transparent about it.

 

[Daverich4]

According to this post, Roon should handle convolution of DSD files just fine:

Native DSD processing

Unlike with PCM, processing 1-bit DSD signals in their original form is not practical because 1-bit signals do not have enough dynamic range to perform common operations like volume adjustment, eq, mixing, or convolution directly on the 1-bit representation. So when DSD IS processed, the input...

community.roonlabs.com

Basic scheme:

DSD -> 64 bit high rate PCM -> DSP -> modulate back to 1 bit DSD

If the convolution file for the specific sample rate is missing, it should also create it automatically.

Thanks for the link. To be honest with you, I didn’t quite follow along with all of it but it seems like my convolution is working with DSD as long as I’m using Roon which I am. Thanks again.

 

[Keith_W]

The only player capable of DSD convolution is HQPlayer. i.e. input is DSD, it convolves it with your PCM .WAV file, and the output is DSD, at whatever sample rate that you wish. But be warned, a lot of CPU power is required. We are talking gamer style PC's with nVidia cards and CUDA cores. Not only is it expensive, it also generates a lot of heat, which means a lot of cooling fans and therefore noise! In the end, some people say it makes a difference, but I can't hear any difference whatsoever.

 

[Daverich4]

The only player capable of DSD convolution is HQPlayer. i.e. input is DSD, it convolves it with your PCM .WAV file, and the output is DSD, at whatever sample rate that you wish. But be warned, a lot of CPU power is required. We are talking gamer style PC's with nVidia cards and CUDA cores. Not only is it expensive, it also generates a lot of heat, which means a lot of cooling fans and therefore noise! In the end, some people say it makes a difference, but I can't hear any difference whatsoever.

I run Roon/HQplayer on an M4 Mac Mini. I have a set of Mitch Barnett’s Covolution filters set up in HQPlayer’s Convolution Matrix. Are they doing something different from what you’re describing? Not Convolving somehow?

 

[voodooless]

I run Roon/HQplayer on an M4 Mac Mini. I have a set of Mitch Barnett’s Covolution filters set up in HQPlayer’s Convolution Matrix. Are they doing something different from what you’re describing? Not Convolving somehow?

Here, Roon is doing the convolution, and HQPlayer converts from DSD64 to DSD256. But you have a step in between that converts the multibit convoluted data back to DSD64. Ideally, you should skip that. HQPlayer can do convolution as well. It might be more efficient to do it there.

... at least technically... I think all of this CPU cycle wasting is rather pointless and objectively does not yield any audible diffrence whatsoever.

 

[Daverich4]

Here, Roon is doing the convolution, and HQPlayer converts from DSD64 to DSD256. But you have a step in between that converts the multibit convoluted data back to DSD64. Ideally, you should skip that. HQPlayer can do convolution as well. It might be more efficient to do it there.

... at least technically... I think all of this CPU cycle wasting is rather pointless and objectively does not yield any audible diffrence whatsoever.

HQPlayer isn’t doing the convolution? That’s where the files are installed, I’m not using anything in Roon itself.

 

[voodooless]

HQPlayer isn’t doing the convolution? That’s where the files are installed, I’m not using anything in Roon itself.

That's not what the screenshot shows. You only have the convolution checkmark checked.

Your room screenshot clearly shows that HQPlayer is only used after the conversion back to DSD64.

 

[Daverich4]

That's not what the screenshot shows. You only have the convolution checkmark checked.

Your room screenshot clearly shows that HQPlayer is only used after the conversion back to DSD64.

I wonder how Roon knows what files to use? They’re installed in the HQPlayer Convolution Matrix and the HQP Log file says they’re being used. I guess it doesn’t really matter to me as long as they’re in the stream someplace. Maybe I’ll ask Miska what’s going on. Anyway, thanks for your help.

 

[voodooless]

Can you show a screenshot of the DSP filter section in Roon?

 

[Daverich4]

Can you show a screenshot of the DSP filter section in Roon?

 

[voodooless]

So all of the filters are disabled? That was also the case with the screenshot in post #11?

 

[OCA]

post #8 shows 2,108,000 taps of convolution filter engaged, looks like a 32k FIR filter 64x resampled for DSD.