DSD Convolution

[Jon Catuccio]

I received this response from Jussi at Signalyst:

"Yes, I have it implemented in HQPlayer. If Acourate can export filters in WAV format you can use those. WAV needs to be mono per channel, but stereo WAVs are easy to split to mono ones.

Since PCM filter WAV is by necessity bandwidth limited, I have implemented "HF-expand" option for expanding the filter as flat above it's Nyquist frequency. However I recommend using as high as possible sampling rate for the filter WAV. If 352.8/384k is possible, then things would work pretty nicely without "HF-expand" too. And it's not bad with 176.4/192k either.

To enable DSD processing HQPlayer you need to un-check the "Direct SDM" box in "DSDIFF/DSF Settings" -dialog. Then you can perform DRC and also multichannel speaker distance and level adjustments plus main digital volume control. For any processing I recommend using max -3 dBFS main volume setting to avoid overloads. Overloads in DSD are more nasty than in PCM."

Thoughts?

[Jon Catuccio]

I wonder if Audiolense can be used with 192kHz filter to work for DSD:

"Interestingly Acourate has also a feature called 'Brickwall extension' like 'HF-expand'.
So a filter created on a 48 kHz measurement contains information up to 24 kHz (Nyquist). If you upsample the filter to 192 kHz then the brickwall extension keeps the filter flat above 24 kHz.

As already explained measurements at very high samplerates do not make sense and only require very long filters and processing power.

Acourate can easily create mono wav filters.

IMO it should be worth to first start with an test example at 48 kHz. Attached you find a echo filter (0.3 s delay). The filter is a 48 kHz mono wav file of length 65536 taps.
So Jussi may tell if it is possible to use the filter.

I wonder a bit about 352.8/384k. This means that the source material may use either 352.8 kKz or 384 kHz samplerate. This means that the filter has to be switched. Can the HQPlayer switch automatically and what filter samplerate is basically required."

[Bernt Ronningsbakk]

Based on the feedback you have received from Jussi it should not be a big deal. Audiolense produces multichannel wav files but you can use e.g. Audacity to split the channels. Audacity is free of charge.

 

I recommend that you try 96 kHz and 192 kHz filters. If you go higher the low frequency correction may suffer and you may also get a substantial CPU load from the convolution process.

 

Kind regards,

 

Bernt

--
--
Audiolense User Forum.
http://groups.google.com/group/audiolense?hl=en?hl=en
To post to this group, send email to audio...@googlegroups.com
To unsubscribe, send email to audiolense+...@googlegroups.com
 
---
You received this message because you are subscribed to the Google Groups "Audiolense User Forum" group.
To unsubscribe from this group and stop receiving emails from it, send an email to audiolense+...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.