Resampling

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nsm
Posts: 6
Joined: Sun Feb 16, 2020 12:59 pm

Resampling

Post by nsm » Sun Feb 16, 2020 1:07 pm

I am new to Neutron (on iPad). The first thing I immediately miss as an audiophile user is the ability to limit the sampling frequency. My DAC has a 24 bit 96 kHz upper limit. Ideal would be for me to set a 96 kHz limit and everything above is downsampled but 96 kHz and below is just passed through. At the moment if I set 96 kHz then everything is output at this rate, with lower sampling rates being upsampled. This should be an easy modification to make and for me (and I am sure others) would be most welcome.

blaubär
Posts: 3313
Joined: Tue Apr 02, 2019 6:48 am

Re: Resampling

Post by blaubär » Sun Feb 16, 2020 2:37 pm

nsm wrote:
Sun Feb 16, 2020 1:07 pm
I am new to Neutron (on iPad). The first thing I immediately miss as an audiophile user is the ability to limit the sampling frequency. My DAC has a 24 bit 96 kHz upper limit. Ideal would be for me to set a 96 kHz limit and everything above is downsampled but 96 kHz and below is just passed through. At the moment if I set 96 kHz then everything is output at this rate, with lower sampling rates being upsampled. This should be an easy modification to make and for me (and I am sure others) would be most welcome.
You know about "Follow Source Frequency" ? I don't know what it does if the input sampling rate exceeds the maximum sampling rate of the DAC, but it would be intereresting to find out. Could you give it a try, set the "Frequency" to 96 kHz, activate "Follow Source Frequency" and play files with sampling rates 44.1 kHz, 48 kHz, 96 kHz, 192 kHz ? When > 96 kHz : perhaps it chooses the maximum supported sampling rate. Or the one selected in "Frequency". In the cases where the input sampling rate is supported by the DAC it should do what you want, pass through.

Screenshot_20200216-160222_Neutron-360x385.jpg
Screenshot_20200216-160222_Neutron-360x385.jpg (44.96 KiB) Viewed 2610 times

nsm
Posts: 6
Joined: Sun Feb 16, 2020 12:59 pm

Re: Resampling

Post by nsm » Sun Feb 16, 2020 5:55 pm

I tried and it did exactly what I expected. If I set "Follow Source Fequency" it always passes through the sampling rate of the music file. If it is 192 kHz then this is passed through (and my DAC cannot handle it!). Of course I can solve this problem manually by setting the frequency at 96000 and only switching "Follow Source Frequency" off for 192 kHz files - but this would be so easy to do in the software itself.

blaubär
Posts: 3313
Joined: Tue Apr 02, 2019 6:48 am

Re: Resampling

Post by blaubär » Sun Feb 16, 2020 6:37 pm

Okay, thank you for testing this ! Did you enable "Direct USB Access" ? Does that make a difference ? I would expect this to be a bug - the text with the "Follow Source Frequency" option clearly states "if device supports it". But maybe this will only work with direct USB access. If it doesn't work either way I suggest you write to the developer at neutronmp@gmail.com . And should he tell you that it's a feature then we'll put up a feature request as you suggested.

blaubär
Posts: 3313
Joined: Tue Apr 02, 2019 6:48 am

Re: Resampling

Post by blaubär » Sun Feb 16, 2020 6:46 pm

I found this post :
dmitrykos wrote:
Wed Dec 04, 2019 9:39 am
2) Output via USB DAC connected via USB OTG to the Android device
[...]
In case of 2) all depends on usbaudio driver of Android which might be different from device to device but normally it gives max 24/192 output. Some firmwares are limited to 48 kHz output only (for example Google Pixel) and therefore only Audio Hardware -> Direct USB Access option will help to output hi-res audio to USB DAC. Direct USB Access is Neutron's USB driver which talks to USB DAC directly, so Android's firmware is fully bypassed.
So at least in case of Android the Direct USB Access would be needed, I think ... hmm ... does this option exist on iOs ?

nsm
Posts: 6
Joined: Sun Feb 16, 2020 12:59 pm

Re: Resampling

Post by nsm » Sun Feb 16, 2020 7:09 pm

I have the Apple iOS version on an iPad, which does not require USB OTG or any USB drivers. Indeed the "Follow Source Frequency" might actually limit itself to the maximum frequency of the USB device. In my case, the problem is I am using a USB to SPDIF converter because my excellent but rather old DAC only has SPDIF inputs not USB. The convertor is capable of 192 kHz but the DAC only 96kHz.

blaubär
Posts: 3313
Joined: Tue Apr 02, 2019 6:48 am

Re: Resampling

Post by blaubär » Sun Feb 16, 2020 7:22 pm

Ah .. ok, then let's do the proposal :

Situation : sometimes Neutron cannot find out the supported sampling rates (feature, no bug), for an example see above discussion.
Problem : Activating Follow Source Freqency in such a scenario wouldn't work with all sampling rates
Proposal : add an additional (sub-)option to Follow Source Frequency to manually add an upper limit for the maximum sampling rate

nsm
Posts: 6
Joined: Sun Feb 16, 2020 12:59 pm

Re: Resampling

Post by nsm » Mon Feb 17, 2020 12:33 pm

Excellent - I agree entirely. Thanks!

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