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From plain Debian + Jack2 + MPD to Moode: doubts
#1
Hi,
I'm about to receive my first RPi based audio streamer, an Allo USBridge Signature Player, and I'm preparing for it, since my background is quite different.

Firstly, the USBridge will come with Volumio pre-installed, I've read multiple reviews preferring Moode over Volumio sound quality wise, thus I already have burned a Moode SD card, ready for the jump Smile

As per the subject, today I'm using a plain Debian installation on a mini-itx fanless x86 device, with Jack2 and MPD installed: I have done all the tuning manually (realtime kernel, system minimization, no CPU stepping, unused hardware disabled etc.), especially on the Jack2/ALSA side, where I use fixed 44.1Khz sampling (ripped CDs is all I have), buffer size of 16KB and periods/buffer of 3.
I know that latency and jitter are just loosely related, but achieving a theoretical 0.4ms latency gave me the best audio result with my gear (Topping DX7 Pro DAC).


Will Moode give me this kind of control?
I know the benefits of Allo's USBridge are due to the no-noise signal path, and that will be certainly a gain compared to my current (electrically) noisy mini-PC, I just don't love the idea of loosing the control over low level parameters to obtain that hardware benefit.

Any comment and suggestion is highly appreciated, thanks.
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#2
It looks as if Moode 7 may have some of what you are looking for: http://moodeaudio.org/forum/showthread.php?tid=2856
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#3
@roberto.pierpaoli

Quote: I have done all the tuning manually (realtime kernel, system minimization, no CPU stepping, unused hardware disabled etc.)


Since moOde is based on Linux, these standard Linux tricks are still available. 

All except, perhaps, the "realtime kernel, that is. (As an aside, this is like saying "luxury" car. You have to specify what is the basis for the appellation "realtime".) You can built your own kernel if you're determined, tuning every parameter ever invented. If you've never done this before I'll warn you it can be as much fun as solving a 1000-piece jigsaw puzzle which may or may not be missing some pieces.

I don't know what system minimization means. If you look at moOde's System Config screen you'll see several settings for CPU governor and for disabling unused hardware.

Also, see threads such as Sound tweaks ....

Regards,
Kent
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#4
(08-18-2020, 09:55 AM)roberto.pierpaoli Wrote: Hi,
I'm about to receive my first RPi based audio streamer, an Allo USBridge Signature Player, and I'm preparing for it, since my background is quite different.

Firstly, the USBridge will come with Volumio pre-installed, I've read multiple reviews preferring Moode over Volumio sound quality wise, thus I already have burned a Moode SD card, ready for the jump Smile

As per the subject, today I'm using a plain Debian installation on a mini-itx fanless x86 device, with Jack2 and MPD installed: I have done all the tuning manually (realtime kernel, system minimization, no CPU stepping, unused hardware disabled etc.), especially on the Jack2/ALSA side, where I use fixed 44.1Khz sampling (ripped CDs is all I have), buffer size of 16KB and periods/buffer of 3.
I know that latency and jitter are just loosely related, but achieving a theoretical 0.4ms latency gave me the best audio result with my gear (Topping DX7 Pro DAC).


Will Moode give me this kind of control?
I know the benefits of Allo's USBridge are due to the no-noise signal path, and that will be certainly a gain compared to my current (electrically) noisy mini-PC, I just don't love the idea of loosing the control over low level parameters to obtain that hardware benefit.

Any comment and suggestion is highly appreciated, thanks.

It's Open Source. You can modify it in any way to suit your own needs, and you are welcome to propose changes or features to stock moOde that you feel would be of benefit. 

To get the most out of the SIG, feed it and the DAC with a high quality LPS. Allo's Shanti Dual LPS is a bargain.
Enjoy the Music!
moodeaudio.org | Twitter Feed | Git Repo
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#5
(08-18-2020, 10:58 AM)jonners Wrote: It looks as if Moode 7 may have some of what you are looking for: http://moodeaudio.org/forum/showthread.php?tid=2856

Thank you, these are really interesting previews, but (at first glance) they seem to go beyond my scope: I don't apply resampling in my chain actually, I play 44.1Khz material at that 44.1Khz.

But it's really good to know that such plugins will be available for fine tuning, or "fun tuning", we may say Smile

Thanks for your contribute.
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#6
Quote:Since moOde is based on Linux, these standard Linux tricks are still available.

Yes, I understood that Moode is based on standard Linux, I just don't like to "mess up someone else's room" Smile
When a system is meant to be configured and used in a certain way, I tend to avoid "forcing" my approach, I prefer to play by the rules, otherwise I expect strange behaviors and inconsistencies to occur.

For instance, I wonder if installing a custom kernel, jack daemon and forcing specific parameters for ALSA means to be intrusive (thus not recommended) and or to create conflicts with Moode per se.

Quote:All except, perhaps, the "realtime kernel, that is. (As an aside, this is like saying "luxury" car. You have to specify what is the basis for the appellation "realtime".) You can built your own kernel if you're determined, tuning every parameter ever invented. If you've never done this before I'll warn you it can be as much fun as solving a 1000-piece jigsaw puzzle which may or may not be missing some pieces.

Sorry, you're right: I meant a hard real-time kernel (with the PREEMPT_RT patch applied); in Debian x86 is a trivial task (is available in the official repos), in Ubuntu you just start from the official kernel sources, you use the "low-latency" kernel config file as a template applying just few specific changes and then it's just a build.
In my experience, the RT kernel is needed to obtain a constant streaming to the DAC with the minimum buffer (16KB in my case), otherwise there will be stuttering ("xruns" in Jack's slang).

Quote:I don't know what system minimization means.

Sorry again, I meant "system services minimization": I have removed any single process not strictly necessary for the audio streaming task.

Quote:If you look at moOde's System Config screen you'll see several settings for CPU governor and for disabling unused hardware.
Also, see threads such as Sound tweaks ....

Yep! Really cool tips, I will definitely take a look into them, thanks!
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#7
(08-18-2020, 12:24 PM)Tim Curtis Wrote: It's Open Source. You can modify it in any way to suit your own needs, and you are welcome to propose changes or features to stock moOde that you feel would be of benefit. 

To get the most out of the SIG, feed it and the DAC with a high quality LPS. Allo's Shanti Dual LPS is a bargain.

Tim! You are the architect of the Matrix, I'm honored, thanks for your feedback! Smile 

As you can read in my reply to TheOldPresbyope, I just don't want to mess things up in a well designed system.
My only real target is to control ALSA's buffer size and period/buffer ratio, hence feeding the DAC with a low latency packet stream: in my system it makes a difference, maybe it will result to be not relevant with Moode, but I'd like to be able to try and listen.

The RT kernel and Jack daemon are not targets, they are just means to get there: the data stream was not fluid without them in my installation. Do you have any tip on how to configure Moode for this kind of aim?

(As per the power supply, I'm going to start with the iFi iPower X, I know the mighty Shanti is even quieter (0,08uV versus 1uV), but the iFi has anyway really good numbers considering its price, size and design. If I'm happy, a further test with the Shanti will be mandatory Wink )
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#8
You really should listen to stock moOde with a stock power supply and stock DAC to get a baseline before you "jump on your horse and ride off in all directions."  Smile  No point in trying to fix problems you can't hear.

JACK is not used in moOde but, as Tim said, this is FOSS and you can do whatever you like with it so long as you observe the terms of the license.

Again, be sure to check out other posts on this forum regarding tweaks. I don't find a need for any myself so I'll pipe down now.

Regards,
Kent
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#9
The 64-bit kernel already has preempt-rt applied.
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#10
(08-21-2020, 05:11 AM)swizzle Wrote: The 64-bit kernel already has preempt-rt applied.

Thanks for pointing this out.
So the 64-bit image is enabled for real-time/low-latency out-of-the-box, is it?
Are there processes using the real-time scheduling policy in Moode per your knowledge?
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