Digital out sampling rates

Mikescotland

Got a question.
What's the rationale for spdif sampling rates 96 and 192 kHz in the menu, if the audio is always passed as 48 kHz to spdif and then artificially upsampled?

YAOXILONG

Currently, the Android system defaults to resampling audio at 48kHz before output. However, the SPDIF menu options for 96kHz and 192kHz are provided for the following benefits:

Higher Compatibility – Some external DACs or audio equipment may perform better or require higher sampling rates for optimal processing.
Reduced Resampling Artifacts – If the source material is already in 96kHz or 192kHz, bypassing Android’s internal resampling (when possible) can preserve audio quality.
Future-Proofing – Support for higher sampling rates ensures readiness for high-resolution audio sources or future updates.

While the signal may still be resampled to 48kHz in some cases, these options allow flexibility for devices that support native high-rate processing.

Mikescotland

YAOXILONG
I see.

no known device has 96, or 192 kHz without having 48 kHz.
with this approach, Dudu playing a standard 44.1kHz file is resampling audio TWICE, first 44.1> 48 and then once again to 48 > either 96 or 192. No DAC, DSP etc device will perform better having twice resampled audio versus resampled once.
if that's a future proof, why noone ever bother to answer a few posts if at any point is planned to bypass Android mixer and have other sampling rates supported without usb audio?
The problem I've got with it, is that Dudu looks like it's tricking the users to think they are getting 96 kHz playback which in fact is twice resampled. This option should disappear from menu until that "future proof" possibilities appear. That's my point of view.

janis

I dint know if this is 100% true. But i have read from online that android version 14 and up has better out of the box losless audio support. Also via usb outbut.

Mikescotland

janis It's been tested (RAWCat YT). DUDU7 on spdif never exceeds frequency response over 22kHz which means the output is capped at sampling rate 48 kHz. No matter the player / file sampling rate. Only USB Audio with external DAC plays higher than 48 kHz without resampling.
Android now allows to bypass this, I have a few Android devices (i.e. nvidia shield) which can output for instance native CD sampling rate of 44.1 kHz. This change is I believe since Android 11. I'd wish that could be done with DUDU as well as majority of the tracks are 44.1kHz and Android always resamples them to 48 kHz.

janis

Yes, i am hoping same thing. As i use optical out directly to my dsp. If i am honest i would even brefere headunit without internal amplifier and dsp all together. It would make it cheaper and lot of us why upgrade our headunits to units like this also have aftermarket audio systems unstslled.
Atleast it would be great it this was one model option, with dedicated software where all this audio modifing stuff is removed. Just pure outbut signal.

Sean

Duduauto you need to respond to this question. I feel that I have been misled -one of the reasons that I purchased this unit was the Optical output which I feed directly to my Helix DSP. You claim almost perfect presentation of this digital signal but if you are indeed sampling and converting then your claims amount to lies/mistruths.

YAOXILONG

Sean The selected sampling rate (96kHz/192kHz) in the SPDIF menu reflects the final output resolution delivered to your external DAC/processor. This ensures compatibility with high-resolution audio equipment and aligns with industry-standard digital signal transmission protocols.

For optimal performance, we recommend:

Verifying your external device's supported formats
Using native high-res audio sources
Enabling Passthough Mode in Sound settings
Our engineering team continuously evaluates firmware enhancements to maximize audio fidelity. Stay tuned for updates.

Mikescotland

YAOXILONG @janis @Sean hilarious. Is there anyone at Dudu who actually understands how digital audio works?
In fact, on contrary, sampling rate of 192 kHz /24 bit over optical may cause a lot of problems, as it exceeds the standard bitrate for optical spdif. Usually works but may not.
High resolution devices have no problem with accepting 48 kHz sampling (what compatibility we're taking about, find me a device that, accepts 96 or 192 but doesn't accept 48kHz) . 96khz and 192khz is completely unnecessary and misleading over spdif in Dudu.
"use native High res files", just to be resampled to 48 kHz and back to 192 kHz?

Sean

YAOXILONG I think the issue is this: setting the output to 96kHz for Optical should be seen as a maximum and all sources should then play at native resolution up to that maximum. Otherwise, unnecessary and unwanted conversion is happening for no reason other than poorly designed software.

And thank you for your suggestions but I do understand this stuff pretty well. This is pretty obvious stuff to those who understand high quality digital audio.

Mikescotland

Sean Android stack mixer is set to 48 kHz, that's where the problems arise. No matter what Dudu sets on spdif, goes through Android mixer with hardcoded 48 kHz. Unless they set the audio properties of the mixer to accept other than 48KHz (which even in rooted nexus was easy, just to add some lines to audio config properties file), no matter what's set as spdif sampling by Dudu, will still go through 48 kHz mixer. I'd rather see mixer set to 44.1 and spdif to 44.1, at least in that case, all music files would pass through un-resampled.
96 and 192 on spdif in such designed stack are completely misleading and a big fat lie.
Suggesting playing high resolution files just raised my eyebrows...

Sean

Mikescotland Thanks Mike. I appreciate the explanation. It, however, frustrates the living sh*t out of me that I've been misled by essentially fraudulent advertising. My selection of this damned unit was based on an essentially pure unaltered digital signal being delivered to my processor. If the unit is doing all of this BS conversions then there's no benefit in optical of standard RCA which is unsurprisingly what I've found to the case.

@DUDU-Meng you guys need to resolve this ASAP and modify the lies in your product description. You are saying one thing and delivering something completely different.

Mikescotland

Sean only way is USB audio, but:

DSP either must support usb audio in (expensive addon for Helix for instance), or usb to spdif converter
selected apps will use it only
it's experimental
you loose all system sounds, navi and phone over usb audio.

Sean

Mikescotland God that's frustating. USB would be great from a SQ perspective but losing the functionality you've mentioned is not good. I really didn't believe that I'd hear any benefit using USB out which is why I didn't pursue it (plus the added expense). It appears that with things the way the are I either lose SQ because of the poor way that Dudu has implemented software for SPDIF output or I lose functionality. Not happy as I'm sure you can gather.

abidali

Mikescotland The only reason I'm hesitant to get a DSP, this device, DUDU7 should have close to perfect digital audio out and should set the example to old school brands (kenwood, pioneers etc.) that bit perfect audio is possible without getting boxy small screens with limited functionality.

USB audio is expensive, as you said and if we had to use that, why not we should use our phone to DSP via USB c instead of this unit?

The device is very nice in every aspects, just need to work on audio capabilities, it has hardware to support, software improvement needed.

janis

I agree 100% with you guys, and I am fully avare of this android audio layer stuff. When i first find it out i was quite suprised so simple task is so poorly implemented on android operating system. however there needs to be way around this because lot of dap players are running android and they somehow have solved digital output problem. I also ordered already smsl P100 2024, but then also discovered bluetooth pone calls and nav audio and so on is not passed via usb. stuck from both ends 😃 But as I already sayd in some other thread it is suprising to me that these level headunits dont implement digital audio output as pure output what should be one of the main reason to go digital at first place. And as one of the main goal to upgrade headunit is to get the best possible audio signal. it is little frustrating.
And the thing what is even more frustrating is talking some random general stuff. and not tehnical facts. even when the 3.6E came out i specifically asked in thread where was mentioned better spdif passthroug what was the specific changes, and i never get the answer.

Mikescotland

abidali don't get me wrong, spdif "pass through" is still so far the best on the market (S/N over 120dB, THD 0.002%) compared to other units. However, the resampling is killing it all.
It's not easy to bypass 48kHz in newest androids, however, Dudu could use their own high res stack for spdif (and route as a separate device in mixer), not "speaker output".

Sean

Hey @DUDUAUTORudy @DUDU-HUANG @dudu-langzi @DUDU-Meng @dudu-lai is there any intention to resolve these issues??? You are ghosting people with legitimate issues.

No conversion/resampling etc of Optical Out. This is simply a matter of coding and competitors have done this.
Why do no navigation commands/phone calls etc output via USB audio? THIS MAKES NO SENSE.
Why can't the DUDU share my phone internet connection when it is connected via USB? This is the best connection for high res audio streaming. You can't suggest that this unit is focussed on high quality audio if the functionality is destroyed by using the best streaming connection.

I need to get an answer on this as I am seriously considering returning this unit and posting widely about my very substandard experience.

Mikescotland

Sean I'll wait for anyone from Dudu to comment on first 2.
Regarding 3rd - I have no problems with usb Internet sharing from an android phone. Turned it on on the mobile phone, and Dudu took happily the Internet over usb without any problem.

abidali

Sean this issue to prevent Android Audio Mixer (AudioFlinger) needs serious attention, perhaps a custom audio stack needed for truly bypass android from altering audio signal.

DUDU-HUANG

Sean

Currently, all navigation systems on the market use similar solutions. If you truly try to bypass Android resampling, you'll end up with a navigation system with no volume adjustment or mixing capabilities, significantly reducing product usability. Our goal is to maximize usability, reduce internal audio processing steps, and ensure near-lossless audio output.
Bluetooth phone calls use analog channels and cannot be output digitally.
This has already been addressed in another post.
If a competitor outperforms us, and you've verified it, not just hearsay, we'll conduct in-depth research and study it.

Sean

Mikescotland
Thanks Mike. Must be an iPhone thing but I find it hard to believe that Dudu can't find a work around to this problem. I mean the internet connection clearly works within the CarPlay environment but does not function outside of the Car Link App even if the App continues to run in the background. There must be a way to code around this issue...

Mikescotland

Sean wanted to test with iPhone but sadly all my friends are android fan boys, so can't help 😉