Optical Output / USB DAC Issues

addissimo

Hi all-
I am having difficulty getting my MatchUP 10 DSP to recognize an optical signal from the DUDU 7 head unit that I installed this weekend. The Match does not recognize the SPDIF signal at all when coming from the back of the M7. If I use a USB-SPDIF adapter, the match will get a signal and play music from the stock local music player, as well as Spotify. It does not play radio, car play, streaming bluetooth from my phone, or bluetooth call audio.

If I open car link for car play, the local music player stops, and I have to reboot the head unit in order to get music to play again over the USB-SPDIF adapter.

Are there any settings that need to be adjusted aside from enabling USB audio to get this to work system-wide?

Cheers-
Addis

grindmitya

1) Check the quality of the optical cable, if it works, it should glow red.
2) Audio transmission via USB is possible only from players. Radio, Bluetooth calls, system sounds (for example, navigator) they won't work.

addissimo

@grindmitya
Thank you so much for the reply- the optical cable is brand new and glowing red. It is working with the USB to SPDIF adapter, so it should work with the optical output of the stereo.

Thank you for the info in the USB DAC limitations.

Does SPDIF passthrough have to be enabled to get a signal?

grindmitya

addissimo Does SPDIF passthrough have to be enabled to get a signal?

optional

Chrisjohn

I have my dudu connected to a external dac using optical and usb c outputs to it.
The usb sounds fine through the dac but the optical has distortion, anyone any ideas why that maybe ?

Mikescotland

Chrisjohn check in audio settings if you have pass through enabled. In advanced settings same audio menu there is also a mixer for media, navi, calls. By default after update is set to 36. Turn all down to 30, otherwise clipping occurs.

abidali

Mikescotland that also make the sound loose a bit of clarity or bit depth. Changed the unit from Joying to this and the audio was noticeably dull.

Mikescotland

abidali Perception. 30 is 0dB, anything above is amplification to clipping. I can agree though there is something off with spdif quality of sound compared to 3.6 regardless of gains. Which is, I don't know. Maybe again just perception, because I measured the path and it's spitting out pure 1kHz with THD less than 0.001% and S/N over 96dB. But music might be a different thing than just 1kHz test.

abidali

Mikescotland today received an OTA update for FYT7870 (YL880) and poweramp now feeding 24bit 96khz via AAudio. It was 24 bit 48kHz before. Is that for real?

Edit: Confirmed that 96khz 32bit is unlocked. however, even if we play 44.1khz, it still goes out to 96khz. Not dynamic.

Mikescotland

abidali you'd need to check if 96 kHz is fed via spdif. This shows android layer is now accepting 96kHz but dsp may bring it down to 48.
Best thing would be to create file in 96k with white noise up to 40kHz and check if spdif doesn't cut out the response before 24kHz.
For 44.1 files the difference would be actually non existing, although Power AMP resampler might do slightly better job with upsampling to 96 than 48. Difference though is just theoretical. If that 96 kHz path is true it just means unit can play 96 without resample. Yes, sadly no dynamic sample rate with 44.1k.

abidali

Mikescotland No matter where I play, stock player or PowerAmp, output is always 96kHz, it's fixed for the moment, maybe to the max capability of the DSP. It can be seen via ADB as shown in the image.

For this unit, I'm not using digital output, only RCA to amplifier. it's a different car. I can try installing this in a car using Helix DSP and DUDU7.

I believe if this has to persist, it will come in DUDU7 in the next update. FYT may have pushed this to YL880 to beta test on users.

Mikescotland

abidali I've tested it a bit, haven't done any frequency response measurement as... Can't find my DAC lol.
Looks like now android path is set from 48000 only to 96000 only. It's not the limit of the AKM dsp, as limit is 192kHz / 24bits.
I don't care about 16 bit-32-24 conversion as its literally transparent.
So, if BT audio, navi and other can work with 96 without a problem (contrary to Dudu previous messages it was impossible), my theory that Dudu can change dynamically sample rate according to file is correct. Sadly they did not include in flinger etc string "44100|48000|96000" but just changed 48 to 96.
Some work needs to be done also for this dynamic change as spdif from akm changes sampling rate requiring dudu restart (I still don't know if mcu or soft is communicating with akm). However, akm doesn't need a restart for changing sampling rate.

abidali

Mikescotland on that FYT7870, there's LDAC support, which sends 48kHz 24bits and not 96khz, which I think somewhere in Developet settings or in my poweramp settings needs to be checked and if it really is 96khz, DUDU team should now work on this, at least implement similar changes with different sampling rate instead of 96khz fixed.

Almost same boards and I believe change will come from FYT directly. Competitors offering better audio path and FYT need to up their game and shouldn't wait for DUDU8 to make us beta testers for another two years.

Mikescotland

abidali but I was testing with latest Dudu beta. It's incorporated already into it. 96k/32bits.
UAPP was able to force Android into 44.1 with internal driver also, however akm resampled to 96 kHz.
Let's see what FYT bring next, hopefully dynamic sample rate.
Not sure what you mean by LDAC because it's codec used for BT transmission to the earphones or any other sink device.

abidali

Mikescotland phone connected via BT can transmit audio data to head unit using LDAC codec, highest possible transmission rate, 990kbps.

As I expected, that 96khz is now with DUDU7 internal beta as well. Signs of improvement coming, hopefully dynamic sampling and not too many bugs with it.

Mikescotland

abidali ah, wasn't sure from your post. No, it won't have. LDAC is not implemented on Qualcomm 3031. You have aptx HD (which is slightly lossy and it's Qualcomm technology) but LDAC is Sony development and qualcomm pushes for its own Qualcomm Audio now (which I don't really know what devices actually use it) and aptx lossless (which Dudu7 chip doesn't have).
People would point LDAC is open source so it should be included. Well, partially. Encoder is open source but decoder, which would be on BT module is not open source.

Regarding 96/32b, it just looks good on paper. Benefits only when playing 96kHz files, music which majority is 44.1 doesn't benefit from this change at all.

Mikescotland

abidali spend whole day in the car today and did some listening.
So, overall the sound is really good when it's going to resampling via 96k/32 bit. No harshness in high frequencies, but detailed, and I'd even tend to say, in a car I wouldn't be able to distinguish if it's bit perfect or going via this route implemented now. I think it's because there are less rounding errors and aliasing when doing it in 32 bits and 96k sampling rate. So, i can say I'm really pleased with quality of sound now.
As for 44.1 and dynamic sample rate.
I was able to force Android to do it. However AKM is a different story. All its parameters sit in mediaserver apk, mostly in hex values for dsp, and command to switch sampling rates. However, because akm is set up via i2c/spi interface, these banks of values go to mcu, and mcu initialises AKM at boot. Possibly, otherwise, akm would give a loud pop when switching sample rate.
Anyway, I don't think I'll be digging more into it, takes too much time and, as I said, I'm pretty pleased with spdif now..

abidali

Mikescotland good news. To be sure, you have used SPDIF by selecting 24bit 96khz in sound settings, right?

If sample rate is not being altered even through SPDIF when playing 96khz, it's a major improvement.

Mikescotland

abidali yes. Spdif set to 96.
I don't think it's altered as the whole pipeline seem to be working at native 96/32. The only test that can confirm is measuring frequency response after spdif (after dsp or with a dac).

hella356

Mikescotland Are you using a Beta version that's newer than the current 3.7? BTW, great work you've been doing trying to track down issues.