Shield TV USB audio for DAC use

[madbrayniak]

I just got a ShieldTV Pro and it has an option to output audio via USB to a DAC.

Pretty interesting. Withe the Modius measuring so well I am tempted to test this.

 

[amirm]

Let us know if it works.

 

[jcadduono]

I'd be surprised if it didn't work. They use Android Linux kernel and Android subsystem which both have UAC2 support since like Marshmallow I think.
You should expect Android to dither and resample everything to 16 bit 48 kHz (sometimes 44 kHz, depends on what Android device manufacturer wants to default to) which should not really be an audible issue I suppose...
Some companies like Samsung introduced some hacky code to allow its official media player to change bit depth and sample rate of the whole system to the current playing song to enable bit perfect playback over USB, which is kind of a cool feat I suppose. Would be cool if Nvidia stole that feature.

 

[themystical]

I'd be surprised if it didn't work. They use Android Linux kernel and Android subsystem which both have UAC2 support since like Marshmallow I think.

I have a Sabaj D5 which has XMOS but doesn’t work with the Shield - just freezes the Shield - so doesn’t just seem like a simple matter of UAC2 support. Needs investigation in each case.

 

[jcadduono]

I have a Sabaj D5 which has XMOS but doesn’t work with the Shield - just freezes the Shield - so doesn’t just seem like a simple matter of UAC2 support. Needs investigation in each case.

Interesting, have you tried reporting this to Nvidia? They may look into it as the Shield TV is one of their longterm supported products.
Another option is to try rooting it and using a custom kernel if it happens to be a kernel driver issue. Sometimes kernel devs will catch bugs like that and fix them up. Unlikely to be an issue in UAC2 driver but could be a conflict in the driver used for chipset/HDMI audio. This code often doesn't get tested with operation of external devices unfortunately.

 

[themystical]

Interesting, have you tried reporting this to Nvidia? They may look into it as the Shield TV is one of their longterm supported products.
Another option is to try rooting it and using a custom kernel if it happens to be a kernel driver issue. Sometimes kernel devs will catch bugs like that and fix them up. Unlikely to be an issue in UAC2 driver but could be a conflict in the driver used for chipset/HDMI audio. This code often doesn't get tested with operation of external devices unfortunately.

Every other DAC that I have connected to the Shield works fine and I believe others with the same XMOS 208 chip e.g. Topping D90 work fine. It seems like the issue is with the firmware used by Sabaj for the XMOS chip rather than a Shield issue?

 

[ivvarga]

Researching similar setup produced two threads that might be helpful / worth following.

Nvidia is aware of the freeze issue for several DACs, but fix still not confirmed (I didn't investigate if the fix was even released):
https://www.nvidia.com/en-us/geforc...-freezes-when-connected-to-my-usb-dac-usb-po/

Nvidia staff replied with "no update" 7mo ago on issue with upsampling causing audio quality degradation. MrMC app seems to help with the problem (@jcadduono I'm not arguing about audibility point you made, nor confirming nvidia forum thread OP's issue since I don't own anything similar to the mentioned setup):
https://www.nvidia.com/en-us/geforc...hile-having-problems-with-shieldtv-probably-/

 

[themystical]

Researching similar setup produced two threads that might be helpful / worth following.

Nvidia is aware of the freeze issue for several DACs, but fix still not confirmed (I didn't investigate if the fix was even released):
https://www.nvidia.com/en-us/geforc...-freezes-when-connected-to-my-usb-dac-usb-po/

Nvidia staff replied with "no update" 7mo ago on issue with upsampling causing audio quality degradation. MrMC app seems to help with the problem (@jcadduono I'm not arguing about audibility point you made, nor confirming nvidia forum thread OP's issue since I don't own anything similar to the mentioned setup):
https://www.nvidia.com/en-us/geforc...hile-having-problems-with-shieldtv-probably-/

Thanks very much for the research

 

[ivvarga]

Your are welcome @themystical, but I was researching it anyway... I'm glad if the info helps.

Long list of bug fixes in audio section of 2019 SHIELD Experience Upgrade 8.1.1 (Released 2/26/20) (which is the latest upgrade according to the official web site).

They added support for Sanskrit USB DAC. As stated by nvidia people this was the issue:

On the sanskrit Dac issue, we've found the root cause. The android P audio driver added a timeout on dac discovery. This dac in particular takes a long time to discover, it takes > 10 seconds and the timeout is set to 10 seconds. Will get it addressed.

There are also other fixes like audio passthrough over USB DAC on 3rd party apps like KODI that might be important, but it's best if someone with hands-on experience comments on those.

 

[ivvarga]

Every other DAC that I have connected to the Shield works fine and I believe others with the same XMOS 208 chip e.g. Topping D90 work fine. It seems like the issue is with the firmware used by Sabaj for the XMOS chip rather than a Shield issue?

Was your Shield TV updated to version 8.1.1 for these tests?

 

[themystical]

Was your Shield TV updated to version 8.1.1 for these tests?

Yes

 

[pchmykh]

Is it possible to get unchanged bitperfect signal from shield to usb dac?

 

[DrGogu]

Does the Shield have an internal DAC?

 

[Guddu]

Does the Shield have an internal DAC?

Don't think it has, there is only digital out.

 

[carlmart]

Sorry to resuscitate this thread. But I want to use my Topping as Shield TV output, but the problem is how to manage the audio I want to play. What program should I use?

The Shield allows to use its own internal DAC, which it does have, or passthrough it to the AVR you are using. The OS on the Shield is Android, and AFAIK those two I mentioned are the only two output digital options I have.

Kodi was the program I was using, and I find its music playing having less quality than another option I tried some time ago, with a Raspberry loaded with a Linux audio management program, Picoreplayer, and using the Rasp USB output into the Topping DAC. But the Rasp had its own screen and remote control.
In this case, to use the DAC I would have to use the AVR analog input that has no interface with Kodi to control the player options.

Let's hope I'm being clear on what the problem is.

 

[BDWoody]

The Shield allows to use its own internal DAC, which it does have, or passthrough it to the AVR you are using

The shield doesn't have analog outputs (no internal DAC), but you can connect your DAC via USB.

 

[carlmart]

But how do you use it then with an external DAC?
How you synchronize programs such as Kodi to that external DAC, which will conect into an analog input?

 

[BDWoody]

But how do you use it then with an external DAC?
How you synchronize programs such as Kodi to that external DAC, which will conect into an analog input?

If you go through the setup menu to device preferences, to display & sound, to advanced sound settings, to audio output, you will see this screen:



If you plug in a DAC (had this one sitting in the drawer) it will show up as an option:



Just select it and your audio gets routed to that DAC. Does that answer your question?

 

[Pouyoux]

I've tried on my shield a few DACs : Topping , SMSL, LOXJIE A30 and all of them are working well out of the box.

the only cons is that the Shield doesn't know SMSL or LOXJIE A30 remote control codes so we can't use Shield remote to handle the sound of those boxes.

 

[carlmart]

But how does the AVR know that the audio is in the analog audio inputs? You specify which HDMI syncs with the analog input?