Saturday, August 1, 2020

Vantec NBA-200U external USB sound adapter unable to output 7.1 ANALOG audio from Nvidia Shield via Kodi

TL;DR: As title.  The Vantec will NOT output 7.1 ANALOG audio from an Nvidia Shield TV / TV Pro using Kodi.

It will output 5.1 audio via optical S/PDIF (Toslink).  And it will play most 6.1 and 7.1 video files through that interface. 

You will probably even hear sound through your rear surrounds while playing those files, so you may think that you are actually getting 7.1 sound. 

But you're NOT, because optical S/PDIF is NOT capable of sending 7.1 audio due to bandwidth limitations on that interface (as everybody should know by now).  Most likely your receiver is doing some smart sound processing without you even realizing it.

My receiver is old, and does NOT handle sound via HDMI.  And I figured if I'm upgrading, why not move from 5.1 optical to 7.1?  So I needed 7.1 ANALOG sound. 

The Vantec is supposed to do that by outputting 7.1 sound via four 3.5mm audio jacks.  You use 3.5mm-to-RCA cables to connect these to the analog inputs on your audio-video receiver (AVR).

Obviously, this means you need an AVR that has such inputs.  I have a Pioneer VSX-1016TXV, which has dedicated 7.1 analog inputs.

 (OK, laugh all you want, but it works great.  I'm NOT spending $500-$1,000 for a new HDMI-audio receiver when my existing stuff works perfectly well!)

Once I realized what I needed, I did my homework.  Nvidia recommends the Vantec

So, Vantec to the rescue.  I plugged it in, Android installed it silently.

Except, no matter what, it didn't work.

Here's what DID happen:

1.  At best, all I could get was stereo sound.  In many instances, I got ticking / buzzing only, or no sound at all.

2.  If I tried to play a file the Vantec didn't understand, it often locked up (activity LED stopped). 

It would then refuse to output anything - even stereo or 5.1 - until it was reset, or the Shield was rebooted.  This occurred on nearly all Dolby 7.1 and DTS 7.1 test videos, and (maybe) even a couple of 5.1 test videos.

3.  The Vantec would lock up even on files it should have handled, such as "U-571" in 'standard' DTS Digital Surround 5.1 (i.e. not DTS-HD 7.1 or DTS-HD MA 7.1).  This occurred when using either analog 7.1 out and optical S/PDIF out.

 For reference:

-  The problem is not with my AVR - I checked the multichannel 7.1 inputs, and they work perfectly.

-  The problem is not with my files.  I tried them on my old Minix box, and they work perfectly, including on 5.1 channel test videos.  On the Shield, the 7.1 analog outputs simply do not output anything to anything except for front left/right.

-  The problem is not with passthrough settings.  Using identical settings, optical S/PDIF works (including 5.1 surround), but analog 7.1 outputs do not.

-  The problem is not with the Shield USB.  I tried both, they were both set to always-on, and I even tried setting USB to max performance.  No dice.

There are a bunch of other devices like the Vantec on the market.  Most use the same C-Media chipset, so I don't think any of them will work any better.

I debated keeping the Shield TV Pro since it is faster, x265 capable, and will work as a Plex server.  But having the Vantec lock up on random files is a no-go for me, much less the family.

So, my advice to anyone with an old setup that does not handle HDMI audio is:

-  If you want S/PDIF, the Vantec basically works, and you should get the ability to play back 5.1, 6.1 and 7.1 files via Toslink optical (in 5.1 only).  But be prepared for it to malfunction / lock up if it 'sees' something it doesn't grok. 

-  If you want 7.1 analog out, do NOT buy a Shield TV.  There is no way to get analog surround sound out of it using commonly available USB sound card adapters - regardless of what a few Amazon commentators might say. 

Other devices based on the same chipset may or may not have the same issues.  I don't know, and I'm not spending the time to find out.

However, if S/PDIF / Toslink optical floats your boat - and you can get a USB adapter that doesn't tend to lock up - these are the settings that worked for me:

-  Dolby audio processing ON
-  Available formats to MANUAL
-  Set all available formats to ENABLED
-  Stereo upmix is ON

(Note that "Forced volume" can be set ON or OFF, but it won't work.  It only works for HDMI audio, not for USB audio. )

On Kodi:
-  Number of channels: should not matter, mine was 2.0
-  Output configuration: Optimized
-  Pass-through ENABLED
-  Dolby Digital AC3 capable receiver ENABLED
-  Dolby Digital AC3 transcoding DISABLED
-  [if shown] Dolby DTS capable receiver ENABLED

On receiver:
-  Sound source set to digital / optical

With these, I was able to play:
-    Dolby Digital 5.1
-    Dolby Digital Plus 7.1
-    Dolby TrueHD 7.1
-    Dolby TrueHD 7.1 Atmos
-    DTS Digital Surround 5.1
-    DTS HD MA (Master Audio) 7.1

(These were the reported formats - can't be 100% verified.)

However, channel-check videos showed that the surround channels of Dolby Digital Plus 7.1, Dolby TrueHD 7.1, DTS-HD MA 5.1 and DTS-HD MA 7.1 did not come through.  They were undoubtedly downmixed to 5.1 to get through the optical interface.

Other variations on this may also work.  For example, you could try setting the Shield audio formats to "Automatic", just to see what happens.

For that specific setting, I suspect the formats that will be output may be limited by whatever is hooked to your HDMI.  If you have a new TV that supports "everything", the Shield will likely output everything.  If you have a projector or other device that doesn't support certain audio formats, the Shield might detect this and prevent certain audio formats from playing.

Note the last paragraph above is 100% pure speculation on my part, based only on the fact that the "Automatic" setting didn't seem to work well for me.  (I have an Epson projector and old AVR, neither of which handles HDMI sound.)

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