Nvidia Shield PCM over HDMI quality

[theglobalelite]

In older versions of the Nvidia Shield OS, if you went to the HDMI status page, it would only list PCM 16-bit as the maximum audio mode setting. This page on Nvidia's help site still shows a picture of the setting: https://nvidia.custhelp.com/app/ans...o-is-not-working-with-certain-video-streaming . More recent builds of the OS not longer show this information or provide any audio mode settings mentioning PCM.

How I read this info back when it was visible was that the Shield outputs all PCM audio as 16-bit over HDMI. So any 24-bit content decoded to PCM, or originating as PCM, gets downsampled to 16-bit on it's way to the AVR or processor over HDMI. All PCM audio may have been resampled to 16/48 in older builders as well. The only way to keep 24-bit content as 24-bit would be to bitstream it (as TrueHD or DTS-HD MA) to the AVR or processor (bad if you have a lot of Blu-ray TrueHD and DTS-MA converted to 24-bit FLAC 5.1/7.1).

It's not clear if the audio mode options were removed at some point the because the Shield Experience OS or the underlying Android OS improved their uncompressed audio output handling, or Nvidia just wanted to hide it because it highlights a major downside of the product.

In my current tests the sample rate is kept at it's original rate. For example playing Akira's 24/192 5.1 track stored as FLAC shows as PCM 5.1 192 khz source on my Denon receiver. But I have no way to test the bit-depth.

So does any know if this is true, or how to test for it? I'd guess one way to check would be to have equipment that can check the incoming audio bitrate, 16-bit 5.1 would be 4608 kbps and 24-bit would be 6912 kbps. And it should match source's properties of course, not be all 24-bit or all 16-bit, indicating resampling. The playback software (Kodi, Plex, Emby, etc) could also be a factor complicating testing I believe.

Thanks if anyone can shed some light on this!

 

[Thegoodspot]

Hi, i got the nvidia Shield pro 2019 hooked up to a hdfury diva. The diva shows 16bits PCM for the shield, no matter what app i'm using (netflix or Kodi...).

 

[theglobalelite]

Ahh, thank you for testing! So my fears were confirmed and Nvidia just hid that everything is downsampled to 16-bit.

Now is this a Nvidia/Shield or Android limitation? Do high-end media streamers that run on Android also do this? I wonder how some audiophiles would react if they found out their 24-bit FLAC files were converted to 16-bit the whole time??

 

[omm0910]

Looks like nVidia put one over on us. Is there an easy alternative? The new "Google Chromecast with TV"? Or maybe it is an Android limitation.

 

[wwenze]

Welcome to Android. Enjoy your stay.

Well, as mentioned, the only way out is to bitstream.

Theoretically Linux can do whatever output format, but the build needs to be configured for it. Else the mixer will always run at 16/48.

 

[theglobalelite]

While it's been pretty well established that 24-bit audio does not offer any audible improvements over 16-bit for typical listening scenarios, that usually applies to the finalized output file by audio editing software. Could there be a possible point of concern here since the Shield / Android OS is doing an on-the-fly / realtime downsampling, instead of a slow, quality focused resampling by an audio editing suite? Or is 24-bit to 16-bit audio downsampling basically a "solved problem" that most modern hardware can do at a reasonably high quality? Is there a way to "rate" a Android or Windows 24-bit to 16-bit downsample vs a quality focused software audio processing tool like SoX?

 

[Beershaun]

The concern is that the OS is doing extra work to screw something up and make it worse when it should be just getting out of the way. There is no way to know what is being introduced or lost in the conversion.

So that is a concern for anyone trying to maintain control of their audio chain.

 

[infinitesymphony]

From what I could dig up across a few threads:

The Shield uses fixed resampling with the following resolution and rates:

• High Quality Stereo: 24-bit, 96 or 192kHz
• Stereo: 16-bit 44.1kHz

This appears to be regardless of source material and is also player-dependent. Some people have confirmed that Google Play Music and MX Player may work, while Kodi may or may not work.

 

[Thegoodspot]

From what I could dig up across a few threads:

The Shield uses fixed resampling with the following resolution and rates:

• High Quality Stereo: 24-bit, 96 or 192kHz
• Stereo: 16-bit 44.1kHz

This appears to be regardless of source material and is also player-dependent. Some people have confirmed that Google Play Music and MX Player may work, while Kodi may or may not work.

I did test every configuration inside that box.
What ever USB settings (high resolution or else) i get 16Bits 48K even inside Kodi. In Kodi i can oversample when choosing fixed output up to 382Khz but still 16bits and with delay and strange behavior afterward. So i stick with 16/48 Lpcm for now (nanoAvr->Diy Dac->analog 5.1 Pre amp) but will get the new chinoppo with hdmi in to bitstream to lpcm my shield soon (oppo 203 are too difficult to find).

 

[Sparky]

I was dismayed to find this also.
I have lots of MKV files saved at their original quality to include "TRUEHD" etc etc but checking my DIVA shows only 5.1 LPCM @ 48k

 

[Sparky]

The whole reason I bought the NVIDIA Shield and DIVA is so that I could maintain the highest quality audio signal possible.

Back to the drawing board I guess....

 

[Thegoodspot]

Hi Sparky, having an Oppo 203 (Revealed from your picture from DIVA )why don't you go Bitstream from the shield to the Oppo HDMI IN ???

 

[Sparky]

Hi Sparky, having an Oppo 203 (Revealed from your picture from DIVA )why don't you go Bitstream from the shield to the Oppo HDMI IN ???

Hi. Is that setting buried in the menu somewhere? I've not touched it for ages to be honest...

 

[Thegoodspot]

Hi. Is that setting buried in the menu somewhere? I've not touched it for ages to be honest...

From the manual, i wish i had a 203 like yours. I've read somewhere the input could be the default state upon firing the oppo.

 

[sonci99]

Any blu ray player can do better.
I have a Sony UHP H1, apart from the stereo analog out and playing SACD, DVDA, dsf over dlna or even Monkeys audio lossless files, it outputs correctly 5.1 96Khz flac files to receiver, I haven`t tried any 192khz files though, my receiver is limited to 96khz

 

[infinitesymphony]

Why select the Shield over other playback devices like a phone, tablet, computer, Raspberry Pi -- what's the use specific case? Is the goal to get 24-bit/192 kHz content?

 

[Thegoodspot]

All my movie collection is on a Nas so For me the shield is a fantastic movie player. but i would also like to use it for stereo and multichannel music files (also on NAS) in good quality. I have a pi running slimserver wich does a great job but if i can have one box to "do it all" that's simplier for me and the other family users.

 

[Sparky]

Same for me. The Shield serves as my Plex server aswel as a chromecast device and media streamer.
It's a pretty versatile box really.

 

[Sparky]

From the manual, i wish i had a 203 like yours. I've read somewhere the input could be the default state upon firing the oppo.View attachment 90012

Exactly what I'm using yes....

I altered the settings in the shield so I could manually select which audio files to use. I worked out well.



I use the analogue out of the 203 to my Anthem STR preamplifier. Everything is down mixed to 2.1 by the 203. Works quite well.

 

[infinitesymphony]

Didn't @theglobalelite mention in the OP that they were getting what appeared to be 24-bit / 192kHz / 5.1? They didn't have a way to verify 24-bit but it would be surprising to see 16-bit / 192 kHz.