Question Losless audio over spdif as 2.0 pcm

Manic Ken

Novice Member
Hello and thanks!

Is it possible to transfer lossless audio over spdif, say, flac audio or dolby trueHD? I know that trueHD cannot be transferred as such, because of bandwidth limitations of spdif (or copy protection concerns as a competing explanation). So in normal case the playback device would detect that there is trueHD available, it would know it's connected to receiver with spdif and then decide to send over spdif only (normal) Dolby Digital 5.1.

As it happens, In my home theater setup I only have two main speakers and a woofer (2.1). Because of that I'm really not that concerned about preserving the spacial information of the audio. I would be perfectly happy with a 2.0 signal coming in to my receiver.

What I really want to achieve (if possible) is to use my Nvidia Shield TV as a playback device and a decoder. I want Shield to chew up trueHD and spit it out as 2.0 pcm without losing any audio quality. I know the spacial information will be lost, but not really missed. Same thing with flac files, Shield should decode them and send them over to the receiver as 2.0 pcm.

In all of it's simplicity, I would much prefer good quality 2.0 sound to bad quality 5.1.

Is this at all possible?
 

Mark.Yudkin

Well-known Member
S/PDIF will support two channels of up to 20 bits (there are 24 bit implementations, but this is a non-standard extension) at up to 48 kHz.

I want Shield to chew up trueHD and spit it out as 2.0 pcm without losing any audio quality.
Most devices (and all TVs) allow you to configure PCM over optical / coax, and this will conform to the above limitations. Few TVs support Dolby True HD decoding (my Loewe make a big point of doing so). I can find no indication in the Shield documentation (NVIDIA SHIELD User Guide) that it supports this otherwise universal option for S/PDIF. In addition I have been unable to find any confirmation that the Shield supports Dolby True HD or dts hd, but only a statement that they don't: "For Dolby & DTS 5.1, SHIELD supports Dolby Digital (AC3), Dolby Digital Plus (E-AC3), and DTS Core Audio Streams in pass-through mode.". This would indicate neither lossless surround nor stereo down-conversion is supported.
 

Manic Ken

Novice Member
Thank you Mark!

Bloody Hell-O-Kitty, it really seems like a fools errand. Shield just doesn't have anything that fancy in it. As far as I can tell, Shield can't even convert DD+ signal from Netflix to standard DD.

My receiver is trusty and dusty Yamaha RX-V740. Technical specifications state that it can understand 96kHz/24-bit signal from digital inputs.

My tv is LG E6. I wonder if, with the right software, I could play 96 kHz/24-bit flac files directly in the TV and then transfer them in all of their glory to the receiver. Based on what you said about anything above 48 kHz/20-bit being non standard, I'm guessing that's another village idiots errand.

RX-V740 - RX-V - AV Receivers - Audio & Visual - Products - Yamaha United States
 

Mark.Yudkin

Well-known Member
Your RX-V740 does not appear to support FLAC natively. But since FLAC is about audio, I wonder if you can't solve this directly at source, without going though the TV or Shield.

According to your TV's manual ,it can accept FLAC, so that may be another option. Set your TV to send PCM over its S/PDIF output, and try it out.
 
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