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[kolia]

Hello everyone,
Is there a chance that RPI HDMI output, with MC setup as a client, will play multichannel DSD files sent to an a/v receiver (the receiver is known to play DSD only when using its HDMI input).
Are there any specific considerations I should be aware of to setup the HDMI output in order to maximize SQ?
Thank you

[Awesome Donkey]

A couple of potential issues come to my mind.

1. Multichannel DSD is one of the most demanding tasks MC does, so there's a chance the Pi might not even be remotely powerful enough to handle it (not too sure with DSD bitstreaming, but if you're converting to DSD on-the-fly that won't work at all with a Pi). Not sure, I don't own any Pis to test this.
2. I don't think it's possible to output DSD over HDMI with a Pi (depending on where the HDMI output is connected, e.g. onboard video). In fact, I'm not sure if DSD over HDMI is even possible (or feasible) on a computer in general, partly due to video cards not supporting DSD via their HDMI outputs.
3. The receiver would have to support DoP, which is how MC for Linux handles and sends bitstreamed DSD.

Of course, I could be wrong, but I seem to recall that being the case. If I'm wrong, hopefully somebody corrects me.

[Zhillsguy]

Here is another JRiver related thread:
https://yabb.jriver.com/interact/index.php?topic=97510.0

I find the RPI to be underpowered for any kind of reliable playback, but it makes a cool little music server.

IMO you may find a way to pass through multichannel audio to your AVR, but DSD wouldn't be possible.

[kolia]

Thanks for your valuable inputs and the links provided. I don't want to convert on the fly, I'm just looking for playing files at the original sampling rate and bit depth. I was not aware that MC converts DSD to DoP, is it a CPU intensive task? When using a MC client, is the conversion done at the server level or client level?
I will try first connecting the HTPC HDMI output to the the player and see how it goes it will help to validate the whole setup.

[Awesome Donkey]

Bitstreaming DSD via DoP isn't a conversion. In a nutshell it's a nice little trick to transmit DSD over PCM without any conversion, which is what a lot of DACs these days support. Not sure about receivers - if the receiver doesn't support DoP then then entire idea here is probably a non-starter to begin with, never mind the DSD over HDMI issues from a computer (or a Pi in this case). Native DSD playback (without DoP) with MC is only currently supported on Windows.

The original idea for DoP was invented by dCS in 2011. It involves taking groups of 16 adjacent 1-bit  samples from a DSD stream and packing them into the lower 16 bits of a 24/176.4 data stream. Data from the other channel of the stereo pair is packed the same way. A specific marker code in the top 8 bits identifies the data stream as DoP, rather than PCM. The resulting DoP stream can be transmitted through existing 24/192-capable USB, AES, Dual AES or SPDIF interfaces to a DoP-compatible DAC, which reassembles the original stereo DSD data stream COMPLETELY UNCHANGED.

https://www.dcsltd.co.uk/support/what-is-dop-dsd-over-pcm/
http://www.psaudio.com/pauls-posts/dop-isnt-pcm/13568/
https://www.northstar.it/dsd-native-vs-dop/
http://dsd-guide.com/dop-open-standard#.Wg1eWkqnEuU

If I had to guess where DSD over HDMI works with your receiver, it's probably from something like a SACD player to the receiver.

[kolia]

Thanks Awesome Donkey this is a very valuable information. The receiver I have (Emotiva XMC-1) does not support DoP only plain DSD. So unfortunately it will end the search at this time.
However, while it is supported on Windows (if I understand well using ASIO driver as said here: https://wiki.jriver.com/index.php/DSD), is there a chance it will come on the unix platform?

[Awesome Donkey]

Native DSD bitstreaming will work with ASIO (assuming there's an ASIO driver supporting your device available - usually USB DACs or sound cards), but again, you won't be getting DSD over HDMI working on a computer.

Native DSD on Linux is possible, but requires a) support for the DSD DAC in the Linux kernel itself (from what I've seen, only specific USB DACs are supported with support for other DACs being added as time goes by), b) A minimum ALSA version which has DSD support (which most up-to-date distros meet this requirement these days) and c) support for native DSD in MC itself. If I recall correctly, Bob was experimenting with this a few months back. But, I can atest that DSD via DoP does work fine in MC for Linux with my DSD USB DAC.

If you want DSD playback from a computer you'll likely need a USB DAC which supports it (and DoP support would be great to have too!).

[kolia]

Thanks that's really great info. For my perfect understanding does ASIO implies USB and nothing else?
One other avenue would be then to have XMC-1 supporting DSD over DLNA which has been sort of commited but has not released yet.

[Awesome Donkey]

Looking at the manual for your receiver, looks like I was right that it only supports DSD over HDMI from a SACD player (which some players support playback of DXD or DSDIFF files).

There are a wide variety of disc players which support playback of standard SACD discs (and the
SACD portion of hybrid discs). These discs are recorded in a special digital audio format called
DSD (direct stream digital).
For audio purists who prefer to play the DSD content from SACD discs directly, without
modification or processing, the XMC-1 supports direct playback of DSD audio content received
over an HDMI connection. In order to utilize this feature, your player must be configured to deliver
the unaltered DSD “bitstream” to the XMC-1 via HDMI.
Note: Different players require different settings to enable them to output DSD digital audio
without converting it; and some players may not offer this option. On some players, you will
select “DSD” as your output mode; on some you may select “bitstream” as your output mode
when playing SACDs; and on others you will DISABLE the option “convert SACD output to PCM”;
some players may require you to set multiple options on different menu pages.
Note: Many SACDs include versions of the same content in both Stereo and Surround Sound.
These are actually separate tracks on the disc, and you must choose the one you want when
playing the disc.
Note: Some players can also play DSD audio directly from a DXD or DSDIFF digital audio file. As
long as the result is output to the XMC-1 as standard DSD via HDMI it should play as DSD.
The XMC-1 can play the standard DSD format which is used by SACD discs; it cannot play audio
in the “DSDx2” or “DSD128” format, which is twice the standard SACD sample rate, or any
other non-standard DSD sample rates.

[Awesome Donkey]

Thanks that's really great info. For my perfect understanding does ASIO implies USB and nothing else?
One other avenue would be then to have XMC-1 supporting DSD over DLNA which has been sort of commited but has not released yet.

Depending on the DSD-enabled device and what it supports, you can bitstream over USB, AES, Dual AES or SPDIF. Some devices even support DoP over DLNA (DoPE).

But for the "easiest" solution, it's probably better to bitstream DSD from the computer via USB to a USB DAC (which supports DSD) then to whatever output(s) the USB DAC supports, etc.

[kolia]

But for the "easiest" solution, it's probably better to bitstream DSD from the computer via USB to a USB DAC (which supports DSD) then to whatever output(s) the USB DAC supports, etc.

Yeap. What I'm mostly interested in at this stage (I may change my mind) is to play multichannel files. So no way to add a multichannel DAC to an installation that is already fairly complex. But I have an USB DAC