TOPIC: DIY solution for HDMI to 8ch digital out

Hi

I have been playing with miniDSP boards and my own DAC experiments and nanoAVR seems like an interesting processor for multichannel system (which I don't have atm). It immediately gives me an idea of the chain: sources -> nanoAVR -> 8ch DAC -> 8ch preamp/amp. The problem, or the new thing, is the HDMI.

Does someone know a way to include HDMI in your DIY solution and get the 8 channels of digital audio out of it? HDMI uses some kind of handshaking so I'm thinking of some kind of interface IC or evaluation module I could put in front of 8 channel DAC. Or is DSP/FPGA the only option? Also some ready-made or semi-ready-made solutions can be suggested although it would be very neat to have just one HDMI cable going to the DIY box which then outputs 8 analog channels.

@nihtila

Thanks for your interest in the nanoAVR, unfortunately I'm afraid that this product isn't a DIY product due to licensing issue. i.e. we can't provide a way to perform HDMI to I2S with this board.

Sorry we're not able to help.

DevTeam

I did some googling yesterday and yes, I also think such is the case. I thought it would be license-free since Dolby Digital / DTS is not involved anymore but obviously HDMI has similar harm. We should have a representative of DIY-community in those boards deciding about the standards and their licensing

So I guess I will continue my projects in 2.1-channel world. However, nanoAVR indeed is an interesting product and if I go (back) to multichannel it will most probably stand between my sources and av-receiver.

In case someone is still interested there has been a solution for a while if I understand the goal here: JVB modded Oppo - > 7.1 channel dac

In the use case above the connection would be: source -> NanoAvr -> JVB modded Oppo -> exasound e28 multichannel dac or a DIY 8 channel PCM DAC -> PreAmp/Amp
Oppo has hdmi/optical input that excepts Dolby Digital/DTS and will convert to PCM so you can get DD/DTS. But you would need 2 Oppos: Source/Tivo/Apple TV -> oppo -> NanoAvr -> JVB modded Oppo -> exasound e28 multichannel dac or a DIY 8 channel PCM DAC-> PreAmp/Amp

I was thinking of going this route with the trinnov EQ that excepts dig PCM upto 16 channels. I was going to do: source-> JVB modded Oppo - > Trinnov -> PreAmp. But luckily they invented the DL & saved me $12-14K. So maybe my research can benefit somebody.

www.octavainc.com/HDMI%20switch%204x2_7_1audio.html

In this box the four data, bit clock, word clock and L/R select lines are easy accessible.
With 4 digital interface transceiver or sample rate converter chips it isn't too difficult to get 4 spdiff outputs.
It might even be possible to use one of the JVB mod boards to get the 4 spdiff outputs.

The Octava box also has editable edit configurations so the player will output 8 channels LPCM.

My nanoAVR's ouput is connected to this hdmi switch and I get 4 spdiff channels into my Denon AV Amp that has the ability to combine four spdiff inputs into an 8 channel ext digital input.

devteam wrote:
So, I suspect that this answers my question. But, I'll ask it straight out. Can I get the nanoAVR HDA board/s without the case? I'm interested in integrating everything (amps etc) into one case and saving a few bucks on the case (and shipping) since I wouldn't be using it. And while on the topic of the case, does it really come with that silk screen of a band and crowd? I certainly hope that it's available in plain.

@ chmed,

Unfortunately we don't have a product offering of the nanoAVR without the case (i.e. not really adding much cost actually/same shipping cost). If you don't like the front panel, you can easily replace it by tearing it off. It's easy.

DevTeam

Any info on the I2S lines for this box?
fderks wrote:

Not yet. I'm planning to back engineer the pinout of the expansion headers early next year.

From what I can see, the nanoAVR DSP sports 8 programmable serial interfaces, and one of the formats is I2S. Assuming they interface to Analog Devices HDMI transceivers, their audio interface is I2S. So, there's a good chance there's I2S on the board.

But, one can't make an HDMI to digital audio interface without violating HDMI licensing so zi would expect miniDSP to offer no assistance in this regard.

Pity, because a dual nanoAVR solution INSIDE an Oppo transport that does Bass Management and Dirac Live would be a killer mod. Is is readily available inside the Oppo.

I know this is stale, but in case someone is still interested, there IS a solution: you can convert non-HCDP protected HDMI to SDI with a Blackmagic converter, and from there deembed 4x digital AES/EBU audio, on four 1/4" TRS connectors with another Blackmagic converter. From there, you can use Blackmagic or AJA converters to convert 2x AES/EBU to 4x balanced audio out (the AJA ADA4 does a fine job, and even supports consumer +10dBV or professional +24 dBu 0dBFS signal levels).

It's what I am planning to use after a nanoAVR DL in lieu of a "real" AVR.

Is the "non-HCDP protected" requirement not an issue for watching movies etc?

Not if you use the "secondary" HDMI outputs of players that are designed to interface audio over HDMI to AVRs. They usually send black video, no HDCP, and either bitstream or LPCM audio over the HDMI link. Better players like the Oppo do this, and also decode various formats like Dolby TruHD to LPCM, so you can use them with old AVRs that don't decode that format. The Oppo players also have HDMI inputs that decode HDCP to do video and audio processing so processed external audio can be output as LPCM over HDMI.

Did you ever do this? Details?

rhollan wrote:
I had been searching for a method to do this for many years, then shelved the project, I'm just finishing it recently since the nanoAVR was discontinued (and I've been snatching up used ones to complete this). Anyways...

The referenced method may be a bit noisy, I tried it a while ago (well part of it); I suspected the Blackmagic Mini SDI to 4x AES/EBU adapter converts the SDI audio to analog internally then from analog back to AES/EBU, introducing a bit of noise along the way (too much for my taste). I had bought a used one hoping to use it in keeping my audio pure digital all the way into my speakers, but the noise floor came up, I bought a new one thinking the used one had an issue and same thing. I emailed Blackmagic and they basically said the device was operating normally within the standards and didn't confirm nor deny my assumption.

The nanoAVR can swap and mix channels so I was thinking on using a few of them to swap each pair of extra channels to the front L/R then extract them with a cheap HDMI digital audio extractor. Years ago, I asked miniDSP if they had any other ways to extract all audio channels digitally, they did not (and said using multiple nanoAVRs won't work, turns out it does though...)

The solution I settled on (tested and working).
My source switcher feeds into an HDfury Integral to tell the source what resolution and audio format I want since the large chain of HDMI devices after this really messes with the EDID stuff. One leg of the HDfury feeds the TV and the other goes to a nanoAVR DL (just added it, still working on it) then into another HDMI splitter to split out into the following:
-HDMI to S/PDIF extractor for front L/R
-nanoAVR remapping C/LFE to front L/R then into another HDMI to S/PDIF extractor for C/LFE speakers
-nanoAVR remapping rear channels to front L/R then into another HDMI to S/PDIF extractor for rear speakers

It works great, no extra latency issues, and no issues on reboot, I'm just waiting for the UMIK-1 to arrive to hopefully get the DL online. I'm also still searching for another nanoAVR as a spare incase one fails... (I have a single spare of every other non-nanoAVR component)


My backup plan (untested) was to use the Blackmagic Teranex Mini units to go from HDMI to SDI, then split to 3x SDI to Audio (AES/EBU), but that was more expensive then scraping up the extra nanoAVRs I needed and I was worried about noise after using the first extractor


Another method if anyone wants to try a pure single hardware solution (advanced soldering and programming required), the Analog ADV7611 and ADV7612 can extract HDMI audio with selectable channel mapping; put an HDMI splitter (or equivalent chip) in front of a few of those, Arduino to set the config bits for channel selection and and you can split out all 8 channels via I2S. HDCP might be an issue though. This project used the ADV7611 if you want to see hookups/schematics of the chip. The Analog AD9398 chip does exactly what we want, HDMI to 8 I2S channels, but it's discontinued and pretty old (replaced by above).


I hope miniDSP's replacement for the nanoAVR can output 4x pair of digital audio since they sell plate amps with digital inputs...


Now to wait for someone to tell me I can get HDMI to 4x pair of pure unadulterated digital audio feeds with a simple relatively cheap box, which I would happily switch to...

The solution I settled on (after discussion in this forum) is using 4x i2s to s/pdif converters connected to an internal header in the nanoAVR (details sprinkled in the next two pages of this thread)