HDMI Audio to USB Conversion?

[somebodyelse]

This is a related question: does anyone know of any external boxes that decode and output HDMI CEC volume control instructions?

CEC lets you use your TV remote to send volume control messages to receivers. I'd like to intercept those messages in software to control the volume of a software-based solution.

If there isn't anything like this out there, does anyone know of external HDMI to S/PDIF (or USB) boxes that optionally apply CEC volume control to the outputted S/PDIF stream? i.e., multiply the digital output by the CEC volume control level and then output that via S/PDIF?

https://kwikwai.com/products-2/
There's also some info on diy options here:
https://elinux.org/CEC_(Consumer_Electronics_Control)_over_HDMI

 

[ElNino]

https://kwikwai.com/products-2/
There's also some info on diy options here:
https://elinux.org/CEC_(Consumer_Electronics_Control)_over_HDMI

Thanks -- I hadn't seen the Kwikwai device. That's what I'm looking for, though the price ($370 USD) is a little steep for the convenience of not needing two remotes.

I found this via your second link: http://www.pulse-eight.com/p/104/usb-hdmi-cec-adapter That's perfect!

 

[linuxfan]

Does this use DoP when outputting DSD over the coax/optical outputs?

I don't know for sure, but I suspect there is no form of DSD s/pdif output at all. That converter's main purpose is to extract raw I2S data from either a conventional HDMI signal, or a DSD-over-HDMI signal. The coaxial/optical s/pdif outputs are fed by a s/pdif transceiver chip - which is capable of taking PCM I2S signal (from the board's main output) and converting it to a s/pdif signal. But I don't believe there is any s/pdif transceiver chip which is capable of converting PCM I2S to DoP - that would require some form of software playback engine, configured for DoP output. I can't imagine that board to have such provision - so I suspect when the board is extracting DSD I2S, what appears at the s/pdif outputs will be nothing, or noise.

 

[Keened]

So...is there anybody making one of those HDMI I2S extractors and mating it something like the MiniDSP USB streamer which has bidirectional conversion via USB for an 8 channel I2S in?

Because you could just stick one of those on the side of an RPi, feed the result to DSP and then back out to a good multichannel DAC to reclock it seems.

 

[mdsimon2]

So...is there anybody making one of those HDMI I2S extractors and mating it something like the MiniDSP USB streamer which has bidirectional conversion via USB for an 8 channel I2S in?

Because you could just stick one of those on the side of an RPi, feed the result to DSP and then back out to a good multichannel DAC to reclock it seems.

I saw your posts recently about I2S isolators, are you giving this a try?

I have a MCHStreamer and figured it was worth the $30 to try a 7.1 HDMI to I2S extractor. I went with this one -> https://www.aliexpress.com/item/33031920347.html, although the one I received is a different layout than what is shown. My plan was to use the TOSLINK output of the extractor to clock the MCHStreamer using the I2S_TOSLINK firmware.

The MCHStreamer seems fine being clocked from the extractor TOSLINK output and the MCHStreamer has no issue receiving a signal via the TOSLINK input but I2S so far has not been working. I've only done a bit of troubleshooting but I am getting very distorted signals via I2S. I plan on trying a few different grounding / power supply options but not super confident it will improve anything. As the clocking options on the MCHStreamer are a bit limited the only other thing I can think of as an alternative is using an 8 channel ASRC that accepts an external clock input (from the MCHStreamer) but I don't know if such a thing exists and not super interested in spending more money on an experiment.

I did try the extractor with a DIYINHK I2S input 8 channel DAC and that worked great so I think the extractor is OK but obviously multichannel I2S integration is always a bit of a pain.

Michael

 

[Keened]

I saw your posts recently about I2S isolators, are you giving this a try?

I have a MCHStreamer and figured it was worth the $30 to try a 7.1 HDMI to I2S extractor. I went with this one -> https://www.aliexpress.com/item/33031920347.html, although the one I received is a different layout than what is shown. My plan was to use the TOSLINK output of the extractor to clock the MCHStreamer using the I2S_TOSLINK firmware.

The MCHStreamer seems fine being clocked from the extractor TOSLINK output and the MCHStreamer has no issue receiving a signal via the TOSLINK input but I2S so far has not been working. I've only done a bit of troubleshooting but I am getting very distorted signals via I2S. I plan on trying a few different grounding / power supply options but not super confident it will improve anything. As the clocking options on the MCHStreamer are a bit limited the only other thing I can think of as an alternative is using an 8 channel ASRC that accepts an external clock input (from the MCHStreamer) but I don't know if such a thing exists and not super interested in spending more money on an experiment.

I did try the extractor with a DIYINHK I2S input 8 channel DAC and that worked great so I think the extractor is OK but obviously multichannel I2S integration is always a bit of a pain.

Michael

I am, or rather I will. I'm waiting on the extractor (completed v2 of the one you used) to show up via aliexpress.

I started asking about isolation and repeaters that might help alleviate this. When you say distorted signals, distorted in which manner? The I2S output from the LVDS/HDMI out port on yours doesn't include a clock line?

 

[mdsimon2]

I was running 1 kHz FFTs from the HDMI output of my macbook pro with the MCHStreamer as a capture device in REW, have not done any listening.

FFT showed 1 kHz fundamental as expected but at too low of level (-20 dBFS for 0 dBFS input) with harmonics nearly matching the level of the fundamental and a very high noise floor. I would show a screenshot but it seems like I may have bricked by MCHStreamer by trying to upgrade to the newest firmware . I just opened a ticket with miniDSP and if I can get it back up on in running I will post more.

I was using the pin header (mine doesn't have I2S over HDMI) but the issue with clocking is that the MCHStreamer needs to be a clock master and cannot accept a clock input over I2S. It expects that all I2S input data will be synchronized to the MCHStreamer clock domain. Using the I2S_TOSLINK firmware you do have the option of recovering the clock from the TOSLINK input and clocking the MCHStreamer from that which is what I attempted to do with the TOSLINK output from the HDMI extractor without success.

I have read a little bit on DIY Audio about the possibility of converting a USBStreamer to accept a master clock input -> https://www.diyaudio.com/community/threads/usbstreamer-problem-with-biii-bii-in-i2s.273393/ but don't personally have any interest in that as I have actual use cases for the MCHStreamer (ADAT I/O) and this was just an experiment to see if I could get multichannel HDMI to USB for low cost.

Also, are you sure that your extractor does 7.1? Reason I ask is the I2S pin connector only shows 1 data line instead of 4.

Michael

 

[wisechoice]

I'd sooner investigate playing with a used Meridian H621 and feed the 4xAES3 outputs to an Okto DAC8 Pro or a miniDSP U-DIO8. There is also a possible option for AES-EBU.

Thanks for this suggestion, Kal. It was quite finicky, but eventually I got it working with the Dac8 Pro (and an HDMI splitter to get 4K video to my TV.)