Electronics > Projects, Designs, and Technical Stuff
Making a HDMI audio type detector
ve7xen:
I believe it's just re-framed S/PDIF packed into the data islands, so format detection would happen more or less the same as it does with an S/PDIF receiver. Which is to say "not in a very well defined manner".
NiHaoMike:
--- Quote from: ve7xen on November 12, 2019, 09:47:28 pm ---I believe it's just re-framed S/PDIF packed into the data islands, so format detection would happen more or less the same as it does with an S/PDIF receiver. Which is to say "not in a very well defined manner".
--- End quote ---
Except HDMI supports a bunch of audio formats S/PDIF does not.
hamster_nz:
Looking through the HDMI Standard 1.4 (search for "hdmi 1.4 standard filetype:pdf") it looks like there are two ways to transmit audio.
- A packet that contains audio samples, and metadata bits out of the S/PDIF stream.
- A one-bit audio packet. That I assume moves raw bits from source to sink.
Looking at the S/PDIF info at http://www.hardwarebook.info/S/PDIF, I would guess that the coding is transmitted in the "Channel status and subcode information".
I assume that the source asked over E-DID what formats are supported, then sends a standard S/PDIF stream with the correct metadata for the desired audio format.
If the stream is not compatible for with SPDIF framing/packets I assume the raw stream of bits is transmitted over a one-bit audio packet...
cvanc:
Wouldn't the easiest answer be to just use a surround sound receiver and observe what format it detects?
Or am I misunderstanding your goal here?
teddyng:
--- Quote from: cvanc on November 13, 2019, 03:57:37 am ---Wouldn't the easiest answer be to just use a surround sound receiver and observe what format it detects?
Or am I misunderstanding your goal here?
--- End quote ---
That's what I am doing at the moment with a receiver, but I am trying to build a portable one.
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