Because the audio carried by HDMI isn't analog.

jmarsh wrote on 2024-11-28, 10:35:

Because the audio carried by HDMI isn't analog.

Fair but the vga to hdmi convertors use analog audio input. I’m not saying that I’m looking for a passive adaptor more like wondering why is there no market for such simple device

Bruno128 wrote on 2024-11-28, 10:14:

Why doesn't such device exist? It would allow having the image from AGP card and sound from ISA card. Because the DVI-D signal is already digital there would be no scaling which is always bad in those cheap VGA to HDMI dongles.
Audio injectors exist but they are uncommon and mostly combined with some other functionalities often in professional application.

Wouldn't the below gadget, combined with a DVI to HDMI passive adapter (for input) theoretically do what you want, not much more, and at an arguably reasonable cost (below 50 US$) ? I have no idea if this specific one works well or not, it is just an example. There may be cheaper and/or better options

If you were hoping for something with just DVI and analogue audio input + DVI HDMI output and nothing else, I suspect that this may have existed at some point (and might still). EDIT: But I suspect that an adapter with both VGA and HDMI/DVI input is more likely to exist

Additionally, if I wanted to do this (and have been considering it), I would rather do the analogue to digital conversion for audio in a separate step and then feed the digital audio + DVI to an embedder, or use a sound card with digital out to begin with . I have my doubts about the potential quality and noise isolation of such an inexpensive device (on the analogue side) .

https://www.amazon.com/Embedder-Inserter-Digi … /dp/B0CHBGLTHY/

Bruno128 wrote on 2024-11-28, 12:08:

jmarsh wrote on 2024-11-28, 10:35:

Because the audio carried by HDMI isn't analog.

Fair but the vga to hdmi convertors use analog audio input. I’m not saying that I’m looking for a passive adaptor more like wondering why is there no market for such simple device

The question of who would need/want one springs to mind.

I suspect that most of the use cases for a VGA+analogue audio to HDMI adaptor handle the old PC to modern display problem. As old PCs will at least have analogue audio, that is a must on the input side. Old PCs will also have analogue VGA output, so that is a must too.

Adding an HDMI or DVI in in to such a device might make sense IF enough people cared about it to justify the extra cost, but it would not bother most people with the VGA+ analogue audio use case (except maybe by raising the price slightly).

Replacing the VGA input with an HDMI or DVI one would make the device useless (without needing extra converters) to the initial target market of people needing VGA input, making it a niche product that is harder to sell .

My point is that simple, task specific devices make sense to mass produce if there is a big market for them.

It also makes sense to mass produce a more multifunctional device that can address several niche scenarios. This makes the device more expensive than a single task one, but increases potential market size.

Audio extractors/de-embedders are more common than embedders because stripping digital audio out of a TMDS audiovisual stream (HDMI) is easier and cheaper than encoding analogue audio into an existing TMDS video stream (DVI). I don't know if the licencing and copy-protection nonsense of HDMI (which DVI lacks) plays a part in making them rarer.

I have a DVI embedder so I can inject TOSLINK SPDIF into the output of my OSSC (via passive HDMI-DVI adapter). It's a no-name part I got for cheap because the eBay listing was incorrectly categorised. Another one I got for my PS2 on-the-go is the CYP SY-P290 which was cheap secondhand.