Separate Audio Output with Digital IO Board

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Gerri
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Separate Audio Output with Digital IO Board

Unread post by Gerri »

I have a question regarding Audio. Can the Mister Digital I/O board output the sound via the optical output via 3.5 mm jack? Normally I do this via the HDMI output. I have here a BenQ BL912 monitor that has no speaker, and must output the sound separately to an active speaker.

I ordered the Mister with the Digital iO board, but I'm not so sure if that was a good decision. For the 2 Ram module I did without the analog connections.

I would be happy if someone can help me here.

Many thanks!

Gerri
Xbytez
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Re: Separate Audio Output with Digital IO Board

Unread post by Xbytez »

The digital IO board only supports optical audio out via the 3.5mm jack. It has no line level output at all for analog audio. Easiest solution is output sound via 3.5mm using mini TOSlink cable into a DAC, then connect the speakers to the DAC.
Gerri
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Re: Separate Audio Output with Digital IO Board

Unread post by Gerri »

Does it make sense to do without the analog section for 256 MB Ram, or will I have no bottlenecks with 128 MB in the future?
AngelicLiver
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Re: Separate Audio Output with Digital IO Board

Unread post by AngelicLiver »

The amount of RAM isn't really the bottleneck, it's the potential bandwidth requirements some potential cores may need. It this point it's purely academic so I would not get too hung up on "future-proofing" your MiSTer build with a 2-module setup. 128MB is really only needed for some of the larger Neo-Geo ROMs.

PlayStation doesn't need 2 modules (in fact you can use a 32MB module alone), Saturn looks like it will be fine with 1 (but this may change) and Jaguar it's still very early days. Cores beyond that are a ways off and may very well be targeting significantly larger FPGA platforms.
Gerri
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Re: Separate Audio Output with Digital IO Board

Unread post by Gerri »

Thank your for your explanation.

In another forum I have found following hint to the Digital IO Board.

>> The analog board also has TOSLink output combined with the analog mini-jack connector.

Wouldn't that mean that I can output audio through this port via 3.5mm connector as well? I´m a little bit confused. :-)
jca
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Re: Separate Audio Output with Digital IO Board

Unread post by jca »

With the analog board you can connect either an optical cable or a regular audio cable but the quality won't be as good and have annoying "pops" when starting cores
Gerri
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Re: Separate Audio Output with Digital IO Board

Unread post by Gerri »

So I would have a better sound via digital board?
jca
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Re: Separate Audio Output with Digital IO Board

Unread post by jca »

No, the quality problem refers only to the regular audio output, if you use optical it will be the same as with the digital board. Sorry for the confusion, I should have been more precise.
Gerri
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Re: Separate Audio Output with Digital IO Board

Unread post by Gerri »

Thank you very much the help. You have helped me a lot.
Stinky
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Re: Separate Audio Output with Digital IO Board

Unread post by Stinky »

Get an HDMI inline audio extractor they're fairly cheap. I used to use one with my xbox360.
Malor
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Re: Separate Audio Output with Digital IO Board

Unread post by Malor »

Gerri wrote: Wed Jun 22, 2022 1:48 pm So I would have a better sound via digital board?
The sound via the digital board comes out as a standard S/PDIF connection, and is exactly the same as the audio part of the HDMI signal. It will run at 96K, too, which is nice. So you'd plug a S/PDIF cable in (called Toslink in Europe, I believe), and plug the other end into a device that understands digital sound. I'm using a receiver here.

If you have a reasonably modern receiver, you can also use two HDMI cables to put it between the Mister and the monitor. Depending on the receiver, however, this can add lag or video issues, as the Mister is often doing some rather oddball things with its output. Running separate S/PDIF and HDMI cables gives you the exact same signal, while sending the video directly to the monitor without interference.

Any DAC with a S/PDIF input should work, you don't need an actual receiver. But if it doesn't also have an amplifier, you may need one if you want to drive speakers.

There's also a mini-optical connector that plugs in via a 3.5mm headphone-style jack. I don't think that jack carries analog audio, however, I think it's just an empty barrel connection with an LED on the end for the hybrid cables. Using the standard larger connector is probably going to be easier.

edit: in other words, the hybrid headphone cables have an optical core, and then a copper surround to carry an analog signal. I think Apple pioneered these to save on port space, so they could cram both digital and optical into one jack. AFAIK, the jack on the digital board doesn't do the analog part, it only uses the fiber in the center. The bigger S/PDIF cable is entirely optical, and is super easy to find, so that's probably what you want to use.
Gerri
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Re: Separate Audio Output with Digital IO Board

Unread post by Gerri »

I think that an adapter from HDMI to VGA will help me. The adapter I found has a normal output 3.5mm. I'm just not so sure if I need an extra DAC.
Malor
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Re: Separate Audio Output with Digital IO Board

Unread post by Malor »

Gerri wrote: Thu Jun 23, 2022 3:14 pm I think that an adapter from HDMI to VGA will help me. The adapter I found has a normal output 3.5mm. I'm just not so sure if I need an extra DAC.
I don't understand how HDMI to VGA could possibly help. VGA doesn't carry audio.

The digital board emits a standard optical signal via both a 3.5mm jack and a standard S/PDIF jack. AFAIK, it does not emit analog audio at all, period. You will need a DAC of some kind if you want to get sound out of the digital board. You may also need an amplifier to drive speakers.

You can get analog sound out of the analog board, but the quality will be reduced, possibly quite sharply. Digital sound to a reasonably good DAC will give you the best results.
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