Digital Audio In

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    A feature I originally proposed on the System11 forums, which I’m publishing here for greater exposure.

    A number of legacy consoles, including the SNES and the Saturn, cannot be modded for digital video, but can be modded for digital audio out with an SPDIF interface. The solution I propose is for the OSSC to be capable of combining this signal and the analog video source for the digital AV out. This would be made easier with the recently developed add-on board for digital audio out.


    I know it’s a niche of a niche, but I’d also like to see this, primarily for my PS2 and Xbox consoles.

    I would expect this to primarily be used with YPbPr-capable consoles (PS2, PS3, Xbox, Xbox 360, GameCube), but I can also see it being used with SCART-capable consoles, modded or otherwise (PS1, PS2, PS3, Xbox with the elusive XB752A cable, Xbox 360, GameCube, SNES, Saturn), and, perhaps to a lesser extent, emulator PCs and TOSLINK-modded Dreamcasts via HD15.


    I’ll keep this mind if I’ll be ever doing an updated / new board. Some older consoles also would need audio samplerate conversion (e.g. SNES 32kHz) to be compatible with HDMI specs (48kHz, 96kHz etc.).


    +1 !

    It would be great !




    Looking at the IT6613 HDMI transmitter chip ( used in the OSSC, it apparently has a S/PDIF input port, quote: “In addition, an S/PDIF input port takes in compressed audio of up to 192kHz frame rate”. For the laymen that sounds like the chip would be capable of just muxing any normal digital audio format into the HDMI output. Does this mean the OSSC could have a digital audio in for the price of the input jack and maybe a few jellybean parts? I guess that wouldn’t help with older consoles that have non-standard sample rates and don’t do ‘compressed’ audio, but at least the usual suspects could be routed this way. Might make for an interesting add-on board / mod project 🙂

    +1 in any case


    I wouldn’t mind an addon board, but I’d still want each AV input to have a digital input as well, and for the OSSC to do input switching on the digital board. I’ve read about how the audio addon boards for the 1.5 only had one input, and that sounds too limiting. I’m also not a fan of decoupling audio from video; there will be times where I’ll have my PS2 with TOSLINK running a game, and I’ll want to use a different console on a different input, which would likely result in the audio from the PS2 playing over the video from the other console.

    The OSSC might also have to determine whether it’s receiving TOSLINK audio for a given input and send only that audio to the HDMI chip, the assumption being that the digital audio is higher quality and/or has more channels than the stereo analogue audio it might also be receiving at the same time.

    I’m hoping that any integration of TOSLINK I/O and switching would also come with a change in board layout. The TOSLINK I/O could very well be added to a PCB that sits where the center acrylic sits, but I’m not a fan of having I/O on three sides of a device, and especially not having to input YPbPr video on one side and audio on another.

    Would be nice if all the I/O was on the back and logically grouped, so that AV1’s SCART port, the TRS audio breakout, and a TOSLINK input are together; AV2’s RCA connectors, TRS audio input, and TOSLINK input are together (Or take the opportunity to make this a 3-wide, 2-high RCA block, so we don’t need to use an RCA->TRS adapter, and make that sixth hole a full-size TOSLINK jack); and AV3’s DE-15, TRS audio input, and TOSLINK input are together.

    Personally, I would advise against switching out the TRS jacks for TRS/mini-TOSLINK jacks, because users (myself included) may not be using only one type of audio source. For example, my Audio Authority 1154A component video switcher is wired for both analogue stereo and digital via TOSLINK, because not all of my component video sources will do TOSLINK (Think SNES/Genesis/Saturn/PS1/Neo Geo with HD Retrovision cables but without TOSLINK mods, or NESRGB, or GameCube without TOSLINK mod). For those who have the TOSLINK addon board for the gscartsw, they most certainly will not have 100% analogue or 100% digital audio sources. (Although, in that case, analogue audio would be carried over SCART, so, would it make more sense to have a full-size TOSLINK port AND a TRS analogue audio breakout, or force users to choose with a combo port for one of digital in or analogue out?)

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