Hacker News Reader

Comment by theandrewbailey | Hacker News Reader

> TOSLINK/SPDIF turns this into a manchester coded serial signal, at around 1.5Mbps that is much more resiliant to analog interference

When I was connecting my surround sound receiver to my PC, I was bummed that SPDIF standard was never improved to support 5.1 or 7.1 uncompressed surround sound. 5.1 DTS compression is the best it can do (due to the 1.5 mbps bandwidth), but PC support is rather limited. I gave up, and I've been using it with HDMI for 10 years. Running it through my video card/drivers has introduced (bearable) complexity, but I wonder why receivers to this day can't connect to PCs over USB instead. (Yes, most receivers have USB ports, but those are for playing MP3s off a flash drive. A PC isn't a flash drive.)

View on HN

I think the root of the problem is lack of bidirectional signalling means you have to manually configure for capabilities on both sides (which actually already happens for DTS/Dolbly over SPDIF, so it wouldn't have been the end of the world...). Lack of bidirectional signalling also precludes content protection that's more effective than setting a "don't pirate" flag, which might be the real reason.

Part of the answer is that toslink does not support DRM, while HDMI does.

So they never was any compelling reason to improve it like that. They even removed toslink output from many devices nowadays even if they didn’t have too.

I'm reminded that it did offer https://en.wikipedia.org/wiki/Serial_Copy_Management_System

> A PC isn't a flash drive

That could be a kind of cool app that would allow you to present a folder on your PC as a media device. However that would then require a dreaded USB-A to USB-A type of cable <shudder>

Target disk mode on a lot of older Mac machines did that over Firewire. You could boot the machine into target disk mode and it would present its mass storage over Firewire. It was pretty cool.

But you couldn't use the machine at the same time. This would be like a SAMBA share, but over USB

You can connect two computers with usb and setup network between them, so you can just use smb/cifs. Microsoft has even handy tutorial for that: https://learn.microsoft.com/en-us/windows-hardware/design/co...

again this is not the same thing has allowing a USB cable to connect from a PC to another device that is expecting a device that would present itself as a mass storage device

I loved that feature- I could take my shitty old laptop into a university computer lab and boot a powerful brand new mac with fast internet from my hard drive- and use all of my software as if it was my own computer.

You can do this (in Linux, at least. Mobile devices like Android as well.) if the USB port of the peripheral side is a USB OTG port. I've only seen USB OTG ports as USB-B (standard and micro) or USB-C.

Edit: I didn't notice before, but USB OTG is on the front page right now https://news.ycombinator.com/item?id=42585167

I think there was a RPi Zero project doing the round some years back that made use of this.

It could be done with USB-C. The computers would need to figure out which is the computer and the USB host, and which is the drive and act like USB device.

This is called gadget mode. I don't know what PCs can do it, but Raspberry Pi can do it.

i doubt about the 1.5mbps limit as many DAC specs toslink as 24bit 96khz pcm stereo capable, which sums up to almost 5mbps

Reply on news.ycombinator.com