USB-C Digital AV Multiport Adapter - USB Speed?

[camotron]

Just wondering if anyone knows the speed/specs of the USB-A port on the Apple USB-C Digital AV Multiport Adapter? The Apple site is conspicuously bereft of proper specs! Hoping it's 3.1 but not holding my breathe.

 

[joevt]

It's 5 Gbps. The adapter has only 2 lanes of DisplayPort 1.4 to produce a HDMI 2.0 signal. The adapter can use DSC to do full HDMI 2.0 bandwidth (600 MHz 8bpc 4:4:4). Two lanes of DisplayPort 1.4 (540 MHz) is not sufficient for that without DSC (but it can do 648 MHz 10bpc 4:2:2 without DSC).

Some GPUs only support DisplayPort 1.2 (360 MHz 8bpc 4:4:4, 720 MHz 8bpc 4:2:0) or don't support DSC. Apple might have disabled DSC in Big Sur? On an Intel Mac, you can use the AGDCDiagnose command to see the connection type (lanes, link rate) and to see if DSC is enabled.

I don't know how well the adapter works on an iPad. Only an iPad with a USB-C port can use the adapter. Which iPad do you plan to use the adapter with? I suppose an M1 iPad should be able to support DisplayPort 1.4 and DSC but I have no way to verify that. Maybe you have a TV that can tell you the signal type (resolution, refresh rate, chroma sub sampling) that it is receiving.

 

[joevt]

The CalDigit SOHO is a nice adapter that supports HDMI 2.0b and HDR and USB 10 Gbps and doesn't require a power supply.

I suppose an M1 iPad which supports Thunderbolt can also do USB 10 Gbps. The SOHO uses an MST hub to provide a DisplayPort 1.4 and HDMI 2.0b output. While Apple doesn't support MST for multiple displays, Apple does allow an MST hub for converting DisplayPort formats (for example, two lanes of HBR3 with DSC to four lanes of HBR2). Again, I don't know if DSC is enabled in Big Sur or iPad OS. I know Catalina supports DSC. While the SOHO should support HDR output, I've only seen HDR work with Apple's HDMI adapters. https://forums.macrumors.com/thread...ransfers-recommendation.2278473/post-29466205

 

[camotron]

It's 5 Gbps. The adapter has only 2 lanes of DisplayPort 1.4 to produce a HDMI 2.0 signal. The adapter can use DSC to do full HDMI 2.0 bandwidth (600 MHz 8bpc 4:4:4). Two lanes of DisplayPort 1.4 (540 MHz) is not sufficient for that without DSC (but it can do 648 MHz 10bpc 4:2:2 without DSC).

Some GPUs only support DisplayPort 1.2 (360 MHz 8bpc 4:4:4, 720 MHz 8bpc 4:2:0) or don't support DSC. Apple might have disabled DSC in Big Sur? On an Intel Mac, you can use the AGDCDiagnose command to see the connection type (lanes, link rate) and to see if DSC is enabled.

I don't know how well the adapter works on an iPad. Only an iPad with a USB-C port can use the adapter. Which iPad do you plan to use the adapter with? I suppose an M1 iPad should be able to support DisplayPort 1.4 and DSC but I have no way to verify that. Maybe you have a TV that can tell you the signal type (resolution, refresh rate, chroma sub sampling) that it is receiving.

Wow - that level of detail is amazing. Thank you so much. Apple could learn a thing or two about spec listings from your good self. I actually have a Multiport adapter that I bought for my M1 Macbook Air but I quickly moved onto a Lenovo USB-C dock which has been fantastic. I am toying with the idea of getting one of the new M1 iPads and realised I could possibly use the Multiport (they are listed on the Apple site as being compatible) for video out and the USB-A out to a USB3 hub that I currently use with my non Pro 2020 iPad. Main use for the hub is for audio interfaces and midi controller connections.

I originally thought I may get another Lenovo to use with the M1 iPad however not sure on compatibilty and also the above option saves some $$$

Thanks again for your thoughts!