DSDPlus Built-in USB Devices May Rob USB Bandwidth?


Premium Subscriber
Jan 18, 2023
Just on DSD Plus Fastlane any version on the local L3 Harris APCO P25 PII TDMA system audio can sometimes be choppy. I was googling around and found USBTreeView which tells you alot of information like which USB version which port on which hub. I found out that the built in camera and bluetooth are permanently connected to the exHCI Controller. One on each hub. So now my brain wants to think. AHA!


All those devices are using USB 2.0 on a USB 3.0 bus. There is an unused USB 3.1 bus. I am thinking that my mouse being bluetooth might be hogging some USB bandwidth but no DSD was doing the same choppy audio without it. On a USB wired mouse I can rapidly spin the cursor on the screen and then DSD Plus Fastlane would stop being choppy during the time I was spinning the mouse cursor. Kind of weird? No. It's more common than you think.

A camera can pull down on the USB bus because there is alot of processing it has to do. You should see the size of the descriptors. I don't use the camera. It's permanently wired in from HP. I suspect it's always on in a suspended state with bandwidth reserved. The more you add on a usb bus the less bandwidth available.

I might be over thinking it but it sure feels like factory cameras and bluetooth in laptops permanently connected to exHCI limits USB bus bandwidth. Less for DSDPlus Fastlane to work with.
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Premium Subscriber
Feb 17, 2003
Suffolk County NY
Some bios let you do more than others. I seem to recall some Costco bjs and dell not having as much fine tuning as say Asrock or other high end mb manufacturers.