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USB Cheat Sheet

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Re: USB Cheat Sheet

#91

Post by jayd16 »

Chilinot wrote: post #36
birktj wrote: post #31

Earlier quoted context omitted.

There already exists some fiber-optic USB cables that come in lengths >50m and with support for USB 3.1 so it doesn't seem like a very unrealistic option.

That sounds more like fiber optic adapters/converters that fit into usb-ports and talk usb, rather than USB-cables that can be 50+ meters.

Seems like you can get 3m optical usb-c cables. Oculus sells an official "Full featured USB active optical cable. USB 3.2 Gen 1 Type-C" for tethered play.

That's what the cheatsheet says so maybe that's part of the spec.

Re: USB Cheat Sheet

#92

Post by IshKebab »

Someone wrote: post #47

No USB On-The-Go ( https://en.wikipedia.org/wiki/USB_On-The-Go ) or Wireless USB ( https://en.wikipedia.org/wiki/Wireless_USB )? USB is a triumph of marketeers over engineers. All these things are called USB because USB sells (see also: Bluetooth).

I don't know anything about wireless USB but USB OTG is called USB because it is USB. It's not some totally unrelated protocol.

Re: USB Cheat Sheet

#93

Post by IshKebab »

This is wrong. For example Full Speed isn't a name for USB 1, it's the name for a speed which is supported by USB 1 and 2 (not sure about 3). Most USB microcontrollers are Full Speed USB 2.

Re: USB Cheat Sheet

#94

Post by jsjohnst »

jbverschoor wrote: post #82
jsjohnst wrote: post #46

Earlier quoted context omitted.

It’s why I always buy TB3 (or now TB4) cables rather than a cheaper USB-C to USB-C. Due to the strict requirements on TB cables, you can pretty much guarantee it’ll support any use case (alt modes, PD, etc). Sometimes overspending is worth the headache prevention.

Apple just released a €159 cable

And? Apple used to sell a way more expensive than that TB2 cable if high price is your point and besides, saying Apple charges a premium price for a premium product (like this) is about as insightful as saying the sky is blue.

Re: USB Cheat Sheet

#95

Post by BayAreaEscapee »

grishka wrote: post #87
IvanK_net wrote: post #74

Fun fact: USB 2.0 webcams have been existing for over 10 years. USB 2.0 is 60 MB/s. A pixel of an image is 3 Bytes. A 1920x1080 FullHD image is 6.2 MB. At 30 frames per second, second of a FullHD video is 186 MB. How did they do that? Answer: frames are transferred as JPEG files. Even a cheap $15 webcam is a tiny computer (with a CPU, RAM, etc), which runs a JPEG encoder program.

Hm. But then wouldn't it make more sense to just stream the raw sensor data, which is 1 byte per pixel (or up to 12 bits if you want to get fancy), and then demosaic it on the host? Full HD at 30 fps would be 59.33 MB/s, barely but still fitting into that limit. But then also I think some webcams use H264? I remember reading that somewhere.

I don't know where you get "1 byte per pixel" from. At minimum, raw 4:2:0 video would be two bytes per pixel, and RGB would be three bytes per pixel with 8-bit color depth.

Re: USB Cheat Sheet

#96

Post by CharlesW »

jbverschoor wrote: post #82
jsjohnst wrote: post #46

Earlier quoted context omitted.

It’s why I always buy TB3 (or now TB4) cables rather than a cheaper USB-C to USB-C. Due to the strict requirements on TB cables, you can pretty much guarantee it’ll support any use case (alt modes, PD, etc). Sometimes overspending is worth the headache prevention.

Apple just released a €159 cable

FWIW, Monoprice's 1m USB4/TB4 cable (100W) is $25.

https://www.monoprice.com/product?p_id=41946

Re: USB Cheat Sheet

#98

Post by username190 »

CharlesW wrote: post #96
jbverschoor wrote: post #82

Earlier quoted context omitted.

Apple just released a €159 cable

FWIW, Monoprice's 1m USB4/TB4 cable (100W) is $25. https://www.monoprice.com/product?p_id=41946

Apple's cable is 3m, which is likely most of why it's more expensive.

https://www.apple.com/shop/product/MWP02AM/A/thunderbolt-4-p...

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