Electronic – Why (almost) all HDMI connectors in devices are female

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I have just bought an HDMI 10m cable and of course it comes with male plugs on both ends, and that's because almost all HDMI devices have a female socket.

But why is that? I can understand that when a sender-receiver difference is not clear that can work, e.g. the always wrong type RS232 connector, but for HDMI there clearly is a device that produces video, and a device that consumes it, end of story. Of course there's some sort of symmetric communication going on but the data flow is pretty clear.

This came to my mind since you can't make longer chords just by plugging two extenders one in another, as you would do with mains extenders. You can yell at me that's out of spec, but female to female adapters exist and who the hell cares about the standard anyway?

Some of the reasons that came to mind:

  • you only need to design female pcb/panel mound connectors, and male cable connectors
  • you can use tha same physical connector both as an input and an output (maybe capture video on a VGA?)
  • ?

I'm hoping not to get opinion based close votes since I (want to) believe that there's a perfectly legitimate reason behind this choice.

Best Answer

from http://www.hdmi.org/learningcenter/faq.aspx#94

Q. How will HDMI change the way we interface with our entertainment systems? The most tangible and immediate way that HDMI changes the way we interface with our components is in the set-up. One cable replaces up to 11 analog cables, highly simplifying the setting up of a home theater as well as supporting the aesthetics of new component design with cable simplification.

Next, when the consumer turns on the HDMI-connected system, the video is of higher quality since the signal has been neither compressed nor converted from digital to analog and back.

Lastly, because of the two-way communication capabilities of HDMI, components that are connected via HDMI constantly talk to each other in the background, exchanging key profile information so that content is sent in the best format without the user having to scroll through set-up menus. The HDMI specification also includes the option for manufacturers to include CEC functionality (Consumer Electronics Control), a set of commands that utilizes HDMI’s two- way communication to allow for single remote control of any CEC-enabled devices connected with HDMI. For example, CEC includes one-touch play, so that one touch of play on the DVD will trigger the necessary commands over HDMI for the entire system to power on and auto-configure itself to respond to the command. CEC has a variety of common commands as part of its command set, and manufacturers who implement CEC must do so in a way that ensures that these common command sets interoperate amongst all devices, regardless of manufacturer.

It's pretty clear that in the standard, they were trying to make sure that you would ALWAYS have the right cable when trying to assemble consumer-grade AV systems, and one way to do that is to have one cable style. Also, they want to play up the two-way communication features of HDMI.

Of course, that's speculation, but I can honestly assert that I've never cursed at HDMI connections anywhere near as loudly as I've cursed at USB connections.

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