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Comment by pontifier | Hacker News Reader

This is one thing I really miss about analog tv. You could switch channels as fast as you could press the button.

Everything now is so slow.

This is one of the things on my TODO-list for when I stumble upon a way to have infinite amounts of time:

Learn "FPGA 'n stuff" and build my own display controller. Like many people here, I don't understand why this takes so much bloody time. Not just the input switching, but also switching resolution or refresh rate on the same input. So either I'd have an a-ha moment and see why it's not possible (more likely outcome), or well, it'll just work and I can write a cool hackaday post.

The EDID explanation given in the comment currently at the top doesn't make too much sense: Even if the display is off and not in some super hardcore energy saving mode, EDID works, i.e. your computer can query the EDID data from the screen and know what its preferred resolution is, etc. Likewise, even if your display is switched to HDMI-1, a machine connected to HDMI-2 can already be outputting 1080p60 to it, so why does switching inputs take more than a few milliseconds?

Afaik (and I only have very rough knowledge here), there is no side-channel in HDMI/DVI that tells the display what mode it's actually receiving, so the display has to look at the signal and make sense of it. So you have to put some brains in it. But that can hardly take several seconds, i.e. hundreds of frames? Maybe two or three frames! I could see this being a cost cutting measure, maybe doing the dumb implementation that takes seconds instead of milliseconds saves you a cent or two per device.

Or, perhaps, weird regulatory/big customer energy saving reasons - “TCO” stickers and whatnot imply some kind of standard measurement, can imagine a “wake from sleep on source change” benchmark driving odd behaviours.

Top comment leaves out HDCP entirely as well which I would wager is where a lot of people experience delay. If you want to learn more about it search for the edid hotplug detection. Once that gets negotiated it is followed by the hdcp handshake. Keep in mind while reading up on this the industry terms for devices are "source" and "sync". Video goes from source to sync.

The hdcp handshake is a particularly bad mess which most manufacturers don't implement well due to a very confusing spec. My experience has been some devices start showing video right away and kill it if hdcp handshake fails, while other devices don't show video until hdcp handshake succeeds. Behavior is quite hardware dependent.

The commercial vendors like Extron (crosspoint switchers) and Crestron (digitalmedia switchers) have this figured out pretty well where switching is almost instant so it's definitely possible. I think Crestron has some technical papers out there that discuss the challenges involved.

I assume this is for a different reason - buffering and stream compression, you have to wait for a key frame before your TV can display anything.

Similar root cause though - technology becomes available that makes the steady state performance much better in return for some setup costs, the setup costs are worth paying in almost all applications so it's an obvious choice to go with the new technology but still annoying when you encounter its drawbacks.

Good point.

What would be nice is if it had a low-quality stream with more keyframes so it could switch quickly and then go to the higher quality stream when that gets to a keyframe.

But I can see why that kind of complexity wouldn't be added just so you can switch quickly to 3 seconds of low quality video.

This was the reason I stopped watching TV with my cable box back in the day. I used to love channel surfing, but that became impossible because I would have scrolled through 2-3 channels by the time the next one loaded.

Sure, soon after I would give up TV for other reasons, but I probably would have kept regular TV for way longer if this delay was never introduced.

My current (Samsung) display is a pain to switch off. If I forget and switch the PC off first, it goes to sleep and starts blinking its annoying bright blue LED, which I managed to disable when it's on or off, but not when it's asleep. To get it to switch off I have to wake it up, wait until it cycles through all its inputs, gives up and shows me the menu, from which I can finally turn it off.

I'd plug the thing into a switched wall socket!

This is the way. Too much electronics has LEDs which remain on as long as there is power connected. A switched wall socket or switched power strip is the only sane way to keep electronics in a bedroom.

I destroy or cover with electrical tape any blue leds that mistakenly come into the home. I try to avoid them but sometimes not possible.

I remember the sound of just keeping the "Channel Up" button on the remote of my parent's 90ies TV pressed. It was like 10 channels a second, just gliding through syllables. "Br-Da-Wi-Pl-Ka-Ts-Mm-Di-Tu-S-Za-Ol-".

> You could switch channels as fast as you could press the button.

Yep, and everything was exactly the same video format, and all TVs had the same capabilities.

The slowness was present on VGA monitors as well, if you recall.

Slow switching is a tradeoff worth having, given that it allows me to have any number of digital resolutions and color depths available to me.

Yes! I remember running my finger down the column of electrical contact switches and changing the channel at 60 fps. "brrrrrrip!"

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