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A new PNG spec

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616 points bluedel | 8 comments | 24 Jun 25 13:01 UTC | HN request time: 0s | source | bottom
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LeoPanthera ◴[25 Jun 25 05:06 UTC] No.44373778[source]▶
> I know you all immediately wondered, better compression?. We're already working on that.

This worries me. Because presumably, changing the compression algorithm will break backwards compatibility, which means we'll start to see "png" files that aren't actually png files.

It'll be like USB-C but for images.

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mrheosuper ◴[25 Jun 25 06:20 UTC] No.44374139[source]▶
Does usb-c spec break backward compatibility ?, a 2018 macbook work perfectly fine with 2025 usb c charger
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danielheath ◴[25 Jun 25 06:37 UTC] No.44374221[source]▶
Some things don't work unless you use the right kind of USB-C cable.

EG your GPU and monitor both have a USB-C port. Plug them together with the right USB cable and you'll get images displayed. Plug them together with the wrong USB cable and you won't.

USB 3 didn't have this issue - every cable worked with every port.

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mrheosuper ◴[25 Jun 25 06:40 UTC] No.44374244[source]▶
That is not backward compatible problem. If a cable that does 100w charging when using pd2.0, but only 60w when using with pd3.1 device, then i would agree with you.
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yoz-y ◴[25 Jun 25 06:51 UTC] No.44374298[source]▶
The problem is not backward compatibility but labeling. A USB-C cable looks universal but isn’t. Some of them just charge, some do data, some do PD, some give you access to high speed. But there is no way to know.

I believe the problem here is that you will have PNG images that “look” like you can open them but can’t.

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1. mystifyingpoi ◴[25 Jun 25 07:05 UTC] No.44374387{3}[source]▶
Cable labeling could fix 99% of the issues with USB-C compat. The solution should never be blaming consumer for buying the wrong cable. Crappy two-wire charge-only cables are perfectly fine for something like a night desk lamp. Keep the poor cables, they are okay, just tell me if that's the case.
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2. ay ◴[25 Jun 25 07:32 UTC] No.44374559[source]▶
Same thing with PNG. Just call the format with new additions it PNGX, so the user can clearly see that the reason their software can’t display the image is not a file corruption.

This is just pretending that if you have a cat and a dog in two bags and you call it “a bag”, it’s one and the same thing…

3. lelanthran ◴[25 Jun 25 07:47 UTC] No.44374654[source]▶
> Cable labeling could fix 99% of the issues with USB-C compat.

Labelling is a poor band-aid on the root problem - consumer cables which look identical and fit identically should work wherever they fit.

There should never have been a power-only spec for USB-C socket dimensions.

If a cable supports both power and data, it must fit in all sockets. If a cable supports only power it must not fit into a power and data socket. If a cable supports only data, it should not fit into a power and data socket.

It is possible to have designed the sockets under these constraints, with the caveat that they only go in one way. I feel that that would have been a better trade-off. Making them reversible means that you cannot have a design which enforces cable type.

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4. Xss3 ◴[25 Jun 25 08:27 UTC] No.44374908[source]▶
So since my vape (example, i dont vape) has a power and data slot for charging and firmware updates, i should be limited to only using dual purpose cables day to day rather than a power only cable?
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5. mystifyingpoi ◴[25 Jun 25 08:38 UTC] No.44374974[source]▶
> If a cable supports only power it must not fit into a power and data socket

That's even more confusing than the current state of affairs. If my phone has power and data socket, then I cannot use power only cable to only charge it? Presumably with the charger that has power only socket. So I need a cable with two different ends anyway. Just go micro-USB at this point :)

Funnily enough, there is a 100% overkill way to solve such issues. Just use super expensive certified TB cables. Well... plus a A-to-C adapter for noncompliant devices, I guess.

6. lelanthran ◴[25 Jun 25 09:14 UTC] No.44375182{3}[source]▶
> So since my vape (example, i dont vape) has a power and data slot for charging and firmware updates, i should be limited to only using dual purpose cables day to day rather than a power only cable?

Well, yes.

Why can't you use a power+data cable for the vape (or whichever appliance takes both)? What's the deal-breaker here?

The alternative is labeling, or plugging cables in to see if they do what you want them to do.

Both are a poor user interface.

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7. kevin_thibedeau ◴[25 Jun 25 19:49 UTC] No.44381220[source]▶
Two wire cables are not in the specification, just like A-to-A cables aren't. The whole charging above 100mA with resistor hacks wasn't in the standard either until they had to grandfather it in. The implementers forum isn't responsible for non-members breaking their spec.
8. Xss3 ◴[25 Jun 25 20:22 UTC] No.44381492{4}[source]▶
Is the same true for my laptop? Or soldering plate? Both take over 150w of power. Buying a power and data cable is expensive compared to just power, and the length of cable is severely limited...or the data speed impaired significantly. How slow does the data have to be for it to be non compliant?