Hello everyone !
(Sorry for my bad English, I'm french)
I am looking for a way to read the VGA signals coming from a computer or another device (with a HDMI to VGA converter) in order to analyze each pixel.
I have an esp8266 and I found on the internet that I can output a VGA signal from the esp8266 but I didn't find a way to read a input VGA signal ...
Thank you !
You don't have anywhere near enough processing or A/D conversion horsepower.
I think you've already been told this on the French forum
Why does the esp8266 have enough processing to do an output but not an input? What's the difference?
Do some simple arithmetic.
640x480 pixels at, let's say 30Hz.
A bit more than 9MHz. (It's worse than that, because you've got horizontal and vertical blanking, but let's keep it simple)
And you've got three channels of that.
So, how are you going to convert, input and store 27 million analogue samples per second?
(You can get a simple VGA output from a Uno)
And so, what kind of MCU would I need to do that? I mean, what minimum clock rate, flash memory etc?
Stop.
Think.
A DAC can be created using a few digital pins and a few resistors.
An ADC is a lot harder.
Ok thanks, next time be less arrogant and it'll be perfect.
Keep in mind that we are not all electronics professional
I'm not an electronics professional.
but you did not deny being arrogant 
Technically, it's not arrogance if you actually are superior.
RobSqui:
Why does the esp8266 have enough processing to do an output but not an input? What's the difference?
It has sufficient processing power to do an extremely crude VGA output of perhaps a few basic colours at a very low resolution.
You seem to misunderstand. Video processing of the sort you have in mind, is always performed by special purpose chips - called video processors - specifically designed for the job. That includes both video output and video input. To say that a microprocessor can do a party trick and generate a "blocky" image means nothing.
Abusing respondents who simply state facts is unlikely to be productive. All the more so if they are moderators. If you cross-posted the same question to different forums, you would usually have been merged; only because they are different languages have you been spared.
AWOL:
Technically, it's not arrogance if you actually are superior.
