I am trying to understand the processing limit of Arduino UNO board.
Can Arduino UNO board generate video signal?.
If it can't then why it can't do it. ?
speed, memory, i/o requirements
It can drive third party video products.
An analogue video signal (PAL/SECAM/NTSC) has a line period of around 64 microseconds, with the active (visible) portion of the line around 51-52 microseconds.
That's at most just 830 Uno instructions.
Monochrome VGA text from an Uno.
Composite TV-out may be easier.
But why build graphics into a controller chip? Connect a controller up to modules to extend capabi;ities as a system. For graphics, use a board with highspeed ARM chip instead of a slower AVR chip. The Teensy 4.1 clocks at 600MHz, has audio quality analog out and an FPU in an M4 chip and a microSD slot onboard.
So Arduino uno does not have enough speed to generate video signal.
What is the speed required to generate the video signal?
What frame rate, resolution and colour depth?
Full resolution standard dev runs around 270mbit/s. (~27MHz), or 1MB / 24-bit frame as a wet finger estimate.
Wide screen, higher res & frame rates add significantly to that, then you can spend a lot of cycles on compression to reduce the bitrate.
BUT, there are video overlay generators for text etc that use very little of any resources, but the live action background is quite a load.
If Gray black and white colors are visible in an image. i don't understand what is a scan line in image.
https://www.sciencedirect.com/topics/computer-science/active-scan-line
They're also called "rasters"
I think you’re looking for monochrome which still asks the question…
What bit depth and resolution on the single luminance channel?
I am trying to understand what are vertical signals, horizontal signals and synchronization signals and what is the use of these signals in the image. What is scane line
Raster scan images traditionally scan horizontally.
A scan line may consist of an analogue representation of the image, and possibly sync pulses to denote (effectively) horizontal end of line and vertical end of frame or field.
Other information may include a colour burst in the case of a composite colour signal, where the colour information is carried by a sub-carrier within the bandwidth of the video signal.
Modern digital video signals are significantly different.
What are you trying to do?
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You really need to get back to basics.
Try googling video formats, bitmapped rasters,and interlaced video to get started.
If you want to move on to digital video, read up on ‘digital video formats… 99% of what you’re ‘asking’ is beyond the capabilities of the basic arduinos, and requires significant programming skills once you understand what you actually want to achieve,
There are custom chios that can help with specific functions, but thus one of the reasons that graohi s cards can cost more than the PC that is running them.
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I gave a link to make VGA text with an Uno in post 5 and you post that in post 6.
Uno has the speed to generate low resolution graphics. It's a demonstration.
Get a Mega2560 to run a TFT screen and you can show high res slide shows slowwwly.
AVR's have the ability to process text on the fly. The data rate depends on how much you do but simple things can be done at 25000 cps with good code.
i have a mega but i'm missing a lot of the basics of video signals
Probably the best way to understand color video is to understand how the Apple ][ created color:
Colour Without Colour: Apple II Computer Graphics - Paleotronic Magazine
The image is divided into scan-lines, An image is built from 625scanlines, The scan-lines are all 64us long.
PAL format
Number of lines = 625 lines
How many time intervals does the processor have to generate each scan line?
That's the total number of lines in one frame, but a frame is composed of two fields each of 312.5 lines, but only 288 lines of each field are visible, for a total of 576 visible lines per frame. However, if the processor is bit-banging a mono signal, it is still working flat-out in both horizontal and vertical banking (the invisible lines).
So, no time at all, pretty much
what does no time at all mean in your post.
Does it means that the AVR cannot generate the scan line within 64 micro seconds.
IT's all changing now. TFT screens have chips and interfaces. I have one that plugs into a Mega and has a library to code through.
But whatever it is, it's likely been done.
Arduino HDMI board. TV, not TFT. Build with blocks.