video processing?

igor

Could I use Propeller chip to solve the following task:

1. on input: VGA video signal from PC
2. apply processing algorithm
3. on output: VGA video signal to beamer

Alternative: VGA -> TV signal
Signal parameters (min): 640x480 full color 10Hz
Processing: line-by-line, e.g. out(x)=in(639-x)

Mike Green

Think about it. 640 x 480 = about 300000 pixels. If you are using 24 bits (8 bits x RGB) for each pixel, that becomes around a megabyte for a frame buffer and the Propeller has only a small fraction of that available. If you want to use external RAM, you would need some kind of external memory controller and you could also do the video input timing there ... we're talking about a fast logic array.

The Propeller's video logic only handles a limited color palette. It's possible to have 8 bit video with some fancy work if the scan rate is low enough by using only 4 pixels per WAITVID cycle and you could theoretically sync 3 cogs to produce 24 bit video, but you run up against the memory limitations again.

If your processing algorithm is simple and only uses adjacent pixels, you might be able to do this by only storing adjacent lines and using several synchronized cogs to do the work.

The short answer is "no". The longer answer is "maybe", but it would take a huge amount of experimentation and development just to see if it's feasible. Cutting down the resolution would help and cutting down on the color depth would help. QVGA (320 x 240) with 8 bit color would be much easier (although you'd still need to have external RAM and the associated control circuitry).