Hi. I am trying to create a vhdl code for sending image from pal camera to vga screen. I use decoder which converts pal video output to 4 4 2 ycbcr format. I want to convert data from ycbcr to rgb format inside fpga. There are formulas on internet but I dont fully understand the logic. For example I got 1440 byte data coming per line which means 11,520 bit. Rgb requires 12 bit per pixel and my monitor have 1280 pixel in one line. So I need 15,360 bit. How do I arrange these numbers? And do I have to store data in memory? Can't I just send coming data to vga output?
4 4 2 YCbCr to RGB conversion
- Thread starter varden
- Start date
BobaMosfet
- Joined Jul 1, 2009
- 2,113
In order to convert PAL to RGB on the fly, there are 2 ways, depending on your performance requirements:
1. You reverse the calculation of the YCbCr (which is YUV, disregarding the bipolar aspect) and output the RGB Values, or (slower)
2. You precalculate a table and use the YCbCr as an index into the table and spit out the table value (faster)
Having said that, I'm not sure where you're getting a 4:4:2 combination- it doesn't seem to be common, but it is possible to use just 6 bits.
As for actually displaying it on a VGA screen, you need to know something about timing and feeding video signals (vbl, front porch, back porch, etc)- that is not what an FPGA is good for.
1. You reverse the calculation of the YCbCr (which is YUV, disregarding the bipolar aspect) and output the RGB Values, or (slower)
2. You precalculate a table and use the YCbCr as an index into the table and spit out the table value (faster)
Having said that, I'm not sure where you're getting a 4:4:2 combination- it doesn't seem to be common, but it is possible to use just 6 bits.
As for actually displaying it on a VGA screen, you need to know something about timing and feeding video signals (vbl, front porch, back porch, etc)- that is not what an FPGA is good for.
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