Join Date: May 2004
Location: London Ont. CANADA
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OK I think I need to put this all in laymans terms for you all.
EDID came about in the late 90s.
It was designed to talk to the new batch of video cards with smart chips on to let them know what res. and frequency they where to run at.
The format was set back then as cells 1 to 53.
We can now ignore most of that stuff for the new HDMI/DVI format. ( this stuff still has to be there for padding only ). cells 18/19 tell the device that it is EDID 1.3 . cell 20 tells it it is a digital device not analog. cells 21/22 also tell it it is digital with no aspect ratio and to use the frequency the work out the aspect ratio. cell 23 is not used with HDMI as this is set by the chip set later. all the rest are also ignored.
So this brings us to cell 54. This is where we can make a difference.
cells 54-71 Detailed timing / Descriptor Block 1.
In the above example we have :-
(54-71) Detailed Timing / Descriptor Block 1:
1280x720 Pixel Clock: 74.25 MHz
Horizontal Image Size: 708 mm Vertical Image Size: 230 mm
Refreshed Mode: Non-Interlaced Normal Display - No Stereo
Active Time: 1280 pixels Blanking Time: 370 pixels
Sync Offset: 110 pixels Sync Pulse Width: 40 pixels
Border: 0 pixels Frequency: 45.00 KHz
Active Time: 720 lines Blanking Time: 30 lines
Sync Offset: 5 lines Sync Pulse Width: 5 lines
Border: 0 lines Frequency: 60.00 Hz
Digital Separate, Horizontal Polarity (+) Vertical Polarity (+)
This is telling the HDMI complyant DVD player or Video output card that the device preferred res. is 1280 X 720P 60Hz.
Most HDMI source units stop there and if it can, outputs that res.
If it can not output that res. then it will switch to the next lowest one, this may be 50Hz for our PAL users.
THIS IS WHERE WE NEED TO REPROGRAM THE EDID CHIPS TO SAY 1920 x 1080i.
But this is only for people that have fully HDMI complyant units.
This is where it get into a gray area.
For all Sony HD and SD up converting players we have to set this cell block to the res. we will like to display. So 1920 X 1080i or 1280 X 720p as they will only output what is in this cell block.
Toshiba HD and SD players will read this block and with the old software will switch to this res. With the new software will switch to any res. that is outlined in cell block 108-125.
They being the Min and Max settings.
Now another problem we have is that HDMI/DVI and EDID have two channels of communication.
We will look at Sony first.
Sony DVD players first look for the EDID chip to receive there info.
They then look at the HDMI unit chipset to see if it is secure and complyant.
Once this is done video is sent and tokens exchanged via the HDMI secured channel.
If we interrupt this exchang. Then the DVD player stops video and again askes the EDID chip what res. it likes.
It will then hand shake with HDMI and display video once again.
Now another problem exists here in that the EDID chip is powed from the DVI bus and the HDMI chip set is powed by the display device.
So with Sony DVD players, the display device this to be powed first followed by the DVD player soon after.
Toshiba units are a little different in that once it is working the EDID chip is still polled and if it changes in any way, the Video link is stopped and a power down is needed.
So both unit should be powed up as follows.
DVD player second and within a few seconds of the PJ.
With Toshiba units if you change the res. on the DVD player you have to do a power off and restart all of it.