Ok. I'll describe some experiments I've made with that program:
1) A (very) few artifacts appear on the right side whatever you do.
2) The program starts at 704x480. A black vertical line of about 4 pixels width is shown on the right side of the image. If you put another window on top of the left edge of this window, that black line changes its width from the initial value (4?) to zero.
3) Horizontal stretching (>352) seems to have no effect when the vertical size remains <=480 (that misterious vertical line on the right side is also stretching with the image).
4)However, when you stretch (horizontally) the window to 352 pixels (the half of the original width) you get a image 1 pixel wide. If you strech it to 351 you get a 2 pixel wide image, 350 -> 4 pixels, 349 -> 8 pixels, and so on. To 188. When you strech the window to 187 pixels you get similar behavior (one pixel wide), etc... but this time with some flickering. To 118. Before reaching this point the resulting image is larger (mosaic) than the original. 117 shows an image of 2 pixels wide.
5) Vertical stretching is causing HEAVY artifacts on the right side of the image ONLY when you past 703 pixels wide. However 3 zones are showing (the 3rd zone is difficult to see).
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So, summarizing:
a) Very few artifacts showing on the right side whatever happen.
b) A misteryous black vertical line showing on the right side, however its width depends on another window covering the left edge.
c) (width <= (704/2)) {strange horizontal zomming effects}
d) (width >= 704) && (height > 480) {heavy artifacts on the right side}
I have a Savage4 chip. Hope this can help.
David.
I've been able to see the same artifacts on my ProsavageDDR For a & b & c, I see the same behavior. For the d case, my artifacts are showing up on the left side not the right.
I'll add some more observations.
I think the black line is the padding in the image between rasterlines. Shouldn't be there. I don't have a theory for why it is yet.
It now looks to me that the source of our problems is the hardware scaler. It looks like we are scaling correctly vertically but we get into a bad place because the horizontal scaling is hosed. Horizontally, we drive it too strongly for certain ranges.
The source image in our example is 704 x 480.
As I scale the destination window width down, here is what I see.
Widths Description
703-352 Normal image, scaled appropriately.
351-235 The image scales, but too much so. At 351 pixels wide, the image is stretched excessivly such that only one pixel or so is visible in the destination window. As you continue to shrink the destination window, the exessive scaling lessens the point that at a width of 235 or so, the image appears almost normal, there is still some moderate stretching, however it becomes apparent that you are looking at the right half of the source image.
234-177 The displayed image switches to show the left half of the source image. It too is streched, though not excessively. As you lessen the width, to 177, the image returns to the natural unstreched appearance.
176-141 The pattern expressed in the 351-235 range repeats. There is a great deal of flickering at this width, however.
140-118 The pattern expressed in the 234-177 range repeats. Still lots of flickering.
etc....
The patterns continue at pixel widths representing power of two divisions of the original width (i.e 1/2, 1/4, 1/8, 1/16, etc)
until it is too small to see anything.
As I scale the width up, for all widths greater than the size of the source image, the image shows two regions that contain the right half of the image.
As I scale the image down horizontally, if the width is in the 703-352, 234-177, 140-188, etc, then correct vertical down scaling also occurrs with destination window height changes.
In the other width ranges (351-235, 176-141, etc) smaller than the source image witdh and all widths greater than the source width, then vertical scaling does occur, but there are noticeable image distortions that occur when the destination height is changed.
On another note, I've found a solution to get gdb pointed at this driver while it runs so I should be able to test some things out.
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