Re: Undefined video mode number: 314
Stephen Powell wrote:
> On 2010-01-13 at 07:18:51 -0500, Stanisław T. Findeisen wrote:
>> What are those sync frequency ranges?
>
> The sync frequency ranges that the X server assumes for a
> non-EDID monitor when nothing is specified for them
> in the config file can be found by examining the startup messages.
> Going back to your original Xorg.0.log output, they are:
>
> (II) s3(0): Configured Monitor: Using default hsync range of 31.50-37.90 kHz
> (II) s3(0): Configured Monitor: Using default vrefresh range of 50.00-70.00 Hz
>
> As you can see, this is considerably more restrictive that the published specs
> in the owners manual, which are 30-70 kHz horizontal and 50-160 Hz vertical.
> Manual configuration is nearly always required to get the most out of a non-EDID
> monitor. And there's no substitute for knowing what the correct specs are.
Yeah, but what *are* those "sync frequency ranges"? Sorry I don't understand. My monitor's manual does not specify any display modes with vertical refresh rate >86Hz. Is it so, that there are "hidden modes" available that are not specified in the manual? For instance some low resolution, few colors and 160Hz vertical refresh rate?
Your help was invaluable but if you explained me this one more thing that would be even better.
> You're confusing the frame length and the resolution. They are not the same.
> Let's work out the timings for a specific example. Let's use this one:
>
> (**) s3(0): *Default mode "1024x768": 78.8 MHz, 60.0 kHz, 75.0 Hz
> (II) s3(0): Modeline "1024x768"x75.0 78.75 1024 1040 1136 1312 768 769 772 800 +hsync +vsync (60.0 kHz)
>
> This is a good example because the pixel clock rate is 78.8 MHz, which is not
> far from the maximum pixel clock rate (often referred to informally as
> a "dot clock" rate) supported by the video card, which is 80 MHz. Let's look
> at those numbers in the modeline. The first number, 78.75, is the pixel clock
> rate, assumed to be megahertz. (If you round this number to three significant
> digits, you get 78.8, which is what is listed in the summary line above it.
> But the actual clock rate is 78.75 MHz.) The second number, 1024, is the
> horizontal *resolution*. It is the number of *visible* pixels in each horizontal
> line. The third number, 1040, represents the start of the horizontal sync
> pulse. The fourth number, 1136, represents the end of the horizontal sync pulse.
> And the fifth number, 1312, represents the end of the horizontal frame. It
> is this number, the horizontal *frame length*, not 1024, the horizontal
> *resolution*, that you use in your division. For example,
>
> 78,750,000 / 1312 = 60,022.865
>
> This is the horizontal refresh rate, which rounded to three significant digits
> is 60 kHz. This is within the horizontal sync frequency range of 30-70 kHz;
> so we're within specs.
>
> Continuing on, the sixth number, 768, is the vertical *resolution*. It is the
> number of *visible* scan lines on the screen. The seventh number, 769,
> represents the start of the vertical sync pulse. The eighth number, 772,
> represents the end of the vertical sync pulse. And finally, the ninth number,
> 800, represents the end of the vertical frame. It is this number, the
> vertical *frame length*, not 768, the vertical *resolution*, that you use
> in your next division.
>
> 60,022.865 / 800 = 75.028581
>
> This is the vertical refresh rate, which when rounded to three significant
> digits yields 75.0 Hz. This is within the vertical sync frequency range of
> 50-160 Hz; so again we're within specs.
Uhm. I see.
STF
http://eisenbits.homelinux.net/~stf/
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