Hi Laurent,
Laurent Pinchart wrote:
On Tuesday 10 January 2012 00:26:46 Sakari Ailus wrote:
Laurent Pinchart wrote:
On Monday 09 January 2012 23:32:06 Sakari Ailus wrote:
Laurent Pinchart wrote:
On Monday 09 January 2012 18:38:25 Sakari Ailus wrote:
...
A fourth section may be required as well: at this level the frame rate
(or frame time) range makes more sense than the low-level blanking
values. The blanking values can be calculated from the frame time and
a flag which tells whether either horizontal or vertical blanking
should be preferred.
How does one typically select between horizontal and vertical blanking
? Do mixed modes make sense ?
There are minimums and maximums for both. You can increase the frame
time by increasing value for either or both of them --- to achieve very
long frame times you may have to use both, but that's not very common in
practice. I think we should have a flag to tell which one should be
increased first --- the effect would be to have the minimum possible
value on the other.
But how do you decide in practice which one to increase when you're an
application (or middleware) developer ?
I think it's the responsibility of this library to do that, unless the
user wants really, really precise control in which case they have to
deal with the blanking values directly. In general it should be the
library.
And how does the library decide ? :-)
frame_time = pixel_rate / ((width + hblank) * (height + vblank))
The user gives you frame time and the configuration contains the
information which one to prefer. Let's say the user prefers hblank (from
the above):
(width + hblank) * frame_time = pixel_rate / (height + vblank_min)
hblank = pixel_rate / (height + vblank_min) / frame_time - width
width, height, pixel_rate and blankings are as in the pixel array.
Elsewhere these values may depend on the link frequency and other
factors so the pixel array is the only reliable place to do this.
--
Sakari Ailus
sakari.ailus@xxxxxx
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