Trent Piepho wrote:
On Mon, 23 Feb 2009, Hans de Goede wrote:
Trent Piepho wrote:
On Sun, 22 Feb 2009, Hans de Goede wrote:
Trent Piepho wrote:
On Sun, 22 Feb 2009, Hans de Goede wrote:
Yes that is what we are talking about, the camera having a gravity switch
(usually nothing as advanced as a gyroscope). Also the bits we are talking
about are in a struct which communicates information one way, from the camera
to userspace, so there is no way to clear the bits to make the camera do something.
First, I'd like to say I agree with most that the installed orientation of
the camera sensor really is a different concept than the current value of a
gravity sensor. It's not necessary, and maybe not even desirable, to
handle them in the same way.
I do not see the advantage of using reserved bits instead of controls.
The are a limited number of reserved bits. In some structures there are
only a few left. They will run out. Then what? Packing non-standard
sensor attributes and camera sensor meta-data into a few reserved bits is
not a sustainable policy.
Controls on the other card are not limited and won't run out.
Yes but these things are *not* controls, end of discussion. The control API is
for controls, not to stuff all kind of cruft in.
All kind of cruft belongs in the reserved bits of whatever field it can be
stuffed in?
Not whatever field, these are input properties which happen to also be pretty
binary so putting them in the input flags field makes plenty of sense.
What is the difference? Why does it matter? Performance? Maintenance?
Is there something that's not possible? I do not find "end of discussion"
to be a very convincing argument.
Well they are not controls, that is the difference, the control interface is
for controls (and only for controls, end of discussion if you ask me). These
are not controls but properties, they do not have a default min and max value,
Camera pivot sensor ranges from 0 to 270. How is that not a min and max?
they have only one *unchanging* value, there is nothing the application can
Camera sensors don't have an unchanging value.
And who says scan order can't change? Suppose the camera returns raw bayer
format data top to bottom, but if you request yuv then an image processing
section needs to kick in and that returns the data bottom to top.
Yes, because hardware designers like throwing away lots of transistors to
memory so they are going to put memory in the controller to buffer an entire
frame and then scan out the memory buffer in different order then the sensor
gave them the data, so they cannot do FIFO, so they will actually need 2 frames
of memory.
If the sensor is soldered upside down on the PCB that is a very much unchanging
value, and an input property if you ask me.
So new proposal: use 2 bits in the input flags to indicate if the input is
hardwired vflipped and/or hflipped.
Create a new class of controls for querying possible changing camera properties
like pivoting and aperture.
Regards,
Hans
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