Re: [ANN] Notes on IRC meeting on new sensor control interface, 2012-01-09 14:00 GMT+2

[Sakari Ailus <sakari.ailus@iki.fi>]

Laurent Pinchart wrote:
> Hi Sakari,
>
> On Tuesday 10 January 2012 10:42:58 Sakari Ailus wrote:
>> 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):
>
> That was my question, how does the user decide whether hblank or vblank is
> preferred ?

I think that should be defined in the configuration itself. It's very 
unlikely there's any need to change this dynamically.

-- 
Sakari Ailus
sakari.ailus@iki.fi