GSoC: automatic brightness adjustment

Dario Freddi drf54321 at
Sun Apr 8 13:20:01 BST 2012

Il 08 aprile 2012 13:25, Mike Dean <miketdean at> ha scritto:
> FACTS people, FACTS.  Idle speculation will
> get you nowhere in life.

As you wish:

1. In what kind of ideal world where we have working and documented
drivers for everything we could do what you said even remotely, and
most of all into userspace?

2. Your assumption that the fact a webcam might take 10 sec to start
up due to the driver is highly disputable, but let this be true - in
what way do we bypass this since we happen to be using drivers and
operating systems? I don't care about the fact that a webcam could be
much faster, I care about the fact I should use it and play by the
rules of the OS.

3. "Sharing the bitstream is impossible" is outrageous - it's the
DEVICE which gets shared, and not the bitstream. Some investigation
wouldn't hurt before calling others ignorant or lazy - have you tried
starting up two applications using a webcam at the same time? I guess
you didn't. And most of all - supposing that it was the bitstream
being shared, how do you cope with the fact that in your ideal
solution we are using a bitstream in an extremely low resolution? How
do you know when to set a higher resolution when needed? Do you want
to write a bitstream server for a webcam just for the sake of creating
a light sensor?

4. There's a neat thing called "powertop", you should try it. It tells
you stuff like, how much power is wasted after and before the webcam
gets power. On my macbook pro, powering up my webcam brought the
consumption from 20.8W to 32.7W roughly, with of course several
possible other agents affecting the measurement. You were right, it's
not an hour as I said, it's roughly 50% less of my battery life.

5. You didn't back up any of your statements with any of the facts
you're advocating for. You know, state of the art, papers,
implementations doing the same for other OSs, existing linux
implementations (there are some already, why don't you test them?
Google is your friend), stuff like that.

6. If you still think all of these people are ignorant and you are the
only gifted one who knows how a computer works from top to bottom,
this is open source and even if we are lazy you could always write a
patch, provide me a benchmark, and see your patch integrated if all of
our concerns were actually nonsense as you said.

> Oh, and an arduino is grossly overkill for something so simple.  More
> importantly, it requires an additional piece of hardware, which is very
> inconvenient and cumbersome.
> On Thu, Apr 5, 2012 at 2:24 PM, Simon Oosthoek <somlist at> wrote:
>> On 05/04/12 16:39, Dario Freddi wrote:
>> > Any other engineers want to give out their opinion? :D (joking)
>> Sure ;-)
>> On my laptop, the webcam is covered by a bit of paper (not joking, some
>> of us are paranoid ;-)
>> But why not design and build a real ambient light sensor with a usb
>> interface and use that? It probably isn't that complicated with an
>> arduino and some hobbying...
>> Cheers
>> Ir. Simon (going back into deep-lurk mode)

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