Re: [PATCH 10/11] ov534: Add Powerline Frequency control

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On 3 March 2010 02:30, Max Thrun <bear24rw@xxxxxxxxx> wrote:
>
>
> On Tue, Mar 2, 2010 at 9:27 PM, M.Ebrahimi <m.ebrahimi@xxxxxxxx> wrote:
>>
>> On 2 March 2010 16:06, Max Thrun <bear24rw@xxxxxxxxx> wrote:
>> >
>> >
>> > On Tue, Mar 2, 2010 at 10:39 AM, Antonio Ospite
>> > <ospite@xxxxxxxxxxxxxxxxx>
>> > wrote:
>> >>
>> >> On Tue, 2 Mar 2010 11:26:15 +0000
>> >> "M.Ebrahimi" <m.ebrahimi@xxxxxxxx> wrote:
>> >>
>> >> > On 28 February 2010 19:55, Jean-Francois Moine <moinejf@xxxxxxx>
>> >> > wrote:
>> >> > > On Sun, 28 Feb 2010 20:18:50 +0100
>> >> > > Antonio Ospite <ospite@xxxxxxxxxxxxxxxxx> wrote:
>> >> > >
>> >> > >> Maybe we could just use
>> >> > >>       V4L2_CID_POWER_LINE_FREQUENCY_DISABLED  = 0,
>> >> > >>       V4L2_CID_POWER_LINE_FREQUENCY_50HZ      = 1,
>> >> > >>
>> >> > >> It looks like the code matches the DISABLED state (writing 0 to
>> >> > >> the
>> >> > >> register). Mosalam?
>> >> > >
>> >> > > I don't know the ov772x sensor. I think it should look like the
>> >> > > ov7670
>> >> > > where there are 3 registers to control the light frequency: one
>> >> > > register tells if light frequency filter must be used, and which
>> >> > > frequency 50Hz or 60Hz; the two other ones give the filter values
>> >> > > for
>> >> > > each frequency.
>> >> > >
>> >> >
>> >> > I think it's safe to go with disabled/50hz. Perhaps later if needed
>> >> > can patch it to control the filter values. Since it seems there is no
>> >> > flickering in the 60hz regions at available frame rates, and this
>> >> > register almost perfectly removes light flickers in the 50hz regions
>> >> > (by modifying exposure/frame rate).
>> >> >
>> >> > Mosalam
>> >> >
>> >>
>> >> Mosalam did you spot the register from a PS3 usb dump or by looking at
>> >> the sensor datasheet?
>>
>> None, I got that register from sniffing a Windows driver for another
>> camera that turned out to be using ov7620 or something similar, though
>> I thought it has the same sensor. I double checked, this register is
>> for frame rate adjustment (decreasing frame rate / increasing
>> exposure) . And this has been used in some other drivers (e.g.
>> gspca_sonixb) to remove light flicker as well.
>>
>> >>
>> >> --
>> >> Antonio Ospite
>> >> http://ao2.it
>> >>
>> >> PGP public key ID: 0x4553B001
>> >>
>> >> A: Because it messes up the order in which people normally read text.
>> >>   See http://en.wikipedia.org/wiki/Posting_style
>> >> Q: Why is top-posting such a bad thing?
>> >> A: Top-posting.
>> >> Q: What is the most annoying thing in e-mail?
>> >
>> > I'd also like to know where you got the 2b register from, cause someone
>> > else
>> > also said 2b was filtering but the datasheet says it LSB of dummy
>> > pixel...
>> >
>> >- Max Thrun
>>
>> Definitely it is adjusting the frame rate (see the ov7620 DS for the
>> description how the register value is used, for instance). I have no
>> idea why the ov7720 datasheet says otherwise.
>>
>> Since this patch does not use the banding filter registers mentioned
>> in the datasheet maybe should be discarded. I am working on 75 FPS at
>> VGA, when I get that working well I can get back to this again.
>>
>> Thanks for the comments.
>> Mosalam
>
> Do you have a link by any chance to ov7620 DS? Also 75 FPS at VGA would be
> awesome (if its possible?). I managed to get QVGA up to 200 the other day..
>
> -- Max Thrun
>

http://mxhaard.free.fr/spca50x/Doc/Omnivision/OV7620.pdf

Mosalam
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