Re: MR97310A and other image formats

[Thomas Kaiser <v4l@kaiser-linux.li>]

kilgota@banach.math.auburn.edu wrote:
> 
> 
> On Thu, 19 Feb 2009, Thomas Kaiser wrote:
> 
>> kilgota@banach.math.auburn.edu wrote:
>>> Yes, what you quote is the SOF marker for all of these cameras. The 
>>> total header length, including the SOF marker ought to be 12 bytes. 
>>> On all of the mr97310 cameras that I have dealt with, the last 5 
>>> bytes are obviously related somehow to the image (contrast, color 
>>> balance, gamma, whatever).  I have no idea how to interpret those 
>>> values, but we can hope
>>> that someone will figure out how.
>>
>> Two of them are luminance values (middle and edge) for the PAC207.
> 
> Which two, and how do those numbers translate into anything relevant?

Looks like I had some off list (private) email conversation about the 
frame header of PAC207 with Michel Xhaard. I just paste the whole thing 
in here:

michel Xhaard wrote:
 > Le Samedi 18 Fe'vrier 2006 12:16, vous avez e'crit :
 >
 >> michel Xhaard wrote:
 >>
 >>> Le Samedi 18 Fe'vrier 2006 10:10, vous avez e'crit :
 >>>
 >>>> Hello Michel
 >>>>
 >>>> michel Xhaard wrote:
 >>>>
 >>>>> Le Mercredi 15 Fe'vrier 2006 12:43, vous avez e'crit :
 >>>>> Just relook the snoop, the header is always 16 bytes long 
starting with:
 >>>>> ff ff 00 ff 96 64 follow
 >>>>> xx 00 xx xx xx xx  64 xx 00 00
 >>>>> let try to play poker with the asumption the R mean G0 mean B mean G1
 >>>>> mean is encoded here.
 >>>>> Not sure about the 64 can you look at your snoop?
 >>>>
 >>>> I never thought about that. So, you see I have not experience with
 >>>> webcams.
 >>>>
 >>>> Anyway, here are my observations about the header:
 >>>> In the snoop, it looks a bit different then yours
 >>>>
 >>>> FF FF 00 FF 96 64 xx 00 xx xx xx xx xx xx 00 00
 >>>> 1. xx: looks like random value
 >>>> 2. xx: changed from 0x03 to 0x0b
 >>>> 3. xx: changed from 0x06 to 0x49
 >>>> 4. xx: changed from 0x07 to 0x55
 >>>> 5. xx: static 0x96
 >>>> 6. xx: static 0x80
 >>>> 7. xx: static 0xa0
 >>>>
 >>>> And I did play in Linux and could identify some fields :-) .
 >>>> In Linux the header looks like this:
 >>>>
 >>>> FF FF 00 FF 96 64 xx 00 xx xx xx xx xx xx F0 00
 >>>> 1. xx: don't know but value is changing between 0x00 to 0x07
 >>>> 2. xx: this is the actual pixel clock
 >>>> 3. xx: this is changing according light conditions from 0x03 (dark) to
 >>>> 0xfc (bright)
 >>>> 4. xx: this is changing according light conditions from 0x03 (dark) to
 >>>> 0xfc (bright)
 >>>> 5. xx: set value "Digital Gain of Red"
 >>>> 6. xx: set value "Digital Gain of Green"
 >>>> 7. xx: set value "Digital Gain of Blue"
 >>>>
 >>>> Regards, Thomas
 >>>
 >>> Thomas,
 >>> Cool good works :) so 3 and 4 are good candidate . To get good picture
 >>> result there are 2 windows where the chips measure the ligth condition.
 >>> Generally one is set to the center of the image the other are set 
to get
 >>> the background light. At the moment my autobrightness setting used 
simple
 >>> code and only one windows of measurement (the center one) .
 >>
 >> Some more info, 3 is the center one.
 >
 > :)
 >
 >>> Did you want i try to implement these feature ? or maybe you can have a
 >>> try :) the only problem i see is between interrupt() context and 
process
 >>> context. I have set up a spinlock for that look at the code how to 
use it
 >>> ( spca5xx_move_data() )
 >>
 >> Yes, please. Because I have no idea how to do this :-(
 >> I am good in investigating :-)
 >
 > I know, but can be very good in code to, as you know the hardware :) 
now let try to look at 1
                          ^^ What does this mean?
 > is there the black luma level ?
I don't get it. What is the black luma level?

Regards, Thomas


-- 
http://www.kaiser-linux.li


> By any chance, you do not have a JL2005B or JL2005C or JL2005D camera 
> among them, do you? AFAICT they all use the same compression algorithm 
> (in stillcam mode), and it appears to me to be a really nasty one. Any 
> help I could get with that algorithm is welcome indeed.

I have to check. Please send me the USB ID.

Thomas

PS: Now we have the 5. season in Liechtenstein, Fasnacht (means 
carnival). So, you can guess what I am doing the next couple of days :-)