Re: [Elphel-support] broken files from footage?

[support-list]

 On Mon, 29 Oct 2012 19:34:00 -0700 flavio soares wrote 
 
 > Btw, do you know what might be the cause of this header error? The cam 
 > didn't output any error messages while at the shooting set... 

Flavio, I do not know what caused it - maybe by analyzing th footage you (the 
very end of it) you can make some guesses - what did happen at that time. It 
seems that camogm just crashed, because it writes the header (atl least the 
major part of it - frame index) when it is closing the file (if it runs out of 
the reserved space for the table - it just closes that file and starts a new 
one). While the file is being recorded, the index table (displacement to the 
beginning of next frame chunk) is being built in memory. And only in the very 
end that table is known camogm writes it into the reserved space in the 
beginning of the file. It is possible to write the index at the end of file, 
but then you'll not be able to view it over the Internet simultaneously to 
downloading.

Andrey


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Re: [Elphel-support] c to cs mount adaptor ring

[support-list]

 On Tue, 30 Oct 2012 06:14:44 -0700 Venkat R  wrote  
>Hi Andrey,
>
>Attached is a side shot this time and it also has the ring in the picture.
>
>
>Thanks,
>Venkat


Venkat, it is nice that you finally found that 5mm adapter ring ( 
http://www.google.com/search?q=5mm+adapter+ring&tbm=isch ) -  "ring in the 
picture" . Yes, on the right on the image you can see both the 5mm adapter ring 
(black anodized aluminum) and the black plastic cap that is screwed into it.
Andrey



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Re: [Elphel-support] the discussion on the Heptaclops camera

[support-list]

Hi Biel, have you read the article - 
http://www3.elphel.com/linuxdevices/articles/AT9913651997.html? And maybe also 
about the shot noise - http://en.wikipedia.org/wiki/Shot_noise ?

 On Tue, 30 Oct 2012 09:25:24 -0700 Biel Bestué de Luna  wrote  

>Andrey, about only having 150 gray levels, why does the camera only output 150 
>gray levels when the image that comes out of the sensor has 4096 output 
>values? maybe this is because this amount of sampled information contain a lot 
>of noise?

You know, when they have polls to measure public opinion on something - they 
have "margin of error"?  The totla group of electrons "polled" in a pixel is 
limited to the "full well capacity" - in our case ~8500. ADC has just a little 
less precision - can count by groups of two persons (4096 levels). So even if 
you had ideal 13-bit ADC (and zero noise preamplifier) that could count each 
single person (electron) and you can get measurement where "each vote counts", 
the difference between 8000 and 8001 is meaningful for democracy, but not a 
statistically meaningful difference if you try to measure public opinion. So 
depending on the "margin of error" you are willing to accept, there could be 
certain number of polling results that are different (by at least that "margin 
of error) from each other, and theer will be much less than 8500 or even 4096 
outcomes from such public opinion measurements. And yes, you can use just 8 
bits to represent such results.

>and, if 8 bits allow 256 shades of gray, does that meant that, while 8 bits 
>per pixel allows it the camera can't reach the 256 shades of gray? if so, 
>wouldn't it mean having a lot of banding?

When the quantisation step is safely smaller than the noise, there will be no 
banding because even the sensor looks at perfectly evenly illuminated surface, 
you will not get the same output code, because pixel-to-pixel variations (from 
the same noise) will be larger than the output code levels


>what factors need to change in order to have a camera that at least has the 
>full 256 colours from 8 bits from the sensor?

It is good to have more quantization level than the number of S+N levels you 
can discriminate. Quantization noise add to the total noise, just when it is 
smaller than the sesnor noise, it's contribution is smaller in the total.

> maybe a sensor with higher ADC would do the job?

ADC is trying to measure number of electrons, so there is a natural limit to 
the ADC resolution needed.

>about shot noise, what factors make shot noise optimal for gamma 0.5, can this 
>factors be changed for other gamma values? like 0.46 (1/2.2)?

Why do you need 0.46? Shot noise (predominant source of noise when you have 
good ADC and analog circuitry) is Math.sqrt() or Math.pow(x, 0.5). It is about 
preserving sensor information. When you want different contrast on the result 
video - that would be a separate story - you can apply it in post-processing, 
in the video editor - not in the camera.

Andrey
 



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Re: [Elphel-support] the discussion on the Heptaclops camera

[Biel Bestué de Luna]

Andrey, about only having 150 gray levels, why does the camera only output
150 gray levels when the image that comes out of the sensor has 4096 output
values? maybe this is because this amount of sampled information contain a
lot of noise?

and, if 8 bits allow 256 shades of gray, does that meant that, while 8 bits
per pixel allows it the camera can't reach the 256 shades of gray? if so,
wouldn't it mean having a lot of banding?

what factors need to change in order to have a camera that at least has the
full 256 colours from 8 bits from the sensor? maybe a sensor with higher
ADC would do the job?

about shot noise, what factors make shot noise optimal for gamma 0.5, can
this factors be changed for other gamma values? like 0.46 (1/2.2)?

2012/10/29 support-list 

>  >
>  Biel Bestué says:
>  >  October 28, 2012 at 5:31 PM
>  >  damn, that is a lot of info.
>  >  the “GAINR,GAING,GAINB and GAINGB” values in the Elphel 353 is this
> analog gain in the CMOS?
>
> Not directly - autocampars.php -> parsedit.php (or directly with
> parsedit.php) you may see these parameters as well as the sesnor analog
> gain registers. Sesnor has rather larger gaing steps (you may read more in
> the sensor datasheet), while the GAINx parameters are 16-bit values. Camera
> sets the analog gain to the nearest, and then multiplies the digital code
> by a value close to 1.0 to make it possible to balance colors with finer
> steps than the sensor can do that.
>
>  >  what do you mean by “linear bits” versus “2^12 2^14″?
> 12 bit ADC has 4096 output codes. But a sensor with 12-bit ADC while
> having 4096 output values has only say 150 distinct grey levels.
>
> > maybe by  “linear bits” do you mean the colour gradient from black to
> white  resulting from using a gamma value of 1, versus the same colour
> gradient  but with gamma 0.46?
> >  shot noise is the noise in the “well exposed” areas isn’t it? the
>  minimum “vibration” of the colours in the well exposed part of the  range?
>
> Ideal gamma for working with shot noise is 0.5 - so the result function is
> Math.sqrt(). With gamma 1.0 (linear) there will be no meaningful difference
> between 4095 and 4050. having ideal illumination and static objects, the
> same pixel will provide 4000+/-44 (+/- Math.sqrt(8500)*(4095/8500) where
> 8500 is the number of electrons that fits in the pixel and correspond to
> 4095 ADC output).
>
>  >  what part does “Black level” play in this issue? I’ve seen that Black
>  level changes where the gamma curve starts to affect the picture, Black
>  level is an effector after the acquisition, as gamma seems to be, but
>  before the  picture compression? I’ve seen that there are colour
>  deviations closer to the dark tones, like colour getting too green in the
>  dark tones, is this possible that green black level should be displaced
>  further closer so the lowered green could deliver a much cleaner dark
>  colour representation?
> Black level here is just "fat zero". As the random noise on the output can
> be either sign, and cutting it at zero (pixel value should be positive)
> would skew the results. So sesnor is programmed to output small positive
> value for the zero output, default value is 160 (of 4095). You do not
> really need to change it in most cases.
>
> And, by teh way - if you use autocampars.php and open parsedit.php with
> it, each parameter has short explanation - what iis it - it appears as a
> "tooltip" when you keep mouse pointer over it.
>
> Andrey
>
>
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Re: [Elphel-support] broken files from footage?

[flavio soares]

Oleg, this made the trick! Thank you very much! =)

And thanks for modifying the script to work via command line, that was also
very helpful!

I left my house today and the footage was about 80% converted. Raise the
drums! =)

2012/10/30 flavio soares 

> Oleg, thank you very much! I'll definitely test it tomorrow
> (currently, my comp is gasping with the bunch or raw frames). I
> believe I can proceed from the jp4s using one of Carlos Padial scripts
> =)
>
> I don't believe I had wb on, I always kill the autoexposure before
> recording and I believe I turned it off in autoicampars also. I'll
> check the change in colors then.
>
> Btw, do you know what might be the cause of this header error? The cam
> didn't output any error messages while at the shooting set...
>
> Again -- thanks a lot, this doubles my security with the footage! =)
>
> 2012/10/30, Oleg :
> > I was able to split it into jpegs, here's a
> > sample<
> http://community.elphel.com/incoming/Videos/1351368477_370584.jpeg>
> > .
> >
> > Looked at the file header - the MOV header is emtpy (all zeros), while
> the
> > images exif headers are ok.
> >
> > Uploaded a modified
> > script >
> > (erase
> > .txt extension) - then you will be able to launch it from a command line:
> >
> >> php split_mov_2.php  
> >
> > example:
> >
> >> php split_mov_2.php /data/oleg/test_flavio/s01p4t2_1351346876_661174.mov
> >> jp4
> >
> >
> > Though it's not to difficult to enable php in apache))
> >
> > Note: the script will get you a bunch of jp4s right in the folder where
> the
> > mov is stored.
> >
> > BTW, I looked through the sequence - did you have auto white-balance on
> - I
> > think I noticed changes in the color.
> >
> > Oleg
> >
> >
> > On 29 October 2012 17:33, flavio soares  wrote:
> >
> >> oh, sorry, the first one was sort or 'readable' (with defect by
> >> mplayer) so I decided to upload one that was completely non-readable,
> >> sorry. but since that one ends, (it's bigger, 200mb), if you'd be so
> >> kind to test it, i'd appreciate!!! =)
> >>
> >> 2012/10/29, Oleg :
> >> > Ok, you just don't have php enabled on the web server.
> >> >
> >> > I see you have been uploading 2 files - one is already done ~21MB and
> >> > another one is still being uploaded. Shall I try the 1st one?
> >> >
> >> > Oleg
> >> >
> >> > On 29 October 2012 17:20, flavio soares  wrote:
> >> >
> >> >> Ok, one last try. I have Apache installed now and followed your steps
> >> >> - copied the file to the folder. The /teste/ folder is writable by
> >> >> everyone.
> >> >>
> >> >> Now the browser tells me "you selected to open split_mov.php". If I
> >> >> download it, it downloads the script.
> >> >>
> >> >> *I'm also uploading a 100mb sample to the ftp as I write!
> >> >>
> >> >> 2012/10/29, Oleg :
> >> >> > 1. You have apache installed right? In Ubuntu the www-root folder
> is
> >> at
> >> >> > /var/www - copy split_mov.php there,
> >> >> > 2. Make "/home/livre/Desktop/teste/" writable for everyone.
> >> >> > 3. Then go:
> >> >> >
> >> >>
> >>
> http://127.0.0.1/split_mov.php?path=/home/livre/Desktop/teste/s05cp01t03_1351438147_418343.mov&ext=jpeg
> >> >> >
> >> >> > If that won't work just upload a sample to our ftp.
> >> >> >
> >> >> > Oleg
> >> >> >
> >> >> > On 29 October 2012 17:01, flavio soares 
> wrote:
> >> >> >
> >> >> >> Something like this?
> >> >> >>
> >> >> >>
> >> >> >>
> >> >>
> >>
> http://127.0.0.1/home/livre/Desktop/teste/split_mov.php?path=/home/livre/Desktop/teste/s05cp01t03_1351438147_418343.mov&ext=jpeg
> >> >> >>
> >> >> >> It's not working -- sorry, I never used php before...
> >> >> >>
> >> >> >> 2012/10/29, Oleg :
> >> >> >> > You should be running it from a browser window like:
> >> >> >> >
> >> >> >> >> http:127.0.0.1/
> >> >> >> >>
> >> >> >>
> >> >>
> >>
> /split_mov.php?path=/home/livre/Desktop/test/testfile.mov&ext=jpeg
> >> >> >> >
> >> >> >> >
> >> >> >> > Oleg
> >> >> >> >
> >> >> >> > On 29 October 2012 16:40, flavio soares 
> >> wrote:
> >> >> >> >
> >> >> >> >> Mmmm... it says:
> >> >> >> >>
> >> >> >> >> Usage
> >> >> >> >>
> >> split_mov.php?path=&ext=
> >> >> >> >>
> >> >> >> >> I'm trying:
> >> >> >> >>
> >> >> >> >> php -f split_mov.php?path=&ext=
> >> >> >> >>
> >> >> >> >> Is that it?
> >> >> >> >>
> >> >> >> >> 2012/10/29, flavio soares :
> >> >> >> >> > Hi, Oleg! Please help me man*! =)
> >> >> >> >> >
> >> >> >> >> > * Also because this info is super relevant for the blog
> >> >> >> >> > article.
> >> >> >> >> >
> >> >> >> >> > Ok, I downloaded it, but how do I use it from a terminal?
> >> >> >> >> >
> >> >> >> >> > In the annex, goes a single teaser frame from the movie,
> >> >> >> >> > before
> >> >> >> >> > post!
> >> >> >> >> > =)
> >> >> >> >> >
> >> >> >> >> > Sebastian, I think I can upload to a server, yes. One of them
> >> has
> >> >> >> 250mb
> >> >> >> >> > I
> >> >> >> >> > guess.
> >> >> >> >> >
> >> >> >> >> > 2012/10/29

Re: [Elphel-support] Elphel camera with Raspberry Pi

[Alexandre Poltorak]

David,
This should solve the problem on raspberry pi:
mii-tool -A 100baseTx eth0 

Best regards
Alexandre Poltorak
Alsenet SA

- Mail original -
| De: "Alexandre Poltorak" 
| À: "David Haberthür" 
| Cc: support-list@support.elphel.com
| Envoyé: Lundi 29 Octobre 2012 19:42:25
| Objet: Re: [Elphel-support] Elphel camera with Raspberry Pi
| 
| Hello David,
| 
| Auto-negotiation between raspbery-pi and Elphel 353 with a
| power-injector in the middle may not work. Please try to manually set
| the network link using mii-tool on Raspbery-pi.
| 
| Regards,
| Alexandre
| 
| On Mon, Oct 29, 2012 at 6:03 PM, David Haberthür
|  wrote:
| > Dear All.
| > I intend to run an Elphel NC353L [1] on a Raspberry Pi [2], but run
| > into
| > troubles with the connection. Whenever I connect the camera via
| > Ethernet,
| > the yellow LED starts to blink, but I cannot connect to the camera
| > with the
| > Browser. Whenever I ping the camera on 192.168.0.9, the green LED
| > periodically blinks, but the terminal of the Raspberry Pi complains
| > that the
| > "host is unreachable".
| > Whenever I plug the Ethernet cable into my Macbook Pro I get a
| > connection
| > without troubles. Do I need to configure the Ethernet port on
| > Debian to talk
| > to the camera while I don't need to do that on OS X? Whenever I
| > connect a
| > LAN cable I can access the web on the Raspberry Pi, just not the
| > camera...
| > I would be grateful for some help,
| > David
| >
| > [1]: Currently on loan by the "Swiss office" of Elphel, Alexandre
| > Poltorak.
| > [2]: http://www.raspberrypi.org/
| >
| > --
| > Dr. David Haberthür
| > Swiss Light Source
| > Paul Scherrer Institut
| > WBBA/207
| > CH-5232 Villigen
| > +41 56 310 31 80
| >
| > ___
| > Support-list mailing list
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| > http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
| 
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