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CameraFi, USB Webcam-to-Android App

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#1 MattT

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Posted 03 May 2015 - 12:00 PM

Has anybody tried this app?

https://play.google.....camerafi&hl=en

 

Website here:

http://vaultmicro.bl...ml?view=sidebar

 

If it can display live video from an astronomy "webcam" like the Celestron Neximage 5 or the Orion USB Eyepiece II, it might be a fun and easy way to show live views on a tablet at outreach events. I installed the app on my Acer A500 tablet and it seems to work, but I don't have an astro-webcam to test it with.

 



#2 LoveChina61

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Posted 04 May 2015 - 08:24 AM

The free app is a nice compliment to the software application on my laptop that I use to access one of my Foscam FI8918W Wireless IP Cams. I just downloaded the app and installed it on my Android. My camera responded quite slowly to commands from the app but I will enjoy having it on my Android to give curious friends a peak around my observatory.

 

Mike


Edited by LoveChina61, 04 May 2015 - 08:28 AM.


#3 MattT

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Posted 04 May 2015 - 09:26 AM

Great! I know little about these things.....do you think it would work with a simple astro-webcam like the Orion USB Eyepiece II? What about a more sophisticated one like the Neximage 5?



#4 ccs_hello

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Posted 04 May 2015 - 05:07 PM

Matt,

 

First, let's understand the imager type that will have to feed an Android:

1. IP webcam: these are digital video format, further compressed down (usually severely) then packetized (into IP packets)

                         They usually use WiFI to connect to the Android.  They are not really using USB interface thus not in-scope with your original question

                         BTW, their usage in asro applications are fairly limited due to lack of manual control and other limiting factors.

 

2. Videocam with an analog video output, which then feed into a video-to-USB dongle.

              These USB dongles usually generate tremendous amount of traffic in USB 2.0 high-speed form and require isochronous transfer mode.

              I have yet seen any Android can handle such type of load feeding into it.

 

3. Astro-imager with USB interface: these IMO really shouldn't be called webcams but "imager head".  

              These are hard nut to crack for an Android due to lack of device driver (which needs to be compiled into the Kernel), so many flavors,

              and lack of downstream processing power in the Android itself.

 

4. USB webcam using UVC as its software interface protocol: many modern USB webcams took this common approach, since UVC is a common interface definition

               thus less a need on proprietary driver need to be written.

               However, IMO, the basic UVC spec is written mainly for a common video interface, it is less feature-rich for many still shoots in astro use cases.

               Some vendors tried, however you know the "wall" is just a distance away.

               In a way, it is the word "common" that kills the niche.

               I will describe it in the next post.

 

5. USB webcam using proprietary interfaces.   This is similar with (3) except that the webcams is more or less a commercial  or consumer grade "webcam"

                and the features are pretty limited.  Due to garden variety, you usually will not find a device driver for Android.

 

6. Android's own built-in camera(s): these have special feed into Android Main processor's GPU section via CSI data highway.

               The image processing algorithms are GPU proprietary in the firmware and some useful features are not directly exposed.

 

For Android, the main hope is (4), but subject to many limitations and set-backs described in the next post.

 

Clear Skies!

 

ccs_hello


Edited by ccs_hello, 04 May 2015 - 05:15 PM.


#5 ccs_hello

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Posted 04 May 2015 - 05:31 PM

UVC webcam is a dream for software developers.  One common interface definition and to support UVC (USB Video Class) webcams, develop once and use many times.

It's a convincing proposition.

 

Can it happen on Android?

 

For requirements has to be met:

 

1. The specific Android device has to support USB OTG mode 

 

2 The Android device has to supply power to the attach USB UVC webcam, some can't and its OTG mode will shutdown automatically

   Some can but this poor Android battery quickly runs out.

   There are simple external wiring arrangement thru a powered USB Hub to get around it.  But it's ugly and need one more external power supply.

 

3. (this is the common approach) You will hear some Android can support UVC webcam with the following two conditions met

    (a) Android's factory Linux Kernel is compiled with UVC driver included or somehow someone root your Android and put in a custom Kernel, and

    (b) Android has to be rooted, since /dev/vid0 (a video device) need to have the proper mode setting in order to be accessed by the user-mode apps

 

4. Then there is a recent development, call it a serious hack.  (This is what the thread title refers to.)

    What it does is to take advantage of recent Android OS's exposing of the "USB Host" mode.

    With modern OS and that mode, the USB traffic is now exposed to user-space as it is.

    The CPU is using its raw power to decode USB traffic, understand it's UVC, extract the data in fairly low level, then give the app access to UVC webcam images.

    It's fairly complicated and would burn CPU cycles (and lower battery usage time.)

 

These are technical details.

Sorry for so wordy.  But if you and read in between the lines... (you need the right tools to do the right job in the first place ...)

 

Hope it helps.

 

Clear Skies!

 

ccs_hello



#6 MattT

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Posted 05 May 2015 - 01:11 AM

Thanks for the crash course in webcams!

 

As a liberal arts luddite....it sounds unlikely that even a basic 480 resolution webcam like the Orion USB Eyepiece will work with my Android tablet, at least not without some hacks that are probably beyond my skills. Still, next time I'm passing by Orion I'll pop in with my tablet and see if they have a camera I can hook up and try.



#7 ccs_hello

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Posted 05 May 2015 - 07:52 AM

Matt,

 

Let me use a direct-approach...

 

For new comers in astro, I'd suggest an easier path.

Android and USB webcam sounds cool but the underlying details can be hard and challenging.

If you are die hard fan of using Android OS, then just wait for a proven solution is found.  Not using your own funds for trials and errors.

 

I also do not suggest the very lowend CMOS "solar system" imagers.  These quickly worn out your patience.

Ask around, many have these toys, used once, and now in their closet.

 

For a quick answer and if it must be Android, use its own built-in camera and pointing into the telescope eyepiece.

It is called afocal photography.

 

Clear Skies!

 

ccs_hello




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