Re: security camera software/RPi
On 10/1/2014 8:19 AM, ken wrote:
> On 10/01/2014 03:49 AM Scott Ferguson wrote:
>> On 01/10/14 17:42, Andrei POPESCU wrote:
>>> On Ma, 30 sep 14, 21:01:52, Jerry Stuckle wrote:
>>>> On 9/30/2014 7:11 PM, Andrei POPESCU wrote:
>>>>> On Sb, 27 sep 14, 05:23:29, ken wrote:
>>>>>>
>>>>>> What other cheap devices devices were you referring to that
>>>>>> would better handle the load?
>>>>>
>>>>> https://wiki.debian.org/RaspberryPi
>>>>
>>>> You've never actually tried a RPi with a camera, have you?
>>>>
>>>> As Ken said, the RaspberryPi is a very bad choice for such a
>>>> job.
>>
>> The plural of anecdote is not fact.
>> Have *you* tried it?
>>
>> The TP-Link TL-WR703N is less powerful than the Raspberry, yet it does
>> run 'monitor' with dual cameras.
>>
>>>
>>> 1. I think you're mixing up who said what 2. You haven't actually
>>> read that page, have you?
>>
>> Or these:-
>> ;http://through-the-interface.typepad.com/through_the_interface/2012/08/creating-a-motion-detecting-security-cam-with-a-raspberry-pi-part-1.html
>>
>> ;http://programmaticponderings.wordpress.com/2013/01/01/remote-motion-activated-web-based-video-surveillance-with-raspberry-pi/
>>
>>
>>>
>>> Kind regards, Andrei
>>>
>>
>>
>> Kind regards
>
> While it's understandable, unless one rereads the posts in a thread,
> that who said what can be lost, so I'll clarify: I didn't say the RPi
> was a bad choice for a security camera. What I did say was that I'd
> read that some people claimed to have done it (and were happy with the
> result). Here's one I just read which provides step-by-step instructions:
>
> <http://www.codeproject.com/Articles/665518/Raspberry-Pi-as-low-cost-HD-surveillance-camera>
>
>
> There are others.
>
> Re: the contention that "it doesn't work": That would need more
> clarification. E.g., perhaps full-motion video doesn't work, but this
> isn't necessary for a security camera. In the article I reference
> above, the author configured 2fps @ 1280x720. But then he also was
> running a webserver on the same RPi. I probably wouldn't do that, but
> rather offload the video to another machine and watch it from there. The
> point is, as is often the case, whether this works or doesn't may well
> be contingent on the system's configuration.
>
>
2fps is not considered adequate for security. Too much can get lost.
The minimum generally recognized is 7.5 fps. The RPi has trouble with
that, even if a webserver isn't running. As for offloading the video -
if you do it via the ethernet port (vs. pulling the SD card), you'll
find your RPi won't handle it. 7.5fps at 720p with 24 bit color comes
out to over 20 megabytes/sec. - far beyond the RPi's capabilities.
So, is the solution to go to a lower resolution camera? Not really.
There are three levels of detail considered for security cameras:
1. Observation - something happened
2. Recognition - something happened and it's someone you recognize
3. Identification - something happened and you don't recognize the
person but can match the person to a picture, lineup, etc.
#1 doesn't help much - other than to maybe tell you the exact time it
happened. After all, you already KNOW something happened.
#2 works if you know the person - i.e. you can see and recognize your
kid when he/she comes home. Much better, but it doesn't help much if
you don't know the person.
#3 is required for usable security. To get this, you need a resolution
of around 5px/cm (12.5px/in) at the face. Anything less and you will be
*very* lucky to get any useful information.
There are a lot of people who know nothing about what they are doing,
yet think they have security. But how many of these people have
actually used the information after a crime has been committed?
Additionally, as I said before - the RPi doesn't run Debian - the
processor the RPi uses is ARM V6 - which is old and not supported by
Debian (or any of the standard distributions). So you are required to
use their version (Raspbian) and the software they supply (unless you
can compile for ARM V6 yourself).
The RPi is a cheap toy, but that's about all it's good for. The ones I
evaluated are now in the landfill. There are much better ones out there
for very little more.
You really shouldn't comment on things you know nothing about.
Jerry
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