Category Archives: Stuff

Hate ads on your smart phone? Pi-hole it permanently!

Sorry about spammy headline ;).

Below I will describe how I got rid of ads on my android phone without rooting it.
It is very easy to get rid of ads on an android smart phone if you have root access. Unfortunately pesky manufacturers insist on declining warranty if the phone is rooted.
I will probably one day test this is in small claims court for a cheaper phone. I digress…

The requirements:

  • Some linux box/container/VM. In this post I used Ubuntu 16.04 LTS
  • Public IP on the box from above
  • Some linux/cli/unix experience

How does it work?

  1. Smart phone connects to the Linux box via OpenVPN
  2. Linux box is running Pi-hole which acts as a selective DNS server
  3. ???
  4. Proft!

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Simple IMAP to IMAP migration/sync tool

I had a need for a simple IMAP to IMAP sync tool, yet the only useful things I could find were offlineimap and imapsync.
The offlineimap is too complex and does not exactly do what I want; while the latter went commercial and not is not a clean install (requires messing with CPAN/perl libraries).

How hard can it be to write one?

Here it is:

The configuration is fairly simple (and self explanatory):

trash=Deleted Items


Here how it works:

It logs in into both IMAP servers and basically copies (with optional source deletion) the messages across. It also avoids duplication by checking Message-ID header. It should be stable enough to “daemon”-ify.

Here is a systemd unit for it (if one wants it to run all the time):


Description=IMAP to IMAP sync tool



Part 1: Implementing communication protocol for GT06E GPS tracker – WTF is CRC-ITU???


As an experiment I bought a relatively cheap GPS tracker that supported 3G (most of them at the time were 2G only).
After quick google search I found a suitable model GT06E from Concox.

The idea was I would implement my own server, as I do not trust 3rd party GPS tracking services (who would?), especially free ones ;).

I did not realise at the time what a mess the protocol is.
The “engineers” who wrote the spec for the protocol are crazy! They reinvented the wheel, which instead of tyre utilizes boots.

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Hikvision applied shotgun to the foot and squeezed the trigger

I guess I will not be recommending Hikvision any more to anyone.

Here is why:

So in short, Hikvision decided to only sell their cameras to authorized installers. The same installers that want $800 for $80 camera.
Well guess what, screw you Hikvision this is not pre-internet era where greedy corporation can dictate what is happening on the market.
I guarantee that this move will not curb prevalence of Chinese sourced cameras on ebay and aliexpress.
Granted this only affects UK and EU. I think this is just a beginning.

I personally will not be buying Hikvision and will definitely advising against buying Hikvision (be that from authorized rip-off artists or aliexpress).

As a company you should not screw with enthusiasts, as the same enthusiasts will be making purchasing decisions for their employers, and you will be losing many million of dollars at the end of the day. I am glad we went with Dahua.

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I decided to replace the 6300k HID bulbs on one of my cars, with more sensible 4300k OEM solution.

I came across reasonably priced Toyota Genuine Bulbs on (NZ ebay type of thing).

The particular bulbs I was after were D4R, or Toyota Genuine Part 90981-20015 (alternatively Philips 42406).

They were priced (~$80NZD) similar to Genuine Philips 42406 in USA (~$50USD), so seemed to be reasonable. The Toyota Genuine are after all Philips 42406 in TGP box.

When I tried to fit the bulbs I noticed they were extremely tight. Then I looked closely and did some googling.

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HUSQVARNA rip-off pricing in NZ

So, I came across an interesting, but not surprising thing with Husqvarna MSRP prices in NZ compared to USA.

I recently looked at Husqvarna 445 and when googled for it, I got multiple MSRP prices (one for NZ, on for AU and another for USA).

Husqvarna 445 MSRP by country:
USA: 329.95 USD

AU: 899.00 AUD (~$690 USD)

NZ: 1019.00 NZD (~$745 USD)

According to NZ customs duty calculator using US MSRP price as base the fair MSRP price in NZ should have been $599 NZD (~$440 USD).

What is with the ~$150 USD price difference between NZ and Australia? According to Husqvarna Americans are twice better than Australians and more than twice better than Kiwis. They treat Kiwis like chumps that will buy thing at whatever prices Husqvarna feels like.

Guess what, from now on I will be avoiding the Husqvarna until these greedy corporate types will pull their heads out of their asses and set fair MSRP prices. In this global economy it is very stupid not to have standardised prices across the globe.

If I really wanted to buy one, no way in hell I would be buying it in NZ, as for about $150NZ I can get it shipped from the states.

python OpenCV basic motion detection

Here I will describe how I use OpenCV for capturing RTSP streams, with purpose of motion detection.

For basic OpenCV I use these two libraries:

import cv2
import numpy as np

cv2 is OpenCV library (second version), and numpy is python numeric lybrary (useful for manipulating matrices among other things).

To initiate capture one simply does following:

cap = cv2.VideoCapture('rtsp://')

In this example I use second stream (of lower resolution) for motion detection.

From there you can get heigh and width of the frame (this will be useful later):

width = cap.get(3)
height = cap.get(4)

I use BackgroundSubtractorMOG for motion detection (somewhat cheating ;)):

bg = cv2.BackgroundSubtractorMOG(100,3,0.6,30)

The magic is in parameters, I used following:
100 – history
3 – number of Gaussian mixtures
0.6 – background ratio
30 – noise strength
The numbers above are not necessarily “correct” but I came to them with error and trial (and “guestimation”).
Here is document in detail describing this algorithm:

The actual capture loop looks something like this:

    ret, frame =
    motion = bg.apply(frame, learningRate=0.005)
    kernel = np.ones((3, 3), np.uint8)
    motion = cv2.morphologyEx(motion, cv2.MORPH_CLOSE, kernel, iterations=1)
    motion = cv2.morphologyEx(motion, cv2.MORPH_OPEN, kernel, iterations=1)
    motion = cv2.dilate(motion,kernel,iterations = 1)
    contours, hierarchy = cv2.findContours(motion, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
ret, frame =

captures a single frame

motion = bg.apply(frame, learningRate=0.005)

extracts a black and white image with the background removed (learnignRate value has been chosed by error and trial).

Next four lines simply manipulate extracted image in such that it does following:
MORPH_CLOSE: removes small holes (up to 3×3 pixel, defined by kernel) within the object (“white”) in the extracted motion matrix.
MORPH_OPEN: removes small dots within the “background” (black) in the extracted motion matrix.
dilate: is making sure there all adjacent islands are joined together, so when we extract contours we get small amount of contours as result.

The “3×3 pixel” block comes from here:

kernel = np.ones((3, 3), np.uint8

The last step from processing frame is extracting the contours:

contours, hierarchy = cv2.findContours(motion, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)

The extracted contours can then be iterated and hull drawn around them:

for cnt in contours:
    hull = cv2.convexHull(cnt)

The hull points then can be checked against the mask if motion is inside of the area of interest:

Lets define the mask as the whole frame (I am pretty sure there is a better way;)):

mask_points = [
( 0 , 0 ),
( 1 , 0 ),
( 1 , 1 ),
( 0 , 1 ),

for point in mask_points:
    mask_array.append([[int(point[0] * width ), int(point[1] * height )]])
mask = np.array(mask_array, np.int32)

This looks cumbersome, but what I am achieving here is converting mask_points list of human readable relative coordinate tuples (eg: centre will be at (0.5,0.5)). Mask can be defined as a polygon with relative positioning of each corner to the frame (independent from pixel size).

We check if hull point is inside our mask

for point in hull:
    distance = cv2.pointPolygonTest(mask,tuple(point[0]),1)
    if distance > 0:

and vice-versa (in case if mask is smaller than the frame):

Note: The colour is defined by this tuple: (0,255,0)

Then do display the whole thing insert this inside of the while(True):

k = cv2.waitKey(30) & 0xff
if k == 27:

The above is basic idea behind my motion detection scripts. I have omitted a lot of glue logic and arithmetic due to my script is not ready for public display ;).

Subaru Genuine Parts in New Zealand

I have owned numerous Toyotas in past.
When switching from Toyota to Subaru I did not expect to be shocked by such price difference of genuine parts between each brand.
Both Japanese, both of good quality vehicles, similar niche…

Oil and air filters are priced very close (about ~$20NZD for oil filter and ~$40NZD for air filter), beyond that Subaru parts are rip-off.

For example, for my 1998 ST205 Celica GT4, the genuine front brake rotors were ~130NZD each. About double of aftermarket from BNT or Partmaster.
Considering brake rotors are consumables that is very reasonable price.
When I inquired about rotors for my 2008 GRB Subaru WRX STI (JDM), initially I was quoted ~1060NZ each (retail), that came down to $900NZ each. After shopping around I found the cheapest price in New Zealand for genuine front rotor would be ~$695NZ each (trade price BTW).

What is the difference between Toyota Celica GT4 and Subaru WRX STI rotors:
dimensionally they are very close:
315mm x 32mm
326mm x 30mm
So please explain to me why such a price difference?
Genuine Brembo rotors can be bought in USA for about $160USD retail (it would cost uneconomical amount of $$$ to get them shipped to NZ).

Another example is another consumable, brake pads, Toyota Genuine front pads for ST205 Celica (very similar to STI pads) cost about ~$90NZD.
Subaru, at first I was quoted ~$730NZD, then I got “trade” price of ~$620NZD (from Winger). In USA same pads cost around $200USD ($260NZ).

So given the options I got rotors from Partmaster (“Italian made”) for $90NZD each, and pads (Bendix SRT) from BNT for $280NZD a set. Bendix SRT pads were later replaced by Ferodo DS2500 all round (a bit better pad in my opinion).

When I imported my STI it had rear cargo blind missing (BTW Subaru calls it “TONNEAU COVER”, Part number 65550FG002ML).
I enquired about it locally, Winger quoted me ~$430NZD and that was “trade” price (fuck that differentiation). The retail was about $630NZD. For piece of vinyl on a stick with a spring, FFS!?!?
Same part in USA costs around $140USD ($180NZD).
In Japan I got price of 22000JPY, which works out to $235NZD (I don’t have to pay shipping due to special arrangements).
So how does $250 (retail) item becomes $630 item, by just arriving to NZ?

I don’t even dare to think about how much Subaru will charge me for wear items like shocks (Toyota price is ~$140NZD each) and bushes…

Hopefully due to Toyota’s stake in Subaru will have some culture changes, which will lead to price standardisation, making consumables cost like consumables (and not gold-pressed latinum). One would only hope.

Buying Hikvision cameras in New Zealand

This is how you buy genuine Hikvision cameras in New Zealand:
You don’t.

All I wanted to buy is a genuine Hikvision camera locally (with correct Language flag set in firmware, and basic support).
I went onto global Hikvision website and checked listed distributors for New Zealand. I also e-mailed Hikvision regarding the New Zealand distributor.

The Hikvision website lists Atlas Gentech as their distributor. This was confirmed via email as well.

From quick look on Atlas Gentech website it appears that they are deal with trade only (ie wholesale shop).
I have contacted Atlas Gentech, and they confirmed that you need to be a company to deal with them.
They provided me with couple of their customers I could enquire regarding buying Hikvision cameras.
Both of the contacts given were security companies (not a retail shop), as well as what appeared to be “one-man” operations. The security companies naturally have no interest in selling hardware to customers, they are more naturally inclined to sell services (ie. installation and monitoring). There is simply a conflict of interest there to start off.

I have contacted these companies. Only one responded.

Originally I have enquired about DS-2CD2032-I with 12 mm lens. I have been told that it is unavailable and was given two options:
DS-2CD2232-I5 for approximately $700NZ + GST (~$620USD). BTW I have bought DS-2CD2232-I5 from Aliexpress for $95USD. The most expensive DS-2CD2232-I5 on Amazon was around $240USD, while the US version (with correct language flag) is sold around $170USD.
and DS-2CD4232FWD-I a vari-zoom/vari-focal camera for approximately $1200 + GST (~$1073USD). The DS-2CD4232FWD-I can be bought for about $400 USD on Aliexpress.

The camera bought from Aliexpress physically does not differ from cameras that being sold here. The only difference is the language flag (which is fixable), and obviously support/CGA.

I also found that the Aliexpress sourced camera can be bought on trademe for $250NZ ($194USD).

I had expectations of paying maybe 2 times of the US Version, the expectations were completely shattered when Atlas Gentech confirmed that quoted $700NZD + GST was reasonable (and not bullshit RRP price). lets assume that US Version retails for $200USD (a bit higher than $170USD on Amazon). The $620USD is over 3 times of the retail price of US Version.
Remember when camera sold on Aliexpress for $95USD the Alixpress makes a cut, the seller on Alixpress makes a cut and the Hikvision still makes a profit. Looking at the cost of Ambarella SoC (wholesale around $20USD), the cost of making the camera is around $40-50USD. Selling camera for $620 USD is pure greed.

Hikvision is blatantly ripping off New Zealanders, because they can. Shame on you Hikvision for doing so, and shame on you for artificial differentiation of the markets by setting the language bit. Geo-locking in Internet world is stupid and futile.

Shame on you Hikvision for violating GPL as well, since when I bought the cameras there was no mention of the licence, and the camera definitely uses GPL licensed software. The GPL code requests were fallen to silent ears. This company is behaving like a greedy parasite, taking from community and not giving anything back.