Coffee with crema from an Aeropress – a howto

What makes crema?

Crema is a foam comprising coffee oils, carbon dioxide created during coffee roasting and air trapped in coffee grounds. There are several exhaustive Coffeegeek articles in the subject. (I  also think electric-pump-based coffee/espresso machines increase crema by aerating brewing water.)

Why there is little crema in coffee from Aeropress?

Oils and bubbles, being lighter than water, travel up when brewing. When Aeropress is used as described in the manual, crema is filtered last and gets absorbed in the grounds and paper filter.

crema in inverted aeropress

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Video Stabilization with Deshaker in Blender

Action video is often lacking clear persistent references to stabilize video with – they either are not present in the frame for very long, or often compressed out of frame as the codec is trying to spend most of its bandwidth on moving objects in the shot.

Deshaker, a plugin for Windows program VirtualDub, with its capability to find and track multiple visual references (literally hundreds of them) automatically from frame to frame is the king of action video stabilization. (It works on Linux, too, see below).

Deshaker scanning a file

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Beat 500 points gpx track limit using Qmapshack as gpx file editor

Many Garmin devices have a limit of how many points a gpx track might have. You can bypass the limit by splitting a GPS track to segments of 500 points or less. Here is how to do it with a free Qmapshack program:

As an example, I took a 100km ride track from Strawberry Fields Forever ride. (Click on the link, click on 100km, export tab, download as GPX)

Let’s see the complete track on map: In Qmapshack, File-> Load GIS Data, select the gpx file. “Open SFF 100K” folder in Data window and double-click on the track.


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Server Wake-on-LAN on access

Most ethernet NICs support Wake on LAN feature – when a so-called magic packet wakes up the computer. This can save money, as running a Mac Pro 1,1 server fully awake could cost you at least $24.5 per month of electricity in California prices (that’s at the lowest tier of consumption).

To put my server to sleep, I use powernap (easy install via apt in Ubuntu). As I use ssh to access files, tracking TCP port 22 connection to keep server awake is a no brainer config setting.

There is a number of software utilities that could be used to send a magic packet to wake a remote machine, but if all you want is to access a file, firing up the utility each time seems too much hassle.

Running the command below on a unix-based router (OpenWRT, DD-WRT) connected to the same LAN as server will send a magic packet to your server on any access attempt. It works by sniffing for broadcast ARP packets looking for server’s IP address (e.g. and issues a magic packet to its MAC address (e.g 00:17:f2:0a:a6:3f).

Just edit the address values below, substituting LAN bridge interface, server’s IP address and MAC address, and put this line into the startup script of your router:

tcpdump -i eth1 -l arp and ether[0x26:1]=192 and ether[0x27:1]=168 and ether[0x28:1]=1 and ether[0x29:1]=191|while read -r line; do etherwake -i eth1 00:17:f2:0a:a6:3f; done&

good  luck!