Mencoder Timelapse

Thursday, July 23, 2015 at 11:09:04

Ages ago I blogged about creating timelapse videos from my GoPro using Mencoder. This takes the output JPEGs from the camera (at 10s intervals) and the uses Mencoder to stack them in to an MJPEG using this command:

mencoder “mf://.jpg” -mf fps=6 -o test.avi -ovc lavc -lavcopts vcodec=mjpeg:vbitrate=1600 vqmin=3

However I found that some of the JPEGs were out of sync - they are all sequentially numbered from the camera, but the OS *doesnt
pipe the filenames in the right order. The solution to this is to create a textfile with the sequential list (the /on switch) and stripped of any other information (the /a-d and /b switches). In Windows I used

dir /a-d /b /on > list.txt

This is then followed by

mencoder “mf://@list.txt” -mf fps=3 -o test.avi -ovc lavc -lavcopts vcodec=mjpeg:vbitrate=1600 vqmin=3 

which fixed the problem!

P.S. After pulling the JPEGs off the camera I used Xnview to batch resize the photos to 666x500
P.P.S. The MJPEG is then uploaded to Youtube to create an mp4.

Drone Rangers

Tuesday, July 21, 2015 at 09:58:20

Great short “Future Works” film from The Economist on the Drone Rangers….. very nicely researched and presented looking at monitoring poaching in South Africa, to disaster response in the USA and then construction site monitoring. Lots of nice examples (thanks to Paolo for passing on).

Pixel Shift Marvel

Monday, July 20, 2015 at 09:05:14

The newly released Pentax K3 II is a top end APS-C DSLR in a similar vein to the Canon 70D and Nikon D7200, with a BIG however….. Ricoh have introduced in-camera image stabilisation (like other manufacturers notably Olympus) which allows several degrees of movement on the sensor. As a result of this they have added what they call “Pixel Shift Resolution” mode. With the camera immobilised on a tripod and imaging a stationary subject, the sensor is moved by one pixel in each direction producing four images that are then merged back in to one pixel-shift image. Given that the sensor has a Bayer filter, the one pixel shift allows full colour information to be recorded for each and every pixel so removing the need for demosaicing (the the interpolation of RGB pixel values). It gives the benefit of no bayer filter yet with full colour (so detail should be similar to the Leica Monochrom). It also has the benefit of reducing noise as well.

So… you’re not going to use this on a UAV for capturing aerial imagery (which you could do with the Monochrom) but it could be very interesting for terrestrial capture of static objects. Update

Tuesday, July 7, 2015 at 21:04:12

Well the devs must have been reading my earlier post on the (very good!) because they’ve fixed my two biggest gripes!!! Yes, you can now specify the SD card to download and store your maps to meaning that the 100s Mb don’t eat up valuable storage on your device and you can now opt out on returning usage statistics.

The user interface has been simplified (although this has moved some options two presses away), but the maps remain as good as ever and regularly updated. This was driven home when on a bike ride to Normandy recently - the group lead had a road touring map which covered most country roads but was not detailed enough for city use. just came up trumps although I had forgotten to take my handlebar mount so kept having to pull the phone out of my pocket. Makes me think that a 7” tablet in a bar mounted map case would be a great addition!!

Can’t get enough of a good thing.

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