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Picture in picture (pip) video with ffmpeg

The following command line worked on Ubuntu 13.10. However it does not work with the avconv/ffmpeg shipped with Ubuntu. Instead a static build was used from this site:

 ~/bin/ffmpeg -i inlay.mkv -i background.mp4 -filter_complex "[0]scale=iw/5:ih/5 [pip]; [1][pip] overlay=main_w-overlay_w-10:main_h-overlay_h-10" PIP_video.mp4

This part:


...seems to control the size of the inlay, so a bigger divisor yields a smaller inlay. It may be that the [pip] follwing the part, tags file 0 as a pip thingy.


This part:


...seems to control where the inlay is placed, with coordinates being x,y with origo in the top left of the background (main) video. "main_w", "main_h", "overlay_w" and "overlay_h" seems to be variables available denoting the width and height of each video.

It may be that the "[1][pip]" preceding it first refers to the background video (being indexed as 1, that is the second video in a 0-based system), and the the "[pip]" somehow carries over from the preceding part and then references the video there. "pip" may have some pippy meaning or it is just a tag.



In a recent time I had a task to make a picture in picture effect of two videos using ffmpeg.In this blog I am going to share the details of how to make a PIP effect using ffmpeg and also configuring some of its factors.

Read more: Link - PICTURE IN PICTURE effect using FFMPEG

Aug 21, 2014 08:20

How could one automatically sync two audio recordings?

Let's say I want to do a video presentation, where I want to record the audio that I want to use, onto a separate device, separated from the video camera.

I have now tested Allison Deal's Video sync (also linked under "Update II" in the question) and it seems to do the job.

In the root of its git directory there is a file called "". If you comment out the test code at the end of that file, it can take two mp4 videos and print the time offset between the audio in the two videos.

I tested it with a Canon HF200 video camera and an LG G2 android phone, with talk and finger snaps and very low volume on the video camera. I then manually analyzed the sound tracks with audacity.

The script indicated an offset between the two track of 15.1893 seconds. My manual analysis by looking at waveforms gave 15.181 seconds (audacity does not output less than millisecond resolution, at least not by default).

The difference is only 8.3 milliseconds or thereabouts which seems to indicate that "" does the job.

(Beware that the git repo is hefty, probably due to deleted big objects)

One way of doing that is to record the audio also with the camera, and then use your eyes and ears to sync the audio up using Audacity. How do that is described here:

How to Sync Video and Separately Recorded Audio, Using Only Open-Source Software

Update: I have found this python application with matching Android clapboard that could do the trick. It seems to work by syncing to a special sound recorded both in the video file and in the external audio file.

Update II: And here is another one in python, that is meant to be used to sync up Yotube videos recorded at the same concert.

Aug 19, 2014 08:05

A protected address book for Android - how to make one

Many apps that get installed on an Android tablet or phone take a keen interest in the system address book. It is a place where Google can check your Facebook contacts and vice versa, and where Microsoft (in the shape of Skype) and many smaller companies also can take a stab at analyzing your social network.

There have been attempts at protecting the system address book from prying eyes, but as far as I know there are no simple up-to-date solutions.

So the obvious solution ought to be instead to create an app that is your address book, your real address book with its own database and hence with your contacts stored away from the system address book.

Someone ought to make such an app, and it cannot be that hard to do. Let's call it the Protected Address Book. It should be open source of course or we are back in the morass.

Initiating communication from the Protected Address Book

Many communication apps surely rely on the system address book for pulling contact information out, but it ought to be possible to initiate communication from the Protected Address Book, similar to a share button (or indeed use that one). In order to get around idiosyncracies of different apps, a plug-in system could be in place to get the right behavior from Gmail, Telegram, WhatsApp, Facebook, Skype and other apps.

Anyone up for getting the Protected Address Book rolling?

Aug 19, 2014 07:10

Wireless microphone options for video presentations

I am currently researching wireless microphones for video presentations. I considered lavalier type microphones, which you clip on to your clothing, but decided to go for the earmic type, where the microphone is mounted on a wire around your ear.

To me the earmic seems to be in a position that is more predictable than clipping a lavalier mic onto whatever clothing you may be wearing at the moment. Ear mics may possibly pick up smacking and hissing from your mouth as you are talking to a larger degree than a lavalier type mice would, but I will take that risk. A lavalier type microphone also has the problem of picking up noise as it scratches towards your clothes.

These ones I've found interesting so far:

AKG WMS 40 Mini Earmic ISM3 - Thomann UK (~ €100)
the t.bone TWS Headset 863 MHz - Thomann UK (~ €100)
the t.bone TWS One C Headset - Thomann Sverige(~ €50)

t.bone is Thomann's own brand, apparently AKG compatible on the mic connector side. The AKG seems to have better sound quality

A video report on two of the units listed above, including the AKG (in German): Link - Mit Nackenbügelmikrofon aufnehmen - YouTube

Aug 18, 2014 04:55

Getting Skype to work again in Linux

If you are on Skype 4.2, it has stopped working on Linux. You will not get an upgrade message, just a cryptic "Can't connect" message. The recommended solution is to upgrade to 4.3, which is supported by Microsoft. However that alone did not work for me, even when uninstalling the old version with "purge" (getting rid of old config files).


I also needed to delete the hidden Skype folder in my home directory:


First get rid of the old skype from repo: sudo apt-get purge skype Second, delete your ~/.Skype folder rm -R ~/.Skype

Read more: Link - Skype can't connect - Ask Ubuntu

Aug 13, 2014 08:56

Tip on masking tape when painting

Basically when painting in two colours with masking tape, after you have done the masking over the "Base" colour, paint the base colour again on the non masked areas where you want the accent colour, let it dry an apply the accent colour. In this way the base colour will bleed under the tape, and seal and prevent bleeding from the accent colour.


The base is the color that's under the tape. Doing it this way lets that color bleed under the tape, but you won't see it because that's what color that part of the wall already is.

Read more: Link - icaruscoil comments on We painted our bedroom orange and grey, and threw up a neat wall pattern. No more boring brown walls.


masking, maskeringstejp, painting, måla, måleri

Aug 05, 2014 08:45

Discussion on avoiding spam in comments

I run a custom-designed and developed system on my webforms. While the implementation is typically specific to a site, CMS, forms plugin, or what have you, the concepts behind it are general enough to be applied anywhere you have a form. It doesn't prevent 100% of spam, but by targeting the primary behaviors spambots use it prevents the majority of spam on web forms. There's two basic behavior-blocking elements at play in it:

Read more: Link - Strycken1 comments on Your users deserve better than Disqus

Jul 29, 2014 09:02

Skriv på bästa amerikanska

Assisterar med att ta bort passivum, använda verb istället för adverb med mera, i engelska språket.



Read more: Link - Hemingway

Jul 22, 2014 06:04 | Comments (2)

A handbook on how to build trust and topple dictators

Written by Gene Sharp. Can be downloaded here:

Deals with how to build trust between people and slowly strengthen the civil society until the dictator can be toppled (and something better come in his place).


From Dictatorship to Democracy, A Conceptual Framework for Liberation

Read more: Link - From Dictatorship to Democracy - Wikipedia, the free encyclopedia

Jul 12, 2014 12:04

Python's dateutils: "Generic parsing of dates in almost any string format"

Worked like a charm for me:


Generic parsing of dates in almost any string format;

Read more: Link - python-dateutil - Labix

Jun 27, 2014 09:19