phayz's blog

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Category Archives: tip

Online web-based notes

In a previous blog entry (https://phayz.wordpress.com/2011/04/11/online-and-offline-notes-for-chromeium/) I wrote that I had been trying to find a way of maintaining notes using the Chrom(e|ium) web browser. I wanted to be able to make a note of little bits and pieces of information via my web browser *plus* have these available when I was offline. At the time I settled on the Scratchpad extension because it did what I wanted and had a bonus of keeping notes in sync on Google Docs.

After a little while I stopped using Scratchpad because I didn’t like how it looked, nor how it stored the notes on Google Docs. I later tried the SpringPad web service but this was much more than I wanted and offered an offline option only if using Chrome (or Chromium). I didn’t want my choice limited by the browser I was using at the time. For the moment I am using a web-based service named SimpleNote (http://simple-note.appspot.com) because it’s very simple but offers searching of notes. It doesn’t work offline unfortunately but I usually need these notes when the PC is on and I have Internet connectivity most of the time. If I am desperate I could try one of the third-party applications which allow for notes to be exported.

Once again I’m happy at the moment with my choice. I may change my mind again, so be prepared for future blog entries on the topic. ­čśÇ

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HowTo: Rotate a video using ffmpeg

Note:I am using Linux and have not tested this on other operating systems, so your results may vary.

I recently received a video from someone with a request to post it to a video hosting site. It all sounded simple until I found that the video had been recorded using an iPad in landscape mode so when I played the video the image was rotated. Before posting it I was going to have to rotate the video so that playback looked normal but how was I going to do that?

I first considered a video editor but the ones I considered had too many dependencies so I continued my search and eventually found a solution here:┬áhttp://stackoverflow.com/questions/3937387/rotating-videos-with-ffmpeg, which gave instructions on using ffmpeg’s “transpose” feature to┬árotate the video.

For my task here’s the command line I used. This is to entered as one line, but may be appear wrapped in your browser:

ffmpeg -i <input_video_filename> -vf "transpose=1" -r 30 -sameq -acodec copy <output_video_filename>

The “transpose” function is one of ffmpeg’s many video filters which, according to the ffmpeg man page is used to “Transpose rows with columns in the input video and optionally flip it.” Below is a list of other transpose parameters and what they do. For full details, refer to the transpose video filter┬ásection of ffmpeg’s man page for details of the necessary values.

0 = 90CounterCLockwise and Vertical Flip (default)
1 = 90Clockwise
2 = 90CounterClockwise
3 = 90Clockwise and Vertical Flip

Note: In this example I used three additional parameters:

  • “-acodec copy” parameter, which instructs ffmpeg to copy the audio, not process it again (Note: Thanks to a comment on this blog entry from Tim;
  • “-sameq” parameter so that the video’s original quality was not lost during the rotation because without it ffmpeg degraded quality;
  • “-r 30” to maintain a framerate of 30 frames per second.

Zoom zoom in GNOME 3’s Overview

When you press the Windows (AKA “Super”) key, GNOME presents the Overview, a thumbnail view of all the open windows. By accident I discovered that if you hover the mosue cursor over any of the thumbnails and move the mouse’s scroll button, you can zoom in and out the thumbnail. I’m not sure in what version of GNOME 3 this was introduced, nor what you would use it for my I thought I would mention it here anyway. ­čśÇ

How to run a Chromium “snapshot” build on Fedora 15

First, a little background: although Chromium is kindly packaged by Tom Callaway (a maintainer of a LOT of Fedora packages), when I installed it I had several problems occur. Instead I decided to try running a Chromium snapshot and it seemed simple enough:

Download the latest snapshot build (in Zip file)

  1. Unzip it to ~/bin
  2. Run the chrome binary contained

When I tried this, though, it complained that it couldn’t load a BZip2 library. Chromium was looking for the library by a different name so I created a symlink in /lib64:

ln -s libbz2.so.1.0.6 libbz2.so.1.0

 

WARNING – WARNING – WARNING: Although the next step(s) won’t harm your system I have worked out a better method of getting “Open with…” functionality working for Chromium. I will update this post with those details when I have time.

My next problem was that when I tried to use the “Open with…” functionality anywhere, a new instance of Chromium was started with a separate window and it complained that it couldn’t access my profile. I guess it didn’t like two instances running at the same time. As an ugly hack I installed the packaged version of Chromium, then:

  1. Renamed /bin/chromium-browser to chromium-browser.OLD
  2. Created a symlink /bin/chromium-browser to ~/bin/chrome-linux/chrome

So far everything’s working as I want it to but only time will tell if I have been successful. In the future I expect I’ll revert to the packaged version but for now this method is without errors and that’s what I need.

GNOME 3 tip: remove title bar from maximised windows

Note: This tip was presented by the Web Upd8 site but I wanted to mention it here in case people hadn’t already seen it there.

In a standard GNOME 3 windows have a titlebar which contains only the window’s title and a close button. To maximise the amount of vertical space available, the tip presented on the Web Upd8 site changes the theme so that maximised windows no longer have a title bar. Since the name of the application also appears in the panel at the top of the screen, there’s no information lost there. And even though the close button is no longer visible, you can easily access the window controls menu by pressing [Alt] + [Space].

If you have a netbook or simply want a little extra vertical space, try this tip for yourself.