Troubleshooting GDM error message "Oh no! Something has gone wrong"

After a recent update of several packages I booted and instead of the GDM's login screen it showed me a full-screen error message featuring a wonderfully smiling monitor: "Oh no! Something has gone wrong." My first reaction was to panic but I soon calmed down. My problem was that I had never seen a fatal message like this from GDM and so didn't know how to diagnose the problem. I Googled the title of the message and found that the following log file should contain any detailed error messages that GDM is reporting.

/var/log/gdm/:0-greeter.log

I successfully logged in at a console (i.e. non-GDM) by appending "3" to the GRUB kernel line (which specifies the run level to be booted into). I then looked at the above log file and, amongst the messages found that the file "/usr/share/gnome-shell/theme/gdm.css" was reported missing. I confirmed that that file was not there. I'm not sure what package is supposed to contain it but from doing a "pacman-g2 -Qo <file>" on other files in the same directory, it seems it should have come with the Frugalware GDM theme. For the moment I copied this file from another distribution, logged out and rebooted. This time GDM started as normal and I could log in.

Problem solved! \O/

Online web-based notes

In a previous blog entry (http://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. :D

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: http://stackoverflow.com/questions/3937387/rotating-videos-with-ffmpeg, which gave instructions on using ffmpeg's "transpose" feature to rotate 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 section 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. :D

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.

Searching for the "right" application

As I often do, I have recently been trying to find just the right application to meet my needs. My latest search is for a "communications client", whatever that means. I am usually online when I use my PC but there are also times, usually when I'm writing the Frugalware Linux newsletter, that I am not so I need offline access.

Like most people, I use both online and offline communications:

• Online - instant messaging: usually IRC;
• Offline - mail and RSS feeds.

For offline access I believe a traditional email client would probably suit since I use an IMAP server and so can download select IMAP folders. I have tried several email clients and the results so far are summarised below. In this case I was trying to find an application which had several features, which I know goes against the Unix way but that's my preference in this case.

Thunderbird

* Mail

It looks good, works well in sync-in select IMAP folders, just as I want. Thunderbird's configuration seems more complex than that of most other applications, especially when you have multiple mail accounts. Like all other mail clients, you can easily maintain a list of contacts. In summary Thunderbird works as I expect it to but I can't seem to get comfortable with its user interface with elements that I think take up too much space. I could use it if I need to.

* RSS feeds

Thunderbird works well with RSS feeds, including allowing you to import your RSS feed list.

* Extra features?

Thunderbird can also sync calendars via the Lightning extension so that's a bonus. The only problem here is that Lightning is an add-on, not an integral part of Thunderbird so as I upgrade I need to wait for Lightning's development to catch up. Of course I didn't mention above that I want sync-in of my calendar but if the application can do it I think it's a bonus.

Evolution

* Mail

Same as Thunderbird. Evolution's configuration dialog boxes seem a lot simpler than those of Thunderbird.

* RSS feeds

It seems that there was once an extension for Evolution to allow this but the project appears to be dead. Of course I can use something like Liferea but that means I don't have all my offline communications in one place.

* Extra features?

Evolution offers calendar sync-ing as a native feature and works well with Google Calendar, for example.

Opera

* Mail

I like the look and feel of Opera, user interface and so like its mail interface. I particularly like that you can compose messages in a tab, which it seems none of the other two offer. There are of course reasons for and against this so it's usually a matter of personal taste. What is annoying about Opera is trying to troubleshoot problems with mail sync-ing. It only offers a log file and then only if you manually configured it to do this. Otherwise its error reporting is poor because it doesn't help you find what's wrong. In summary I like Opera a lot but it's not open source. :(

* RSS feeds

Like Thunderbird, RSS feeds appear in Opera's mail panel and are easily managed and read.

* Extra features?

Where Opera is lacking is that there's no calendar sync-ing function, even as an extension. It has several other features that neither Thunderbird nor Evolution offer but they're not really related to this blog post.

 

I haven't yet found the "right" application but I'll keep looking...