OpenShot, libmp3lame and Ubuntu

If you’re getting the following error while trying export a video under several different codecs in OpenShot including AVI, MOV and MPEG using (mpeg2, mpeg4 or h.264) chances are this might help you with that error.

The following formats/codecs are missing from your system:

libmp3lame

You will not be able to use the selected export profile. You will need to install the missing formats/codecs or choose a different export profile.

This is a simple fix:

  • Open up Synaptic Package Manager
  • Search “libavformat”,
    • If the current package installed is “libavformat52″ select “libavformat-extra-52″ (alternativly “libavformat-unstripped-52″ should also work).
    • Else the package might be “libavformat53″ so simply change to “libavformat-extra-53″, basically it might end in different numbers, it should work the same.
  • Hit Apply and approve the changes.

HowTo: Remove Every Other Line in Text Files – Linux

Let’s say you’ve got a text file, of any size, big or small, and you want to remove every other line of that file, well here are a few commands in Linux that allow you to do this.

Example, you want to get from this:

1
2
3
4
5
6
7
8
9
10

To this:

1
3
5
7
9

The sed way:

 sed -n "p;N;" file.txt > newfile.txt

The awk way:

 awk 'NR%2 != 0' file.txt > newfile.txt

Here you can actually specify N lines, replace 2 in the above command and you’ll be able to take out every N’th number. As an example, here’s the above replaced with a 3 on the file:

1
2
4
5
7
8
10

Easy as pie, right?

Error: “end_request: I/O error, dev sr0, sector xxxxx” – Linux

Error:

end_request: I/O error, dev sr0, sector 537392

If you’re getting a similar error filling your screen once you’ve installed Ubuntu, don’t panic. It’s pretty common which is basically because Ubuntu (or any other Linux distro) can’t control your CD/DVD drive properly, it’s probably trying to open/close it but doesn’t know if it has or not. The problem is that you don’t get to see what Ubuntu wrote before because it’s filled your screen up with this error.

If you’ve just installed Ubuntu this probably happened when it wanted you to take the disc out and close the cd tray (if there is one) then hit Enter to finish the installation, so just do that and ignore this error.

Realtek RTL8191S in Ubuntu 10.10

Errors:

$ sudo ifconfig wlan1 up
SIOCSIFFLAGS: Resource temporarily unavailable

$ dmesg usb
rtl819xU:FirmwareDownload92S(): failed with TCR-Status: a
rtl819xU:ERR!!! _rtl8192_up(): initialization is failed!

Solution 1:

To get this wifi dongle working I simply had to download the above firmware and place it in /lib/firmware/RTL8192SU/ and then reboot my computer. You should check that location before hand and make a backup of anything inside of it if you’re not sure what you are doing. If it’s empty you can use the following commands to make the directory and then download the firmware directly.

sudo mkdir /lib/firmware/RTL8192SU/
cd /lib/firmware/RTL8192SU/
sudo wget http://svn.debian.org/wsvn/kernel/dists/trunk/firmware-nonfree/realtek/RTL8192SU/rtl8192sfw.bin

Solution 2:

Alternatively download the source and build it:

wget http://launchpadlibrarian.net/33927923/rtl8192se_linux_2.6.0010.1012.2009.tar.gz
tar -zxvf rtl8192se_linux_2.6.0010.1012.2009.tar.gz
cd rtl8192se_linux_2.6.0010.1012.2009
make
sudo make install

Downloads:
Firmware: http://svn.debian.org/wsvn/kernel/dists/trunk/firmware-nonfree/realtek/RTL8192SU/rtl8192sfw.bin

Source: http://launchpadlibrarian.net/33927923/rtl8192se_linux_2.6.0010.1012.2009.tar.gz

HowTo: Mount USB Persistent casper-rw File in Linux

So, you’ve created an awesome Live USB Linux stick with a persistence file which let’s you boot anywhere and carry all your sweet sweet datas around on it too. If you want to see those files in Linux on your desktop or laptop outside the USB you’re going to have to mount the loop device (the casper-rw file) somewhere first. The following commands show how to make a folder and mount the loop and then unmount it too.

Just change the /media/USB/ for the mounted location of your mounted USB stick which contains the casper-rw file you want to view the contents of and the /home/alex/caspermnt/ for the mount point on your system.

Mount:

 mkdir ~/caspermnt
sudo mount -o loop /media/USB/casper-rw /home/alex/caspermnt/

Unmount:

 sudo umount ~/caspermnt/

This can be useful for recovering data from a borked Live USB stick or for backing up your files on your computer just to be sure.

Using pdfcrop to Remove White Margins | Ubuntu

One of the most annoying things about PDF files are their fixed font size, the only real way of getting a better view at the text is to zoom the whole page in. This isn’t really a fix for that annoyance but it’s a way of getting more info to screen ratio by removing the wasted white space around the body of the file for each page, this really comes in useful when displaying PDF files on your Kindle, Nook, Smart Phone or other eBook Readers.

 sudo apt-get install texlive-extra-utils

It’s really simple to use and by default it crops all the white space from around an image, it does this per page rather than for the entire document which allows for the best results (as long as you don’t mind changes in font size when you’re reading it).

Change input.pdf to the name of the file you want to crop and output.pdf to the output cropped file.

 pdfcrop input.pdf output.pdf

Some PDFs have better results than others and some PDFs will look the same on eBook readers if they crop the whitespace, but it’s a useful tool to have for some of those old pesky JPEG PDF files with massive borders all the way around.

Example: Left = input, right = output

Some PDF files seem to bring up the following error:

!!! Error: Ghostscript exited with error code 1!

I’m currently not sure what causes this, possibly something to do with the encoding type of the PDF? or maybe just some missing dependencies..

For more info about pdfcrop check out the Ubuntu Manpage: http://manpages.ubuntu.com/manpages/gutsy/man1/pdfcrop.1.html

Auto Sync Kindle in Ubuntu

For Christmas I got a Kindle 3 and it was instantly filled with Free eBooks (http://www.gutenberg.org/wiki/Main_Page) and research papers (PDFs). I found myself wanting to be able to automatically synchronize it with a folder on my desktop when it was plugged in and found no one else had posted online how to do this, so I began researching into udev and rsync to get something working.

Setting up udev rules to run a script when the Kindle is plugged in.

Firstly, we need to find some parameters of the Kindle which are unique to it so that udev can identify that it is the Kindle being plugged in and not another USB mass storage device. We’ll need to find out where the device is mounted in /dev/ which can be a little tricky because this folder is pretty full.

An easier way to do this is to first, without the Kindle plugged in do the following command (list the directory and pipe the output to a file called dev1 in the home dir):

ls /dev/ > ~/dev1

Now plug the Kindle in and redo the command, changing the destination output:

ls /dev/ > ~/dev2

The difference between the two files will show what has changed in the /dev/ directory:

 sdiff ~/dev1 ~/dev2

The output for mine (show in the image below) shows that 3 things changed when I plugged in the Kindle, sdb, sdb1 and sg2 directorys were added (shown by the > sign to the left). The folder I am looking for is the sdb1, this is where the mass storage device is found.

Write down where it’s found in /dev/ and then you can clean up those two files you previously made:

rm ~/dev1 | rm ~/dev2

The next thing we want to do is use udevadm to collect some useful information about the device which we can do by the following command (I have chosen to pipe the output to a file called kindle in the home dir, because the output was pretty big. If you don’t want to remove the > ~/kindle from the end of the command):

udevadm info -a -p $(udevadm info -q path -n /dev/sdb1) > ~/kindle

WARNING: This can look pretty daunting but, (in the words of Douglas Adams) Don’t Panic.

  looking at device '/devices/pci0000:00/0000:00:1d.0/usb2/2-2/2-2:1.0/host21/target21:0:0/21:0:0:0/block/sdb/sdb1':
    KERNEL=="sdb1"
    SUBSYSTEM=="block"
    DRIVER==""
    ATTR{partition}=="1"
    ATTR{start}=="16"
    ATTR{size}=="6410672"
    ATTR{alignment_offset}=="0"
    ATTR{discard_alignment}=="4294959104"
    ATTR{stat}=="     151     3389     4239     3776        0        0        0        0        0     2424     3776"
    ATTR{inflight}=="       0        0"

  looking at parent device '/devices/pci0000:00/0000:00:1d.0/usb2/2-2/2-2:1.0/host21/target21:0:0/21:0:0:0/block/sdb':
    KERNELS=="sdb"
    SUBSYSTEMS=="block"
    DRIVERS==""
    ATTRS{range}=="16"
    ATTRS{ext_range}=="256"
    ATTRS{removable}=="1"
    ATTRS{ro}=="0"
    ATTRS{size}=="6410688"
    ATTRS{alignment_offset}=="0"
    ATTRS{discard_alignment}=="0"
    ATTRS{capability}=="51"
    ATTRS{stat}=="     156     3389     4279     3808        0        0        0        0        0     2456     3808"
    ATTRS{inflight}=="       0        0"

  looking at parent device '/devices/pci0000:00/0000:00:1d.0/usb2/2-2/2-2:1.0/host21/target21:0:0/21:0:0:0':
    KERNELS=="21:0:0:0"
    SUBSYSTEMS=="scsi"
    DRIVERS=="sd"
    ATTRS{device_blocked}=="0"
    ATTRS{type}=="0"
    ATTRS{scsi_level}=="3"
    ATTRS{vendor}=="Kindle  "
    ATTRS{model}=="Internal Storage"
    ATTRS{rev}=="0100"
    ATTRS{state}=="running"
    ATTRS{timeout}=="30"
    ATTRS{iocounterbits}=="32"
    ATTRS{iorequest_cnt}=="0xe1"
    ATTRS{iodone_cnt}=="0xe1"
    ATTRS{ioerr_cnt}=="0x1"
    ATTRS{modalias}=="scsi:t-0x00"
    ATTRS{evt_media_change}=="0"
    ATTRS{dh_state}=="detached"
    ATTRS{queue_depth}=="1"
    ATTRS{queue_type}=="none"
    ATTRS{max_sectors}=="240"

While this many look daunting, what you want to do if find some attributes from the output which mean only your Kindle will be found when looking for them all, the problem I have found is that, with udev rules you cannot go too far down in the parent tree which stops me being able to use the Kindles serial to identify it. This could mean that my computer will sync any Kindle that’s plugged into it but I don’t have 2 to check. The following are the attributes I chose:

KERNEL=="sd?", ATTRS{vendor}=="Kindle  ", ATTRS{modalias}=="scsi:t-0x00"

Now you’ll want to write the udev rule in /etc/udev/rules.d/

cd /etc/udev/rules.d/

According to the readme the numbers represent the priority of the rule (higher overriding lower) followed by a descriptive name and it must end in .rules eg (xx-description.rules).

sudo gedit 81-kindle-sync.rules

The following is the whole line I used for the udev rule, the only addition to the above is the RUN+=”/home/alex/.scripts/kindlesync.sh” which will run the script in that directory, this script contains the rsync command.

KERNEL=="sd?", ATTRS{vendor}=="Kindle  ", ATTRS{modalias}=="scsi:t-0x00", RUN+="/home/alex/.scripts/./kindlesync.sh"

Save and close the file and then restart the udev service:

sudo service udev restart

Writing a script to sync a folder on the Desktop with a folder on the Kindle using rsync:
Change the first directory from “/home/alex/ebooks/kindle_sync” to the directory on your computer where you want to keep the files that will be synced onto your Kindle and the second from “/media/Kindle/documents/sync/” to the location on your mounted Kindle where you want the files to be stored, save this file as kindlesync.sh. This is the script you call from the udev rules so for mine it’s saved as “/home/alex/.scripts/kindlesync.sh”.

#!/bin/bash

#Sync
rsync -av /home/alex/eBooks/kindle_sync/ /media/Kindle/documents/sync/

Go to the location of the script and make it executable with the following command:

chmod +x kindlesync.sh

Now try plugging in your Kindle and make sure it syncs up!

Problems

In the udev rule, ACTION==”add” can be used to specify when the Kindle is first plugged in, however when trying to use this Ubuntu’s auto-mounting service mounts the drive after the script is ran so the sync becomes useless. Without this it runs the script 3 times, twice before it has mounted and then once it has mounted – this is currently the best I have found but it’s extremely messy.

How To: Fix “Failed to download repository information Check your Internet connection.”

If you’re getting this error but you’re still connected to the internet this page might help. This error is sometimes caused by repository’s which are down or broken.

Failed to download repository information
Check your Internet connection.

From terminal run the following command:

 sudo apt-get update

If the output runs through a few repositorys but ends with something similar to the below (most probably with different repositorys failing) and ultimately stopping your updating process then there is a good chance you can fix it by just removing those failing sources from the software sources.

Err http://ppa.launchpad.net maverick/main Sources
404 Not Found
Err http://ppa.launchpad.net maverick/main amd64 Packages
404 Not Found
W: Failed to fetch http://ppa.launchpad.net/bugs-sehe/gparted/ubuntu/dists/maverick/main/source/Sources.gz 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/bugs-sehe/gparted/ubuntu/dists/maverick/main/binary-amd64/Packages.gz 404 Not Found
E: Some index files failed to download, they have been ignored, or old ones used instead.

Software Sources can be found under either:

Applications > Ubuntu Software Centre > Edit > Software Sources..
OR
System > Administrator > Synaptic Package Manager > Settings > Repositorys

Click the Other Software tab.

Nnow find the repositories which caused the failure on the update and uncheck them and then close the Software Centre.

Re-run the update command and hopefully everything will work!

 sudo apt-get update

Check the example below where gparted was causing the error:

How To: Restore Default sources.list

Having gone through several upgrades and countless repository’s added to the software sources, things can begin to get really messy really quickly and often begin to screw up when updating the system if you’re not careful. You may find yourself, like I have, wanting to restore your sources.list file back to its default in order to get things working again.

In order to do this there is a pretty handy webapp available called the “Ubuntu Sources List Generator” - http://repogen.simplylinux.ch/

By moving through each section it enables you to select your country, release and then check each repository you want to add, not only does it support all the official ones for things like security and updates, it also allows for 3rd party repos such as Banshee, Chromium, Conky and VLC amongst a bunch others. Once you have what you want hit generate and it’ll create a nice, comment, new sources.list file ready for you to replace your old one with.

You may want to backup your old sources.list just in case with the following command:

 sudo cp /etc/apt/sources.list /etc/apt/sources.list.bkup

Once you have that you can open the sources.list and simply paste the new one in from the repogen:

 sudo gedit /etc/apt/sources.list

Paste, Save and Close the file and now you should paste the generated GPG keys, found just below the generated sources.list file, into your terminal.

Everything should be back to default and allow you to once again update everything.