Saturday, December 13, 2008

Adding Reiser4 and Ext4 support in the 2.6.27 kernel

I recently bought a new hard drive, and thought that I might try some "new" filesystems that I haven't used before. Therefore I went with the Reiser4 (not supported in the kernel, and won't be in the near feature for several reasons) and Ext4 (which will be in 2.6.28).

To add support for these file systems we need to patch the kernel with the official patches that we can find here and here respectively. Download the files (to your desktop in this case) and extraxt them into your kernel directory.

# cd ~/Desktop/
# gunzip reiser4-for-2.6.27.patch.gz
# bzip2 -d 2.6.27-ext4-2.bz2
# sudo cp reiser4-for-2.6.27.patch 2.6.27-ext4-2 /usr/src/linux/
# cd /usr/src/linux

Then su and type in you password (or do the rest with sudo). To apply the patch we use the command "patch", with the -p argument.

# patch -p1 < reiser4-for-2.6.27.patch
# patch -p1 < 2.6.27-ext4-2

Then we need to enable it.

# make menuconfig

and enable the new filesystems that exists under the "File Systems". Build the kernel and install it.

# make all modules_install
# make install

Then let's cross our fingers and hope it works!

Tuesday, November 18, 2008

Hell has finally frozen over!

Today marks a milestone in human history, like when man crawled onto land and decided to stay there, or the industrial revolution. Adobe has finally released a 64 bit Flash version for Linux! And not only for Linux, but also for.. oh wait, no ONLY for Linux! It must be the first time ever a large, closed source, company releases a linux version before any other platform. Kudos to them! I just wish they would focus on a 64 bit ver... oh wait.

This is just an early version, "pre release quality", but it does mean alot. I'll download it as soon as possible, and I hope you don't forget to also report bugs on their official bugtracker, and not only complain on a forum somewhere. But what took them so long? Tinic Uro explains some of it on his blog.

This was probably one of the last things that my girlfriend complains daily about, which usually goes like:
"Why the HELL do you want things like this?! Never ANYTHING working! Always spending half an hour fixing this and that, EVERYTIME we are supposed to watch a movie (with subtitles), youtube video or listen to internet radio."
I also saw that Sun is actually about to release (newly released) their 64-bit version of their JRE and their java plugins as well. It only took them 4 years to fix that bug! Now it is supposed to work on Linux/Windows/Mac and soon Solaris. Hell, maybe soon I won't even bitch monthly about surfing the web.

Monday, October 27, 2008

Sound problems on Ubuntu Intrepid Ibex

I've been running the Intrepid Ibex Beta for about a month now, and I must say it is surprisingly unstable and troublesome. At least for a beta. Now, when it is slowly approaching the release date of 8.10, it is starting to reach a certain level of stability and usability.

Something that was a bit more annoying than losing wifi - since I have an extra network cable close to the couch - is actually the loss of all sound. Except a crackling sound every now and then when trying to play a file (no matter if it is video or music). I have an Intel card, but I don't know if it only happens on those cards.

I did however find a small fix for it, I just needed to restart alsa, and force it to reload the modules. Why this had to be done, I don't know, but 2 seconds later the sound was back. Crisp and crystal clear.

The key?
alsa force-reload

This fixes the issue for good, also after a reboot.

Wednesday, September 17, 2008

Working some magic in (G)Vim

It's hard not to love Vim when substitutions and movement is as beatiful as it is. The commands of the day are:
:%s/_LIT(K\(.*\),.*);/TBool CAudioMgmtServerWrapper::\1()/g
These few commands actually lets us completely reformat a block of text, remove comments, add variable names and then turn it into a list of functions again. Sweeet.
Let's go through them a bit more in detail:

:g/exp1/d - cut (delete) the text that matches the expression1 inside the "//".

ggVG - go to the top (gg), go into 'mark mode' (V) and then go to the EOF (G). This is performed in ordinary command mode.

:retab! - Let's replace whitespaces with real tabs instead.

:%s/exp1/exp2/g - Replace expression1 with expression2, and do it for all occurences on every line (g).

Tuesday, September 9, 2008

How to change/update the URL of your SVN repository

Sourceforge has done some huge updates and changes during the last couple of months, and I might not be the busiest bee regarding updates and commits to my own project, Subspace Battle.

Today when I was doing some updates and fixes, I tried to call it a night and did the final touch: a commit. But for some reason I kept getting a '403' error, which means there is some security issue. I knew my password was correct, and also the user, so what could it be? Perhaps the UUID of the server had changed after sourceforge's updates, and that somehow stopped the update. I checked their website to see if there were any changes or big "REMEMBER TO DO THIS" signs waving at me, but saw none.

After reading through parts of the svn guide, I compared my repository URL to the one I got from the 'svn info' command. It turns out that they have switched to https (instead of http), which means my URL was wrong. So how do we update it without downloading another local copy of everything? I tried several different solutions, and finally find the right one!
svn switch --relocate
This simply changes the URL of the repository that your local version maps to. Or as the 'help' chapter describes it, if only I had read that sooner...
switch (sw): Update the working copy to a different URL.
usage: switch --relocate FROM TO [PATH...]

Rewrite working copy URL metadata to reflect a syntactic change only.
This is used when repository's root URL changes (such as a scheme
or hostname change) but your working copy still reflects the same
directory within the same repository.
Now let's get on with the commits!

Sunday, September 7, 2008

Sending output from one command to another

When I recently updated xorg-server to version 1.5.0 (which comes with the new that is released soon!) I needed to rebuild some of the drivers (packages) that comes with it. To get the list of drivers I use the command qlist.
$ qlist -I -C x11-drivers/
which outputs a list of packages from the category x11-drivers that are installed (-I) and without color (-C). Although it's nice to get a list like the one I got:
$ qlist -I -C x11-drivers/
it's a bit annoying if you have to copy and past all these onto the command line as parameters to the 'emerge' command. So what we do is get the qlist to list these packages into the emerge command. This is done using the "$" symbol, which first evaluates the output of its embedded command, and then outputs it as a parameter to the parent command. To clarify:
$ parent-command $(command we want the output from)

which in our case turns out to be:
# emerge $(qlist -I -C x11-drivers/)
This starts the emerge and re-compile of all our drivers. Now we wait... ;)

Sunday, August 31, 2008

Using find to recursively unrar all files in subfolders

Sometimes when I've downloaded something, it is compressed into several small rar files, divided into lots of subfolders. This can be handy to keep track of files, but at the same time a pain in the ass when uncompressing them. You simply have to go into each subfolder and either run:
$ unrar x *01.rar
or using a gui-tool to unrar/unzip them. A little trick to make this a lot faster is to simply use the "find" command to find all the files you need, and then send them into whatever program you need to decompress them. You can use the same command to pipe files into playlists or even to compress files into several folders.

Now in this example we have a folder structure like the following:
$ ls -l
totalt 2,3G
First we start with the find command.
$ find ./software-foo*/
This will list all files in the folders. Each subdirectory in its turn contains:
$ ls -l
To unrar, we need to define the first file (or any really, but just one) in each subdirectory. To show just the files we add the "-type f" flag. To then be able to parse the list, we also add a check for filenames. This is done with the "-name" flag.
$ find ./software-foo*/ -type f -name '*01.rar'
This gives us a list of the filenames that match the pattern *01.rar.
$ find ./software-foo*/ -type f -name '*01.rar'
So here is our list of files that we want to unrar. We then add the flag "-exec" to perform a command on the given files. The command we want is "unrar x", and then we also need to add some extra syntax to give the command its parameters.
$ find ./software-foo*/ -type f -name '*01.rar' -exec unrar x {} \;
Now we just wait! This decompresses all the files in all the subdirectories into the current directory. Perhaps not the best thing if it's hundreds of sourcefiles, so we have one more trick. Instead of using the "-exec" flag, we use the "-execdir" flag. Instead of performing the command from the directory where "find" was invoced, it performs it from each subdirectory. This sorts the files into subfolders for us!
$ find ./software-foo*/ -type f -name '*01.rar' -execdir unrar x {} \;
Hope this helps in the future! This is one reason why the command line is hard to replace fully in a GUI application.

Saturday, August 30, 2008

Using the PlayStation 3 as a media center with Linux

I recently got a PlayStation 3 from my wonderful girlfriend, and one of the reasons I wanted one was for its great possibilities of being a media center. I installed MediaTomb on my Linux machine (Gentoo) and after half an hour of configurations, it was ready to stream content to the PS3.

Installing MediaTomb
Portage is wonderful, and of course contains MediaTomb. It is an open source uPnP media server with DLNA support. DLNA is a protocol that computers and other devices can use to talk to each other, for instance when supplying video files over a network. It can do much more too, just have a look at the link to wikipedia for more info. When I did my install, I followed the guide at To get more information (especially regarding transcoding), check the site there, this is my "shortcut" guide to it.

Install it using portage:
# emerge mediatomb
Make sure you have the use flags that you need enabled. I'm using
[I] net-misc/mediatomb
Available versions: 0.11.0 {curl debug exif expat ffmpeg javascript libextractor mysql taglib}
Installed versions: 0.11.0(22.28.13 2008-08-17)(curl exif expat ffmpeg javascript taglib -debug -libextractor -mysql)
Description: MediaTomb is an open source UPnP MediaServer
and that works well for me. Since I rather use sqlite instead of a full mysql install, I haven't enabled that use flag.

When streaming to the PS3, you also need to enable some transcoding support. This also allows you to get thumbnails on the different video files. I use ffmpeg as my transcoder, since I already have it installed. Make sure you have the "encode" use flag enabled. If you need video thumbnails, also install ffmpegthumbnailer. support.
# emerge ffmgeg
# emerge ffmpegthumbnailer
Then you have to create 2 scripts to launch the transcoding for you. First the script for audio (/usr/bin/mediatomb-transcode-audio):


exec "${FFMPEG_PATH}" -i "${INPUT}" -vcodec ${VIDEO_CODEC} -b ${VIDEO_BITRATE} \
-ac ${AUDIO_CHANNELS} -f ${FORMAT} - > "${OUTPUT}" 2>/dev/null
and then the one for video (/usr/bin/mediatomb-transcode-video)


exec "${FFMPEG_PATH}" -i "${INPUT}" -vcodec ${VIDEO_CODEC} -b ${VIDEO_BITRATE} \
-ac ${AUDIO_CHANNELS} -f ${FORMAT} - > "${OUTPUT}" 2>/dev/null
We need to make them both executable:
# chmod +x /usr/bin/mediatomb-transcode-audio
# chmod +x /usr/bin/mediatomb-transcode-video
My config file now looks like the following. Copy it to /etc/mediatomb/config.xml and start MediaTomb.
<?xml version="1.0" encoding="UTF-8"?>
<config version="1" xmlns=""
<ui enabled="yes">
<accounts enabled="no" session-timeout="30">
<account user="mediatomb" password="mediatomb"/>
<sqlite3 enabled="yes">
<mysql enabled="no">
<protocolInfo extend="yes"/>
<import hidden-files="no">
<scripting script-charset="UTF-8">
<virtual-layout type="builtin">
<extension-mimetype ignore-unknown="no">
<map from="mp3" to="audio/mpeg"/>
<map from="ogg" to="application/ogg"/>
<map from="asf" to="video/x-ms-asf"/>
<map from="asx" to="video/x-ms-asf"/>
<map from="wma" to="audio/x-ms-wma"/>
<map from="wax" to="audio/x-ms-wax"/>
<map from="wmv" to="video/x-ms-wmv"/>
<map from="wvx" to="video/x-ms-wvx"/>
<map from="wm" to="video/x-ms-wm"/>
<map from="wmx" to="video/x-ms-wmx"/>
<map from="m3u" to="audio/x-mpegurl"/>
<map from="pls" to="audio/x-scpls"/>
<map from="flv" to="video/x-flv"/>
<map from="avi" to="video/x-divx"/>
<map from="divx" to="video/x-divx"/>
<map from="vob" to="video/x-divx"/>
<map from="audio/*" to="object.item.audioItem.musicTrack"/>
<map from="video/*" to="object.item.videoItem"/>
<map from="image/*" to="object.item.imageItem"/>
<treat mimetype="audio/mpeg" as="mp3"/>
<treat mimetype="application/ogg" as="ogg"/>
<treat mimetype="audio/x-flac" as="flac"/>
<treat mimetype="image/jpeg" as="jpg"/>
<treat mimetype="audio/x-mpegurl" as="playlist"/>
<treat mimetype="audio/x-scpls" as="playlist"/>
<treat mimetype="audio/x-wav" as="pcm"/>
<treat mimetype="audio/L16" as="pcm"/>
<treat mimetype="video/x-msvideo" as="avi"/>
<treat mimetype="video/divx" as="avi"/>
<treat mimetype="video/vob" as="avi"/>
<transcoding enabled="yes">
<transcode mimetype="application/ogg" using="audio-common"/>
<transcode mimetype="application/ogg" using="video-common"/>
<transcode mimetype="audio/x-flac" using="audio-common"/>
<transcode mimetype="video/x-flv" using="video-common"/>
<transcode mimetype="video/divx" using="video-common"/>
<transcode mimetype="video/divx" using="video-thumbnail"/>
<profile name="audio-common" enabled="yes" type="external">
<agent command="mediatomb-transcode-audio" arguments="%in %out"/>
<buffer size="1048576" chunk-size="131072" fill-size="262144"/>
<profile name="video-common" enabled="yes" type="external">
<agent command="mediatomb-transcode-video" arguments="%in %out"/>
<buffer size="10485760" chunk-size="262144" fill-size="524288"/>
<profile name="video-thumbnail" enabled="yes" type="external">
<agent command="ffmpegthumbnailer" arguments="-i %in -o %out -s 128"/>
<buffer size="524288" chunk-size="512" fill-size="1024"/>
Start it using
# /etc/init.d/mediatomb start
Adding files and directories
To add files to the MediaServer, simply point your favourite browser to and then press the "Filesystem" link to the left. There you can add the directories you want, and the server parses them for you. If you have inotify enabled in you kernel (which you probably do) it will be possible to let the server automatically know when something has been changed, and it reparses that directory when needed.

Thursday, August 28, 2008

Mesa releases v.7.1

On the 26th of August, Mesa released the 7.1 version of their open-source implementation of the OpenGL library.

This is a development release, and warns that users focused on stability should go for the 7.0.4 release instead (or wait for 7.2). There are some interesting features added though, like DRI enhancements, "lots of DRI driver fixes", and GL_EXT_texture_from_pixmap in Xlib driver. They also mention the upcoming change to the GEM Memory Manager. The last is not in this release, but it is in the master branch of the GIT source tree, so I guess now we just wait...

The most interesting for me however is probably the support for the GL shading language on the i965 driver (Intel cards), this might actually mean that the integrated graphics card on my laptop finally supports shaders! Welcome to 2004! I bought the laptop with the intel card because of their great open source support, but was very (to say the least) surprised when it didn't have support of OpenGL2.0 or higher (or at least the shader side of it). Now my masters thesis might actually look a bit better, or at least as crappy as it looked on my desktop computer. +