Screen brightness after suspend in Ubuntu

Many laptops have their screens dimmed after returning from “suspend” and cannot get back to their original brightness. The bug hasn’t been fixed for 3 years. A fix is provided in the bug report by putting something like the following in /etc/rc.local:

<pre class="src src-sh"><span style="color: #eedd82;">brt</span>=<span style="color: #fa8072;">`cat /sys/devices/virtual/backlight/acpi_video0/brightness`</span>

abrt=cat /sys/devices/virtual/backlight/acpi_video0/actual_brightness if (( $brt != $abrt )) ; then echo $abrt > /sys/devices/virtual/backlight/acpi_video0/brightness fi

Use the following

find /sys/ -iname 'bright'

to see if you need to change the exact path to the files.

Enable root account in Ubuntu?

After my recent experience with broken su and sudo commands in a failed system upgrade, I realized that although disabling the root account has many advantages, one of the disadvantage is that I can’t login as root in the terminal when I’m physically in front of the system. This is a major issue if su, sudo, and passwd binaries are broken somehow. Luckily, chroot was there to the rescue for me. Now, I contemplate whether I should enable the root account on my systems…

Flipping the classroom: creating screencast lectures in Linux

I’m debating the idea (hype) of flipping the classroom for one of my classes next Fall where students watch lecture videos at home (or elsewhere) so I could spend class time doing more hands-on activities like discussing the art of data analysis and how to solve problems with statistics. I think Khan Academy, Udacity, and Coursera are doing a great service for humanity by offering high quality courses taught by excellent teachers online that are accessible to anyone with an internet connection.

I don’t claim to be a great teacher, but I think my own students might benefit from this pedagogical method. My main concern with this approach is that not all students will watch the lectures, just as how not all students read the assigned readings (guilty as a student). I guess I can give students short quizzes during lecture to push them to watch the videos. Also, I’ll give my usual challenging homework so that only students that study the material well could excel. By flipping the classroom, more material could be covered, students have access to the recordings in addition to my slides, and I could make sure everything I want to be said are recorded (as opposed to a live session where I could forget a few points). Lecture times can then be more interactive as opposed to me lecturing them for an hour.

I think most of the online education sites use Camtasia with a Wacom Cintiq to produce their videos. I use Linux and cannot afford such an expensive device. I plan on using a screencast software like recordMyDesktop or Istanbul to record the desktop screen and audio. For recordMyDesktop, I had issues with the encode on the fly option, which means recording very long videos could be an issue (1 minute of raw video takes up about 210MB, and 1 minute encoded video takes up about 8MB). Istanbul records on the fly without problem (I think). I haven’t tried recording for an hour and 20 minutes yet.

My plan is to create my lecture slides with LaTeX Beamer and use Xournal to annotate the slides as I’m lecturing; hopefully my Asus T101MT netbook is strong enough to do the recording as I utilize it’s touchscreen capabilities. I can just switch over to Emacs to illustrate data analysis in R when needed. My main concern now is where I could host these (large) videos…

Update 4/27/2012: Screencast with ffmpeg

After some testing, I think the best screencast software on Linux would have to be ffmpeg. First, remove ffmpeg and compile it from source based on the latest version per this post. Then, create

#! /bin/bash
DATE=`date +%Y%m%d`
TIME=`date +%Hh%M`
ffmpeg -y -f alsa -ac 2 -i pulse -f x11grab -r 24 -s $(xwininfo -root | grep 'geometry' | awk '{print $2;}') -i :0.0 -c:v libx264 -preset veryfast -crf 22 -c:a libmp3lame -ar 44100 -ab 24k -threads 0 /tmp/screencast_$DATE-$TIME.mp4

For more libx264 options, see this page.

Record streaming radio with streamripper

Yes, many radio shows are available as podcasts. However, some are not. If a radio show is also broadcasted via a live stream online, then we could record it with streamripper. I did so as follow:

<pre class="src src-sh">sudo apt-get install streamripper <span style="color: #ff4500;">## </span><span style="color: #ff4500;">install</span>

## record for 60 seconds streamripper -s -l 60 -a “Prarie – %d”

To have the show be recorded automatically, first create

#! /bin/bash

## set in crontab: ## 59 17 * * 6 /path/to/ cd /path/to/save/; streamripper -s -l 3720 -a "Prarie - %d" &> /dev/null

Then add the following cron entry via crontab -e:

59 17 * * 6 /path/to/