The eflow blog » linux

Screencasting in Ubuntu

Ben — Sun, 31 Jan 2010 16:22:33 +0000

After futile searches and a lot of old pages, I finally found a linux screencast tool: recordmydesktop.

Using the synaptic package manager, I installed recordmydesktop. Eventually I discovered that this was not the gui part of the program and installed gtk-recordmydesktop.

I’ve been very happy with the results.

Converting Everio MOV Files to FLV Using FFMPEG

Ben — Fri, 15 Jan 2010 01:07:12 +0000

I struggled with getting the mpeg2 movies from my JVC Everio HD camera into a smaller file and up onto a video sharing site with high quality.

My first attempt was with Handbrake. That converted the MOV to an MP4 very nicely. However, I wasn’t able to upload those to Blip.tv and have them convert successfully every time to an flv. Blip was timing out on the longer videos and poorly converting the smaller ones.

I then decided to try the command line ffmpeg. There weren’t any gui tools around it that I found in the repo’s, so I just tried the standard

ffmpeg -i inputfilename.mov outputfilename.flv

but that did not work. Apparently JVC doesn’t put all the right properties into the mpg2 for ffmpeg to automatically pick up the properties because I kept getting a Floating point exception.

I assumed I needed to just manually set the full command with all the different video and audio settings, but I didn’t know what those should be.

After a bit more googling I found winff. From that app I copied the command line arguments over, tweaked them a bit, and came out with this:

ffmpeg -i INPUTFILENAME.mov -vcodec libx264 -deinterlace -vpre hq -crf 22 -r 29.97 -s 960×540 -aspect 16:9 -bf 2 -b 2000kb -ac 1 -ar 22050 -ab 96k OUTPUTFILENAME.flv

The trick is to use the libx264 codec instead of the flv one. After uploading these converted movies to Blip.tv I was pleased with the results.

Grep Across Multiple Lines

Ben — Sat, 20 Sep 2008 13:28:57 +0000

I struggled for a long while to get the unix “grep” program to do a true multi word search. However, grep merely searches within lines, so only files that had all words in the phrase on the same line would be returned. I wanted to know which files in the current folder contained the words “Reuben”, “Onida” and “Cornelius” anywhere (and in any order) within them.

The solution turned out to be to grep three times and pipe each result into the next:

grep -l Reuben * | xargs grep -l Onida | xargs grep -l Cornelius

The first grep -l Reuben * returns all file names that contain the word “Reuben”. Piping that to xargs makes the second argument essentially grep -l Onida file1 file2 file3 file4 etc. This chaining can go on for as many search phrases as you have. The final output is a list of files that contain every word in your search phrase.