Desktop Recording on my Laptop

Submitted by gfranken on Thu, 11/26/2009 - 15:27

After retiring from 34 years of teaching high school computer science and mathematics, I finally thought I'd have some time to create some good instructional video lessons. My initial goal is to produce series of instructional videos for software that is cross-platform FLOSS--Inkscape, the GIMP, OpenOffice.org, computer programming in Ruby and Python, and so on. Along with my desktop computers, I wanted to use my new Acer laptop to produce these videos.

So, I need a good screen recorder program, that will record video to the screen and also record my audio.

RecordMyDesktop won't do the job on my Acer laptop! The on board ALC888 audio records with skips, tonal anomalies, and a great deal of hiss. I've spent a lot of hours try to fix these issues. No joy. So I look around for another Linux screen recorder program that will work. I find DemoRecorder.

The commercial (I purchased a copy) DemoRecorder program does work in its opengl mode, and fixes the sound skips and tonal anomalies, but the video sound still has a (very) loud background hiss. While DemoRecorder records the video in its own proprietary format, I discovered that the sound is recorded as a wav audio file (without the .wav extension), which I can then open and edit with Audacity to remove the hiss. Then I run the demorec-to-avi DemoRecorder program to assemble and transcode the recorded files into one avi video. It works well, and gives good video and audio quality, but the extra step of editing the audio is a lot of work.

Time to look for portable audio hardware compatible with Linux and my Acer laptop. After some searching on the Net, I find the Diamond Sound Tube, a USB Audio sound device. Diamond claims compatibility with Linux. It's available at Newegg for $29.99 US, so I order it.

It arrived yesterday, and looks like an old radio vacuum tube--kind of dorky, but fun too. I plug it in, and try to get it to work with Mandriva 2010, the distro I have installed on my laptop.

I can't seem to get Mandriva to recognize it as my primary sound device. Off to the Net again to see if I can figure out how to do this. I finally discover a solution posted by Adam Williamson when he was working for Mandriva (yes, they were fools to let him go, but, he's now doing good things for Red Hat/Fedora).

To make this long story slightly shorter, suffice to say the Diamond Sound Tube device works well with both RecordMyDesktop and DesktopRecorder. No skips, tonal anamolies, or hiss. My videos now look and sound great. And general sound output to my external speakers is much better too. The Diamond Sound Tube is recommended, particularly if your laptop built-in sound is lacking.

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Sound tube howto?

Submitted by srlinuxx on Thu, 11/26/2009 - 23:30.
Quote:

I finally discover a solution posted by Adam Williamson when he was working for Mandriva

You still got the link for that?

Set USB SoundTube device as default sound device.

Submitted by gfranken on Mon, 12/14/2009 - 12:33.

Here's what I've done:

  1. Turn off pulseaudio (using the Mandriva Control Center - Sound option).
  2. Go into KDE Control Center, click the multimedia option, and set the backend from Gstreamer to Xine
    1. You may have to download and install the Xine related packages to see the Xine backend option.
    2. Setting the backend from GStreamer to Xine may not be necessary--I've had some issues with Mandriva in the past with GStreamer as the backend--but this is probably fixed now.
  3. As user root, open the /etc/modprobe.d/sound file.
    My built-in-laptop sound uses the snd-hda-intel driver, while the USB SoundTube uses the snd_usb_audio driver. (Yes, one driver name uses (-) hyphens as separators, while the other uses (_) underscores.)
  4. I've entered the following lines into this sound file:
    alias snd-card-0 snd_usb_audio
    alias snd-slot-0 snd_usb_audio
    alias snd-card-1 snd-hda-intel
    alias sound-slot-1 snd-hda-intel
    options snd_usb_audio index=0
    options snd-hda-intel index=1
  5. Reboot your machine.
  6. Go back into the KDE control center, select multimedia, and set KDE to use the preferred sound card devices.
  7. No guarantees with this howto--good luck!