We had a sparse turnout this month (as we did last month). One thing notable: We had two visitors, Tammy and Bridget from Modis, who came to give their organization some exposure to our group. Because there are many more people who read the email than attend the meeting, I suggested that they might be better served to be mentioned here. Modis provides a service to connect companies which have staffing needs to the talent to fill those needs. I will ask them to fill in the details in a separate message of their own in this mailing-list.

Modis has offered to sponsor our January meeting and provide refreshments (soft drinks and pizza were suggested.) Since they will be the ones organizing the refreshments, I will leave it to them to leave a message about the details, but I think that an RSVP would be in order, just so they can plan on how many people to provide for. During the meeting, they will give a description of the services they offer. We will still have our regular program as well.

Although I doubt that this is necessary, I should mention that I have no connection to Modis or their representatives aside from what has been described in this message. If there are other corporate interests who would like to sponsor a future meeting and give a brief talk on why they want to contact linux-o-philes, I will be glad to make some similar arrangements.

For the December meeting (unless someone has another suggestion,) we will proceed with the "programming workshop" program. If anyone who is familiar with a particular language would like to contribute, I would welcome their contribution. This could work out to be a several-month topic if there is enough interest.

I will cover C and AWK for sure. Jose has offered to talk about NetLogo. I will try to find someone, or learn enough, to talk about Python as well.

Program notes from November meeting:

I gave a demonstration of the Audacity software package, showing various functions that I use frequently. I often use it for splitting large files into smaller ones. The example I used was a capture of an audio cassette (played into the LINE-IN port) which had many songs on it. I selected one short song to work with because the computer I was using was slow. I demonstrated using the "crop" function to separate that song from the rest of the file, and also demonstrated various functions that Audacity offers, such as:

  • Changing the pitch of the music (keeping the tempo the same)
  • Changing the tempo of the music (keeping the pitch the same)
  • speeding up or slowing down the music (changing both pitch and tempo together.)

It was noted that many of these functions introduce some distortion to the music. For example, changing the pitch one octave up, then changing it one octave down gives you a noticeably different sound than the original.

One thing I have done since the meeting (which I had hoped to do at the meeting, but dropped due to lack of time to prepare) was to work on an audio track I had captured in a wilderness setting with some bird calls on the track. I had several problems to overcome:

  • there was a lot of wind noise.
  • the volume was very, very faint.
  • there was some extraneous noise (footsteps, breathing, other animals).

I ran a frequency distribution on a section of the track that had only the bird calls, then another section with wind noise and noticed that almost all of the wind noise was below 2KHz, while the bird calls were around 3KHz. My first effort was to run a high-pass filter (or low-frequency-blocking filter) set just below 3KHz. This eliminated almost all of the wind noise. I followed up with a band-pass filter to select only sounds near 3KHz.

Next, I ran a "Normalize" on the results to bring up the volume to an acceptable level. There remain a few "weird" sounds (the footsteps and wind noise primarily) that were loud enough and broad-spectrum enough to survive the 3 KHz selection filters. But overall, there is quite a lot of nothing-but-bird remaining on the track. (Anyone who is interested, email me privately and I can forward the starting, interim and final results.)

Anyway, that's just one more example of a way that you can use Audacity.

Please feel free to suggest ideas for the programming language workshop meta-topic. And, as always, any other ideas for the meeting programs are always welcome.

-Shay