Audio Engineering With Linux


This project will use the alsasound (audio), libgoffice which is used by gnumeric (plots), and the fftw (fast-fourier transform analysis). This project will use these three libraries and gtk (for the gui). There are many different ways to perform this task, I chose these packages because of my experience with all of them. I am using the M-Audio Mobile Pre USB for audio I/O. Laptop soundcards stunk and typically only have one input, but if used properly, it may be possible to do this project with one input.


I am a Linux user. I use Ubuntu 6.10. I have tried other Linux distros and I currently run several. But my main laptop, is Ubuntu. This is a problem/challenge to the real world and the workplace, as most software is written for MS Windows. An example is <an unnamed pricey proprietary software package>, an audio diagnostics tool.

I usually use this pricey proprietary software package to calibrate professional sound systems using its “Transfer Function” feature (output over input). It works very well and is quick to perform, but very difficult to set up and actually perform accurately. The basic idea is that I need to be able to view the output of my sound card divided by the input to it, in the frequency domain usually done using the FFT. I have written a program that takes samples from the mic input, and send data to the line out. I have also used the fftw library to analyze samples. I have even written a few small GTK (a nice gui toolkit) programs. I think I can pull it off, but it will take some time. I am an old school C programmer. I have used many languages such as PHP, Python, Perl, but I always come back to C.

What I am going to do is write a simple GTK based program that allows me to perform the transfer function on a system. It will need to take several samples at different room locations and average them together so that I can use them to calibrate the system. It will need to be able to time-align the frequency data (delay) so that we end up with accurate curves.

Assuming I am not violating any software patents, I will release the project under the GPL on sourceforge. I have looked for a similar open-source project but it doesn’t seem to exist yet.

As I always do for any design, I will Sketch it out Before Coding™. This helps me avoid a complete rewrite midway through the coding.


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