Matthieu Brucher's blog

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In a previous post, I’ve tried to use Qt for the editor window of a VST plugin. The thing is, I want to do more than just play with a GUI, I also want to see what is done to an audio stream by a plugin.

To do so, I’ve decided to expose the VST interface to Python. There are some implementation I’ve heard of, but they are based on Cython or other wrapping tools. Ctypes has the advantage of not needing a compilation step. There are also every functionality needed, as callback creation (plugins use a callback to ask the host some stuffs), and Python provides the additional mathematical tools to display what the plugin does. It may not be perfect, but it will be enough for a starter.
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I’m pleased to announce the first release of one of my projects. This scikits is based on a generic framework that can support unconstrained cost function minimization. It is based on a separation principle and is also completely object oriented.

Several optimizers are available:

• Nelder-Mead or simplex minimization
• Unconstrained gradient-based minimization

The usual criterias can be used:

• Iteration limit
• Parameter change (relative and absolute)
• Cost function changer (relative and absolute)
• Composite criterion generation (AND/OR)

Different direction searches are available:

• Gradient
• Several conjugate-gradient (Fletcher-Reeves, …)
• Decorators for selecting part of the gradient
• Marquardt step

Finally several line searches (1D minimization) were coded:

• Fibonacci and gold number methods (exact line searches)
• Wolfe-Powell soft and strong rules
• Goldstein line search
• Cubic interpolation

Additional helper classes can be used:

• Finite difference differentation (central and forward)
• Quadratic cost (for least square estimation)
• Levenberg-Marquardt approximation for least square estimation

Although it is the 0.1 version, the code is quite stable and is used in the learn scikit.

The package can be easy-installed or can be found on PyPI.

Several tutorials are available or will be available on the future at the following locations:

• http://matt.eifelle.com/tag/optimization/
• http://projects.scipy.org/scikits/wiki/Optimization/tutorial

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I’ve decided for once to read a novel about software. This book is about the story of Chandler, a piece of software that was a dream that didn’t quite came true.
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There are more stories of failed software projects than of failed insert_another_field projects. But why is that so? Of course, software management is young, contrary to the other fields, but there are a set of management practices that should help project managers in their jobs. Why are they failing? Is it because they are not applied? Because the field is really too young? Or something else?
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Due to the end of the free lunch, manufacturers started to provide differents processing units and developers started to go parallel. It’s kind of back to the future, as accelerators existed before today (the x87 FPU started as a coprocessor, for instance). If those accelerators were integrated into the CPU, their instruction set were also.

Today’s accelerators are not there yet. The tools are not ready yet (code translators) and usual programming practices may not be adequate. All the ecosystem will evolve, accelerators will change (GPUs are the main trend, but they will be different in a few years), so what you will do today needs to be shaped with these changes in mind. How is it possible to do so? Is it even possible?
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It’s all about passion. The second edition of the book saw its title changed (it was called My Job Went To India) to something less depressing and more adequate to what we all should do: be passionate about our work and be happy to do it (it also applies to other job than developers!).
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Some months ago, I’ve finished my manifold learning posts serie. As support for the manifold learning toolkit, I’ve also developed an optimization framework, which I’ll be blogging about, starting now.
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Is there a Google way of doing things? How did Google become the company we know? Did the society change its way of consuming? These are the kind of questions that this book tries to answer. Jeff Jarvis, the author, has a blog on which he writes about his book and the issues of the new economy.
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Free lunch is over, it’s time to go concurrent. The Art of Concurrency addresses the need for a workflow to develop concurrent/parallel applications.
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Years ago, I’ve tried to use the GPL version of Qt, but it couldn’t be done without a Qt Solution that was at the time non-free. Now, Nokia has freed and Qt and the appropriate Qt Solution.

I’ve searched if someone has already used this new version to create a VST plugin. The only blog post I’ve found does not use the Qt Solution and is not perfect. According to the documentation what is missing in this solution is precisely what the Solution should do. So let’s try it.
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