Spek updates: Debian, Windows, macOS

After a long hiatus Spek is back in Debian. It’s already in testing which means it will be included in the upcoming Debian Bookworm version to be released later this year. It also means Spek will eventually find its way into Ubuntu, Mint, and other Debian derivatives. I want to give a huge shout-out to Matteo Bini for making this happen! 🤘

Spectrogram of a FLAC file shown in Spek 0.8.5 running under Windows (translated to Ukrainian)

Beta versions of v0.8.5 installers for Windows and macOS are now available, you can get them on the download page. The packages include all the features and fixes accumulated over the last few years. Some of the highlights:

• A recent version of FFmpeg (used for decoding audio files).

• Adjustable colour palette, DFT window size and function.

• The ability to switch between audio streams and channels.

• Support for High DPI displays.

The Windows installer supports only 64 bit systems, let me know if you have a use case for a 32 bit build. The macOS installer requires Catalina or a newer version. It’s built for Intel CPUs but should work with the new ARM chips. Report bugs on GitHub if you bump into any issues.

The next step for the project is fixing outstanding bugs and making an official release. Please comment if there’s anything else you want prioritised.

Spek status update

January 2023

Spek has been moved to Substack, this will make it easier for me to keep the website up to date and for you to follow the project.

There was a flurry of activity in the codebase in 2022, the most notable change was updating Spek with the latest FFmpeg version.

A new source-only version has been released (v0.8.5), this is mainly done to bring Spek back to Debian and derivatives. There’s another independent effort to make a Flatpack package for Spek.

The next step for the project is releasing binary packages for Windows and macOS, this will bring all the features added to the project over the last few years. I’ll post a detailed list when the packages are available, in the meantime post a comment if you are interested in beta-testing a new Windows or macOS build.

Faster Fast Fourier Transform

Spek is already pretty fast at analyzing audio files and creating their spectrograms. Apparently, it can be made even faster!

A sizable chunk of processing time is spent calculating discrete Fourier transforms of audio samples. In this post I'm going to explore a few DFT libraries and compare their performance to what Spek is currently using.

This won't be a comprehensive overview of all available libraries. I'm going to benchmark only what Spek needs:

• Relatively small, power of 2 transform sizes. The default size in Spek is 2¹¹, this will be adjustable in the future, but not by much.

• Single precision floating point numbers. 24-bit significand is enough when working with audio samples.

• Only one-dimensional forward real transforms.

• Last but not least, the DFT library should be free software, actively maintained, fairly popular and multi-platform.

The list of candidates is surprisingly short:

• avfft, which is part of the FFmpeg project. This is what Spek uses.

• FFTW. Probably the most respectable FFT library of all. Supports both in-place and out-of-place transforms.

• djbfft by Dr. Bernstein of daemontools fame. It's not as performance tuned as the other two (e.g. it doesn't use SIMD instructions), but I want to see how it fares against them.

The test setup is straightforward (the code is on GitHub in case you're curious):

• Generate pseudo-random single-precision floating point samples. The number of samples corresponds to 10 minutes of signal at standard 44.1 kHz sampling rate.

• For all libraries and for all transform sizes from 2⁹ to 2¹³ run non-overlapping FFTs for the entire signal.

• Measure wall clock time only for FFTs (exclude sample generation and library initialization), take 5 measurements for every combination, report the fastest.

Results:

As expected, djbfft is the slowest, using SIMD instructions does make things faster. I am however surprised how fast the FFTW is compared to avfft (approximately 60% faster!)

Conclusion: Next version of Spek will switch to FFTW.

Spek 0.8.0 Released

After more than a year in the baking, a new version of Spek is out!

This release is almost a complete rewrite driven by the switch from GTK+ to wxWidgets to simplify packaging and to improve integration on Windows and Mac OS X. The switch also allowed to make a singe-exe version of Spek on Windows, which was a frequently requested feature.

Spek now allows to change the spectral density range, which is essential when trying to detect lossy transcodes. It also handles the low end of the density better resulting in less noisy spectrograms.

There were also some infrastructure changes: downloads and issues have been moved from Google Code to GitHub, and wiki pages with platform-specific installation instructions have been moved to a single INSTALL file.

Read the changelog for the full list of changes in this release. Download links and installation instructions are available on the Spek homepage, get it while it's hot!

Spek and Lion

Spek is now fully compatible with the recently released Mac OS X Lion. The bug that prevented it from starting up is now fixed, thanks to John Ralls and the awesome GTK-OSX project.

Get your copy of Spek today!