Weekly notes 10 — Life has restarted


Still more spec, with reviews on the side.

This week, two main topics: how to properly test audio/video synchronization as a unit test on the Web, and color spaces when it comes to videos.

For the former, I ended up writing a web page that does an animation that is 640 x 480 pixels. Using <canvas> and the Web Audio API, and considering my machine was idle, I was able to record a video of this animation and sound, where we know the audio and video are synchronized. When capturing the video frame where the sound begins, one can check how far off the video is, because one grey line represents one frame worth of shift (in the future or past). I’ve checked the videos in the excellent Davinci Resolve, that is free to use but not Free Software, and then encoded using ffmpeg of course.

For the latter, I ended up digging in various sources, but it was a long time I did anything related to that. It’s really complicated, but it wasn’t that hard to remember most things I needed to remember. Of course this is for specifying how colors work in Web Codecs. I also did my first PR (number 28 no less) this week for this spec as well, a normative definition of all audio sample types.


I started again with my Eurorack modules project, that I had put aside for more than a year, because I couldn’t find the physical and mental space to work on it. I did a new face plate for my 1U Stereo Mixer (Intellijel format), which is able to mix four stereo signal into an output, with level control for each. This time using an 1.5mm aluminium sheet, that is a lot easier to cut and drill without specialized equipment.

I also soldered a 4x4 matrix mixer that I designed more than a year ago, it works well. It’s not much, but it’s honest work. I’ll be working on the face plate for this one before putting it in the case and routing dub delays through it, with ridiculous feedback paths. It’s the second module that I started from scratch. The third one is going to be more complicated, the first two were to learn Kicad and electronics design and such.

A picture of the matrix mixer without a face plate, just soldered.

Unrelated, but if your browser supports it (Chrome, Firefox in Nightly with a pref, release any minute now), the above is an image in the AVIF format. It is less than twice smaller than the JPEG used as fallback (which has been encoded using MozJPEG, which is already quite good). 135kB vs 285kB, maybe it’s time to use something else than the venerable JPEG, or maybe not.