Mix with sin

An experiment in mixing two videos using a continuous cross fade, synchronised loosely to the audio track.

The video is a 60 sec loop, with exact transition from the end back to beginning, designed for Instagram. It started life as two separate videos, each 60 sec long and each comprising six 10 sec sections.

The individual sections are each made from an image. This image is rotated through one full rotation over 10 sec. A rotating photograph is quite boring, until it is processed.

There are two processes applied to each of the rotating photographs. The first is sorting. The pixels of each frame are sorted vertically. The second is scraping. The pixels of each frame are scraped horizontally, rather like Gerhardt Richter scraped his Cage paintings (YouTube).

The individual sections are assembled to create two 1 minute videos, the first being all the sorted sections, the second being all the scraped sections.

If you watched these component videos individually, you would see violent jump cuts between sections because the photographs they are based on were all very different.

To avoid the jump cuts, the component videos are now cross blended using a mask (travelling matte) based on a 10 sec sine wave (hence, mixed with sine).

The sine wave mask ensures that at each peak a different jump cut is hidden. The side effect is that the video is continually cross-fading from one component to the other. This was the video effect that was originally sought. The original idea for the experiment.

The accompanying audio experiment produces a 60 sec audio loop with individual 10 sec sections cross-fading into each other in a way that loosely synchronises with the video.

This audio cross-fading is achieved in a different way, using a form of granular synthesis. The audio grains used are about 1/10 sec in duration and have all been obtained from a recording of a single string (diddly) bow being struck and scraped.

A short sequence of these grains is then elongated to a full 60 sec loop by sliding a 1/2 sec window along the recording in such a way that a vague beat is established.

Each tone sounds similar to the previous tone because they have four out of five grains in common.

This sliding window technique has been used on many tracks with different grain and window sizes and seems to have great potential. In particular it easily extends to creating very long pieces of experimental music, from relatively short samples. It also seems to capture quite well the notion of development in music.

The loose synchronisation between video and audio is created by the amount of variety in the original recording of the diddly bow and the carefully chosen assembly of audio grains that, as a consequence of the moving window, shifts to a new tone-effect over the 10 sec of the cross-fade.

The methods used to construct the video and the audio both lend themselves to extending to very long durations without repetition, while retaining a familiar feel.

Updated July 2018