Spectrograms are images formed through audio-spectrographic analysis. With respect to 77 Days, thus far, the technique has been applied to the YouTube videos of both Pronunciation Book and renunciationbook.
Pronunciation Book
Spectrogram as of "How to Pronounce 32"
Audio-spectrographic analysis was first applied to PB by analysing the silences at the end of every countdown video starting from 77, with a new layer added every day a new countdown video (with accompanying silence at the end for analysis) has released.
The 154x154 spectrogram produced, referred to as the spectrogram, appears to resemble wartime recruitment posters such as Lord Kitchener's 1914 "your country needs you", as well as later imitations such as Uncle Sam's 1917 "I want you!".
Apparent noise increased up to the line from Day 55 and from then upwards the image is much clearer. This could be a hidden message in the image, or something made to look like a paused magnetic video tape, or a sync issue, like those experienced when a TV screen is recorded on camera.
However, a more likely explaination is that the creator of the videos saw how the script works and adjusted the subsequent videos to be decoded more accurately by removing the noise. Supporting evidence of this is that the script shades a pixel based on the RMSE of the samples in that pixel's frame. This means that noisier frames will get a darker pixel, whereas the audio is only binary: the frequency (≈24Hz) is either there or not, regardless of how much surrounding noise there is.
A more thorough technique to decode the spectrogram would be to use a discrete fourier transform to establish whether the 24Hz tone exists in each pixel's frame or not.
The spectrograms can be easily obtained and updated simply by running this python script:
It depends on youtube-dl and Python Imaging Library (PIL). Other than that it, automatically downloads the needed youtube files.
Renunciation Book
Though the user Renunciation Book only has one video, it was also analysed using this software, though initially the resultant spectrogram was circular in format.
