![]() In this example there are no chords, and the base frequency is easily seen. It is best to try what seems like the lowest possibility first in order to avoid confusing the first harmonic (the second line from the bottom) with the base frequency (the first line), but in the case of a chord, it is best to try to erase the higher notes first. This is fairly straightforward, however things can sometimes be a bit confusing. To help you find that base frequency, you can, using any brush tool and the harmonics modifier (the button with four vertically stacked dots), hover over the image to see an overlay of the first few harmonics and with your mouse cursor try to match the cross hair overlay with the lines on the screen. It might not always be easily seen, and sometimes it's entirely absent. ![]() It is crucial to be able to identify the position of the base frequency, which is the lowest of those lines. This synthesiser is harmonic, which means it is composed of vertically stacked parallel lines, separated by constant vertical distances. In this video we see how to extract a continuous synth line graphically using those new tools. Frequency knobs to 20 and 20,000 to obtain the desired result. Once you've entered those two values in the file config.txt for 'min_frequency' and 'max_frequency' you can load Photosounder, load your sound, set the Min. Same formula for the minimum frequency by replacing 20,000 in the formula with 20, which gives you 93.808 Hz. We'll use the following formula :įmax' = Fcentre * (Fmax / Fcentre)^(1 / ratio) which gives us hereįmax' = 440 * (20,000 / 440)^(1 / 2) which you can type in Google to obtain the answer which is Because we will expand the sound in pitch by a factor of two, we need half the interval (in octaves) between the centre frequency of 440 Hz and the maximum frequency for analysis than we'll have between the cetnre frequency and the maximum frequency of the synthesised sound, which is 20,000 Hz. So with all these parameters, we now need to calculate the minimum and maximum frequencies we want to use for analysis, that's what we'll put in config.txt prior to opening the sound. Now, we want to cover the entire audible range for the output, so we want the result to range from 20 Hz to 20,000 Hz. There are two factors that need deciding, the expansion ratio we want, here 2, and which centre frequency we want, that is, which frequency will stay the same throughout the expansion. This is done here by setting analysis parameters so that only about 5 octaves of the original sound are analysed, then the frequency settings are changed so that these 5 octaves are stretched in pitch across 10 octaves. Therefore, two notes one semitone apart become two semitones apart, which creates a melody that sounds different from the original melody. It consists in expanding the spacing in pitch between notes so that each interval doubles. The video shown above is an example of interval expansion, an effect that can only be achieved through spectrogram resynthesis.
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