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Pitch Shifting, and Time Stretching<\/p>\n\n\n\n
It occurs to me that pitch shifting (while keeping time), and time stretching without changing frequency may not be as easy as I thought. I will have to return to MathCad and study that concept some more. One problem I have is that when using FFT, a number of points that is a power of 2 is used. That means, I will have to zero-pad a time-signal at the end with a zero signal prior to entering into an FFT routine. How does that zero-padding with FFT compare to just FT without zero-padding. I must study this and understand it.<\/p>\n\n\n\n I may encounter sinc function considerations as I do this, as the above functions can be thought of an arbitrary time signal multiplied by a time-shifted step function that is initially 1, and then 0 after the signal is played. This would be equivalent to zero-padding.<\/p>\n\n\n\n O(N-N) or O(N-log(N))<\/p>\n\n\n\n Will pitch shifting while maintaining time, and time-stretching while maintaining involve convolution? If so, the run times will tend to N-squared. If not then then run times can remain as N-log(N). If convolution is unavoidable, then I may be better off not using Fast Fourier Transforms that would need 0-padding. I should just use Fourier Transforms since N-squared run-times become unavoidable.<\/p>\n\n\n\n It’s time to do some simulations. This time I will use a single frequency sine wave run over part of a time interval, after which it is turned off to simulate 0-padding. I must then determine what happens in frequency space during pitch shifting, and time-stretching.<\/p>\n\n\n\n <\/p>\n","protected":false},"excerpt":{"rendered":" FFT and IFFT Implementation This week I was able to implement FFT, and IFFT functions into my program. I proved to myself that it was working by printing out the original time-based real data, followed by FFT transform of that data, followed by IFFT transform of the frequency data. I was excited to verify that… Continue reading Audio Loop Station, 5th Entry<\/span><\/a><\/p>\n","protected":false},"author":11630,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-41","post","type-post","status-publish","format-standard","hentry","category-uncategorized","entry"],"_links":{"self":[{"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/posts\/41","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/users\/11630"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/comments?post=41"}],"version-history":[{"count":1,"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/posts\/41\/revisions"}],"predecessor-version":[{"id":46,"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/posts\/41\/revisions\/46"}],"wp:attachment":[{"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/media?parent=41"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/categories?post=41"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.oregonstate.edu\/mccludav\/wp-json\/wp\/v2\/tags?post=41"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/osu-wams-blogs-uploads.s3.amazonaws.com\/blogs.dir\/4756\/files\/2021\/11\/Blog-7-Pic-1.png\")
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