tag:blogger.com,1999:blog-7225698277211840079.post6151472212956935707..comments2020-03-07T11:21:25.605-08:00Comments on bjorg: Frequency detection using the FFT (aka pitch tracking) With Source CodeBjorn Rochehttp://www.blogger.com/profile/17072425815152893296noreply@blogger.comBlogger19125tag:blogger.com,1999:blog-7225698277211840079.post-80377020564931963002013-07-21T17:23:18.103-07:002013-07-21T17:23:18.103-07:00It's not necessary, but it's standard prac...It's not necessary, but it's standard practice when working with floating point audio for it to be in the range [-1,1].Bjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-580175436547087342013-07-21T10:07:12.095-07:002013-07-21T10:07:12.095-07:00Why there is a need to get input data from -1 to 1...Why there is a need to get input data from -1 to 1 range? Can't sampled data be processed straighforward?ufixhttps://www.blogger.com/profile/14706110661740048707noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-4783628112752125632013-07-07T07:52:26.528-07:002013-07-07T07:52:26.528-07:00Eman, sorry for the misunderstanding. Unfortunatel...Eman, sorry for the misunderstanding. Unfortunately, I still don't understand what you are asking. If you are trying to figure out something to do with autocorrelation, the comments on a blog post about something else may not be the best forum.Bjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-54719559579534402652013-07-06T15:15:08.035-07:002013-07-06T15:15:08.035-07:00Bjorn, i know that autocorrelation is the cross-co...Bjorn, i know that autocorrelation is the cross-correlation of a signal with itself. i meant that we would get the 2 signals, find the FFT of each one, and then do cross-correlation between them.Anonymoushttps://www.blogger.com/profile/03858554082292026156noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-11106899787588162992013-07-04T18:06:12.101-07:002013-07-04T18:06:12.101-07:00Eman, I think you are lost. auto-correlation is th...Eman, I think you are lost. auto-correlation is the cross-correlation of a signal with itself. See the Wikipedia entry: https://en.wikipedia.org/wiki/AutocorrelationBjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-5365396564123693712013-07-04T15:33:20.229-07:002013-07-04T15:33:20.229-07:00FROM what i read,, were supposed to do FFT and the...FROM what i read,, were supposed to do FFT and then correlation to see if 2 audio files are the same... is that true? or am i lost?Anonymoushttps://www.blogger.com/profile/03858554082292026156noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-33944947232536736752013-06-27T12:22:36.094-07:002013-06-27T12:22:36.094-07:00Thanks I will read it now. Btw I mentioned you in ...Thanks I will read it now. Btw I mentioned you in my bachelor thesis because of this topic. Thank you very muchAnonymoushttps://www.blogger.com/profile/13438092428399966778noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-80270192868876470852013-06-27T12:01:16.509-07:002013-06-27T12:01:16.509-07:00My entry on the topic is here: http://blog.bjornro...My entry on the topic is here: http://blog.bjornroche.com/2012/08/basic-audio-eqs.htmlBjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-14211578959177776662013-06-27T11:50:21.450-07:002013-06-27T11:50:21.450-07:00oh thank you didn t know that , can you share a go...oh thank you didn t know that , can you share a good tutorial about IIR? and based on what formula is implemented yours? I don t understand much from wikipediaAnonymoushttps://www.blogger.com/profile/13438092428399966778noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-52315111630491540192013-06-27T11:43:20.199-07:002013-06-27T11:43:20.199-07:00Yes, the low-pass filters are IIR.Yes, the low-pass filters are IIR.Bjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-17383595245812512932013-06-27T11:39:39.788-07:002013-06-27T11:39:39.788-07:00isn't that an IIR filter that you implemented?...isn't that an IIR filter that you implemented?Anonymoushttps://www.blogger.com/profile/13438092428399966778noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-81053296430080705022013-04-20T19:47:10.876-07:002013-04-20T19:47:10.876-07:00Sorry I don't know how to help you with cross ...Sorry I don't know how to help you with cross compiling. You'll need to edit the makefile or maybe even rewrite it from scratch. It's not a lot of code, though, and should be easy to compile.Bjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-87329891936571142122013-04-20T00:18:01.686-07:002013-04-20T00:18:01.686-07:00Nice Blog....
How to cross compile guitar tuner wi...Nice Blog....<br />How to cross compile guitar tuner with arm in ubuntu 12.04. Followed al steps as u have written in README.While doing make i getting below error:<br />src/main.c:56:21: error: storage size of 'action' isn't known.<br />Plz reply<br /><br />Anonymoushttps://www.blogger.com/profile/11423884496764865463noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-17796598907533887022013-02-26T08:00:36.425-08:002013-02-26T08:00:36.425-08:00The link to the code is under the word "Guita...The link to the code is under the word "Guitar tuner".Bjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-43803573980269564632013-02-26T04:21:36.433-08:002013-02-26T04:21:36.433-08:00Really nice blog. Did you also post the code? I am...Really nice blog. Did you also post the code? I am new to portaudio and it takes me a long time to work with it<br /><br />thanks,<br />RafiAnonymoushttps://www.blogger.com/profile/13820872384930108081noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-37310179703672718162012-09-27T12:51:31.927-07:002012-09-27T12:51:31.927-07:00Thanks, Paul.Thanks, Paul.Bjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-842281967755415962012-09-27T12:51:08.508-07:002012-09-27T12:51:08.508-07:00Yes, autocorrelation-based techniques are great, a...Yes, autocorrelation-based techniques are great, and, as I said in my second paragraph, the techniques outlined here are not necessarily they best, but they work, and, based on my following of stack overflow, many people already have an intuitive concept of the Fourier transform, but not autocorrelation, so this is easier.<br /><br />As for FFTW, yes, it's an excellent library. It is "better" in that it's usually faster, but it's worse in that it has a more restrictive license that prevents many users from using it commercially or in something closed source (unless they want to pay), and the library I used here is more than fast enough.Bjorn Rochehttps://www.blogger.com/profile/17072425815152893296noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-12582083167446741972012-09-27T12:35:58.266-07:002012-09-27T12:35:58.266-07:00I've found that autocorrelation is a much more...I've found that autocorrelation is a much more accurate way of determining pitch than the FFT. This assumes the input has a single primary pitch. If there are multiple pitches, autocorrelation does not work. However, for a guitar tuner type app, autocorrelation is great. You need far fewer samples to get an accurate autocorrelation than you need for an FFT.<br />Autocorrelation can be computed as F'(F(x) * conj(F(x))) where F' is the inverse Fourier transform and F is the forward Fourier transform. Also, check out FFTW - a fantastic, fast Fourier transform library.Matthttps://www.blogger.com/profile/07345142192361131162noreply@blogger.comtag:blogger.com,1999:blog-7225698277211840079.post-12638810771559424372012-07-25T18:11:00.924-07:002012-07-25T18:11:00.924-07:00This is a fantastic little post! It is written so ...This is a fantastic little post! It is written so even if someone knows music theory but is not an EE, they can still get it.<br /><br />Fortunately, as an EE, I was able to really appreciate this fully :)<br /><br />Thanks Bjorn!Anonymoushttps://www.blogger.com/profile/06081758166890249703noreply@blogger.com