# Pitch detection and frequencies found **URL:** \ **Category:** FMOD Engine\ **Created:** [October 23, 2015, 10:45am UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110 "2015-10-23T10:45:05Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Keitel](https://avatars.discourse-cdn.com/v4/letter/k/e5b9ba/32.png) [@Keitel](https://qa.fmod.com/u/Keitel)\ **Post date:** [October 23, 2015, 10:45am UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/1 "2015-10-23T10:45:05Z")
Hi, I have made a pitch detection program with dsp and the GetParameterFloat command, detecting the frequency every 100th millisecond. I am however puzzled by the frequencies I get as output. I made a sound file playing a plain, single C note from a keyboard, which I belive should have the frequency of 2093.0096 hz. However, I don’t understand why the frequencies from my program varies so much. The frequenciy of the note below C, B, is 1975.53, and the one above, C#, is 2217.46, and as I can see from the ouput, some of the frequencies are more than half a note higher or lower than the C note. I therefore hope someone could give a comment why this is so. Here’s the output: 2020.356567 1990.973511 2074.719971 2372.341553 1989.259766 2520.695068 2055.541748 2041.533203 2183.365967 1936.559082 2266.481934 2026.778931 1995.836182 1942.678589 1983.223755 2100.231689 2025.617798 1929.928833 1941.497437 2019.644043 2097.964600 1977.790894 1972.209961 1905.834839 2028.224243 Thanks in advance. Sincerely ---
**Author:** ![brett](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/brett/32/261_2.png) [@brett](https://qa.fmod.com/u/brett)\ **Post date:** [October 25, 2015, 11:14pm UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/2 "2015-10-25T23:14:26Z")
Try changing your window to a triangle window if you are using a pure tone. You use different windows for different types of sounds. Also try reducing or enlarging the FFT window size. It wont just give 1 solid value the whole time, but it should be pretty close, but from the numbers you give above they probably average out to about 2093. You should keep a running average to smooth the values out. ---
**Author:** ![brett](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/brett/32/261_2.png) [@brett](https://qa.fmod.com/u/brett)\ **Post date:** [October 25, 2015, 11:15pm UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/3 "2015-10-25T23:15:18Z")
Try changing your window to a triangle window if you are using a pure tone. You use different windows for different types of sounds. Also try reducing or enlarging the FFT window size. It wont just give 1 solid value the whole time, but it should be pretty close, but from the numbers you give above they probably average out to about 2093. You should keep a running average to smooth the values out. ---
**Author:** ![Keitel](https://avatars.discourse-cdn.com/v4/letter/k/e5b9ba/32.png) [@Keitel](https://qa.fmod.com/u/Keitel)\ **Post date:** [October 26, 2015, 10:18am UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/4 "2015-10-26T10:18:07Z")
Ok, thank you, but you have to explain how I change the window to a triangle and change the FFT window size. I only understand that I have to place “FMOD\_DSP\_FFT\_WINDOW\_TRIANGLE” somehwere. ---
**Author:** ![brett](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/brett/32/261_2.png) [@brett](https://qa.fmod.com/u/brett)\ **Post date:** [October 26, 2015, 9:03pm UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/5 "2015-10-26T21:03:33Z")
> [@](#): > > Ok, thank you, but you have to explain how I change the window to a triangle and change the FFT window size. I only understand that I have to place “FMOD\_DSP\_FFT\_WINDOW\_TRIANGLE” somehwere. Hi, you should use the documentation. [http://www.fmod.org/documentation/#content/generated/FMOD\_DSP\_FFT\_WINDOW.html](http://www.fmod.org/documentation/#content/generated/FMOD_DSP_FFT_WINDOW.html) has a link to [http://www.fmod.org/documentation/#content/generated/FMOD\_DSP\_FFT.html](http://www.fmod.org/documentation/#content/generated/FMOD_DSP_FFT.html) which shows DSP::setParameterInt can be used to set FMOD\_DSP\_FFT\_WINDOWTYPE and FMOD\_DSP\_FFT\_WINDOWSIZE ---
**Author:** ![Keitel](https://avatars.discourse-cdn.com/v4/letter/k/e5b9ba/32.png) [@Keitel](https://qa.fmod.com/u/Keitel)\ **Post date:** [October 28, 2015, 12:36pm UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/6 "2015-10-28T12:36:12Z")
Ok, so I did like this: ``` result = FMOD_DSP_SetParameterInt(mydsp, FMOD_DSP_FFT_WINDOW_TRIANGLE, 0); result = FMOD_DSP_SetParameterInt(mydsp, FMOD_DSP_FFT_WINDOWSIZE, 4096); ``` Hope that’s correct. 4096 seems to be what gives the most stable results. However, I am still puzzled about the output. In my program I print the average of 200 measurements made with 10 milliseconds intervals. Like this: ``` while(going){ if (_kbhit()) going = 0; result = FMOD_System_Update(system); result = FMOD_DSP_GetParameterFloat(mydsp, FMOD_DSP_FFT_DOMINANT_FREQ, &frq, 0, 0); ++counter; totalfrq += frq; if(counter==200){ frq = totalfrq / 200; printf("Detected frequency : %f\n", frq ); fwprintf(output, L"%f\n", frq); totalfrq = 0; counter = 0; } Sleep(10); FMOD_System_Update(system); } ``` When I play the C note on a keyboard I get the following results: 2325.231934 2327.076660 2367.127441 2270.046631 2366.404785 2244.767090 2289.176025 2223.448242 2175.976318 2196.502686 2197.390625 2081.131348 2138.204590 2078.389404 2172.810059 2355.056641 2375.444580 2331.669189 2342.987549 2340.032715 2299.864258 2326.206299 2169.465820 2227.807617 2145.235107 2152.538818 2052.996338 2091.300781 1967.640747 2352.203857 2387.549805 Not only do the measurements vary a lot, but neither do I find that they correspond to any frequency of the equal temperament C, whatever octave. I also run the same program with another sound file that is a harmonica playing the C in the same octave as the previous fil. Then I get this result: 3605.675537 3513.960693 3250.236572 3313.126221 3546.079346 3470.497559 3336.862305 3249.795898 3380.970703 3562.777100 3384.564697 3287.515625 3304.250977 3580.893799 3417.386475 3285.365723 3314.378662 3418.399658 3504.573975 3322.640381 3226.164063 3310.930908 3575.778320 3412.447266 3246.031494 3311.082520 3484.239258 3454.739746 3316.436279 This output also varies a lot, while it also doesn’t correspond with the previous sound file. And in addition I have difficulty with finding how it correspond with the frequency of equal temperament C. Sincerely ---
**Author:** ![nick1](https://avatars.discourse-cdn.com/v4/letter/n/47e85d/32.png) [@nick1](https://qa.fmod.com/u/nick1)\ **Post date:** [October 29, 2015, 3:29am UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/7 "2015-10-29T03:29:45Z")
> [@](#): > > Ok, so I did like this: > > ``` > result = FMOD_DSP_SetParameterInt(mydsp, FMOD_DSP_FFT_WINDOW_TRIANGLE, 0); > > result = FMOD_DSP_SetParameterInt(mydsp, FMOD_DSP_FFT_WINDOWSIZE, 4096); > > ``` > > Hope that’s correct. 4096 seems to be what gives the most stable results. However, I am still puzzled about the output. In my program I print the average of 200 measurements made with 10 milliseconds intervals. Like this: > > ``` > while(going){ > > if (_kbhit()) going = 0; > > result = FMOD_System_Update(system); > > result = FMOD_DSP_GetParameterFloat(mydsp, FMOD_DSP_FFT_DOMINANT_FREQ, &frq, 0, 0); > > ++counter; > totalfrq += frq; > > if(counter==200){ > frq = totalfrq / 200; > printf("Detected frequency : %f\n", frq ); > fwprintf(output, L"%f\n", frq); > totalfrq = 0; > counter = 0; > } > > Sleep(10); > > FMOD_System_Update(system); > > } > > ``` > > When I play the C note on a keyboard I get the following results: > > 2325.231934 > 2327.076660 > 2367.127441 > 2270.046631 > 2366.404785 > 2244.767090 > 2289.176025 > 2223.448242 > 2175.976318 > 2196.502686 > 2197.390625 > 2081.131348 > 2138.204590 > 2078.389404 > 2172.810059 > 2355.056641 > 2375.444580 > 2331.669189 > 2342.987549 > 2340.032715 > 2299.864258 > 2326.206299 > 2169.465820 > 2227.807617 > 2145.235107 > 2152.538818 > 2052.996338 > 2091.300781 > 1967.640747 > 2352.203857 > 2387.549805 > > Not only do the measurements vary a lot, but neither do I find that they correspond to any frequency of the equal temperament C, whatever octave. > > I also run the same program with another sound file that is a harmonica playing the C in the same octave as the previous fil. Then I get this result: > > 3605.675537 > 3513.960693 > 3250.236572 > 3313.126221 > 3546.079346 > 3470.497559 > 3336.862305 > 3249.795898 > 3380.970703 > 3562.777100 > 3384.564697 > 3287.515625 > 3304.250977 > 3580.893799 > 3417.386475 > 3285.365723 > 3314.378662 > 3418.399658 > 3504.573975 > 3322.640381 > 3226.164063 > 3310.930908 > 3575.778320 > 3412.447266 > 3246.031494 > 3311.082520 > 3484.239258 > 3454.739746 > 3316.436279 > > This output also varies a lot, while it also doesn’t correspond with the previous sound file. And in addition I have difficulty with finding how it correspond with the frequency of equal temperament C. > > Sincerely It should be FMOD\_DSP\_SetParameterInt(mydsp, FMOD\_DSP\_FFT\_WINDOW\_TYPE, FMOD\_DSP\_FFT\_WINDOW\_TRIANGLE); ---
**Author:** ![Keitel](https://avatars.discourse-cdn.com/v4/letter/k/e5b9ba/32.png) [@Keitel](https://qa.fmod.com/u/Keitel)\ **Post date:** [October 29, 2015, 10:52am UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/8 "2015-10-29T10:52:28Z")
I tried this, but it gave syntax error. ---
**Author:** ![brett](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/brett/32/261_2.png) [@brett](https://qa.fmod.com/u/brett)\ **Post date:** [November 1, 2015, 10:00am UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/9 "2015-11-01T10:00:20Z")
Please look at the documentation or the header, you could have solved that one yourself in seconds. The code above that Nick gave has an extra underscore, it should be WINDOWTYPE ---
**Author:** ![Keitel](https://avatars.discourse-cdn.com/v4/letter/k/e5b9ba/32.png) [@Keitel](https://qa.fmod.com/u/Keitel)\ **Post date:** [November 1, 2015, 12:01pm UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/10 "2015-11-01T12:01:37Z")
Ok, so I changed the code to this: ``` result = FMOD_System_CreateDSPByType(system, FMOD_DSP_TYPE_FFT, &mydsp); result = FMOD_ChannelGroup_AddDSP(channelgroup, FMOD_CHANNELCONTROL_DSP_TAIL, mydsp); ERRCHECK(result); result = FMOD_DSP_SetParameterInt(mydsp, FMOD_DSP_FFT_WINDOWTYPE, FMOD_DSP_FFT_WINDOW_TRIANGLE); ERRCHECK(result); result = FMOD_DSP_SetParameterInt(mydsp, FMOD_DSP_FFT_WINDOWSIZE, 8192); ERRCHECK(result); ``` Then I also changed the code to print the average of 800 measurements made with 10 milliseconds intervals. But I still can’t make any sense of the result. First of all, the measurments also now varies a lot, while I also can’t find the relationship to the actual frequency of equal temperament C - and it doesn’t help using other window sizes. The note of C has the frequency of 523.2524, but however I divide or multiply this number to lower or higher octaves, I don’t make it fit with the output from the program. 1891.583252 1830.896118 1762.204834 1737.798096 1886.142700 1806.150024 1749.045044 1786.455200 1870.773438 1793.697388 1726.604492 1831.142944 1850.975098 1783.625732 1691.478394 1896.159180 1830.121216 1760.763184 1740.061523 1884.362183 1806.524658 1746.637939 1788.418945 1869.995117 1793.126465 1725.528442 1832.563110 Sincerely ---
**Author:** ![brett](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/brett/32/261_2.png) [@brett](https://qa.fmod.com/u/brett)\ **Post date:** [November 1, 2015, 8:56pm UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/11 "2015-11-01T20:56:38Z")
> [@](#): > > Ok, so I changed the code to this: > > ``` > result = FMOD_System_CreateDSPByType(system, FMOD_DSP_TYPE_FFT, &mydsp); > > result = FMOD_ChannelGroup_AddDSP(channelgroup, FMOD_CHANNELCONTROL_DSP_TAIL, mydsp); > ERRCHECK(result); > > result = FMOD_DSP_SetParameterInt(mydsp, FMOD_DSP_FFT_WINDOWTYPE, FMOD_DSP_FFT_WINDOW_TRIANGLE); > ERRCHECK(result); > > result = FMOD_DSP_SetParameterInt(mydsp, FMOD_DSP_FFT_WINDOWSIZE, 8192); > ERRCHECK(result); > > ``` > > Then I also changed the code to print the average of 800 measurements made with 10 milliseconds intervals. But I still can’t make any sense of the result. First of all, the measurments also now varies a lot, while I also can’t find the relationship to the actual frequency of equal temperament C - and it doesn’t help using other window sizes. The note of C has the frequency of 523.2524, but however I divide or multiply this number to lower or higher octaves, I don’t make it fit with the output from the program. > > 1891.583252 > 1830.896118 > 1762.204834 > 1737.798096 > 1886.142700 > 1806.150024 > 1749.045044 > 1786.455200 > 1870.773438 > 1793.697388 > 1726.604492 > 1831.142944 > 1850.975098 > 1783.625732 > 1691.478394 > 1896.159180 > 1830.121216 > 1760.763184 > 1740.061523 > 1884.362183 > 1806.524658 > 1746.637939 > 1788.418945 > 1869.995117 > 1793.126465 > 1725.528442 > 1832.563110 > > Sincerely is it a looping sound that doesnt loop properly and has high frequency clicks in it because of that? ---
**Author:** ![brett](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/brett/32/261_2.png) [@brett](https://qa.fmod.com/u/brett)\ **Post date:** [November 1, 2015, 11:11pm UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/12 "2015-11-01T23:11:36Z")
I added this code very quickly using a 440hz sine wav that loops properly. first ``` result = gSystem->createDSPByType(FMOD_DSP_TYPE_FFT, &dspfft); result = channelGroupMaster->addDSP(0, dspfft); ``` then in my loop ``` if (dspfft) { float val; dspfft->setParameterInt(FMOD_DSP_FFT_WINDOWTYPE, FMOD_DSP_FFT_WINDOW_TRIANGLE); dspfft->setParameterInt(FMOD_DSP_FFT_WINDOWSIZE, 4096); dspfft->getParameterFloat(FMOD_DSP_FFT_DOMINANT_FREQ, &val, 0, 0); printf("dom freq = %d\n", (int)(val + 0.5f)); // round to nearest } ``` Here is the output dom freq = 440 dom freq = 440 dom freq = 440 dom freq = 440 dom freq = 440 dom freq = 440 dom freq = 440 dom freq = 440 dom freq = 440 dom freq = 440 ---
**Author:** ![Keitel](https://avatars.discourse-cdn.com/v4/letter/k/e5b9ba/32.png) [@Keitel](https://qa.fmod.com/u/Keitel)\ **Post date:** [November 3, 2015, 9:08pm UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/13 "2015-11-03T21:08:25Z")
I understand that there are certain factors that will influence the result, like the clicking sound when the looop transition is not smooth, or the quality of the sound. The last sound I used was from a harmonica lasting about 25 seconds before it is looped with a fade out and a fade in. The outputs is the average of 400 measurements with 10 milliseconds invertals: 2563.455078 2419.706055 2428.343994 2497.666992 2371.210205 2398.550049 2604.717773 2406.706787 2441.078369 2492.871826 2380.274414 2378.002686 2618.081299 2401.799561 2449.688965 2483.237061 2401.814697 2339.447754 2630.663086 2399.175049 2471.438477 2469.524658 2413.720947 2318.586426 2622.350342 The outputs that are above 2600 is after the loop transition has occured, and can therefore be taken out. The list seems to be more even than the previous ones, but still some variance, while I still find it somewhat difficult to make it correspond to equal temperament C, which I guess in this case should be 2616.262. However, there might be a possibility that a harmonica gets slightly out of tune over time. I also tried a very pure electronic C sound file, which I believe is in the same octave as the sound from the harmonica above. The output was as follow: 261.628571 261.531738 261.522705 261.527924 261.523285 261.533844 261.521820 261.535950 261.520844 261.536224 It is fairly even, while the frequency measures have about one tenth of the value of the harmonica sound file, which I also find puzzling. Sincerely ---
**Author:** ![brett](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/brett/32/261_2.png) [@brett](https://qa.fmod.com/u/brett)\ **Post date:** [November 4, 2015, 12:10am UTC](https://qa.fmod.com/t/pitch-detection-and-frequencies-found/12110/14 "2015-11-04T00:10:58Z")
> [@](#): > > I understand that there are certain factors that will influence the result, like the clicking sound when the looop transition is not smooth, or the quality of the sound. The last sound I used was from a harmonica lasting about 25 seconds before it is looped with a fade out and a fade in. The outputs is the average of 400 measurements with 10 milliseconds invertals: > > 2563.455078 > 2419.706055 > 2428.343994 > 2497.666992 > 2371.210205 > 2398.550049 > 2604.717773 > 2406.706787 > 2441.078369 > 2492.871826 > 2380.274414 > 2378.002686 > 2618.081299 > 2401.799561 > 2449.688965 > 2483.237061 > 2401.814697 > 2339.447754 > 2630.663086 > 2399.175049 > 2471.438477 > 2469.524658 > 2413.720947 > 2318.586426 > 2622.350342 > > The outputs that are above 2600 is after the loop transition has occured, and can therefore be taken out. The list seems to be more even than the previous ones, but still some variance, while I still find it somewhat difficult to make it correspond to equal temperament C, which I guess in this case should be 2616.262. However, there might be a possibility that a harmonica gets slightly out of tune over time. > > I also tried a very pure electronic C sound file, which I believe is in the same octave as the sound from the harmonica above. The output was as follow: > > 261.628571 > 261.531738 > 261.522705 > 261.527924 > 261.523285 > 261.533844 > 261.521820 > 261.535950 > 261.520844 > 261.536224 > > It is fairly even, while the frequency measures have about one tenth of the value of the harmonica sound file, which I also find puzzling. > > Sincerely if the sound is not pure, you use different window types, and it is just an RMS value, you have to use the raw spectrum data in the array if you want to scan for harmonics and the like yourself. The value is generally fine but you’re talking about noisy signals that have all sorts of different harmonics in them.