Mercurial > hg > js-dsp-test
comparison fft/test.html @ 19:26056e866c29
Add FFTW to comparison table
| author | Chris Cannam |
|---|---|
| date | Tue, 06 Oct 2015 13:08:39 +0100 |
| parents | 9619d2da67c2 |
| children |
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| 18:8db794ca3e0b | 19:26056e866c29 |
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| 16 <script src="jsfft/lib/fft.js"></script> | 16 <script src="jsfft/lib/fft.js"></script> |
| 17 <script src="cross/Cross.js"></script> | 17 <script src="cross/Cross.js"></script> |
| 18 <script src="cross/FFT.js"></script> | 18 <script src="cross/FFT.js"></script> |
| 19 <script src="kissfft/KissFFT.js"></script> | 19 <script src="kissfft/KissFFT.js"></script> |
| 20 <script src="kissfft/FFT.js"></script> | 20 <script src="kissfft/FFT.js"></script> |
| 21 <script src="fftw/FFTW.js"></script> | |
| 22 <script src="fftw/FFT.js"></script> | |
| 21 <script src="test.js"></script> | 23 <script src="test.js"></script> |
| 22 | 24 |
| 23 </head> | 25 </head> |
| 24 <body> | 26 <body> |
| 25 | 27 |
| 41 <td>Dntj</td><td id="dntj-result"></td><td id="dntj-1"></td><td id="dntj-2"></td><td id="dntj-itr"></td> | 43 <td>Dntj</td><td id="dntj-result"></td><td id="dntj-1"></td><td id="dntj-2"></td><td id="dntj-itr"></td> |
| 42 </tr><tr> | 44 </tr><tr> |
| 43 <td>Cross</td><td id="cross-result"></td><td id="cross-1"></td><td id="cross-2"></td><td id="cross-itr"></td> | 45 <td>Cross</td><td id="cross-result"></td><td id="cross-1"></td><td id="cross-2"></td><td id="cross-itr"></td> |
| 44 </tr><tr> | 46 </tr><tr> |
| 45 <td>KissFFT</td><td id="kissfft-result"></td><td id="kissfft-1"></td><td id="kissfft-2"></td><td id="kissfft-itr"></td> | 47 <td>KissFFT</td><td id="kissfft-result"></td><td id="kissfft-1"></td><td id="kissfft-2"></td><td id="kissfft-itr"></td> |
| 48 </tr><tr> | |
| 49 <td>FFTW</td><td id="fftw-result"></td><td id="fftw-1"></td><td id="fftw-2"></td><td id="fftw-itr"></td> | |
| 46 </tr> | 50 </tr> |
| 47 </table> | 51 </table> |
| 48 | 52 |
| 49 <h3>Notes</h3> | 53 <h3>Notes</h3> |
| 50 | 54 |
| 51 <ul> | 55 <ul> |
| 52 <li><b>Nayuki</b>: in-place single-precision complex-complex</li> | 56 <li><b>Nayuki</b>: in-place single-precision complex-complex. Around 7kb.</li> |
| 53 <li><b>Nayuki (obj)</b>: Nayuki with the sin/cos tables pre-calculated on object construction</li> | 57 <li><b>Nayuki (obj)</b>: Nayuki with the sin/cos tables pre-calculated on object construction. Around 4kb.</li> |
| 54 <li><b>Nockert</b>: double-precision real-complex</li> | 58 <li><b>Nockert</b>: double-precision real-complex. Around 25kb.</li> |
| 55 <li><b>Dntj</b>: double-precision complex-complex. Forward | 59 <li><b>Dntj</b>: double-precision complex-complex. Forward |
| 56 transform is scaled and I've scaled it back again here, which may | 60 transform is scaled and I've scaled it back again here, which may |
| 57 introduce rounding error.</li> | 61 introduce rounding error. Around 10kb.</li> |
| 58 <li><b>Cross</b>: double-precision real-complex in C, compiled | 62 <li><b>Cross</b>: double-precision real-complex in C, compiled |
| 59 with Emscripten. This is considered a slow implementation amongst | 63 with Emscripten. This is considered a slow implementation amongst |
| 60 native code ones.</li> | 64 native code ones. Around 60kb.</li> |
| 61 <li><b>KissFFT</b>: single-precision real-complex in C, compiled | 65 <li><b>KissFFT</b>: single-precision real-complex in C, compiled |
| 62 with Emscripten. This should be faster than Cross. Despite its | 66 with Emscripten. A reasonably sophisticated implementation. Around |
| 63 name, it is the most sophisticated implementation here.</li> | 67 70kb.</li> |
| 68 <li><b>FFTW</b>: single-precision real-complex in C, compiled with | |
| 69 Emscripten. GPL licensed. Around 3Mb.</li> | |
| 64 </ul> | 70 </ul> |
| 65 | 71 |
| 66 <h3>Rationale</h3> | |
| 67 | |
| 68 <p>If 2150 iterations of real-to-complex FFT of size 2048 takes less | |
| 69 than 10 seconds, then we may be able to make a high quality | |
| 70 real-time phase vocoder (just).</p> | |
| 71 | |
| 72 <p>A phase-vocoder of course must use overlapped windowed FFT | |
| 73 (although you can choose the size, within limits), IFFT, and | |
| 74 cartesian-polar conversion to calculate the phase for the | |
| 75 instantaneous frequency.</p> | |
| 76 | |
| 77 <p>A reasonable estimate of CPU cost for the whole thing is | |
| 78 somewhere around 10x the cost of simple non-overlapping short-time | |
| 79 forward Fourier transforms across the signal. </p> | |
| 80 | |
| 81 <p>2150 iterations corresponds to 100 seconds of audio | |
| 82 non-overlapped at 44.1kHz, so if that takes less than 10 seconds, | |
| 83 then in theory we might be OK.</p> | |
| 84 | |
| 85 </body> | 72 </body> |
| 86 | 73 |