spectrum

How to develop a Spectrum Analyser from a realtime audio?

前提是你 提交于 2019-11-30 11:39:01
问题 I am developing an app that get a source audio from mic in realtime, with no file storage. Basically, I use: mRecorder = new MediaRecorder(); mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC); mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB); mRecorder.setOutputFile("/dev/null"); My question is, how I can do a spectrum graphic from this realtime audio, with no files. It can be done? All post that I read are

Units of a Fourier Transform (FFT) when doing Spectral Analysis of a Signal

杀马特。学长 韩版系。学妹 提交于 2019-11-30 06:09:42
问题 My question has to do with the physical meaning of the results of doing a spectral analysis of a signal, or of throwing the signal into an FFT and interpreting what comes out using a suitable numerical package, Specifically: take a signal, say a time-varying voltage v(t) throw it into an FFT (you get back a sequence of complex numbers) now take the modulus (abs) and square the result, i.e. |fft(v)|^2. So you now have real numbers on the y axis -- shall I call these spectral coefficients?

How to develop a Spectrum Analyser from a realtime audio?

徘徊边缘 提交于 2019-11-30 00:50:43
I am developing an app that get a source audio from mic in realtime, with no file storage. Basically, I use: mRecorder = new MediaRecorder(); mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC); mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB); mRecorder.setOutputFile("/dev/null"); My question is, how I can do a spectrum graphic from this realtime audio, with no files. It can be done? All post that I read are analyzing a buffered file. Thank you, and sorry for my english. yes it can be done. All you need is a fast

Units of a Fourier Transform (FFT) when doing Spectral Analysis of a Signal

独自空忆成欢 提交于 2019-11-28 15:13:28
My question has to do with the physical meaning of the results of doing a spectral analysis of a signal, or of throwing the signal into an FFT and interpreting what comes out using a suitable numerical package, Specifically: take a signal, say a time-varying voltage v(t) throw it into an FFT (you get back a sequence of complex numbers) now take the modulus (abs) and square the result, i.e. |fft(v)|^2. So you now have real numbers on the y axis -- shall I call these spectral coefficients? using the sampling resolution, you follow a cookbook recipe and associate the spectral coefficients to

convert RGB pixel to wavelength

风格不统一 提交于 2019-11-28 12:55:45
I need to identify a spectrum emitted from a light source (spectrometer). To do that, I need to convert each pixel to a wavelength. To overcome the problem that the RGB values do not have a single value, I will use a prism so that I will get an optical lattice. This way, I'm receiving a deployment of the spectrum, and the difference in the spectrum is only along the X axis. My question is, how do I convert the pixels to wavelengths and receive a plot of intensity as a function of wavelength. OpticsSoftware Late to the party. But here is an idea for accurately(close to scientific methodology)

Why do I need to apply a window function to samples when building a power spectrum of an audio signal?

霸气de小男生 提交于 2019-11-28 04:44:39
I have found for several times the following guidelines for getting the power spectrum of an audio signal: collect N samples, where N is a power of 2 apply a suitable window function to the samples, e.g. Hanning pass the windowed samples to an FFT routine - ideally you want a real-to-complex FFT but if all you have a is complex-to-complex FFT then pass 0 for all the imaginary input parts calculate the squared magnitude of your FFT output bins (re * re + im * im) (optional) calculate 10 * log10 of each magnitude squared output bin to get a magnitude value in dB Now that you have your power

Spectrogram C++ library

只谈情不闲聊 提交于 2019-11-28 04:43:43
For my current project in C++ / Qt I need a library (LGPL is preferred) which can calculate a spectrogram from a signal ( basically an array of doubles ). I already use Qwt for the GUI part. Any suggestions? Thanks. It would be fairly easy to put together your own spectrogram. The steps are: window function (fairly trivial, e.g. Hanning) FFT (FFTW would be a good choice but if licensing is an issue then go for Kiss FFT or similar) calculate log magnitude of frequency domain components (trivial: log(sqrt(re * re + im * im)) David Cary "How do I create a frequency vs time plot?" lists several

convert RGB pixel to wavelength

柔情痞子 提交于 2019-11-27 06:26:28
问题 I need to identify a spectrum emitted from a light source (spectrometer). To do that, I need to convert each pixel to a wavelength. To overcome the problem that the RGB values do not have a single value, I will use a prism so that I will get an optical lattice. This way, I'm receiving a deployment of the spectrum, and the difference in the spectrum is only along the X axis. My question is, how do I convert the pixels to wavelengths and receive a plot of intensity as a function of wavelength.

openlava图形化监控工具openlavaMonitor

北城以北 提交于 2019-11-27 06:24:59
OpenLava是100%免费、开源、兼容IBM® Spectrum LSFTM的工作负载调度器,支持各种高性能计算和分析应用,在各大IC公司被广泛引用。 openlava开源免费,兼容LSF,是IC公司(尤其是中小型IC公司)的福音。但是由于种种原因,开源团队不再进行开发工作,且工具缺少配套的job/resource监控类工具,所以并不易用。以往的工作中,根据openlava使用中的实际需求,我开发过一些openlava辅助类工具,以帮助openlava的工具配置,数据采集,前台监控。出于资源共享的目的,我把数据采集和前台监控的功能采用标准python工具的格式进行了重新开发,命名为openlavaMonitor,开源到了github上,以方便大家下载使用 (地址 https://github.com/liyanqing1987/openlavaMonitor )。 下面对工具做一下简单介绍,帮助大家了解。 1. 工具介绍 工具的使用分为两部分: 后台数据采集,前台数据展示。这一部分主要讲一下工具的前台展示部分。 工具为图形界面,包含4个页面,分别展示不同的内容。 1.1 第一个页面为JOB页,主要展示job相关信息。 在Job输入框输入job id,点击Check按钮,可以显示出job的关键信息,job的详细信息,job的memory使用量变化曲线。

Spectrogram C++ library

江枫思渺然 提交于 2019-11-27 00:37:12
问题 For my current project in C++ / Qt I need a library (LGPL is preferred) which can calculate a spectrogram from a signal ( basically an array of doubles ). I already use Qwt for the GUI part. Any suggestions? Thanks. 回答1: It would be fairly easy to put together your own spectrogram. The steps are: window function (fairly trivial, e.g. Hanning) FFT (FFTW would be a good choice but if licensing is an issue then go for Kiss FFT or similar) calculate log magnitude of frequency domain components