Questions tagged [audio-processing]

Audio processing involves the study of mathematical and signal processing techniques to understand or alter the nature of audio signals. The different kind of audio signals under study include speech, music, environmental audio and computer audio. Audio is analyzed in the temporal or spectral domain by applying various filters.

Key concept is to transform the audio into PCM format so you have access to the raw audio curve. Each channel will have its own curve.

Digital audio is represented by a series of points on this curve. Each point is called an audio sample. Numerical value of each sample can be represented in either integer or floating point.

Be aware to map each audio sample numerical value to memory typically requires several bytes of storage. One byte can store only 2^8 distinct values (256) which will result in noticeable distortion. High quality audio is typically stored using at least two bytes of storage per audio sample. When we use two bytes this gives us 2^16 possible values of the raw audio curve height as the audio wobbles up and down. The more bytes we use for storage the higher fidelity we gain as this reduces the gap between each distinct curve height measurement. This called bit depth. CD quality audio uses two bytes per audio sample per channel. The other fundamental aspect of digital audio is Sample Rate with determines the number of samples per second of time.

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How to disable audio output processing on an htc phone with Android

I am trying to measure the audio path from speaker to microphone on two different phones, an htc Wildfire S running Android 2.3.5, and an htc One X running Android 4.0.3. Using Eclipse, I coded an app that has wave files played back using an…
Ingo Schalk-Schupp
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Music Detection (Not Identification)

I'm trying to build a C# app that detects when music is present in a video. I can get at the Audio find, in whatever format required. I however have hit a brick wall in music detection. There are loads of posts about audio fingerprinting and how to…
Ben Ford
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How to emulate Vinyl Scratch effect in Audio Processing?

I'm trying to make a simple "virtual scratcher" but I don't know the theory behind it. Since I've found nothing useful on google I'm asking it here: What happen when I scratch (move the track forward)? Do I raise the pitch and/or rate of the…
d.lime
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How to add seconds of silence at the end of a .wav file?

I have 1,440 audio files to feed into a neural network. The problem is that they are not all the same length. I used the answer posted on: Adding silent frame to wav file using python but it doesn't seem to work. I wanted to add a few seconds of…
dustyrock
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How to plot a waveform from wav file in python?

import os import scipy.io import scipy.io.wavfile import numpy as np import matplotlib.pyplot as plt dataset_path = os.path.join(os.environ['HOME'], 'shared', 'data', 'assignment_1') wavedata = os.path.join(dataset_path, 'example.wav') fs,…
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Librosa load many MP3 memory usage

I want to load about 25K mp3 audio files in a loop and process them in a Jupyter Notebook. When loading these audio files my RAM usages keeps growing when this should not be the case. When examining the variables in RAM the audio files do not show…
Mark wijkhuizen
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How to get frequency spectrum from an audio wav file using fft.js with node.js

I'm trying to extract frequency information of simple 16 bit pcm wav file containing only one pure tone (750hz created with audacity) in JavaScript with nodejs. I'm using: node-wav for reading the wav file fft.js to perfom fft operation nodeplotlib…
E.Brandonn
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BPM detection from pyAudioAnalysis is producing the wrong number of beats for any signal

Any help would be much appreciated. I am trying to extract the BPM from any .wav file that is loaded onto the python script by using the pyAudioAnalysis library. For some reason it is not outputting the correct BPM? I tried to change the window size…
AhmedB
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AAC Packet Size

I am working on an M4a file with the following metadata: Metadata: major_brand : M4A minor_version : 0 compatible_brands: M4A mp42isom creation_time : 2019-08-14T13:45:39.000000Z iTunSMPB : 00000000 00000840…
Ahmed Hawary
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How can a chromagram file produced by librosa be interpreted as a set of musical keys?

I have a chroma features file here. How can these numbers be interpreted as belonging to different musical keys? I need to use the key found at a particular time code to produce a solution similar to this in order to mix between two tracks. How can…
plgent
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How to use a context window to segment a whole log Mel-spectrogram (ensuring the same number of segments for all the audios)?

I have several audios with different duration. So I don't know how to ensure the same number N of segments of the audio. I'm trying to implement an existing paper, so it's said that first a Log Mel-Spectrogram is performed in the whole audio with 64…
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ios Native webrtc : How to record remote audio stream as wav file on client side.

I am experimenting on webrtc, My goal is to store remote audio stream as a local file without using the media server, I am aware of aecdump but I don't find proper method or blog to unzip in iOS. I am using googleWebrtc native framework. Thanks.
Sumit Meena
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Signal Processing: Can someone explain for me the different type of spectrogram?

I'm newbie with signal processing and I search on Google many terminology of spectrogram but I can't find any thing talk about the difference of type of spectrogram. Can anyone help me to explain the definition and meaning of diffenrent spectrogram…
Toan Nhu
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How to read real-time frequencies from a microphone input?

I want to get frequencies of a voice input acquired from microphone in real-time. I searched about this and got to know about FFT and another 2, 3 algorithms but implementing those algorithms seemed very complicated. I am looking for a C# library…
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Guitar tuner with Ruby

I've never worked with real-time audio features. I would like to know whether there are ruby libraries out there that would allow me to create something like a guitar tuner.
soulnafein
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