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.

556 questions
3
votes
1 answer

How to get complete fundamental (f0) frequency extraction with python lib librosa.pyin?

I am running librosa.pyin on a speech audio clip, and it doesn't seem to be extracting all the fundamentals (f0) from the first part of the recording. librosa documentation: https://librosa.org/doc/main/generated/librosa.pyin.html sr:…
jmhead
  • 887
  • 1
  • 12
  • 25
3
votes
1 answer

Reading raw PCM samples from an MP3 file using QtMultimedia?

Is there a way to use QtMultimedia to access the PCM raw audio samples of MP3 files stored on a, say, Nokia N950 phone? If it is not possible, what would be the reasonable alternative. Something which could be reasonably easily integrated with an…
KT.
  • 10,815
  • 4
  • 47
  • 71
3
votes
1 answer

Is there a way to add gain to an audio signal with Librosa in python?

I am currently working on augmenting audio in Python. I've been using Librosa due to its speed and simplicity but need to fallback on PyDub for some other utilities such as applying gain. Is there a mathematical way to add gain to the Numpy array…
Coldchain9
  • 1,373
  • 11
  • 31
3
votes
0 answers

Get fundamental frequency and harmonics of an audio

After calculating the Fourier transform of a signal, I would like to recover the fundamental frequency as well as the harmonics of the recorded sound to determine its timbre. Here is my code : [signal,fe] =…
Moussa Sow
  • 31
  • 2
3
votes
1 answer

ExoPlayer: Custom AudioProcessor - Equalizer

I'm working on an ExoPlayer based media player for Android, and I'm attempting to write my own Equalizer. I've looked fairly deeply into ExoPlayer, and I believe the best place to manipulate samples in order to apply Equalier changes, is in a custom…
Tim Malseed
  • 6,003
  • 6
  • 48
  • 66
3
votes
1 answer

AudioWorklet - Set output to Float32Array to stream live audio?

I have audio data streaming from the server to the client. It starts as a Node.js buffer (which is a Uint8Array) and is then sent to the AudioWorkletProcessor via port.postMessage(), where it is converted into a Float32Array and stored in this.data.…
3
votes
1 answer

How to do time streching audio playback using javascript in 2019?

I'm looking for a up-to-date solution to slow down / speed up the audio playback without changing the pitch (so-called "time-stretch"). The processing should be as fast as possible (audio is speech recording). Using Web Workers would be good,…
julianpoemp
  • 1,965
  • 3
  • 14
  • 29
3
votes
1 answer

Python: Compare two audio files which may have noise

For a project purpose, I am recording audio clips(wave files) from different areas near a stage. I need to check if the source audio ie; the audio from the stage is highly audible in the nearby location of the stage using the audio recorded from the…
K K
  • 363
  • 3
  • 6
  • 15
3
votes
1 answer

Qt audio file to wave like audacity

I have to manage movie and audio file and I need to render a wave of the sound like in audacity. But I just find example for realtime render. I want to render all the file without playing it. Expected result: My actual result: With Qt I tried to use…
thibsc
  • 3,747
  • 2
  • 18
  • 38
3
votes
2 answers

Acoustic Audio Comparing Library

I need a software or a library which handles with audio comparison, but not using the tag's inside mp3 ,it should compare similarity or confidence between 2 audio Files, or if i cut a piece from an audio file, the software should point where is that…
Rosmarine Popcorn
  • 10,761
  • 11
  • 59
  • 89
3
votes
1 answer

How to change speed of a wav file while retaining the sampling frequency in Python

I wish to change the speed of an audio file (in the .wav format) by small amounts(±25%). The catch is that I need to retain the previous sample rate of the file. Both solutions involving a change of speed and pitch, and change of speed only (tempo…
Bruno KM
  • 768
  • 10
  • 20
3
votes
1 answer

Is there a constant-time algorithm for generating a bandlimited sawtooth?

I'm looking into the feasibility of GPU synthesized audio, where each thread renders a sample. This puts some interesting restrictions on what algorithms can be used - any algorithm that refers to a previous set of samples cannot be implemented in…
3
votes
2 answers

Calcute note based on frequency

I am creating a tuner on android, I get the audio from the device's microphone and proccess it to get the frequency. However, once I get to transforming the frequency on a note, I wonder if there's a way to do it without having to use a bunch of…
hsteffano
  • 49
  • 7
3
votes
1 answer

Generating a tone in Java and change it's timbre?

I'm wanting to make a Java program that can generate a note, and change it's timbre and pitch, whilst it's playing. I want to change the timbre by using numbers, so I could smoothly transition from one timbre to another, and the same goes for…
pandagoespoop
  • 59
  • 1
  • 4
3
votes
1 answer

Difference between frames and items in libsndfile?

I am writing a software which processes audio files. I am using libsndfile library for reading wave file data, and I come across a doubt that wasn't solved by their documentation: what is the difference between functions that read items and…
Mauren
  • 1,955
  • 2
  • 18
  • 28