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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Is modulation index = "Out" level in Modulator Operator

I'm reading about Algorithms in Frecuency Modulation. In most synthetizers each algorithm operator have an "Out" level knob, in carriers this knob controls the output volume. For modulators however the level knob decides the amount of change it does…
Mr_LinDowsMac
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How do i create and train tensorflow model with audio inputs?

I've audio files say "left.wav", "right.wav" and so forth, I want to create a model which takes audio as input and output label "left" or "right" etc. Question How do I feed my raw audio to my neural network ?
martian1231
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Real time pitch shift using Superpowered Android

I am having problem in using the Superpowered time stretching function for real time pitch shift. I have used this solution for my purpose. The problem is I am applying the change on the input buffer which is a short array and getting back noise…
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Android - opensl es - invert sound - anti noise

I'm very new to audio processing and the opensl es system. I'm currently developing an app that generates anti noise. My idea is to invert the values in the audio buffer queue, however, all the methods I've tried are not working. I'm using opensl es…
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Reading a WAV file using native C++ on Windows

Looking for a simple Windows native call to open and read a WAV file in C++ on Windows (without requiring third party libraries). I can find mmio* functions - deprecated. Media Foundation - seems way more complicated as it "...Builds a DLL that…
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Server Platform for Audio Processing

I'm trying to build a server for processing audio from an incoming UDP connection. I need to be able to do things like change the frequency of the incoming stream (probably a .wav), the amplitude, time shift it, etc. then feed the output back out in…
kurifu
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How to record audio with different frequency?

I am trying to record audio with different frequency. Though I have been trying to implement it by the following code but its not working (app unexpectedly stopped). //importing packages import android.app.Activity; import…
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Subtracting one audio file from another in android

I recorded an audio file A and saved it as testaudio0.gp Then I recorded an audio file B while audio file A was playing at the same time and saved it as testaudio.gp Of course, in audio file B I hear audio file A as well. I use the normal…
fameman
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Perfomance in audio processing with objective-c ++

I'm currently developing an audio application and the performance is one of my main concerns. There are really good articles like Four common mistakes in audio development or Real-time audio programming 101: time waits for nothing. I understood that…
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How to pause offline rendering?

OfflineContext.suspend stops the progression of OfflineContext.currentTime, but what effect does it have while rendering (OfflineContext.startRendering)? What I want to do is start the rendering process, pause it, do some other task and resume it…
Maxime Dupré
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Reuse SuperpoweredDecoder for loading audio files

For benchmarking purposes I repeat loading an .wav-file, processing it offline and saving the output by using the SuperpoweredSDK. But after some iterations (in my case 4) I get the error "A/libc: invalid address or address of corrupt block…
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Media Foundation get encoded bitrate

I am trying to get the encoded bitrate of an audio file (mp4, m4a, aac) using Media Foundation. What I did is: PROPVARIANT prop; IMFSourceReader* reader; MFCreateSourceReaderFromURL(filePath, NULL,…
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Packet size (mBytesPerPacket) or the bitrate for AAC files in Core Audio

I want to configure a AudioStreamBasicDescription with constant bit rate AAC type. AudioStreamBasicDescription clientFormat = {0}; clientFormat.mSampleRate = 44100.0; clientFormat.mFormatID =…
mbaros
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Encode raw PCM to AAC using OSX native library

I wonder if there is a way to encode raw data to aac format using OSX native libraries? If yes, are there some examples or documentation? I looked up the apple documentation but only found decoding related resources using Core Audio…
mbaros
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Using AEC(webrtc) instead of AECM(webrtc)

I used aecm(webrtc) on my ARM-based embedded device for voice communication. Now, I'm trying to change aecm to aec for double-talk echo cancellation. It's simple in aecm:…
azbo
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