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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writing double[] as WAV file in Java

I'm trying to save a double[] array as .WAV file using this method: public static void saveWav(String filename, double[] samples) { // assumes 44,100 samples per second // use 16-bit audio, 2 channels, signed PCM, little Endian …
Guyn
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Is it possible to record sound in torch 7?

As title, Is it possible to record sound in torch 7 ? Is there a library to do this ? Thank you
yutseho
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Audio equalization

I'm developing audio player using FFmpeg and I want to add audio equaliqer to my app. I use FFmpeg to get audio samples and compute FFT, but when I try to apply one of IIR filters, I'm geting very noisy audio signal. This is my code: double Q =…
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Determine the number of samples in audio buffer

I am writing a small program to perform real-time ambient noise removal using PortAudio. To do some of the necessary calculations (like Fourier transforms), I need to supply the sample data, but I also need to know exactly how many samples I am…
Martin Tuskevicius
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Upsampling PCM audio: from 6 kHz to 8kHz

What would a straight-forward way to convert an audio payload (PCM 16bit) from 6 kHz to 8kHz? I understand that this is an interpolation problem. I fear that a linear interpolation would introduce too much noise. If so, what would be a better…
gawi
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Analyze to play audio file (mp3) into multiple parts which has completed sentence

I have a mp3 file (supposed that is conversation in English). Ex: People A: Hello. What your name? People B: My name is Linda. Nice to meet you People A: ... so on I want to play this audio file into multiple parts. Each part have completed…
hahv
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FFT which frequencies are in which bins?

I would like to see how certain frequencies, specifically low bass at 20 - 60hz are present in a piece of audio. I have the audio as a byte array, I convert it to array of shorts, then into a complex number by (short[i]/(double)short.MaxValue, 0).…
Pete B
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getting float array from QAudioInput's qbytearray

When reading low level audio from QAudioInput, the resulting data is a QByteArray. When setting up QAudioInput, you can tell it the Sample Type you want from the data. If you specify float there, does that mean the data in QByteArray is already in…
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How Direcshow Filters exchange Media samples?

anybody know how directshow filters exchange media samples? we know source filter grab sample (from MIC or Live) and pass it to next filter in graph. clearly i want to know how filters pass samples to another filter? is there a known pattern for…
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Removing same audio sections from audio files

As a collecter I've thousands of audio files which downloaded from podcasting services. All feeds start with a 15 seconds same introduction. That's very annoying for me so I tried crop all of them. But all of them are not regular. The voiced…
RarLines
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Ingest(Update hash Code) in echoprint servers using JAVA

I am developing an android application using JAVA. All I want is to record a song and generate its hash(CODE), then query the echoprint server for a match. If a match is not found, then upload it to the server (ingest) for future references. I…
Arijit
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Extracting the AudioBuffer of an

Is there a way to extract the AudioBuffer of an element for analysis? I want to avoid dealing with cross-origin issues that arise when using an XMLHttpRequest, if possible.
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Extracting audio data every t seconds

I am trying to extract amplitude information from a sound loaded from a URL using the Web Audio API instantaneously (not in real time), which will likely require the OfflineAudioContext. I am expecting to obtain something along the lines of an array…
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decode dtmf from array of bytes using C#

I am developing a software that captures outgoing sound (speaker) and identify if there's any dtmf tones. I used NAudio to capture sound into a form of byte array. I want to detect if there's a dtmf tones on those byte array. I already googled it…
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band pass filter matlab

Think about I have an array of time and fundamental frequency of a given audio file. So what I need to do is extract the fundamental frequency from the audio. And what I am thinking is to apply a bandpass filter, for instance 100hz above and below…