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 can I extract audio from video with ffmpeg?

I tried the following command to extract audio from video: ffmpeg -i Sample.avi -vn -ar 44100 -ac 2 -ab 192k -f mp3 Sample.mp3 but I get the following output libavutil 50.15. 1 / 50.15. 1 libavcodec 52.72. 2 / 52.72. 2 libavformat 52.64. 2…
user1269669
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Algorithms for determining the key of an audio sample

I am interested in determining the musical key of an audio sample. How would (or could) an algorithm go about trying to approximate the key of a musical audio sample? Antares Autotune and Melodyne are two pieces of software that do this sort of…
Alex
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How can I Compare 2 Audio Files Programmatically?

I want to compare 2 audio files programmatically. For example: I have a sound file in my iPhone app, and then I record another one. I want to check if the existing sound matches the recorded sound or not ( - similar to voice recognition). How can I…
Shishir.bobby
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Building audio processing Little Endian SDK with NDK

I am trying to use ndk-build to use native code for audio processing from Little Endian in an Android application (I don't have JNI yet). When I executed ndk-build in jni dir I got ($USER_PATH is path to directory on my computer): Android NDK:…
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deeplearning4j - using an RNN/LSTM for audio signal processing

I'm trying to train a RNN for digital (audio) signal processing using deeplearning4j. The idea is to have 2 .wav files: one is an audio recording, the second is the same audio recording but processed (for example with a low-pass filter). The RNN's…
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How to get below 10ms latency using WASAPI shared mode?

According to Microsoft, starting with Windows 10, applications using shared-mode WASAPI can request buffer sizes smaller than 10ms (see https://msdn.microsoft.com/en-us/library/windows/hardware/mt298187%28v=vs.85%29.aspx). According to the article,…
Sjoerd van Kreel
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How do I use audio sample data from Java Sound?

This question is usually asked as a part of another question but it turns out that the answer is long. I've decided to answer it here so I can link to it elsewhere. Although I'm not aware of a way that Java can produce audio samples for us at this…
Radiodef
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Perceptual similarity between two audio sequences

I would like to get some sort of distance measure between two pieces of audio. For example, I want to compare the sound of an animal to the sound of a human mimicking that animal, and then return a score of how similar the sounds were. It seems like…
Bart
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Detecting wind noise

I want to develop an app for detecting wind according the audio stream. I need some expert thoughts here, just to give me guide lines or some links, I know this is not easy task but I am planning to put a lot of effort here. My plan is to detect…
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How to setup for record and playback audio on Mac. VOIP app on Mac

I want to record and playback audio in Mac. Now, I have some problems about the settings for Input/Output/ChannelFormat … I showed you some code I try below. // Setup audio device - (OSStatus) setupAudioDevice { // It's oks …
Long Pham
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Bpm audio detection Library

I'm looking for a library that simplify tempo/bpm audio detection. Something similar to this http://adionsoft.net/bpm/ , but to use on *NIX machines. Any language, but preference goes to php, perl, python.
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Audio and Signal Processing in Haskell

Do you know of alive attempts at audio synthesis / signal processing in Haskell ? Either for live performance or just for offline processing ? I am not looking for libraries relying on an external tool (like bindings to SuperCollider). I have found…
alpheccar
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Sound sample recognition library/code

I don't want sound-to-text software. What I need is the following: I'll record multiple (say 50+) audio streams (recordings of radio stations) from that recordings, I'll mark interesting audio clips - their length ranges from 2 to 60 seconds -…
Daniel Mošmondor
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Music Recognition and Signal Processing

I want to build something similar to Tunatic or Midomi (try them out if you're not sure what they do) and I'm wondering what algorithms I'd have to use; The idea I have about the workings of such applications is something like this: have a big…
Alix Axel
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Algorithm to get the Key and Scale from musical notes?

From a series of MIDI notes stored in array (with MIDI note number), does an algorithm exist to get the most likely key or scale implied by these notes?
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