audio-recording | 易学教程

Calculate decibels

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问题 I'm recording mic input using the XNA library (I don't think this is really technology specific, but it never hurts). Every time I get a sample I would like to calculate the decibels. I have done many searches on the internet and not found a rock solid example... Here is my attempt at calculating decibels from a sample: double peak = 0; for (var i = 0; i < _buffer.Length; i = i + 2) { var sample = BitConverter.ToInt16(_buffer, i); if (sample > peak) peak = sample; else if (sample < -peak)

How to record audio on webpage (iOS, Android, PC/Mac) - no flash

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问题 I have a requirement to allow a user to record an audio file using their microphone, but it has to work without flash as it needs to work on iOS (mobile safari), Android browser or Chrome, and a modern browser on a PC/Mac. Is there a clean, simple HTML5 method for recording audio and posting to a server? I haven't been able to find anything. 回答1: You can use the HTML5 WebAudio API. An introduction to audio and video capturing Capture audio & video in HTML5 A good library to record audio with

How do I capture the audio that is being played?

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问题 Does anyone know how to programmatically capture the sound that is being played (that is, everything that is coming from the sound card, not the input devices such as a microphone). 回答1: Assuming that you are talking about Windows, there are essentially three ways to do this. The first is to open the audio device's main output as a recording source. This is only possible when the driver supports it, although most do these days. Common names for the virtual device are "What You Hear" or "Wave

PCM audio amplitude values?

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问题 I am starting out with audio recording using my Android smartphone. I successfully saved voice recordings to a PCM file. When I parse the data and print out the signed, 16-bit values, I can create a graph like the one below. However, I do not understand the amplitude values along the y-axis. What exactly are the units for the amplitude values? The values are signed 16-bit, so they must range from -32K to +32K. But what do these values represent? Decibels? If I use 8-bit values, then the

Is it possible to capture the rendering audio session from another process?

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问题 I am taking my first dives in to the WASAPI system of windows and I do not know if what I want is even possible with the windows API. I am attempting to write program that will record the sound from various programs and break each in to a separate recorded track/audio file. From the reseacrch I have done I know the unit I need to record is the various audio sessions being rendered to a endpoint, and the normal way of recording is by taking the render endpoint and performing a loopback.

How to record and playback with NAudio using AsioOut

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问题 I'm trying to get the sound input and send output directly with less latency possible with C#. I'm using the library NAudio that supports ASIO for better latency. In particular, I use the AsioOut object for recording and another for playback initialized with a BufferedWaveProvider , which is filled in a Callback function: OnAudioAvailable , which allows me to use the ASIO buffers. The problem is that I hear the sound with various glitches and with a bit of delay . I think the problem is in

Android: Need to record mic input

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Is there a way to record mic input in android while it is being process for playback/preview in real time? I tried to use AudioRecord and AudioTrack to do this but the problem is that my device cannot play the recorded audio file. Actually, any android player application cannot play the recorded audio file. On the other hand, Using Media.Recorder to record generates a good recorded audio file that can be played by any player application. But the thing is that I cannot make a preview/palyback while recording the mic input in real time. Any feedback is very much appreciated! Thanks in advance!

Record and play audio Simultaneously

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Any one help to me to record and play audio Simultaneously in Iphone. You can play and record simultaneously on iOS devices (except the 1st gen Touch) using either the Audio Unit RemoteIO or the Audio Queue API. These are lower level APIs where you have to handle the incoming buffers of outgoing and incoming PCM samples yourself. See Apple's aurioTouch sample app for example code. You can get a use from AVFoundation framework. It has AVAudioPlayer to play audio files and AVAudioRecorder to record. You have to bear in mind that Recorder will record with the use of mic only. So with the

Audio capturing with HTML5 [closed]

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I've tried to see if there's a way to record audio with HTML5 to no avail. I tried using this example but it didn't work. I'm guessing he really meant it when he said that it is not supported by any browser yet. Am I missing something? perhaps it is already possible? What are my options to record audio on a browser-based application? Open Source only please :) Wouter Dorgelo You might wanna have a look at HTML Media Capture and its API . Ericsson labs already achieved this, see: here (Note: Note that the device element and the related APIs are not available in any browser yet, and the APIs may

How avoid automatic gain control with AudioRecord?

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问题 How can I do audio recordings using android.media.AudioRecord without any smartphone-manufacturer-dependent fancy signal processing like automatic gain control (AGC) and/or equalization, noise suppression, echo cancellation, ... just the pure microphone signal? Background MediaRecorder.AudioSource provides nine constants, DEFAULT and MIC initially being there, VOICE_UPLINK , VOICE_DOWNLINK , and VOICE_CALL added in API level 4, CAMCORDER and VOICE_RECOGNITION added in API 7, VOICE