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Raw Sound playing

开发者 https://www.devze.com 2023-01-18 16:56 出处:网络
I\'ve been working for some time with image formats and i know that an image is an array of pixels (24- maybe 32 bits long). The question is: what is the way a sound file is represented? To be honest

I've been working for some time with image formats and i know that an image is an array of pixels (24- maybe 32 bits long). The question is: what is the way a sound file is represented? To be honest i'm not even sure what i should be googling for. Also i would be interested how do you use the data, i mean actually playing the sounds in the file. For an image file you have all sorts of abstract devices to draw an image on(Graphics:java,c#, H开发者_如何学JAVADC:cpp(win32), etc.) .I hope i have been clear enough.


Here's a dandy overview of how .wav is stored. I found it by typing "wave file format" into google.

http://www.sonicspot.com/guide/wavefiles.html


WAV files can also store compressed audio, but I believe most of the time they are not compressed. But the WAV format is designed as a container for a number of options on how that audio is stored.

Here's a snipped of code that I found at another question here at stackoverflow that I like in C# that builds a WAV-formatted audio MemoryStream and then plays that stream (without saving it to a file, like many other answers rely on). But saving it to a file can easily be added with one line of code if you want it saved to disk, but I would think that most of the time, that'd be undesirable.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Windows.Forms;

public static void PlayBeep(UInt16 frequency, int msDuration, UInt16 volume = 16383)
{
    var mStrm = new MemoryStream();
    BinaryWriter writer = new BinaryWriter(mStrm);

    const double TAU = 2 * Math.PI;
    int formatChunkSize = 16;
    int headerSize = 8;
    short formatType = 1;
    short tracks = 1;
    int samplesPerSecond = 44100;
    short bitsPerSample = 16;
    short frameSize = (short)(tracks * ((bitsPerSample + 7) / 8));
    int bytesPerSecond = samplesPerSecond * frameSize;
    int waveSize = 4;
    int samples = (int)((decimal)samplesPerSecond * msDuration / 1000);
    int dataChunkSize = samples * frameSize;
    int fileSize = waveSize + headerSize + formatChunkSize + headerSize + dataChunkSize;
    // var encoding = new System.Text.UTF8Encoding();
    writer.Write(0x46464952); // = encoding.GetBytes("RIFF")
    writer.Write(fileSize);
    writer.Write(0x45564157); // = encoding.GetBytes("WAVE")
    writer.Write(0x20746D66); // = encoding.GetBytes("fmt ")
    writer.Write(formatChunkSize);
    writer.Write(formatType);
    writer.Write(tracks);
    writer.Write(samplesPerSecond);
    writer.Write(bytesPerSecond);
    writer.Write(frameSize);
    writer.Write(bitsPerSample);
    writer.Write(0x61746164); // = encoding.GetBytes("data")
    writer.Write(dataChunkSize);
    {
        double theta = frequency * TAU / (double)samplesPerSecond;
        // 'volume' is UInt16 with range 0 thru Uint16.MaxValue ( = 65 535)
        // we need 'amp' to have the range of 0 thru Int16.MaxValue ( = 32 767)
        // so we simply set amp = volume / 2
        double amp = volume >> 1; // Shifting right by 1 divides by 2
        for (int step = 0; step < samples; step++)
        {
            short s = (short)(amp * Math.Sin(theta * (double)step));
            writer.Write(s);
        }
    }

    mStrm.Seek(0, SeekOrigin.Begin);
    new System.Media.SoundPlayer(mStrm).Play();
    writer.Close();
    mStrm.Close();
} // public static void PlayBeep(UInt16 frequency, int msDuration, UInt16 volume = 16383)

But this code shows a bit of insight into the WAV-format, and it is even code that allows a person to build your own WAV-format in C# source code.

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