raylib/examples/audio/audio_raw_stream.c

/*******************************************************************************************
*
*   raylib [audio] example - Raw audio streaming
*
*   NOTE: This example requires OpenAL Soft library installed
*
*   This example has been created using raylib 1.6 (www.raylib.com)
*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
*
*   Copyright (c) 2015-2018 Ramon Santamaria (@raysan5) and James Hofmann (@triplefox)
*
********************************************************************************************/

#include "raylib.h"

#include <stdlib.h>         // Required for: malloc(), free()
#include <math.h>           // Required for: sinf()
#include <string.h>         // Required for: memcpy()

#define MAX_SAMPLES               512
#define MAX_SAMPLES_PER_UPDATE   4096

int main()
{
    // Initialization
    //--------------------------------------------------------------------------------------
    int screenWidth = 800;
    int screenHeight = 450;

    InitWindow(screenWidth, screenHeight, "raylib [audio] example - raw audio streaming");

    InitAudioDevice();              // Initialize audio device

    // Init raw audio stream (sample rate: 22050, sample size: 16bit-short, channels: 1-mono)
    AudioStream stream = InitAudioStream(22050, 16, 1);
    
    // Buffer for the single cycle waveform we are synthesizing
    short *data = (short *)malloc(sizeof(short)*MAX_SAMPLES);

    // Frame buffer, describing the waveform when repeated over the course of a frame
    short *writeBuf = (short *)malloc(sizeof(short)*MAX_SAMPLES_PER_UPDATE);
    
    PlayAudioStream(stream);        // Start processing stream buffer (no data loaded currently)
    
    // Position read in to determine next frequency
    Vector2 mousePosition = { -100.0f, -100.0f };
    
    // Cycles per second (hz)
    float frequency = 440.0f;
    
    // Previous value, used to test if sine needs to be rewritten, and to smoothly modulate frequency
    float oldFrequency = 1.0f;
    
    // Cursor to read and copy the samples of the sine wave buffer
    int readCursor = 0;
    
    // Computed size in samples of the sine wave
    int waveLength = 1;
    
    Vector2 position = { 0, 0 };

    SetTargetFPS(30);               // Set our game to run at 30 frames-per-second
    //--------------------------------------------------------------------------------------

    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        // Update
        //----------------------------------------------------------------------------------
        
        // Sample mouse input.
        mousePosition = GetMousePosition();
        
        if (IsMouseButtonDown(MOUSE_LEFT_BUTTON)) 
        {
            float fp = (float)(mousePosition.y);
            frequency = 40.0f + (float)(fp);
        }
        
        // Rewrite the sine wave.
        // Compute two cycles to allow the buffer padding, simplifying any modulation, resampling, etc.
        if (frequency != oldFrequency) 
        {
            // Compute wavelength. Limit size in both directions.
            int oldWavelength = waveLength;
            waveLength = (int)(22050/frequency);
            if (waveLength > MAX_SAMPLES/2) waveLength = MAX_SAMPLES/2;
            if (waveLength < 1) waveLength = 1;
            
            // Write sine wave.
            for (int i = 0; i < waveLength*2; i++)
            {
                data[i] = (short)(sinf(((2*PI*(float)i/waveLength)))*32000);
            }
            
            // Scale read cursor's position to minimize transition artifacts
            readCursor = (int)(readCursor * ((float)waveLength / (float)oldWavelength));
            oldFrequency = frequency;
        }
        
        // Refill audio stream if required
        if (IsAudioBufferProcessed(stream)) 
        {
            // Synthesize a buffer that is exactly the requested size
            int writeCursor = 0;
            
            while (writeCursor < MAX_SAMPLES_PER_UPDATE) 
            {
                // Start by trying to write the whole chunk at once
                int writeLength = MAX_SAMPLES_PER_UPDATE-writeCursor;
                
                // Limit to the maximum readable size
                int readLength = waveLength-readCursor;
                
                if (writeLength > readLength) writeLength = readLength;

                // Write the slice
                memcpy(writeBuf + writeCursor, data + readCursor, writeLength*sizeof(short));
                
                // Update cursors and loop audio
                readCursor = (readCursor + writeLength) % waveLength;
                
                writeCursor += writeLength;
            }
            
            // Copy finished frame to audio stream
            UpdateAudioStream(stream, writeBuf, MAX_SAMPLES_PER_UPDATE);
        }
        //----------------------------------------------------------------------------------

        // Draw
        //----------------------------------------------------------------------------------
        BeginDrawing();

            ClearBackground(RAYWHITE);

            DrawText(FormatText("sine frequency: %i",(int)frequency), GetScreenWidth() - 220, 10, 20, RED);
            DrawText("click mouse button to change frequency", 10, 10, 20, DARKGRAY);
            
            // Draw the current buffer state proportionate to the screen
            for (int i = 0; i < screenWidth; i++)
            {
                position.x = i;
                position.y = 250 + 50*data[i*MAX_SAMPLES/screenWidth]/32000;
                
                DrawPixelV(position, RED);
            }

        EndDrawing();
        //----------------------------------------------------------------------------------
    }

    // De-Initialization
    //--------------------------------------------------------------------------------------
    free(data);                 // Unload sine wave data
    free(writeBuf);             // Unload write buffer
    
    CloseAudioStream(stream);   // Close raw audio stream and delete buffers from RAM
    CloseAudioDevice();         // Close audio device (music streaming is automatically stopped)

    CloseWindow();              // Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}