Create audio_stream_effects.c

examples/audio/audio_stream_effects.c

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+/*******************************************************************************************
+*
+*   raylib [audio] example - Music stream processing effects
+*
+*   Example originally created with raylib 4.2, last time updated with raylib 4.2
+*
+*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+*   BSD-like license that allows static linking with closed source software
+*
+*   Copyright (c) 2022 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#include <stdlib.h>         // Required for: NULL
+
+// Required delay effect variables
+static float *delayBuffer = NULL;
+static unsigned int delayBufferSize = 0;
+static unsigned int delayReadIndex = 2;
+static unsigned int delayWriteIndex = 0;
+
+//------------------------------------------------------------------------------------
+// Module Functions Declaration
+//------------------------------------------------------------------------------------
+static void AudioProcessEffectLPF(void *buffer, unsigned int frames);   // Audio effect: lowpass filter
+static void AudioProcessEffectDelay(void *buffer, unsigned int frames); // Audio effect: delay
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [audio] example - stream effects");
+
+    InitAudioDevice();              // Initialize audio device
+
+    Music music = LoadMusicStream("resources/country.mp3");
+
+    // Allocate buffer for the delay effect
+    delayBufferSize = 48000*2;      // 1 second delay (device sampleRate*channels)
+    delayBuffer = (float *)RL_CALLOC(delayBufferSize, sizeof(float));
+
+    PlayMusicStream(music);
+
+    float timePlayed = 0.0f;        // Time played normalized [0.0f..1.0f]
+    bool pause = false;             // Music playing paused
+    
+    bool enableEffectLPF = false;   // Enable effect low-pass-filter
+    bool enableEffectDelay = false; // Enable effect delay (1 second)
+
+    SetTargetFPS(60);               // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        UpdateMusicStream(music);   // Update music buffer with new stream data
+
+        // Restart music playing (stop and play)
+        if (IsKeyPressed(KEY_SPACE))
+        {
+            StopMusicStream(music);
+            PlayMusicStream(music);
+        }
+
+        // Pause/Resume music playing
+        if (IsKeyPressed(KEY_P))
+        {
+            pause = !pause;
+
+            if (pause) PauseMusicStream(music);
+            else ResumeMusicStream(music);
+        }
+
+        // Add/Remove effect: lowpass filter
+        if (IsKeyPressed(KEY_F))
+        {
+            enableEffectLPF = !enableEffectLPF;
+            if (enableEffectLPF) AttachAudioStreamProcessor(music.stream, AudioProcessEffectLPF);
+            else DetachAudioStreamProcessor(music.stream, AudioProcessEffectLPF);
+        }
+
+        // Add/Remove effect: delay
+        if (IsKeyPressed(KEY_D))
+        {
+            enableEffectDelay = !enableEffectDelay;
+            if (enableEffectDelay) AttachAudioStreamProcessor(music.stream, AudioProcessEffectDelay);
+            else DetachAudioStreamProcessor(music.stream, AudioProcessEffectDelay);
+        }
+        
+        // Get normalized time played for current music stream
+        timePlayed = GetMusicTimePlayed(music)/GetMusicTimeLength(music);
+
+        if (timePlayed > 1.0f) timePlayed = 1.0f;   // Make sure time played is no longer than music
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            DrawText("MUSIC SHOULD BE PLAYING!", 245, 150, 20, LIGHTGRAY);
+
+            DrawRectangle(200, 180, 400, 12, LIGHTGRAY);
+            DrawRectangle(200, 180, (int)(timePlayed*400.0f), 12, MAROON);
+            DrawRectangleLines(200, 180, 400, 12, GRAY);
+
+            DrawText("PRESS SPACE TO RESTART MUSIC", 215, 230, 20, LIGHTGRAY);
+            DrawText("PRESS P TO PAUSE/RESUME MUSIC", 208, 260, 20, LIGHTGRAY);
+            
+            DrawText(TextFormat("PRESS F TO TOGGLE LPF EFFECT: %s", enableEffectLPF? "ON" : "OFF"), 200, 320, 20, GRAY);
+            DrawText(TextFormat("PRESS D TO TOGGLE DELAY EFFECT: %s", enableEffectDelay? "ON" : "OFF"), 180, 350, 20, GRAY);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadMusicStream(music);   // Unload music stream buffers from RAM
+
+    CloseAudioDevice();         // Close audio device (music streaming is automatically stopped)
+
+    RL_FREE(delayBuffer);       // Free delay buffer
+
+    CloseWindow();              // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}
+
+//------------------------------------------------------------------------------------
+// Module Functions Definition
+//------------------------------------------------------------------------------------
+// Audio effect: lowpass filter
+static void AudioProcessEffectLPF(void *buffer, unsigned int frames)
+{
+    static float low[2] = { 0.0f, 0.0f };
+    static const float cutoff = 70.0f / 44100.0f; // 70 Hz lowpass filter
+    const float k = cutoff / (cutoff + 0.1591549431f); // RC filter formula
+
+    for (unsigned int i = 0; i < frames*2; i += 2)
+    {
+        float l = ((float *)buffer)[i], r = ((float *)buffer)[i + 1];
+        low[0] += k * (l - low[0]);
+        low[1] += k * (r - low[1]);
+        ((float *)buffer)[i] = low[0];
+        ((float *)buffer)[i + 1] = low[1];
+    }
+}
+
+// Audio effect: delay
+static void AudioProcessEffectDelay(void *buffer, unsigned int frames)
+{
+    for (unsigned int i = 0; i < frames*2; i += 2)
+    {
+        float leftDelay = delayBuffer[delayReadIndex++];    // ERROR: Reading buffer -> WHY??? Maybe thread related???
+        float rightDelay = delayBuffer[delayReadIndex++];
+
+        if (delayReadIndex == delayBufferSize) delayReadIndex = 0;
+
+        ((float *)buffer)[i] = 0.5f*((float *)buffer)[i] + 0.5f*leftDelay;
+        ((float *)buffer)[i + 1] = 0.5f*((float *)buffer)[i + 1] + 0.5f*rightDelay;
+
+        delayBuffer[delayWriteIndex++] = ((float *)buffer)[i];
+        delayBuffer[delayWriteIndex++] = ((float *)buffer)[i + 1];
+        if (delayWriteIndex == delayBufferSize) delayWriteIndex = 0;
+    }
+}