Add SetAudioStreamCallback method to fill audio streams on the audio thread.

examples/audio/audio_raw_stream.c

@@ -20,6 +20,33 @@
 #define MAX_SAMPLES               512
 #define MAX_SAMPLES_PER_UPDATE   4096
 
+// Cycles per second (hz)
+float frequency = 440.0f;
+
+// Audio frequency, for smoothing
+float audioFrequency = 440.0f;
+
+// Previous value, used to test if sine needs to be rewritten, and to smoothly modulate frequency
+float oldFrequency = 1.0f;
+
+// index for audio rendering
+float sineIdx = 0.0f;
+  
+void audioCallback(void* buffer, unsigned int nFrames, void* callbackData)
+{
+    audioFrequency = frequency + (audioFrequency - frequency) * 0.95f;
+    audioFrequency += 1.0f;
+    audioFrequency -= 1.0f;
+    float incr = audioFrequency / 44100.0f;
+    short* d = (short*)buffer;
+    for (int i = 0; i < nFrames; i++)
+    {
+        d[i] = (short)(32000.0f * sinf(2 * PI * sineIdx));
+        sineIdx += incr;
+        if (sineIdx > 1.0f) sineIdx -= 1.0f;
+    }
+}
+
 int main(void)
 {
     // Initialization
@@ -33,9 +60,11 @@ int main(void)
 
     SetAudioStreamBufferSizeDefault(MAX_SAMPLES_PER_UPDATE);
 
-    // Init raw audio stream (sample rate: 22050, sample size: 16bit-short, channels: 1-mono)
+    // Init raw audio stream (sample rate: 44100, sample size: 16bit-short, channels: 1-mono)
     AudioStream stream = LoadAudioStream(44100, 16, 1);
 
+    SetAudioStreamCallback(stream, &audioCallback, NULL);
+
     // Buffer for the single cycle waveform we are synthesizing
     short *data = (short *)malloc(sizeof(short)*MAX_SAMPLES);
 
@@ -47,15 +76,6 @@ int main(void)
     // 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;
 
@@ -78,56 +98,23 @@ int main(void)
             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);
+            waveLength = (int)(22050 / frequency);
-            if (waveLength > MAX_SAMPLES/2) waveLength = MAX_SAMPLES/2;
+            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++)
+            for (int i = 0; i < waveLength * 2; i++)
             {
-                data[i] = (short)(sinf(((2*PI*(float)i/waveLength)))*32000);
+                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 (IsAudioStreamProcessed(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
@@ -147,7 +134,6 @@ int main(void)
 
                 DrawPixelV(position, RED);
             }
-
         EndDrawing();
         //----------------------------------------------------------------------------------
     }

src/raudio.c

@@ -315,6 +315,9 @@ typedef enum {
 struct rAudioBuffer {
     ma_data_converter converter;    // Audio data converter
 
+    void (*audioCallback)(void*, unsigned int); // optional callback for filling in buffer on audio threads
+    void* audioCallbackData;        // optional data passed to callback
+
     float volume;                   // Audio buffer volume
     float pitch;                    // Audio buffer pitch
 
@@ -396,6 +399,7 @@ void PlayAudioBuffer(AudioBuffer *buffer);
 void StopAudioBuffer(AudioBuffer *buffer);
 void PauseAudioBuffer(AudioBuffer *buffer);
 void ResumeAudioBuffer(AudioBuffer *buffer);
+void SetAudioBufferCallback(AudioBuffer* buffer, int callback(void*));
 void SetAudioBufferVolume(AudioBuffer *buffer, float volume);
 void SetAudioBufferPitch(AudioBuffer *buffer, float pitch);
 void TrackAudioBuffer(AudioBuffer *buffer);
@@ -553,6 +557,8 @@ AudioBuffer *LoadAudioBuffer(ma_format format, ma_uint32 channels, ma_uint32 sam
     // Init audio buffer values
     audioBuffer->volume = 1.0f;
     audioBuffer->pitch = 1.0f;
+    audioBuffer->audioCallback = NULL;
+    audioBuffer->audioCallbackData = NULL;
     audioBuffer->playing = false;
     audioBuffer->paused = false;
     audioBuffer->looping = false;
@@ -635,6 +641,16 @@ void ResumeAudioBuffer(AudioBuffer *buffer)
     if (buffer != NULL) buffer->paused = false;
 }
 
+// Audio thread callback to request new data
+void SetAudioBufferCallback(AudioBuffer* buffer, void callback(void*, unsigned int, void*), void* callbackData)
+{
+    if (buffer != NULL)
+    {
+        buffer->audioCallback = callback;
+        buffer->audioCallbackData = callbackData;
+    }
+}
+
 // Set volume for an audio buffer
 void SetAudioBufferVolume(AudioBuffer *buffer, float volume)
 {
@@ -1040,6 +1056,9 @@ void PlaySoundMulti(Sound sound)
 
     AUDIO.MultiChannel.pool[index]->volume = sound.stream.buffer->volume;
     AUDIO.MultiChannel.pool[index]->pitch = sound.stream.buffer->pitch;
+    AUDIO.MultiChannel.pool[index]->audioCallback = sound.stream.buffer->audioCallback;
+    AUDIO.MultiChannel.pool[index]->audioCallbackData = sound.stream.buffer->audioCallbackData;
+    
     AUDIO.MultiChannel.pool[index]->looping = sound.stream.buffer->looping;
     AUDIO.MultiChannel.pool[index]->usage = sound.stream.buffer->usage;
     AUDIO.MultiChannel.pool[index]->isSubBufferProcessed[0] = false;
@@ -1987,6 +2006,12 @@ void SetAudioStreamBufferSizeDefault(int size)
     AUDIO.Buffer.defaultSize = size;
 }
 
+// Audio thread callback to request new data
+void SetAudioStreamCallback(AudioStream stream, void callback(void*, unsigned int, void*), void* callbackData)
+{
+    SetAudioBufferCallback(stream.buffer, callback, callbackData);
+}
+
 //----------------------------------------------------------------------------------
 // Module specific Functions Definition
 //----------------------------------------------------------------------------------
@@ -2003,6 +2028,12 @@ static void OnLog(ma_context *pContext, ma_device *pDevice, ma_uint32 logLevel,
 // Reads audio data from an AudioBuffer object in internal format.
 static ma_uint32 ReadAudioBufferFramesInInternalFormat(AudioBuffer *audioBuffer, void *framesOut, ma_uint32 frameCount)
 {
+    if (audioBuffer->audioCallback)
+    {
+        audioBuffer->audioCallback(framesOut, frameCount, audioBuffer->audioCallbackData);
+        return frameCount;
+    }
+
     ma_uint32 subBufferSizeInFrames = (audioBuffer->sizeInFrames > 1)? audioBuffer->sizeInFrames/2 : audioBuffer->sizeInFrames;
     ma_uint32 currentSubBufferIndex = audioBuffer->frameCursorPos/subBufferSizeInFrames;
 
@@ -2030,7 +2061,8 @@ static ma_uint32 ReadAudioBufferFramesInInternalFormat(AudioBuffer *audioBuffer,
         }
         else
         {
-            if (isSubBufferProcessed[currentSubBufferIndex]) break;
+            if (isSubBufferProcessed[currentSubBufferIndex])
+                break;
         }
 
         ma_uint32 totalFramesRemaining = (frameCount - framesRead);

src/raudio.h

@@ -190,6 +190,7 @@ void StopAudioStream(AudioStream stream);                       // Stop audio st
 void SetAudioStreamVolume(AudioStream stream, float volume);    // Set volume for audio stream (1.0 is max level)
 void SetAudioStreamPitch(AudioStream stream, float pitch);      // Set pitch for audio stream (1.0 is base level)
 void SetAudioStreamBufferSizeDefault(int size);                 // Default size for new audio streams
+void SetAudioStreamCallback(AudioStream stream, void callback(void*, unsigned int, void*), void* callbackData);  // Audio thread callback to request new data
 
 #ifdef __cplusplus
 }

src/raylib.h

@@ -1530,6 +1530,7 @@ RLAPI void StopAudioStream(AudioStream stream);                       // Stop au
 RLAPI void SetAudioStreamVolume(AudioStream stream, float volume);    // Set volume for audio stream (1.0 is max level)
 RLAPI void SetAudioStreamPitch(AudioStream stream, float pitch);      // Set pitch for audio stream (1.0 is base level)
 RLAPI void SetAudioStreamBufferSizeDefault(int size);                 // Default size for new audio streams
+RLAPI void SetAudioStreamCallback(AudioStream stream, void callback(void*, unsigned int, void*), void* callbackData);      // Audio thread callback to request new data
 
 #if defined(__cplusplus)
 }