Added a GetPendingBytes method to the audio backend.

This will (eventually) make SDL_GetQueuedAudioSize() more accurate, and thus reduce latency. Right now this isn't implemented anywhere, so we assume data fed to the audio callback is consumed by the hardware and immediately played to completion.
libsdl-org · Jul 30, 2014 · e5d49c2 · e5d49c2
1 parent db1dd75
commit e5d49c2
Show file tree

Hide file tree

Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/src/audio/SDL_audio.c b/src/audio/SDL_audio.c
@@ -178,6 +178,12 @@ SDL_AudioPlayDevice_Default(_THIS)
 {                               /* no-op. */
 }
 
+static int
+SDL_AudioGetPendingBytes_Default(_THIS)
+{
+    return 0;
+}
+
 static Uint8 *
 SDL_AudioGetDeviceBuf_Default(_THIS)
 {
@@ -253,6 +259,7 @@ finalize_audio_entry_points(void)
     FILL_STUB(ThreadInit);
     FILL_STUB(WaitDevice);
     FILL_STUB(PlayDevice);
+    FILL_STUB(GetPendingBytes);
     FILL_STUB(GetDeviceBuf);
     FILL_STUB(WaitDone);
     FILL_STUB(CloseDevice);
@@ -471,7 +478,7 @@ SDL_GetQueuedAudioSize(SDL_AudioDeviceID devid)
     SDL_AudioDevice *device = get_audio_device(devid);
     if (device) {
         current_audio.impl.LockDevice(device);
-        retval = device->queued_bytes;
+        retval = device->queued_bytes + current_audio.impl.GetPendingBytes(device);
         current_audio.impl.UnlockDevice(device);
     }
 

diff --git a/src/audio/SDL_sysaudio.h b/src/audio/SDL_sysaudio.h
@@ -60,6 +60,7 @@ typedef struct SDL_AudioDriverImpl
     void (*ThreadInit) (_THIS); /* Called by audio thread at start */
     void (*WaitDevice) (_THIS);
     void (*PlayDevice) (_THIS);
+    int (*GetPendingBytes) (_THIS);
     Uint8 *(*GetDeviceBuf) (_THIS);
     void (*WaitDone) (_THIS);
     void (*CloseDevice) (_THIS);