Re-encode S32 audio sample formats without re-enumerating the files

src/audio/aldatasource.h

@@ -56,8 +56,7 @@ struct ALDataSource
 ALDataSource *createSDLSource(SDL_RWops &ops,
                               const char *extension,
 			                  uint32_t maxBufSize,
-			                  bool looped,
+			                  bool looped);
-			                  int fallbackMode);
 
 ALDataSource *createVorbisSource(SDL_RWops &ops,
                                  bool looped);

src/audio/alstream.cpp

@@ -192,11 +192,10 @@ struct ALStreamOpenHandler : FileSystem::OpenHandler
 {
 	bool looped;
 	ALDataSource *source;
-	int fallbackMode;
 	std::string errorMsg;
 
 	ALStreamOpenHandler(bool looped)
-	    : looped(looped), source(0), fallbackMode(0)
+	    : looped(looped), source(0)
 	{}
 
 	bool tryRead(SDL_RWops &ops, const char *ext)
@@ -225,7 +224,7 @@ struct ALStreamOpenHandler : FileSystem::OpenHandler
 				}
 			}
 
-			source = createSDLSource(ops, ext, STREAM_BUF_SIZE, looped, fallbackMode);
+			source = createSDLSource(ops, ext, STREAM_BUF_SIZE, looped);
 		}
 		catch (const Exception &e)
 		{
@@ -258,13 +257,6 @@ void ALStream::openSource(const std::string &filename)
 
 	close();
 
-	// Try fallback mode, e.g. for handling S32->F32 sample format conversion
-	if (!handler.source)
-	{
-		handler.fallbackMode = 1;
-		shState->fileSystem().openRead(handler, filename.c_str());
-	}
-
 	if (!handler.source)
 	{
 		char buf[512];

src/audio/sdlsoundsource.cpp

@@ -24,10 +24,15 @@
 
 #include <SDL_sound.h>
 
+static int SDL_RWopsCloseNoop(SDL_RWops *ops) {
+	return 0;
+}
+
 struct SDLSoundSource : ALDataSource
 {
 	Sound_Sample *sample;
 	SDL_RWops srcOps;
+	SDL_RWops unclosableOps;
 	uint8_t sampleSize;
 	bool looped;
 
@@ -37,34 +42,23 @@ struct SDLSoundSource : ALDataSource
 	SDLSoundSource(SDL_RWops &ops,
 	               const char *extension,
 	               uint32_t maxBufSize,
-	               bool looped,
+	               bool looped)
-	               int fallbackMode)
 	    : srcOps(ops),
+	      unclosableOps(ops),
 	      looped(looped)
 	{
-		if (fallbackMode == 0)
+		/* A copy of srcOps with a no-op close function,
-		{
+		 * so we can reuse the ops if we need to change the format. */
-			sample = Sound_NewSample(&srcOps, extension, 0, maxBufSize);
+		unclosableOps.close = SDL_RWopsCloseNoop;
-		}
-		else
-		{
-			// We're here because a previous attempt resulted in S32 format.
 		
-			Sound_AudioInfo desired;
+		sample = Sound_NewSample(&unclosableOps, extension, 0, maxBufSize);
-			SDL_memset(&desired, '\0', sizeof (Sound_AudioInfo));
-			desired.format = AUDIO_F32SYS;
-
-			sample = Sound_NewSample(&srcOps, extension, &desired, maxBufSize);
-		}
 		
 		if (!sample)
 		{
-			SDL_RWclose(&ops);
+			SDL_RWclose(&srcOps);
 			throw Exception(Exception::SDLError, "SDL_sound: %s", Sound_GetError());
 		}
 
-		if (fallbackMode == 0)
-		{
 		bool validFormat = true;
 		
 		switch (sample->actual.format)
@@ -83,7 +77,18 @@ struct SDLSoundSource : ALDataSource
 			// So we just have to close the sample (which closes the file too),
 			// and retry with a new desired format.
 			Sound_FreeSample(sample);
-				throw Exception(Exception::SDLError, "SDL_sound: format not supported by OpenAL: %d", sample->actual.format);
+			SDL_RWseek(&unclosableOps, 0, RW_SEEK_SET);
+			
+			Sound_AudioInfo desired;
+			SDL_memset(&desired, '\0', sizeof (Sound_AudioInfo));
+			desired.format = AUDIO_F32SYS;
+
+			sample = Sound_NewSample(&unclosableOps, extension, &desired, maxBufSize);
+
+			if (!sample)
+			{
+				SDL_RWclose(&srcOps);
+				throw Exception(Exception::SDLError, "SDL_sound: %s", Sound_GetError());
 			}
 		}
 
@@ -95,8 +100,8 @@ struct SDLSoundSource : ALDataSource
 
 	~SDLSoundSource()
 	{
-		/* This also closes 'srcOps' */
 		Sound_FreeSample(sample);
+		SDL_RWclose(&srcOps);
 	}
 
 	Status fillBuffer(AL::Buffer::ID alBuffer)
@@ -162,8 +167,7 @@ struct SDLSoundSource : ALDataSource
 ALDataSource *createSDLSource(SDL_RWops &ops,
                               const char *extension,
 			                  uint32_t maxBufSize,
-			                  bool looped,
+			                  bool looped)
-			                  int fallbackMode)
 {
-	return new SDLSoundSource(ops, extension, maxBufSize, looped, fallbackMode);
+	return new SDLSoundSource(ops, extension, maxBufSize, looped);
 }