Ticket #8341: output-freq.diff

backends/sdl/sdl-common.h

@@ -133 +133 @@
         
         virtual void setWindowCaption(const char *caption);
         virtual bool openCD(int drive);
+        virtual void setOutputSampleRate(int rate);
         virtual int getOutputSampleRate() const;
 
         virtual bool hasFeature(Feature f);
@@ -169 +170 @@
         SDL_Surface *_tmpscreen;
         bool _overlayVisible;
 
+        // Audio
+        int _samplesPerSec;
+
         // CD Audio
         SDL_CD *_cdrom;
         int cd_track, cd_num_loops, cd_start_frame, cd_duration;

backends/sdl/sdl.cpp

@@ -95 +95 @@
 #endif
         _hwscreen(0), _screen(0), _screenWidth(0), _screenHeight(0),
         _tmpscreen(0), _overlayVisible(false),
+        _samplesPerSec(SAMPLES_PER_SEC),
         _cdrom(0), _scaler_proc(0), _modeChanged(false), _dirty_checksums(0),
         _mouseVisible(false), _mouseDrawn(false), _mouseData(0),
         _mouseHotspotX(0), _mouseHotspotY(0),
@@ -289 +290 @@
 
 bool OSystem_SDL::setSoundCallback(SoundProc proc, void *param) {
         SDL_AudioSpec desired;
+        SDL_AudioSpec obtained;
 
         memset(&desired, 0, sizeof(desired));
 
-        desired.freq = SAMPLES_PER_SEC;
+        desired.freq = _samplesPerSec;
         desired.format = AUDIO_S16SYS;
         desired.channels = 2;
         desired.samples = 2048;
         desired.callback = proc;
         desired.userdata = param;
-        if (SDL_OpenAudio(&desired, NULL) != 0) {
+        if (SDL_OpenAudio(&desired, &obtained) != 0) {
                 return false;
         }
+        // Note: This should be the obtained output rate, but it seems that at
+        // least on some platforms SDL will lie and claim it did get the rate
+        // even if it didn't. Probably only happens for "weird" rates, though.
+        _samplesPerSec = obtained.freq;
         SDL_PauseAudio(0);
         return true;
 }
@@ -309 +315 @@
         SDL_CloseAudio();
 }
 
+void OSystem_SDL::setOutputSampleRate(int rate) {
+        _samplesPerSec = rate;
+}
+
 int OSystem_SDL::getOutputSampleRate() const {
-        return SAMPLES_PER_SEC;
+        return _samplesPerSec;
 }
 
 #pragma mark -

common/system.h

@@ -546 +546 @@
         virtual void clearSoundCallback() = 0;
 
         /**
+         * Set the desired output sample rate. It has to be called before
+         * setSoundCallback(), and it's not certain that we actually get it.
+         * Use getOutputSampleRate() to find out.
+         */
+        virtual void setOutputSampleRate(int rate) = 0;
+
+        /**
          * Determine the output sample rate. Audio data provided by the sound
          * callback will be played using this rate.
          * @return the output sample rate

sound/mixer.cpp

@@ -21 +21 @@
  */
 
 #include "stdafx.h"
+#include "common/config-manager.h"
 #include "common/file.h"
 #include "common/util.h"
 
@@ -111 +112 @@
         _premixProc = 0;
         int i = 0;
 
-        _outputRate = (uint) _syst->getOutputSampleRate();
-
-        if (_outputRate == 0)
-                error("OSystem returned invalid sample rate");
+        if (ConfMan.hasKey("output_rate"))
+                _syst->setOutputSampleRate(ConfMan.getInt("output_rate"));
 
         _globalVolume = 0;
         _musicVolume = 0;
@@ -125 +124 @@
                 _channels[i] = 0;
 
         _mixerReady = _syst->setSoundCallback(mixCallback, this);
+        _outputRate = (uint) _syst->getOutputSampleRate();
+
+        if (_outputRate == 0)
+                error("OSystem returned invalid sample rate");
+
+        debug(1, "Output sample rate: %d Hz", _outputRate);
 }
 
 SoundMixer::~SoundMixer() {