Ticket #8321: elapsed-time.diff

scummvm/sound/mixer.cpp

@@ -49 +49 @@
         int8 _balance;
         bool _paused;
         int _id;
+        uint32 _samplesConsumed;
+        uint32 _samplesDecoded;
+        uint32 _mixerTimeStamp;
 
 protected:
         RateConverter *_converter;
@@ -83 +86 @@
         int getId() const {
                 return _id;
         }
+        uint32 getElapsedTime();
 };
 
 class ChannelStream : public Channel {
@@ -393 +397 @@
                 _channels[index]->setBalance(balance);
 }
 
+uint32 SoundMixer::getChannelElapsedTime(PlayingSoundHandle handle) {
+        Common::StackLock lock(_mutex);
+
+        if (!handle.isActive())
+                return 0;
+
+        int index = handle.getIndex();
+
+        if ((index < 0) || (index >= NUM_CHANNELS)) {
+                warning("soundMixer::getChannelElapsedTime has invalid index %d", index);
+                return 0;
+        }
+
+        if (_channels[index])
+                return _channels[index]->getElapsedTime();
+
+        warning("soundMixer::getChannelElapsedTime has no channel object for index %d", index);
+        return 0;
+}
+
 void SoundMixer::pauseAll(bool paused) {
         _paused = paused;
 }
@@ -465 +489 @@
 
 Channel::Channel(SoundMixer *mixer, PlayingSoundHandle *handle, bool isMusic, int id)
         : _mixer(mixer), _handle(handle), _autofreeStream(true), _isMusic(isMusic),
-          _volume(255), _balance(0), _paused(false), _id(id), _converter(0), _input(0) {
+          _volume(255), _balance(0), _paused(false), _id(id), _samplesConsumed(0),
+          _samplesDecoded(0), _mixerTimeStamp(0), _converter(0), _input(0) {
         assert(mixer);
 }
 
 Channel::Channel(SoundMixer *mixer, PlayingSoundHandle *handle, AudioStream *input,
                                 bool autofreeStream, bool isMusic, bool reverseStereo, int id)
         : _mixer(mixer), _handle(handle), _autofreeStream(autofreeStream), _isMusic(isMusic),
-          _volume(255), _balance(0), _paused(false), _id(id), _converter(0), _input(input) {
+          _volume(255), _balance(0), _paused(false), _id(id), _samplesConsumed(0),
+          _samplesDecoded(0), _mixerTimeStamp(0), _converter(0), _input(input) {
         assert(mixer);
         assert(input);
 
@@ -522 +548 @@
                         vol_r = vol / 255;
                 }
 
+                _samplesConsumed = _samplesDecoded;
+                _mixerTimeStamp = g_system->get_msecs();
+
                 _converter->flow(*_input, data, len, vol_l, vol_r);
+
+                _samplesDecoded += len;
         }
 }
 
+uint32 Channel::getElapsedTime() {
+        if (_mixerTimeStamp == 0)
+                return 0;
+
+        // Convert the number of samples into a time duration. To avoid
+        // overflow, this has to be done in a somewhat non-obvious way.
+
+        uint rate = _mixer->getOutputRate();
+
+        uint32 seconds = _samplesConsumed / rate;
+        uint32 milliseconds = (1000 * (_samplesConsumed % rate)) / rate;
+
+        uint32 delta = g_system->get_msecs() - _mixerTimeStamp;
+
+        // In theory it would seem like a good idea to limit the approximation
+        // so that it never exceeds the theoretical upper bound set by
+        // _samplesDecoded. Meanwhile, back in the real world, doing so makes
+        // the Broken Sword cutscenes noticeably jerkier. I guess the mixer
+        // isn't invoked at the regular intervals that I first imagined.
+
+        // FIXME: This won't work if the sound is paused.
+        return 1000 * seconds + milliseconds + delta;
+}
+
 ChannelStream::ChannelStream(SoundMixer *mixer, PlayingSoundHandle *handle,
                                                         uint rate, byte flags, uint32 buffer_size)
         : Channel(mixer, handle, true) {

scummvm/sound/mixer.h

@@ -154 +154 @@
         /** set the channel balance for the given handle (-127 ... 0 ... 127) (left ... center ... right)*/
         void setChannelBalance(PlayingSoundHandle handle, int8 balance);
 
+        /** get approximation of for how long the channel has been playing */
+        uint32 getChannelElapsedTime(PlayingSoundHandle handle);
+
         /** Check whether any SFX channel is active.*/
         bool hasActiveSFXChannel();