MADE: Fix movie audio glitches caused by reset of audio decoder

The sound buffer used in decompressSound() is now stored so that
it can be re-used in the next call of decompressSound, specifically
in chunk type 1.

This caused some clicking/static in the intro of Return to Zork.

Thanks to eriktorbjorn for noticing the glitch and writing most of the patch.

3 files changed, 37 insertions, 6 deletions

diff --git a/engines/made/pmvplayer.cpp b/engines/made/pmvplayer.cpp
index 6ea0dc24d0..453e2a4872 100644
--- a/engines/made/pmvplayer.cpp
+++ b/engines/made/pmvplayer.cpp
@@ -118,6 +118,8 @@ bool PmvPlayer::play(const char *filename) {
 	// get it to work well?
 	_audioStream = Audio::makeQueuingAudioStream(soundFreq, false);
 
+	SoundDecoderData *soundDecoderData = new SoundDecoderData();
+
 	while (!_vm->shouldQuit() && !_aborted && !_fd->eos() && frameNumber < frameCount) {
 
 		int32 frameTime = _vm->_system->getMillis();
@@ -153,7 +155,7 @@ bool PmvPlayer::play(const char *filename) {
 
 			soundSize = chunkCount * chunkSize;
 			soundData = (byte *)malloc(soundSize);
-			decompressSound(audioData + 8, soundData, chunkSize, chunkCount);
+			decompressSound(audioData + 8, soundData, chunkSize, chunkCount, NULL, soundDecoderData);
 			_audioStream->queueBuffer(soundData, soundSize, DisposeAfterUse::YES, Audio::FLAG_UNSIGNED);
 		}
 
@@ -213,6 +215,7 @@ bool PmvPlayer::play(const char *filename) {
 
 	}
 
+	delete soundDecoderData;
 	delete[] frameData;
 
 	_audioStream->finish();
diff --git a/engines/made/sound.cpp b/engines/made/sound.cpp
index 91e855cbf5..cf602a92bf 100644
--- a/engines/made/sound.cpp
+++ b/engines/made/sound.cpp
@@ -133,10 +133,10 @@ void ManholeEgaSoundDecompressor::update3() {
 		_sample2 += _sample1;
 }
 
-void decompressSound(byte *source, byte *dest, uint16 chunkSize, uint16 chunkCount, SoundEnergyArray *soundEnergyArray) {
+void decompressSound(byte *source, byte *dest, uint16 chunkSize, uint16 chunkCount, SoundEnergyArray *soundEnergyArray, SoundDecoderData *soundDecoderData) {
 
-	int16 prevSample = 0, workSample = 0;
-	byte soundBuffer[1025];
+	int16 prevSample, workSample;
+	byte* soundBuffer;
 	byte deltaSoundBuffer[1024];
 	int16 soundBuffer2[16];
 	byte deltaType, type;
@@ -159,6 +159,15 @@ void decompressSound(byte *source, byte *dest, uint16 chunkSize, uint16 chunkCou
 	if (soundEnergyArray)
 		soundEnergyArray->clear();
 
+	if (soundDecoderData) {
+		soundBuffer = soundDecoderData->_soundBuffer;
+		prevSample = soundDecoderData->_prevSample;
+	} else {
+		soundBuffer = new byte[1025];
+		memset(soundBuffer, 0x80, 1025);
+		prevSample = 0;
+	}
+
 	while (chunkCount--) {
 		deltaType = (*source) >> 6;
 		workChunkSize = chunkSize;
@@ -255,9 +264,13 @@ void decompressSound(byte *source, byte *dest, uint16 chunkSize, uint16 chunkCou
 		prevSample = workSample;
 		memcpy(dest, soundBuffer, chunkSize);
 		dest += chunkSize;
-
 	}
 
+	if (soundDecoderData) {
+		soundDecoderData->_prevSample = prevSample;
+	} else {
+		delete[] soundBuffer;
+	}
 }
 
 } // End of namespace Made
diff --git a/engines/made/sound.h b/engines/made/sound.h
index 6ffca13aaa..72537322f9 100644
--- a/engines/made/sound.h
+++ b/engines/made/sound.h
@@ -53,7 +53,22 @@ struct SoundEnergyItem {
 
 typedef Common::Array<SoundEnergyItem> SoundEnergyArray;
 
-void decompressSound(byte *source, byte *dest, uint16 chunkSize, uint16 chunkCount, SoundEnergyArray *soundEnergyArray = NULL);
+
+// Persistent data for decompressSound(). When calling decompressSound()
+// repeatedly (for the same stream), pass the same SoundDecoderData object to
+// ensure decoding properly resumes.
+class SoundDecoderData {
+public:
+	SoundDecoderData() {
+		memset(_soundBuffer, 0x80, sizeof(_soundBuffer));
+		_prevSample = 0;
+	}
+
+	byte _soundBuffer[1025];
+	int16 _prevSample;
+};
+
+void decompressSound(byte *source, byte *dest, uint16 chunkSize, uint16 chunkCount, SoundEnergyArray *soundEnergyArray = NULL, SoundDecoderData *decoderData = NULL);
 
 } // End of namespace Made