cpp/openttd-patchpack/source Changeset - r23101:10b102b8ce3d

Changeset - r23101:10b102b8ce3d

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Niels Martin Hansen - 6 years ago 2018-11-04 11:58:42
nielsm@indvikleren.dk

Add: Mixer feature for streaming sampled music

2 files changed with 27 insertions and 0 deletions:

src/mixer.cpp

src/mixer.h

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src/mixer.cpp

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@@ @@ -15,6 +15,7 @@ @@
 #include "framerate_type.h"
 #include "safeguards.h"
 #include "mixer.h"
 struct MixerChannel {
 	bool active;
@@ @@ -38,6 +39,7 @@ struct MixerChannel { @@
 static MixerChannel _channels[8];
 static uint32 _play_rate = 11025;
 static uint32 _max_size = UINT_MAX;
 static MxStreamCallback _music_stream = NULL;
 /**
  * The theoretical maximum volume for a single sound sample. Multiple sound
@@ @@ -151,6 +153,9 @@ void MxMixSamples(void *buffer, uint sam @@
 	/* Clear the buffer */
 	memset(buffer, 0, sizeof(int16) * 2 * samples);
 	/* Fetch music if a sampled stream is available */
 	if (_music_stream) _music_stream((int16*)buffer, samples);
 	/* Mix each channel */
 	for (mc = _channels; mc != endof(_channels); mc++) {
 		if (mc->active) {
@@ @@ -215,6 +220,17 @@ void MxSetChannelVolume(MixerChannel *mc @@
 void MxActivateChannel(MixerChannel *mc)
+{
 	mc->active = true;
+}
 /**
  * Set source of PCM music
  * @param music_callback Function that will be called to fill sample buffers with music data.
  * @return Sample rate of mixer, which the buffers supplied to the callback must be rendered at.
  */
 uint32 MxSetMusicSource(MxStreamCallback music_callback)
+{
 	_music_stream = music_callback;
 	return _play_rate;
+}
@@ @@ -222,5 +238,6 @@ bool MxInitialize(uint rate) @@
+{
 	_play_rate = rate;
 	_max_size  = UINT_MAX / _play_rate;
 	_music_stream = NULL; /* rate may have changed, any music source is now invalid */
 	return true;
+}

src/mixer.h

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@@ @@ -14,6 +14,14 @@ @@
 struct MixerChannel;
 /**
  * Type of callback functions for supplying PCM music.
  * A music decoder/renderer implements this function and installs it with MxSetMusicSource, which also returns the sample rate used.
  * @param buffer Pointer to interleaved 2-channel signed 16 bit PCM data buffer, guaranteed to be 0-initialized.
  * @param samples number of samples that must be filled into \c buffer.
  */
 typedef void(*MxStreamCallback)(int16 *buffer, size_t samples);
 bool MxInitialize(uint rate);
 void MxMixSamples(void *buffer, uint samples);
@@ @@ -22,4 +30,6 @@ void MxSetChannelRawSrc(MixerChannel *mc @@
 void MxSetChannelVolume(MixerChannel *mc, uint volume, float pan);
 void MxActivateChannel(MixerChannel*);
 uint32 MxSetMusicSource(MxStreamCallback music_callback);
 #endif /* MIXER_H */

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