Initial community commit

Src/replicant/replaygain/ifc_replaygain_settings.h

@@ -0,0 +1,62 @@
+#pragma once
+#include "foundation/dispatch.h"
+
+/* ok, this could have easily been a config group, but I decided to make it its own interface for two reasons
+1) it's a little more maintainable and easier to understand and use, rather than just using a generic key/value interface
+2) the original ReplayGain specs suggests using the average gain of the last 10 played tracks in cases of missing replay gain data
+http://replaygain.hydrogenaudio.org/proposal/player_scale.html
+So we need a way to have the playback object pass along gain values so they can be averages in this way
+
+*/
+
+// {1CE24DEC-A189-4BC7-86A7-C6CDB0F8953D}
+static const GUID replaygain_settings_interface_guid = 
+{ 0x1ce24dec, 0xa189, 0x4bc7, { 0x86, 0xa7, 0xc6, 0xcd, 0xb0, 0xf8, 0x95, 0x3d } };
+
+class ifc_metadata;
+
+class ifc_replaygain_settings : public Wasabi2::Dispatchable
+{
+protected:
+	ifc_replaygain_settings() : Wasabi2::Dispatchable(DISPATCHABLE_VERSION) {}
+	~ifc_replaygain_settings() {}
+public:
+	static GUID GetInterfaceGUID() { return replaygain_settings_interface_guid; }
+
+	enum
+	{
+		REPLAYGAIN_OFF=0x0,
+		REPLAYGAIN_ON=0x1,
+		REPLAYGAIN_MODE_TRACK=0x2,
+		REPLAYGAIN_MODE_ALBUM=0x4,
+		REPLAYGAIN_MODE_MASK=REPLAYGAIN_MODE_TRACK|REPLAYGAIN_MODE_ALBUM,
+		REPLAYGAIN_PREVENT_CLIPPING=0x8,
+		REPLAYGAIN_AUTO=0x16, // automatically determine gain values for unscanned tracks from prior history
+	};
+
+	/* pass the ifc_metadata associated with the track
+	warning values:
+	NErr_Success: gain is set to the gain adjustment to play this track with
+	NErr_False: gain is set to the default gain adjustment because there was no metadata
+	NErr_Unknown: gain is set to the default gain adjustment, because the metadata object does not understand the ReplayGain metadata keys (MetadataKeys::TRACK_GAIN, etc) 
+
+	return values:
+	NErr_Success: *gain has been assigned and is valid
+	NErr_Disabled: ReplayGain is turned off
+	*/
+	int GetGain(ifc_metadata *metadata, double *gain, int *warning) { return ReplayGainSettings_GetGain(metadata, gain, warning); }
+
+	/* Adds a track to the history, which is optionally used when playing back tracks without ReplayGain
+	pass the track length (or an estimate).  Pass 0.0 for length if don't know.
+	You should only call this if GetGain returned NErr_Success and there was no warning! 
+	*/
+	int AddToHistory(double seconds, double gain) { return ReplayGainSettings_AddToHistory(seconds, gain); }
+private:
+	virtual int WASABICALL ReplayGainSettings_GetGain(ifc_metadata *metadata, double *gain, int *warning)=0;
+	virtual int WASABICALL ReplayGainSettings_AddToHistory(double seconds, double gain)=0;
+
+	enum
+	{
+		DISPATCHABLE_VERSION,
+	};
+};