allow per instrument sample base path

plugin.cpp

@@ -279,6 +279,7 @@ Instrument *Plugin::loadInstrument(Json::Value &jsonInstr, uint16_t channel, flo
     Instrument *instrument = new handrumr::Instrument();
     instrument->name(jsonInstr["iname"].asString());
     float instgain = jsonInstr.isMember("gain") ? jsonInstr["gain"].asFloat() : 0.0;
+    string instbase = jsonInstr.isMember("folder") ? jsonInstr["folder"].asString() : sampleBase;
     // layers
     Json::Value jsonLayers = jsonInstr["layers"];
     uint16_t layerCount = jsonLayers.size();
@@ -309,7 +310,7 @@ Instrument *Plugin::loadInstrument(Json::Value &jsonInstr, uint16_t channel, flo
             uint16_t bufferCount = 0; // overall channel count for sample
             for (uint16_t f = 0; f < fileCount; f++) {
                 const string &filename = jsamples[f]["file"].asString();
-                const string path = fullpath(sampleBase, filename);
+                const string path = fullpath(instbase, filename);
                 const float filegain =
                     jsamples[f].isMember("gain") ? jsamples[f]["gain"].asFloat() : 0.0;
                 const float gain = db2ratio(ogaindb + instgain + layergain + filegain);
@@ -330,7 +331,7 @@ Instrument *Plugin::loadInstrument(Json::Value &jsonInstr, uint16_t channel, flo
             SampleFileBuffer *buffers = new SampleFileBuffer[bufferCount];
             uint16_t index = 0;
             for (uint16_t f = 0; f < fileCount; f++) {
-                const string path = fullpath(sampleBase, jsamples[f]["file"].asString());
+                const string path = fullpath(instbase, jsamples[f]["file"].asString());
                 SampleFile *file = filecache[path];
                 uint64_t frames = file->frames();
                 for (uint16_t c = 0; c < bufferCount; c++) {