basic save support added

effects/volumeeffect.cpp

@@ -7,10 +7,7 @@
 #include "ui/collapsiblewidget.h"
 
 VolumeEffect::VolumeEffect(Clip* c) : Effect(c) {
-	container = new CollapsibleWidget();
-	container->setText(audio_effect_names[AUDIO_VOLUME_EFFECT]);
-
-	ui = new QWidget();
+    setup_effect(EFFECT_TYPE_AUDIO, AUDIO_VOLUME_EFFECT);
 
 	QGridLayout* ui_layout = new QGridLayout();
 
@@ -34,6 +31,10 @@ Effect* VolumeEffect::copy() {
     return v;
 }
 
+void VolumeEffect::save(QXmlStreamWriter *stream) {
+    stream->writeTextElement("volume", QString::number(volume_val->value()));
+}
+
 void VolumeEffect::process_audio(uint8_t *samples, int nb_bytes) {
 	for (int i=0;i<nb_bytes;i+=2) {
 		int16_t full_sample = (int16_t) ((samples[i+1] << 8) | samples[i]);