fixed crashes when exporting only video or only audio

io/exportthread.cpp

@@ -322,9 +322,9 @@ void ExportThread::run() {
 
 	continueEncode = setupContainer();
 
-	if (continueEncode) continueEncode = setupVideo();
+    if (video_enabled && continueEncode) continueEncode = setupVideo();
 
-	if (continueEncode) continueEncode = setupAudio();
+    if (audio_enabled && continueEncode) continueEncode = setupAudio();
 
 	if (continueEncode) {
 		ret = avformat_write_header(fmt_ctx, NULL);
@@ -412,8 +412,8 @@ void ExportThread::run() {
 	if (continueEncode) {
 		// flush remaining packets
 		while (continueVideo && continueAudio) {
-			if (continueVideo) continueVideo = encode(fmt_ctx, vcodec_ctx, NULL, &video_pkt, video_stream);
-			if (continueAudio) continueAudio = encode(fmt_ctx, acodec_ctx, NULL, &audio_pkt, audio_stream);
+            if (continueVideo && video_enabled) continueVideo = encode(fmt_ctx, vcodec_ctx, NULL, &video_pkt, video_stream);
+            if (continueAudio && audio_enabled) continueAudio = encode(fmt_ctx, acodec_ctx, NULL, &audio_pkt, audio_stream);
 		}
 
 		ret = av_write_trailer(fmt_ctx);

io/media.cpp

@@ -10,7 +10,7 @@ extern "C" {
 
 #include "project/clip.h"
 
-Media::Media() : ready(false), preview_gen(NULL), throbber(NULL) {
+Media::Media() : ready(false), preview_gen(NULL) {
     ready_lock.lock();
 }
 
@@ -22,10 +22,7 @@ void Media::reset() {
 	if (preview_gen != NULL) {
 		preview_gen->cancel();
 		preview_gen->wait();
-	}
-	if (throbber != NULL) {
-		delete throbber;
-	}
+    }
     for (int i=0;i<video_tracks.size();i++) {
         delete video_tracks.at(i);
     }

io/media.h

@@ -53,8 +53,7 @@ struct Media {
     int save_id;
     bool ready;
 
-	PreviewGenerator* preview_gen;
-	MediaThrobber* throbber;
+    PreviewGenerator* preview_gen;
     QMutex ready_lock;
 
     bool using_inout;