many improvements to the playback algorithm

io/exportthread.cpp

@@ -341,7 +341,6 @@ void ExportThread::run() {
 	QOpenGLFramebufferObject fbo(sequence->width, sequence->height, QOpenGLFramebufferObject::CombinedDepthStencil, GL_TEXTURE_RECTANGLE);
 	fbo.bind();
 
-	rendering = true;
 	panel_sequence_viewer->viewer_widget->default_fbo = &fbo;
 
 	long file_audio_samples = 0;
@@ -458,4 +457,6 @@ void ExportThread::run() {
 
 	panel_sequence_viewer->viewer_widget->context()->doneCurrent();
 	panel_sequence_viewer->viewer_widget->context()->moveToThread(qApp->thread());
+
+	rendering = false;
 }

io/media.cpp

@@ -1,6 +1,7 @@
 #include "media.h"
 
 #include <QDebug>
+#include <QtMath>
 #include "io/previewgenerator.h"
 
 extern "C" {
@@ -32,7 +33,7 @@ void Media::reset() {
 }
 
 long Media::get_length_in_frames(double frame_rate) {
-    return ceil(((double) length / (double) AV_TIME_BASE) * frame_rate);
+	return qFloor(((double) length / (double) AV_TIME_BASE) * frame_rate);
 }
 
 MediaStream* Media::get_stream_from_file_index(bool video, int index) {

io/previewgenerator.cpp

@@ -74,7 +74,7 @@ void PreviewGenerator::parse_media() {
 			}
         }
     }
-    media->length = fmt_ctx->duration;
+	media->length = fmt_ctx->duration;
 
 	if (fmt_ctx->duration == INT64_MIN) {
 		retrieve_duration = true;
@@ -284,7 +284,7 @@ void PreviewGenerator::generate_waveform() {
 				maximum_stream = i;
 			}
 		}
-		media->length = (double) media_lengths[maximum_stream] / av_q2d(fmt_ctx->streams[maximum_stream]->avg_frame_rate) * AV_TIME_BASE;
+		media->length = (double) media_lengths[maximum_stream] / av_q2d(fmt_ctx->streams[maximum_stream]->avg_frame_rate) * AV_TIME_BASE; // TODO redo with PTS
 		finalize_media();
 	}
 	delete [] media_lengths;