read and utilize the aspect ratio metadata from video files

app/codec/ffmpeg/ffmpegdecoder.cpp

@@ -143,6 +143,18 @@ bool FFmpegDecoder::Open()
       // We should never get here, but just in case...
       qFatal("Invalid output format");
     }
+
+    // Determine sample aspect ratio
+    AVRational sar = av_guess_sample_aspect_ratio(fmt_ctx_, avstream_, nullptr);
+
+    // Use it to determine the display aspect ratio
+    // I'll be honest, I'm not entirely sure how this works or what it does. This code is the DAR code from ffprobe
+    // and seems to retrieve the DAR accurately.
+    av_reduce(&display_aspect_ratio_.num,
+              &display_aspect_ratio_.den,
+              avstream_->codecpar->width * sar.num,
+              avstream_->codecpar->height * sar.den,
+              1024*1024);
   }
 
   // All allocation succeeded so we set the state to open
@@ -180,6 +192,7 @@ FramePtr FFmpegDecoder::RetrieveVideo(const rational &timecode)
     frame_container->set_height(avstream_->codecpar->height);
     frame_container->set_format(native_pix_fmt_);
     frame_container->set_timestamp(Timecode::timestamp_to_time(target_ts, avstream_->time_base));
+    frame_container->set_aspect_ratio(display_aspect_ratio_);
     frame_container->allocate();
 
     memcpy(frame_container->data(), frame_loader.constData(), frame_loader.size());