I am using MediaCapture
to preview camera on the screen, which is working fine.
However, I need to access the current frames in my App. Therefore I added FrameReader
to the MediaCapture
to get the event Reader_FrameArrived.
So the event is working, however the bitmap itself is always null.
I implemented the ecent callback just like shown in the examples:
var mediaFrameReference = sender.TryAcquireLatestFrame();
var videoMediaFrame = mediaFrameReference?.VideoMediaFrame;
var softwareBitmap = videoMediaFrame?.SoftwareBitmap;
if (softwareBitmap != null)
{
Debug.WriteLine("here");
}
else
{
return;
}
and this is how I initialize the reader:
var frameSourceGroups = await MediaFrameSourceGroup.FindAllAsync();
var allGroups = await MediaFrameSourceGroup.FindAllAsync();
var eligibleGroups = allGroups.Select(g => new
{
Group = g,
// For each source kind, find the source which offers that kind of media frame,
// or null if there is no such source.
SourceInfos = new MediaFrameSourceInfo[]
{
g.SourceInfos.FirstOrDefault(info => info.SourceKind == MediaFrameSourceKind.Color),
g.SourceInfos.FirstOrDefault(info => info.SourceKind == MediaFrameSourceKind.Depth),
g.SourceInfos.FirstOrDefault(info => info.SourceKind == MediaFrameSourceKind.Infrared),
}
}).Where(g => g.SourceInfos.Any(info => info != null)).ToList();
if (eligibleGroups.Count == 0)
{
System.Diagnostics.Debug.WriteLine("No source group with color, depth or infrared found.");
return;
}
var selectedGroupIndex = 0; // Select the first eligible group
MediaFrameSourceGroup selectedGroup = eligibleGroups[selectedGroupIndex].Group;
MediaFrameSourceInfo colorSourceInfo = eligibleGroups[selectedGroupIndex].SourceInfos[0];
MediaFrameSourceInfo infraredSourceInfo = eligibleGroups[selectedGroupIndex].SourceInfos[1];
MediaFrameSourceInfo depthSourceInfo = eligibleGroups[selectedGroupIndex].SourceInfos[2];
//_mediaCapture.FrameSources.TryGetValue(cameraDevice.Id, out _source);
var colorFrameSource = _mediaCapture.FrameSources[colorSourceInfo.Id];
if (colorFrameSource != null)
{
_reader = await _mediaCapture.CreateFrameReaderAsync(colorFrameSource, MediaEncodingSubtypes.Argb32);
_reader.FrameArrived += Reader_FrameArrived;
MediaFrameReaderStartStatus result = await _reader.StartAsync();
Debug.WriteLine(result.ToString());
}
Any ideas why the bitmap could be null?
For the scenario, we suggest you use
MediaCapture
class capture bitmap, it containsGetPreviewFrameAsync
method gets a preview frame from the capture device than convert it toSoftwareBitmap
.And here is official code sample that you could refer directly.