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How to have an AWS Lambda/Rekognition Function return an array of object keys

This feels like a simple question and I feel like I am overthinking it. I am doing an AWS project that will compare face(s) on an image to a database (s3bucket) of other faces. So far, I have a lambda function for the comparefacerequest, a class library which invokes the function, and an UWP that inputs the image file and outputs a result. It has worked so far being based on boolean (true or false) functions, but now I want it to instead return what face(s) are recognized via an array. I struggling at implementing this.
Below is my lambda function. I have adjusted the task to be an Array instead of a bool and changed the return to be an array. At the bottom, I have created a global variable class with a testing array so I could attempt to reference the array elsewhere.
public class Function
{
//Function
public async Task<Array> FunctionHandler(string input, ILambdaContext context)
{
//number of matched faces
int matched = 0;
//Client setup
var rekognitionclient = new AmazonRekognitionClient();
var s3client = new AmazonS3Client();
//Create list of target images
ListObjectsRequest list = new ListObjectsRequest
{
BucketName = "bucket2"
};
ListObjectsResponse listre = await s3client.ListObjectsAsync(list);
//loop of list
foreach (Amazon.S3.Model.S3Object obj in listre.S3Objects)
{
//face request with input and obj.key images
var comparefacesrequest = new CompareFacesRequest
{
SourceImage = new Image
{
S3Object = new S3Objects
{
Bucket = "bucket1",
Name = input
}
},
TargetImage = new Image
{
S3Object = new S3Objects
{
Bucket = "bucket2",
Name = obj.Key
}
},
};
//compare with confidence of 95 (subject to change) to current target image
var detectresponse = await rekognitionclient.CompareFacesAsync(comparefacesrequest);
detectresponse.FaceMatches.ForEach(match =>
{
ComparedFace face = match.Face;
if (match.Similarity > 95)
{
//if face detected, raise matched
matched++;
for(int i = 0; i < Globaltest.testingarray.Length; i++)
{
if (Globaltest.testingarray[i] == "test")
{
Globaltest.testingarray[i] = obj.Key;
}
}
}
});
}
//Return true or false depending on if it is matched
if (matched > 0)
{
return Globaltest.testingarray;
}
return Globaltest.testingarray;
}
}
public static class Globaltest
{
public static string[] testingarray = { "test", "test", "test" };
}
Next, is my invoke request in my class library. It has so far been based on the lambda outputting a boolean result, but I thought, "hey, it is parsing the result, it should be fine, right"? I do convert the result to a string, as there is no GetArray, from what I know.
public async Task<bool> IsFace(string filePath, string fileName)
{
await UploadS3(filePath, fileName);
AmazonLambdaClient client = new AmazonLambdaClient(accessKey, secretKey, Amazon.RegionEndpoint.USWest2);
InvokeRequest ir = new InvokeRequest();
ir.InvocationType = InvocationType.RequestResponse;
ir.FunctionName = "ImageTesting";
ir.Payload = "\"" + fileName + "\"";
var result = await client.InvokeAsync(ir);
var strResponse = Encoding.ASCII.GetString(result.Payload.ToArray());
if (bool.TryParse(strResponse, out bool result2))
{
return result2;
}
return false;
}
Finally, here is the section of my UWP where I perform the function. I am referencing the lambda client via "using Lambdaclienttest" (name of lamda project, and this is its only instance I use the reference though). When I run my project, I do still get a face detected when it should, but the Globaltest.testingarray[0] is still equal to "test".
var Facedetector = new FaceDetector(Credentials.accesskey, Credentials.secretkey);
try
{
var result = await Facedetector.IsFace(filepath, filename);
if (result)
{
textBox1.Text = "There is a face detected";
textBox2.Text = Globaltest.testingarray[0];
}
else
{
textBox1.Text = "Try Again";
}
}
catch
{
textBox1.Text = "Please use a photo";
}
Does anyone have any suggestions?

Invalid cast from IDirect3DSurface to SoftwareBitmap

I try to implement processing frames from webcam to the WPF application using UWP API.
There is article how to work with MediaCapture & MediaFrameReader:
https://learn.microsoft.com/en-us/windows/uwp/audio-video-camera/process-media-frames-with-mediaframereader#handle-the-frame-arrived-event
If I set up MemoryPreference to cpu, SoftwareBitmaps are initialized to the null in the event. When I place Auto, I can see IDirect3DSurface objects are in the event, but in conversion to the SoftwareBitmap the exception "Specified cast is not valid." is raised.
How to convert IDirect3DSurface to SoftwareBitmap?
private async void MediaCaptureExample()
{
var frameSourceGroups = await MediaFrameSourceGroup.FindAllAsync();
MediaFrameSourceGroup selectedGroup = null;
MediaFrameSourceInfo colorSourceInfo = null;
foreach (var sourceGroup in frameSourceGroups)
{
foreach (var sourceInfo in sourceGroup.SourceInfos)
{
if (sourceInfo.MediaStreamType == MediaStreamType.VideoRecord && sourceInfo.SourceKind == MediaFrameSourceKind.Color)
{
colorSourceInfo = sourceInfo;
break;
}
}
if (colorSourceInfo != null)
{
selectedGroup = sourceGroup;
break;
}
}
capture = new MediaCapture();
var settings = new MediaCaptureInitializationSettings()
{
SourceGroup = selectedGroup,
SharingMode = MediaCaptureSharingMode.ExclusiveControl,
MemoryPreference = MediaCaptureMemoryPreference.Auto,
StreamingCaptureMode = StreamingCaptureMode.Video
};
await capture.InitializeAsync(settings);
var colorFrameSource = capture.FrameSources[colorSourceInfo.Id];
var preferredFormat = colorFrameSource.SupportedFormats.Where(format =>
{
return format.VideoFormat.Width >= 1080
&& String.Compare(format.Subtype, MediaEncodingSubtypes.Mjpg, true) == 0;
}).FirstOrDefault();
if (preferredFormat == null)
{
// Our desired format is not supported
return;
}
await colorFrameSource.SetFormatAsync(preferredFormat);
mediaFrameReader = await capture.CreateFrameReaderAsync(colorFrameSource);
mediaFrameReader.FrameArrived += MediaFrameReader_FrameArrived;
var result = await mediaFrameReader.StartAsync();
Console.WriteLine("Result = " + result.ToString());
}
private void MediaFrameReader_FrameArrived(MediaFrameReader sender, MediaFrameArrivedEventArgs args)
{
try
{
var mediaFrameReference = sender.TryAcquireLatestFrame();
var videoMediaFrame = mediaFrameReference?.VideoMediaFrame;
var softwareBitmap = videoMediaFrame?.SoftwareBitmap;
var direct3DSurface = videoMediaFrame?.Direct3DSurface;
if (direct3DSurface != null)
{
var softwareBitmapTask = SoftwareBitmap.CreateCopyFromSurfaceAsync(mediaFrameReference.VideoMediaFrame.Direct3DSurface).AsTask();
softwareBitmap = softwareBitmapTask.Result;
}
if (softwareBitmap != null)
{
using (var stream = new Windows.Storage.Streams.InMemoryRandomAccessStream())
{
var encoderTask = BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, stream).AsTask();
encoderTask.Wait();
var encoder = encoderTask.Result;
encoder.SetSoftwareBitmap(softwareBitmap);
Task t = encoder.FlushAsync().AsTask();
t.Wait();
var image = new System.Windows.Media.Imaging.BitmapImage();
image.BeginInit();
image.StreamSource = stream.AsStream();
image.CacheOption = System.Windows.Media.Imaging.BitmapCacheOption.OnLoad;
image.EndInit();
imageElement.Source = image;
}
}
}
catch(Exception e)
{
Console.WriteLine(e.Message);
}
}

The issue was in format subtype. I changed format from Mjpg to Nv12, and everything start working properly (even for MediaCaptureMemoryPreference.Auto):
var preferredFormat = colorFrameSource.SupportedFormats.Where(format =>
{
return format.VideoFormat.Width >= 1080 && String.Compare(format.Subtype, MediaEncodingSubtypes.Nv12, true) == 0;
}).FirstOrDefault();

Handling Parallel POST to API

I have a API Post method that takes is a string which represents a Bae64 string of bytes from a word document that the API converts to PDF. My test client sends multiple documents, each on its own task, to the API to be converted. The problem is with concurrency and writing the files. I end up with a file in use since the calls are parallel. I have tried a lot of different way to block the conversion process until a document is converted but none of it has worked. Everything works fine if it's jsut a single file being converted but as soon as it's 2 or more, the problem happens. Can anyone guide me in the correct direction to solve this issue?
API:
[HttpPost]
public async Task<SimpleResponse> Post([FromBody]string request)
{
var response = new SimpleResponse();
Task t = Task.Factory.StartNew(async () =>
{
try
{
Converter convert = new Converter();
var result = await convert.CovertDocToPDF(request, WebConfigurationManager.AppSettings["tempDocPath"], WebConfigurationManager.AppSettings["tempPdfPath"]);
response.Result = result;
response.Success = true;
}
catch (Exception ex)
{
response.Exception = ex;
response.Success = false;
response.Errors = new List<string>();
response.Errors.Add(string.Format("{0}, {1}", ex.Message, ex.InnerException?.Message ?? ""));
}
});
t.Wait();
return response;
}
Conversion code
public Task<string> CovertDocToPDF(string blob, string tempDocPath, string tempPdfPath)
{
try
{
// Convert blob back to bytes
byte[] bte = Convert.FromBase64String(blob);
// Process and return blob
return Process(bte, tempDocPath, tempPdfPath);
}
catch (Exception Ex)
{
throw Ex;
}
}
private async Task<string> Process(byte[] bytes, string tempDocPath, string tempPdfPath)
{
try
{
string rs = RandomString(16, true);
tempDocPath = tempDocPath + rs + ".docx";
tempPdfPath = tempPdfPath + rs + ".pdf";
// This is where the problem happens with concurrent calls. I added
// the try catch when the file is in use to generate a new
// filename but the error still happens.
try
{
// Create a temp file
File.WriteAllBytes(tempDocPath, bytes);
}
catch (Exception Ex)
{
rs = RandomString(16, true);
tempDocPath = tempDocPath + rs + ".docx";
tempPdfPath = tempPdfPath + rs + ".pdf";
File.WriteAllBytes(tempDocPath, bytes);
}
word.Application app = new word.Application();
word.Document doc = app.Documents.Open(tempDocPath);
doc.SaveAs2(tempPdfPath, word.WdSaveFormat.wdFormatPDF);
doc.Close();
app.Quit(); // Clean up the word instance.
// Need the bytes to return the blob
byte[] pdfFileBytes = File.ReadAllBytes(tempPdfPath);
// Delete temp files
File.Delete(tempDocPath);
File.Delete(tempPdfPath);
// return blob
return Convert.ToBase64String(pdfFileBytes);
}
catch (Exception Ex)
{
throw Ex;
}
}
Client:
public async void btnConvert_Click(object sender, EventArgs e)
{
var response = await StartConvert();
foreach (SimpleResponse sr in response)
{
if (sr.Success)
{
byte[] bte = Convert.FromBase64String(sr.Result.ToString());
string rs = RandomString(16, true);
string pdfFileName = tempPdfPath + rs + ".pdf";
if (File.Exists(pdfFileName))
{
File.Delete(pdfFileName);
}
System.IO.File.WriteAllBytes(pdfFileName, bte);
}
else
{
}
}
}
private async Task<IEnumerable<SimpleResponse>> StartConvert()
{
var tasks = new List<Task<SimpleResponse>>();
foreach (string s in docPaths)
{
byte[] bte = File.ReadAllBytes(s);
tasks.Add(ConvertDocuments(Convert.ToBase64String(bte)));
}
return (await Task.WhenAll(tasks));
}
private async Task<SimpleResponse> ConvertDocuments(string requests)
{
using (var client = new HttpClient(new HttpClientHandler() { UseDefaultCredentials = true }))
{
client.BaseAddress = new Uri(BaseApiUrl);
client.DefaultRequestHeaders.Add("Accept", "application/json");
// Add an Accept header for JSON format.
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));//application/json
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, BaseApiUrl + ApiUrl);
var data = JsonConvert.SerializeObject(requests);
request.Content = new StringContent(data, Encoding.UTF8, "application/json");
HttpResponseMessage response1 = await client.PostAsync(BaseApiUrl + ApiUrl, request.Content).ConfigureAwait(false);
var response = JsonConvert.DeserializeObject<SimpleResponse>(await response1.Content.ReadAsStringAsync());
return response;
}
}
Random String Generator
public string RandomString(int size, bool lowerCase = false)
{
var builder = new StringBuilder(size);
// Unicode/ASCII Letters are divided into two blocks
// (Letters 65–90 / 97–122):
// The first group containing the uppercase letters and
// the second group containing the lowercase.
// char is a single Unicode character
char offset = lowerCase ? 'a' : 'A';
const int lettersOffset = 26; // A...Z or a..z: length = 26
for (var i = 0; i < size; i++)
{
var #char = (char)_random.Next(offset, offset + lettersOffset);
builder.Append(#char);
}
return lowerCase ? builder.ToString().ToLower() : builder.ToString();
}

First, get rid of Task.Factory.StartNew ... t.Wait() - you don't need an additional task, the root level method is async and your blocking Wait just spoils the benefits of async by blocking synchronously.
Second, like a comment suggested above, the file name random string generator is most likely to be not really random. Either do not supply anything to the seed value of your pseudo-random gen, or use something like Environment.TickCount which should be sufficient for this. Guid.NewGuid() will work too.
Another good option for temp files is Path.GetTempFileName (also generates an empty file for you): https://learn.microsoft.com/en-us/dotnet/api/system.io.path.gettempfilename?view=netstandard-2.0
[HttpPost]
public async Task<SimpleResponse> Post([FromBody]string request)
{
var response = new SimpleResponse();
try
{
...
var result = await convert.CovertDocToPDF(...);
...
}
catch (Exception ex)
{
...
}
return response;
}

Based on your code it seems that you have a "faulty" random string generator for file name (I would say _random.Next is a suspect, possibly some locking and/or "app wide" instance could fix the issue). You can use Guid.NewGuid to create random part of file name (which in theory can have collisions also but in most practical cases should be fine) or Path.GetTempFileName:
var rs = Guid.NewGuid().ToString("N");
tempDocPath = tempDocPath + rs + ".docx";
tempPdfPath = tempPdfPath + rs + ".pdf";

if else conditions not checking properly in c#?

I am coming to a problem where I am checking if some of the elements key values are valid in order to proceed with the QR code scanning. For example: If my Active attribute is true, and completed is false and the schedule time is current time +- 30 minutes of start window then proceed with the scanning. If not, let me show them an error. I tried implementing the checking part with a simple if - but only checking the active, and completed key values. Can anyone check and help me solve this issue. thanks for the help.
here is my code:
public void ScanQrCode()
{
BarcodeScanner.Scan(async (barCodeType, barCodeValue) =>
{
BarcodeScanner.Stop();
var results = JsonConvert.DeserializeObject<dynamic>(barCodeValue);
var gettingTheName = (string) results.Evaluation.Value;
TextHeader.text = gettingTheName;
var qrCodeString = $"***************.firebaseio.com/Evaluations/.json?orderBy=\"$key\"&startAt=\"{gettingTheName}\"&limitToFirst=1";
Debug.Log(barCodeValue);
var qrCodeObj = JsonConvert.DeserializeObject<dynamic>(qrCodeString);
try
{
bool parseSuccessful = DateTime.TryParse("ScheduleStartTime", out var scheduledStartTime);
if (results.Contains("Active").Equals(true) &&
results.Contains("Completed").Equals(false) &&
DateTime.Now < scheduledStartTime.AddMinutes(30) &&
DateTime.Now > scheduledStartTime.AddMinutes(-30)) {
var matchingLink = new WebClient().DownloadString(qrCodeString);
var obj = Newtonsoft.Json.JsonConvert.DeserializeObject<JObject>(matchingLink);
var candidateId = obj.First.First["CandiateID"].ToString();
string page = $"https://***********.firebaseio.com/Candidates/.json?orderBy=\"$key\"&startAt=\"{candidateId}\"&limitToFirst=1";
using (HttpClient client = new HttpClient())
using (HttpResponseMessage response = await client.GetAsync(page))
using (HttpContent content = response.Content)
{
// Reading the string.
Dictionary<string, Candidates> evaluationDictionary = new Dictionary<string, Candidates>();
string result = await content.ReadAsStringAsync();
evaluationDictionary = JsonConvert.DeserializeObject<Dictionary<string, Candidates>>(result);
Debug.Log(evaluationDictionary);
foreach (Candidates candidates in evaluationDictionary.Values)
{
string evaluationMessage = candidates.FirstName + " " + candidates.LastName;
candidateMessage = GetComponent<Text>();
candidateMessage.text = evaluationMessage;
}
// Getting a reference to the text component.
candidateMessage = GetComponent<Text>();
candidateMessage.text = matchingLink.ToString();
candidateMessage.text = matchingLink.Trim(new char[] {'"'});
}
}
else
{
EditorUtility.DisplayDialog("Incorrect credentials", "Please scan a valid QR code", "OK");
}
}
catch (Exception e)
{
Console.WriteLine(e);
SceneManager.LoadScene("Verify");
throw;
}
});
}
}
JSON:
{
"Active": true,
"Completed": false,
"ScheduleStartTime": "2019-12-16T20:10:57.649418-08:00"
}

Yeah. I was kind of stuck on that part too. I tried doing it by adding
&& qrCodeString.Contains("ScheduleStartTime").Equals(I GOT STUCK IN
HERE)
I'd accomplish this portion by parsing the date string to a DateTime object, then comparing the current time with your new DateTime shifted in both directions.
I might do something like this:
try {
bool parseSuccessful = DateTime.TryParse( ScheduledStartTimeFromJSON, out var scheduledStartTime );
if ( qrCodeString.Contains( "Active" ).Equals( true ) &&
qrCodeString.Contains( "CompletedMessage" ).Equals( false ) &&
DateTime.Now < scheduledStartTime.AddMinutes(30) &&
DateTime.Now > scheduledStartTime.AddMinutes( -30 ) ) {
var matchingLink = new WebClient().DownloadString( qrCodeString );
...
}
}
You should also check to make sure the date was parsed successfully before comparing it to anything.

According to your JSON example:
First i think you should check for Completed value insted of CompletedMessage.
Secound with this code qrCodeString.Contains("Active").Equals(true) you are just checking if Active is contained in the string. I think you should be looking for the value of it.
In my vision the right way to do the check you need is to first deserialize the JSON like this
var qrCodeObj = JsonConvert.DeserializeObject<dynamic>(qrCodeString);
And then check for the respectives values
if (qrCodeObj["Active"] == true && qrCodeObj["Completed"] == false)
{
var matchingLink = new WebClient().DownloadString(qrCodeString);
var obj = Newtonsoft.Json.JsonConvert.DeserializeObject<JObject (matchingLink);
var candidateId = obj.First.First["CandiateID"].ToString();
string page = $"https://*********.firebaseio.com/Candidates/.json?orderBy=\"$key\"&startAt=\"{candidateId}\"&limitToFirst=1";
using (HttpClient client = new HttpClient())
using (HttpResponseMessage response = await client.GetAsync(page))
using (HttpContent content = response.Content)
{
// Reading the string.
Dictionary<string, Candidates> evaluationDictionary = new Dictionary<string, Candidates>();
string result = await content.ReadAsStringAsync();
evaluationDictionary = JsonConvert.DeserializeObject<Dictionary<string, Candidates>>(result);
Debug.Log(evaluationDictionary);
foreach (Candidates candidates in evaluationDictionary.Values)
{
string evaluationMessage = candidates.FirstName + " " + candidates.LastName;
candidateMessage = GetComponent<Text>();
candidateMessage.text = evaluationMessage;
}
// Getting a reference to the text component.
candidateMessage = GetComponent<Text>();
candidateMessage.text = matchingLink.ToString();
candidateMessage.text = matchingLink.Trim(new char[] {'"'});
}
}
else
{
EditorUtility.DisplayDialog("Incorrect Credentials ",
"Please scan a valid QR code. " , "OK");
}

Recording a video to file with ios

I'm trying to find a working sample to record videos with IOS (using xamarin) but there's always something missing or not working for me.
My best try using several forum posts and samples is the following :
using System;
using CoreGraphics;
using Foundation;
using UIKit;
using AVFoundation;
using CoreVideo;
using CoreMedia;
using CoreFoundation;
using System.IO;
using AssetsLibrary;
namespace avcaptureframes {
public partial class AppDelegate : UIApplicationDelegate {
public static UIImageView ImageView;
UIViewController vc;
AVCaptureSession session;
OutputRecorder outputRecorder;
DispatchQueue queue;
public override bool FinishedLaunching (UIApplication application, NSDictionary launchOptions)
{
ImageView = new UIImageView (new CGRect (10f, 10f, 200f, 200f));
ImageView.ContentMode = UIViewContentMode.Top;
vc = new UIViewController {
View = ImageView
};
window.RootViewController = vc;
window.MakeKeyAndVisible ();
window.BackgroundColor = UIColor.Black;
if (!SetupCaptureSession ())
window.AddSubview (new UILabel (new CGRect (20f, 20f, 200f, 60f)) {
Text = "No input device"
});
return true;
}
bool SetupCaptureSession ()
{
// configure the capture session for low resolution, change this if your code
// can cope with more data or volume
session = new AVCaptureSession {
SessionPreset = AVCaptureSession.PresetMedium
};
// create a device input and attach it to the session
var captureDevice = AVCaptureDevice.DefaultDeviceWithMediaType (AVMediaType.Video);
if (captureDevice == null) {
Console.WriteLine ("No captureDevice - this won't work on the simulator, try a physical device");
return false;
}
//Configure for 15 FPS. Note use of LockForConigfuration()/UnlockForConfiguration()
NSError error = null;
captureDevice.LockForConfiguration (out error);
if (error != null) {
Console.WriteLine (error);
captureDevice.UnlockForConfiguration ();
return false;
}
if (UIDevice.CurrentDevice.CheckSystemVersion (7, 0))
captureDevice.ActiveVideoMinFrameDuration = new CMTime (1, 15);
captureDevice.UnlockForConfiguration ();
var input = AVCaptureDeviceInput.FromDevice (captureDevice);
if (input == null) {
Console.WriteLine ("No input - this won't work on the simulator, try a physical device");
return false;
}
session.AddInput (input);
// create a VideoDataOutput and add it to the sesion
var settings = new CVPixelBufferAttributes {
PixelFormatType = CVPixelFormatType.CV32BGRA
};
using (var output = new AVCaptureVideoDataOutput { WeakVideoSettings = settings.Dictionary }) {
queue = new DispatchQueue ("myQueue");
outputRecorder = new OutputRecorder ();
output.SetSampleBufferDelegate (outputRecorder, queue);
session.AddOutput (output);
}
session.StartRunning ();
return true;
}
public override void OnActivated (UIApplication application)
{
}
public class OutputRecorder : AVCaptureVideoDataOutputSampleBufferDelegate
{
AVAssetWriter writer=null;
AVAssetWriterInput writerinput= null;
CMTime lastSampleTime;
int frame=0;
NSUrl url;
public OutputRecorder()
{
string tempFile = Path.Combine(Path.GetTempPath(), "NewVideo.mp4");
if (File.Exists(tempFile)) File.Delete(tempFile);
url = NSUrl.FromFilename(tempFile);
NSError assetWriterError;
writer = new AVAssetWriter(url, AVFileType.Mpeg4, out assetWriterError);
var outputSettings = new AVVideoSettingsCompressed()
{
Height = 300,
Width = 300,
Codec = AVVideoCodec.H264,
CodecSettings = new AVVideoCodecSettings
{
AverageBitRate = 1000000
}
};
writerinput = new AVAssetWriterInput(mediaType: AVMediaType.Video, outputSettings: outputSettings);
writerinput.ExpectsMediaDataInRealTime = false;
writer.AddInput(writerinput);
}
public override void DidOutputSampleBuffer (AVCaptureOutput captureOutput, CMSampleBuffer sampleBuffer, AVCaptureConnection connection)
{
try
{
lastSampleTime = sampleBuffer.PresentationTimeStamp;
var image = ImageFromSampleBuffer(sampleBuffer);
if (frame == 0)
{
writer.StartWriting();
writer.StartSessionAtSourceTime(lastSampleTime);
frame = 1;
}
String infoString = "";
if (writerinput.ReadyForMoreMediaData)
{
if (!writerinput.AppendSampleBuffer(sampleBuffer))
{
infoString = "Failed to append sample buffer";
}
else
{
infoString = String.Format("{0} frames captured", frame++);
}
}
else
{
infoString = "Writer not ready";
}
Console.WriteLine(infoString);
ImageView.BeginInvokeOnMainThread(() => ImageView.Image = image);
}
catch (Exception e)
{
Console.WriteLine(e);
}
finally
{
sampleBuffer.Dispose();
}
}
UIImage ImageFromSampleBuffer (CMSampleBuffer sampleBuffer)
{
// Get the CoreVideo image
using (var pixelBuffer = sampleBuffer.GetImageBuffer () as CVPixelBuffer)
{
// Lock the base address
pixelBuffer.Lock (CVOptionFlags.None);
// Get the number of bytes per row for the pixel buffer
var baseAddress = pixelBuffer.BaseAddress;
var bytesPerRow = (int)pixelBuffer.BytesPerRow;
var width = (int)pixelBuffer.Width;
var height = (int)pixelBuffer.Height;
var flags = CGBitmapFlags.PremultipliedFirst | CGBitmapFlags.ByteOrder32Little;
// Create a CGImage on the RGB colorspace from the configured parameter above
using (var cs = CGColorSpace.CreateDeviceRGB ())
{
using (var context = new CGBitmapContext (baseAddress, width, height, 8, bytesPerRow, cs, (CGImageAlphaInfo)flags))
{
using (CGImage cgImage = context.ToImage ())
{
pixelBuffer.Unlock (CVOptionFlags.None);
return UIImage.FromImage (cgImage);
}
}
}
}
}
void TryDispose (IDisposable obj)
{
if (obj != null)
obj.Dispose ();
}
}
}
}
This works displaying live camera image and I get "frames captured" message in consol but I don't find how to record to file.
I read somewhere about adding VideoCapture but I don't know how to link with my code.
Any help will is welcome.

From your code, in the construct of class OutputRecorder you have defined the url where you want to save the recording:
string tempFile = Path.Combine(Path.GetTempPath(), "NewVideo.mp4");
if (File.Exists(tempFile)) File.Delete(tempFile);
url = NSUrl.FromFilename(tempFile);
It means you want to save the video in the tmp folder in the app's sandbox. If you want to use the video sometime later, I recommend you to change the folder to documents by using:
string filePath = Path.Combine(NSSearchPath.GetDirectories(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomain.User)[0], "NewVideo.mp4");
I notice that you have called session.StartRunning(); in the method bool SetupCaptureSession() to start recording. please add session.StopRunning(); to end recording then the video will be saved in the path we just defined above.
Moreover, you can retrieve the video with the path like:
NSData videoData = NSData.FromFile(filePath);