Extract Frames from Video C#

Question

I'm trying to make an app that use the camera to record a video and process the images of the video. Here is what I want. First, my app records a 10 second video with Torch. Second, I use a method to playback the video to see what I record.

I'm stuck on three things.

1. How can I convert my video into individual frames (images)?
2. Is it possible to asynchronously convert the video while it is being recorded?
3. When I do convert the video into individual frames, how do I work with them? Are they JPEGs? Can I simply display them as images? Etc.

Main code:

using System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

using Windows.UI.Xaml.Navigation;

namespace App3
{

public sealed partial class MainPage : Page
{          
    DispatcherTimer D;
    double basetimer = 0;
    public MainPage()
    {
        this.InitializeComponent();       
        this.NavigationCacheMode = NavigationCacheMode.Required;
        D = new DispatcherTimer();      
        D.Interval = new TimeSpan(0, 0, 1);
        D.Tick += timer_Tick;
        txt.Text = basetimer.ToString();
        Play.IsEnabled = false;            
    }  
    public Library Library = new Library();
    public object PreviewImage { get; private set; }
    void timer_Tick(object sender, object e)
    {
        basetimer = basetimer - 1;
        txt.Text = basetimer.ToString();
        if (basetimer == 0)
        {
            D.Stop();               
            Preview.Source = null;
            Library.Stop();
            Record.IsEnabled = false;
            Play.IsEnabled = true;
            Clear.IsEnabled = true;
            if (Library._tc.Enabled)
            {
                Library._tc.Enabled = false;
            }                
        }
    }
    private void Record_Click(object sender, RoutedEventArgs e)
    {            
        if (Library.Recording)
        {
            Preview.Source = null;
            Library.Stop();
            Record.Icon = new SymbolIcon(Symbol.Video);                
        }
        else
        {
            basetimer = 11;
            D.Start();
            //D.Tick += timer_Tick;
            Display.Source = null;
            Library.Record(Preview);
            Record.Icon = new SymbolIcon(Symbol.VideoChat);
            Record.IsEnabled = false;
            Play.IsEnabled = false;
        }
    }
    private async void Play_Click(object sender, RoutedEventArgs e)
    {            
        await Library.Play(Dispatcher, Display);
        //Extract_Image_From_Video(Library.buffer);            
    }
    private  void Clear_Click(object sender, RoutedEventArgs e)
    {
        Display.Source = null;            
        Record.Icon = new SymbolIcon(Symbol.Video);
        txt.Text = "0";
        basetimer=  0;
        Play.IsEnabled = false;
        Record.IsEnabled =true;
        if (Library.capture != null)
        {
            D.Stop();
            Library.Recording = false;
            Preview.Source = null;               
            Library.capture.Dispose();
            Library.capture = null;
            basetimer = 11;
        }
        }
    }
}

Library Class:

using System;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using Windows.Devices.Enumeration;
using Windows.Media.Capture;
using Windows.Media.Devices;
using Windows.Media.MediaProperties;
using Windows.Storage;
using Windows.Storage.Streams;
using Windows.UI.Core;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media.Imaging;
using Windows.Graphics.Imaging;
using Emgu.CV.Structure;
using Emgu.CV;
using System.Collections.Generic;

public class Library
{

private const string videoFilename = "video.mp4";
private string filename;
public MediaCapture capture;
public InMemoryRandomAccessStream buffer;
public static bool Recording;
public TorchControl _tc;
public int basetimer  ;   
public async Task<bool> init()
{
    if (buffer != null)
    {
        buffer.Dispose();
    }
    buffer = new InMemoryRandomAccessStream();
    if (capture != null)
    {
        capture.Dispose();
    }
    try
    {

        if (capture == null)
        {
            var allVideoDevices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);               
            DeviceInformation cameraDevice =
            allVideoDevices.FirstOrDefault(x => x.EnclosureLocation != null &&
            x.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Back);
            capture = new MediaCapture();
            var mediaInitSettings = new MediaCaptureInitializationSettings { VideoDeviceId = cameraDevice.Id };
            // Initialize 
            try
            {
                await capture.InitializeAsync(mediaInitSettings);
                var videoDev = capture.VideoDeviceController;
                _tc = videoDev.TorchControl;
                Recording = false;
                _tc.Enabled = false;                                      
            }
            catch (UnauthorizedAccessException)
            {
                Debug.WriteLine("UnauthorizedAccessExeption>>");
            }
            catch (Exception ex)
            {
                Debug.WriteLine("Exception when initializing MediaCapture with {0}: {1}", cameraDevice.Id, ex.ToString());
            }
        }
            capture.Failed += (MediaCapture sender, MediaCaptureFailedEventArgs errorEventArgs) =>
        {
            Recording = false;
            _tc.Enabled = false;
            throw new Exception(string.Format("Code: {0}. {1}", errorEventArgs.Code, errorEventArgs.Message));
        };
    }
    catch (Exception ex)
    {
        if (ex.InnerException != null && ex.InnerException.GetType() == typeof(UnauthorizedAccessException))
        {
            throw ex.InnerException;
        }
        throw;
    }
    return true;
}
public async void Record(CaptureElement preview)
{    
    await init();
    preview.Source = capture; 
    await capture.StartPreviewAsync();
    await capture.StartRecordToStreamAsync(MediaEncodingProfile.CreateMp4(VideoEncodingQuality.Auto), buffer);
    if (Recording) throw new InvalidOperationException("cannot excute two records at the same time");
    Recording = true;
    _tc.Enabled = true;

}
public async void Stop()
{
    await capture.StopRecordAsync();
    Recording = false;
    _tc.Enabled = false;       
}    

public async Task Play(CoreDispatcher dispatcher, MediaElement playback)
{
    IRandomAccessStream video = buffer.CloneStream();

    if (video == null) throw new ArgumentNullException("buffer");
    StorageFolder storageFolder = Windows.ApplicationModel.Package.Current.InstalledLocation;
    if (!string.IsNullOrEmpty(filename))
    {
        StorageFile original = await storageFolder.GetFileAsync(filename);
        await original.DeleteAsync();
    }
    await dispatcher.RunAsync(CoreDispatcherPriority.Normal, async () =>
    {
        StorageFile storageFile = await storageFolder.CreateFileAsync(videoFilename, CreationCollisionOption.GenerateUniqueName);
        filename = storageFile.Name;
        using (IRandomAccessStream fileStream = await storageFile.OpenAsync(FileAccessMode.ReadWrite))
        {
            await RandomAccessStream.CopyAndCloseAsync(video.GetInputStreamAt(0), fileStream.GetOutputStreamAt(0));
            await video.FlushAsync();
            video.Dispose();
        }
        IRandomAccessStream stream = await storageFile.OpenAsync(FileAccessMode.Read);

        playback.SetSource(stream, storageFile.FileType);
        playback.Play();





    });


}   

Answer 1

I ended up using MediaToolkit to solve a similar problem after having a ton of trouble with Accord.

I needed to save an image for every second of a video:

using (var engine = new Engine())
{
    var mp4 = new MediaFile { Filename = mp4FilePath };

    engine.GetMetadata(mp4);

    var i = 0;
    while (i < mp4.Metadata.Duration.Seconds)
    {
        var options = new ConversionOptions { Seek = TimeSpan.FromSeconds(i) };
        var outputFile = new MediaFile { Filename = string.Format("{0}\\image-{1}.jpeg", outputPath, i) };
        engine.GetThumbnail(mp4, outputFile, options);
        i++;
    }
}

Hope this helps someone some day.