Using V4L2 to realize VideoDevice

src/devices/Media/VideoDevice/Devices/UnixVideoDevice.cs

@@ -4,7 +4,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.IO;
 using System.Runtime.InteropServices;
 using System.Threading;
@@ -67,10 +66,7 @@ public UnixVideoDevice(VideoConnectionSettings settings)
         /// <param name="path">Picture save path</param>
         public override async Task CaptureAsync(string path)
         {
-            using (CancellationTokenSource cts = new CancellationTokenSource())
-            {
-                await CaptureAsync(path, cts.Token);
-            }
+            await CaptureAsync(path, CancellationToken.None);
         }
 
         /// <summary>
@@ -87,24 +83,20 @@ await Task.Run(() =>
                 byte[] dataBuffer = ProcessCaptureData();
                 Close();
 
-                using (FileStream fs = new FileStream(path, FileMode.Create))
-                {
-                    fs.Write(dataBuffer, 0, dataBuffer.Length);
-                    fs.Flush();
-                }    
+                using FileStream fs = new FileStream(path, FileMode.Create);
+                fs.Write(dataBuffer, 0, dataBuffer.Length);
+                fs.Flush();
             }, token);
         }
 
         /// <summary>
         /// Capture a picture from the video device.
         /// </summary>
         /// <returns>Picture stream</returns>
+        /// <param name="token">A cancellation token that can be used to cancel the work</param>
         public override async Task<MemoryStream> CaptureAsync()
         {
-            using (CancellationTokenSource cts = new CancellationTokenSource())
-            {
-                return  await CaptureAsync(cts.Token);
-            }
+            return await CaptureAsync(CancellationToken.None);
         }
 
         /// <summary>
@@ -161,7 +153,7 @@ public override VideoDeviceValue GetVideoDeviceValue(VideoDeviceValueType type)
         /// Get all the pixel formats supported by the device.
         /// </summary>
         /// <returns>Supported pixel formats</returns>
-        public override List<PixelFormat> GetSupportedPixelFormats()
+        public override IEnumerable<PixelFormat> GetSupportedPixelFormats()
         {
             v4l2_fmtdesc fmtdesc = new v4l2_fmtdesc
             {
@@ -184,7 +176,7 @@ public override List<PixelFormat> GetSupportedPixelFormats()
         /// </summary>
         /// <param name="format">Pixel format</param>
         /// <returns>Supported resolution</returns>
-        public override List<(uint Width, uint Height)> GetPixelFormatResolutions(PixelFormat format)
+        public override IEnumerable<(uint Width, uint Height)> GetPixelFormatResolutions(PixelFormat format)
         {
             v4l2_frmsizeenum size = new v4l2_frmsizeenum()
             {
@@ -310,7 +302,7 @@ private unsafe void SetVideoConnectionSettings()
                     }
                 }
             };
-            var res = V4l2Struct(VideoSettings.VIDIOC_S_FMT, ref format);
+            V4l2Struct(VideoSettings.VIDIOC_S_FMT, ref format);
 
             // Set exposure type
             v4l2_control ctrl = new v4l2_control

src/devices/Media/VideoDevice/VideoDevice.cs

@@ -71,14 +71,14 @@ public abstract partial class VideoDevice : IDisposable
         /// Get all the pixel formats supported by the device.
         /// </summary>
         /// <returns>Supported pixel formats</returns>
-        public abstract List<PixelFormat> GetSupportedPixelFormats();
+        public abstract IEnumerable<PixelFormat> GetSupportedPixelFormats();
 
         /// <summary>
         /// Get all the resolutions supported by the specified pixel format.
         /// </summary>
         /// <param name="format">Pixel format</param>
         /// <returns>Supported resolution</returns>
-        public abstract List<(uint Width, uint Height)> GetPixelFormatResolutions(PixelFormat format);
+        public abstract IEnumerable<(uint Width, uint Height)> GetPixelFormatResolutions(PixelFormat format);
 
         public void Dispose()
         {

src/devices/Media/VideoDevice/V4l2.csproj → src/devices/Media/VideoDevice/VideoDevice.csproj

@@ -2,12 +2,13 @@
 
   <PropertyGroup>
     <TargetFramework>netcoreapp2.1</TargetFramework>
+    <LangVersion>preview</LangVersion>
     <EnableDefaultItems>false</EnableDefaultItems>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.Drawing.Common" Version="4.6.0-preview7.19362.9" />
+    <PackageReference Include="System.Drawing.Common" Version="4.5.1" />
   </ItemGroup>
 
   <ItemGroup>

src/devices/Media/VideoDevice/samples/Program.cs

@@ -4,7 +4,7 @@
 
 using System;
 using System.Drawing;
-using System.Threading;
+using System.IO;
 using System.Threading.Tasks;
 using Iot.Device.Media;
 
@@ -40,15 +40,19 @@ static async Task Main(string[] args)
             var value = device.GetVideoDeviceValue(VideoDeviceValueType.Rotate);
             Console.WriteLine($"{value.Name} Min: {value.Minimum} Max: {value.Maximum} Step: {value.Step} Default: {value.DefaultValue} Current: {value.CurrentValue}");
 
-            await device.CaptureAsync("/home/pi/jpg_direct_output.jpg");
+            string path = "/home/pi/images";
+            if (!Directory.Exists(path))
+                Directory.CreateDirectory(path);
+
+            await device.CaptureAsync($"{path}/jpg_direct_output.jpg");
 
             // Change capture setting
             device.Settings.PixelFormat = PixelFormat.YUV420;
 
             // Convert pixel format
             Color[] colors = VideoDevice.Yv12ToRgb(await device.CaptureAsync(), settings.CaptureSize);
             Bitmap bitmap = VideoDevice.RgbToBitmap(settings.CaptureSize, colors);
-            bitmap.Save("/home/pi/yuyv_to_jpg.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
+            bitmap.Save($"{path}/yuyv_to_jpg.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
         }
     }
 }

src/devices/Media/VideoDevice/samples/V4l2.Samples.csproj → src/devices/Media/VideoDevice/samples/VideoDevice.Samples.csproj

@@ -2,11 +2,12 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <LangVersion>preview</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\V4l2.csproj" />
+    <ProjectReference Include="..\VideoDevice.csproj" />
   </ItemGroup>
 
 </Project>