c# - 在 C# 中获取视频文件的缩略图

Question

我想显示我网站上列出的视频的缩略图，我想从视频中（从特定时间）获取单个帧并将它们显示为缩略图。

我试过这个http://ramcishna.blogspot.com/2008/09/playing-videos-like-youtube-and.html但不工作。

这可能使用.NET C#吗？

Answer 1

FFMpeg 是一个正确的工具，可用于在某个位置提取视频帧。您可以如上所述调用 ffmpeg.exe 或仅使用现有的 .NET 包装器（例如.NET 的视频转换器（它是免费的），只需一行代码即可获取缩略图：

var ffMpeg = new NReco.VideoConverter.FFMpegConverter();
ffMpeg.GetVideoThumbnail(pathToVideoFile, thumbJpegStream,5);

Answer 2

您可以以编程方式执行FFmpeg以生成缩略图图像文件。然后打开图像文件以根据需要使用它。

这是一些示例代码：

public static Bitmap GetThumbnail(string video, string thumbnail)
{
    var cmd = "ffmpeg  -itsoffset -1  -i " + '"' + video + '"' + " -vcodec mjpeg -vframes 1 -an -f rawvideo -s 320x240 " + '"' + thumbnail + '"';

    var startInfo = new ProcessStartInfo
    {
        WindowStyle = ProcessWindowStyle.Hidden,
        FileName = "cmd.exe",
        Arguments = "/C " + cmd
    };

    var process = new Process
    {
        StartInfo = startInfo
    };

    process.Start();
    process.WaitForExit(5000);

    return LoadImage(thumbnail);
}

static Bitmap LoadImage(string path)
{
    var ms = new MemoryStream(File.ReadAllBytes(path));
    return (Bitmap)Image.FromStream(ms);
}

Answer 3

Xabe.FFmpeg - 免费（用于非商业用途）、开源和跨平台库。为 FFmpeg 提供流畅的 API。从 Xabe.F 中的视频生成缩略图

    string output = Path.Combine(Path.GetTempPath(), Guid.NewGuid() + FileExtensions.Png);
    IConversionResult result = await Conversion.Snapshot(Resources.Mp4WithAudio, output, TimeSpan.FromSeconds(0))
                                               .Start();

它需要像其他答案一样的 FFmpeg 可执行文件，但您可以通过以下方式下载它

    FFmpeg.GetLatestVersion();

此处提供完整文档 - Xabe.FFmpeg 文档

Answer 4

因为人们不想在商业软件中使用 FFMpeg 作为它的麻烦。我在这里有一个旧的解决方案：

ShellFile shellFile = ShellFile.FromFilePath(VideoFileName);
Bitmap bm = shellFile.Thumbnail.Bitmap;

然后您将获得一个可用于绘图的 Bitmap 对象。如果你想要一个文件，只需执行以下操作：

bm.Save(fileName, System.Drawing.Imaging.ImageFormat.Jpeg);

如果你想要一个可以在 Xaml 绑定中使用的 BitmapImage。只需将 Bitmap 传输到 BitmapImage。这是一个例子：

public static BitmapImage ConvertBitmapToBitmapImage(Bitmap bitmap)
        {
            MemoryStream ms = new MemoryStream();
            bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
            BitmapImage image = new BitmapImage();
            image.BeginInit();
            ms.Seek(0, SeekOrigin.Begin);
            image.StreamSource = ms;
            image.EndInit();

            return image;
        }

Answer 5

 [HttpPost]
        [Route("UploadImages")]
        public HttpResponseMessage Post()
        {
            HttpResponseMessage response = new HttpResponseMessage();
            var httpRequest = HttpContext.Current.Request;
            if (httpRequest.Files.Count > 0)
            {
                var docfiles = new List<string>();
                foreach (string file in httpRequest.Files)
                {
                    var postedFile = httpRequest.Files[file];
                    var filePath1 = HttpContext.Current.Server.MapPath("~/ImgFolder/" + postedFile.FileName);

                    Stream strm = postedFile.InputStream;

                    CreateThumbnail(strm, postedFile.FileName);

                    Compressimage(strm, filePath1, postedFile.FileName);


                }
                response = Request.CreateResponse(HttpStatusCode.Created, docfiles);
            }
            else
            {
                response = Request.CreateResponse(HttpStatusCode.BadRequest);
            }
            return response;
        }
        public static void **CreateThumbnail**(Stream sourcePath, string filename)
        {
            Image image = Image.FromStream(sourcePath);
            Image thumb = image.GetThumbnailImage(120, 120, () => false, IntPtr.Zero);
             var filePath1 = HttpContext.Current.Server.MapPath("~/Thumbnail/" + filename);

             thumb.Save(filePath1 + filename);

        }

        public static void Compressimage(Stream sourcePath, string targetPath, String filename)  
        {  


            try  
            {  
                using (var image = Image.FromStream(sourcePath))  
                {  
                    float maxHeight = 900.0f;  
                    float maxWidth = 900.0f;  
                    int newWidth;  
                    int newHeight;  
                    string extension;  
                    Bitmap originalBMP = new Bitmap(sourcePath);  
                    int originalWidth = originalBMP.Width;  
                    int originalHeight = originalBMP.Height;  

                    if (originalWidth > maxWidth || originalHeight > maxHeight)  
                    {  

                        // To preserve the aspect ratio  
                        float ratioX = (float)maxWidth / (float)originalWidth;  
                        float ratioY = (float)maxHeight / (float)originalHeight;  
                        float ratio = Math.Min(ratioX, ratioY);  
                        newWidth = (int)(originalWidth * ratio);  
                        newHeight = (int)(originalHeight * ratio);  
                    }  
                    else  
                    {  
                        newWidth = (int)originalWidth;  
                        newHeight = (int)originalHeight;  

                    }  
                    Bitmap bitMAP1 = new Bitmap(originalBMP, newWidth, newHeight);  
                    Graphics imgGraph = Graphics.FromImage(bitMAP1);  
                    extension = Path.GetExtension(targetPath);  
                    if (extension == ".png" || extension == ".gif")  
                    {  
                        imgGraph.SmoothingMode = SmoothingMode.AntiAlias;  
                        imgGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;  
                        imgGraph.DrawImage(originalBMP, 0, 0, newWidth, newHeight);  


                        bitMAP1.Save(targetPath, image.RawFormat);  

                        bitMAP1.Dispose();  
                        imgGraph.Dispose();  
                        originalBMP.Dispose();  
                    }  
                    else if (extension == ".jpg")  
                    {  

                        imgGraph.SmoothingMode = SmoothingMode.AntiAlias;  
                        imgGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;  
                        imgGraph.DrawImage(originalBMP, 0, 0, newWidth, newHeight);  
                        ImageCodecInfo jpgEncoder = GetEncoder(ImageFormat.Jpeg);  
                        Encoder myEncoder = Encoder.Quality;  
                        EncoderParameters myEncoderParameters = new EncoderParameters(1);  
                        EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, 50L);  
                        myEncoderParameters.Param[0] = myEncoderParameter;  
                        bitMAP1.Save(targetPath, jpgEncoder, myEncoderParameters);  

                        bitMAP1.Dispose();  
                        imgGraph.Dispose();  
                        originalBMP.Dispose();  

                    }  


                }  

            }  
            catch (Exception)  
            {  
                throw;  

            }  
        }  


        public static ImageCodecInfo GetEncoder(ImageFormat format)  
        {  

            ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();  

            foreach (ImageCodecInfo codec in codecs)  
            {  
                if (codec.FormatID == format.Guid)  
                {  
                    return codec;  
                }  
            }  
            return null;  
        }