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转贴: A Simple c# Wrapper for ffMpeg

原帖地址：http://jasonjano.wordpress.com/2010/02/09/a-simple-c-wrapper-for-ffmpeg/

A Simple c# Wrapper for ffMpeg

Posted February 9, 2010 by jasonjano in Asset Management, cSharp, ffMpeg. Tagged: cSharp, ffMpeg.77 Comments

Converting video in .Net is a pain in the butt. The .Net framework, as of 2/8/2010 does not have a nice, simple, conversion process that will take a file in the many different formats out there and drop it into a nicely formatted .flv file for easy slideshowpro (or other flash based package) streaming.

The alternative, that I have most often seen, is using ffMpeg to convert source video into .flv format. Unfortunately, this process can a bit arcane. While there are other libraries out there that wrap up ffMpeg with a nice shiny, albeit complex, bow. I figured there might be some use for a simple c# library that does a couple simple, but very useful processes.

The following class will convert your input file to a .flv file and create a preview image from 1/3 of the way into the movie. By getting the preview image from 1/3 into the movie, we can avoid a completely black preview image that can come from a video that fades in.

Getting Started:

Create a directory in your project that contains the ffMpeg.exe file, this file will be referenced by the class below. This class is also going to use the web.config or app.config to store the location of our ffMpeg.exe file and a couple key settings. To do this, you will need to import system.configuration into your project and include the following line:

using System.Configuration;

To start with, we have a couple properties that expose the working path that ffMpeg will need while it is processing our video file along with a property that exposes the location of our exe file.

private string _ffExe;
public string ffExe
{
    get
    {
        return _ffExe;
    }
    set
    {
        _ffExe = value;
    }
}
 
private string _WorkingPath;
public string WorkingPath
{
    get
    {
        return _WorkingPath;
    }
    set
    {
        _WorkingPath = value;
    }
}

In our constructors, we will call an initialize method that will attempt to grab our exepath from web.config, assuming that one has not been entered into our second constructor.

Note: In this example, the class is name “Converter”

public Converter()
{
    Initialize();
}
public Converter(string ffmpegExePath)
{
    _ffExe = ffmpegExePath;
    Initialize();
}

Initialization

You will note that the we are testing to see if the ffmpeg.exe file location exists before attempting to pull it from web.config.

//Make sure we have valid ffMpeg.exe file and working directory to do our dirty work.
private void Initialize()
{
    //first make sure we have a value for the ffexe file setting
    if (string.IsNullOrEmpty(_ffExe))
    {
        object o = ConfigurationManager.AppSettings["ffmpeg:ExeLocation"];
        if (o == null)
        {
            throw new Exception("Could not find the location of the ffmpeg exe file.  The path for ffmpeg.exe " +
            "can be passed in via a constructor of the ffmpeg class (this class) or by setting in the app.config or web.config file.  " +
            "in the appsettings section, the correct property name is: ffmpeg:ExeLocation");
        }
        else
        {
            if (string.IsNullOrEmpty(o.ToString()))
            {
                throw new Exception("No value was found in the app setting for ffmpeg:ExeLocation");
            }
            _ffExe = o.ToString();
        }
    }
 
    //Now see if ffmpeg.exe exists
    string workingpath = GetWorkingFile();
    if (string.IsNullOrEmpty(workingpath))
    {
        //ffmpeg doesn't exist at the location stated.
        throw new Exception("Could not find a copy of ffmpeg.exe");
    }
    _ffExe = workingpath;
 
    //now see if we have a temporary place to work
    if (string.IsNullOrEmpty(_WorkingPath))
    {
        object o = ConfigurationManager.AppSettings["ffmpeg:WorkingPath"];
        if (o != null)
        {
            _WorkingPath = o.ToString();
        }
        else
        {
            _WorkingPath = string.Empty;
        }
    }
}
 
private string GetWorkingFile()
{
    //try the stated directory
    if (File.Exists(_ffExe))
    {
        return _ffExe;
    }
 
    //oops, that didn't work, try the base directory
    if (File.Exists(Path.GetFileName(_ffExe)))
    {
        return Path.GetFileName(_ffExe);
    }
 
    //well, now we are really unlucky, let's just return null
    return null;
}

Loading Files Without Creating Locks

These subs might be a bit out of place but are useful as they create our memory resident objects without throwing a lock on the source file. This means that we can run more than one process at once, or delete our file without screwing things up for another process.

public static System.Drawing.Image LoadImageFromFile(string fileName)
{
    System.Drawing.Image theImage = null;
    using (FileStream fileStream = new FileStream(fileName, FileMode.Open,
    FileAccess.Read))
    {
        byte[] img;
        img = new byte[fileStream.Length];
        fileStream.Read(img, 0, img.Length);
        fileStream.Close();
        theImage = System.Drawing.Image.FromStream(new MemoryStream(img));
        img = null;
    }
    GC.Collect();
    return theImage;
}
 
public static MemoryStream LoadMemoryStreamFromFile(string fileName)
{
    MemoryStream ms = null;
    using (FileStream fileStream = new FileStream(fileName, FileMode.Open,
    FileAccess.Read))
    {
        byte[] fil;
        fil = new byte[fileStream.Length];
        fileStream.Read(fil, 0, fil.Length);
        fileStream.Close();
        ms = new MemoryStream(fil);
    }
    GC.Collect();
    return ms;
}

Running the ffMpeg Process

Now that we have setup our class and have some basic helper subs to get us going, we need to actually have a method that will run the ffMpeg process.

//Note the private call here and the argument for Parameters.  The private call is
//being made here because, in this class, we don't really want to have this method
//called from outside of the class -- this, however flies in the face of allowing the
//parameters argument (why not just allow out the public call so that a developer can
//put in the parameters from their own code?  I guess one could do it and it would probably
//work fine but, for this implementation, I chose to leave it private.
private string RunProcess(string Parameters)
{
    //create a process info object so we can run our app
    ProcessStartInfo oInfo = new ProcessStartInfo(this._ffExe, Parameters);
    oInfo.UseShellExecute = false;
    oInfo.CreateNoWindow = true;
 
    //so we are going to redirect the output and error so that we can parse the return
    oInfo.RedirectStandardOutput = true;
    oInfo.RedirectStandardError = true;
 
    //Create the output and streamreader to get the output
    string output = null; StreamReader srOutput = null;
 
    //try the process
    try
    {
        //run the process
        Process proc = System.Diagnostics.Process.Start(oInfo);
 
        proc.WaitForExit();
 
        //get the output
        srOutput = proc.StandardError;
 
        //now put it in a string
        output = srOutput.ReadToEnd();
 
        proc.Close();
    }
    catch (Exception)
    {
        output = string.Empty;
    }
    finally
    {
        //now, if we succeded, close out the streamreader
        if (srOutput != null)
        {
            srOutput.Close();
            srOutput.Dispose();
        }
    }
    return output;
}

Now let’s make some functional stuff

Now that we have called the ffMpeg process, we need to get some video info, get a video file, and a preview image. So, with that being said, onto more source code.

Getting the Details

So, we need to now parse the details of our ffMpeg.exe output and read some details about the video file.

//We are going to take in memory stream for this file to allow for different input options.
//Unfortunately, this means that we also need the file extension to pass it out to ffMpeg.
public VideoFile GetVideoInfo(MemoryStream inputFile, string Filename)
{
    //Create a temporary file for our use in ffMpeg
    string tempfile = Path.Combine(this.WorkingPath, System.Guid.NewGuid().ToString() + Path.GetExtension(Filename));
    FileStream fs = File.Create(tempfile);
 
    //write the memory stream to a file and close our the stream so it can be used again.
    inputFile.WriteTo(fs);
    fs.Flush();
    fs.Close();
    GC.Collect();
 
    //Video File is a class you will see further down this post.  It has some basic information about the video
    VideoFile vf = null;
    try
    {
        vf = new VideoFile(tempfile);
    }
    catch (Exception ex)
    {
        throw ex;
    }
 
    //And, without adieu, a call to our main method for this functionality.
    GetVideoInfo(vf);
 
    try
    {
        File.Delete(tempfile);
    }
    catch (Exception)
    {
 
    }
 
    return vf;
}
 
//This sub is just another overload to allow input of a direct path, we are just
//using the videofile class to send in.  More on the video file class further down
//the article.
public VideoFile GetVideoInfo(string inputPath)
{
    VideoFile vf = null;
    try
    {
        vf = new VideoFile(inputPath);
    }
    catch (Exception ex)
    {
        throw ex;
    }
    GetVideoInfo(vf);
    return vf;
}
 
//And now the important code for the GetVideoInfo
public void GetVideoInfo(VideoFile input)
{
    //set up the parameters for video info -- these will be passed into ffMpeg.exe
    string Params = string.Format("-i {0}", input.Path);
    string output = RunProcess(Params);
    input.RawInfo = output;
 
    //Use a regular expression to get the different properties from the video parsed out.
    Regex re = new Regex("[D|d]uration:.((\d|:|\.)*)");
    Match m = re.Match(input.RawInfo);
 
    if (m.Success)
    {
        string duration = m.Groups[1].Value;
        string[] timepieces = duration.Split(new char[] { ':', '.' });
        if (timepieces.Length == 4)
        {
            input.Duration = new TimeSpan(0, Convert.ToInt16(timepieces[0]), Convert.ToInt16(timepieces[1]), Convert.ToInt16(timepieces[2]), Convert.ToInt16(timepieces[3]));
        }
    }
 
    //get audio bit rate
    re = new Regex("[B|b]itrate:.((\d|:)*)");
    m = re.Match(input.RawInfo);
    double kb = 0.0;
    if (m.Success)
    {
        Double.TryParse(m.Groups[1].Value, out kb);
    }
    input.BitRate = kb;
 
    //get the audio format
    re = new Regex("[A|a]udio:.*");
    m = re.Match(input.RawInfo);
    if (m.Success)
    {
        input.AudioFormat = m.Value;
    }
 
    //get the video format
    re = new Regex("[V|v]ideo:.*");
    m = re.Match(input.RawInfo);
    if (m.Success)
    {
        input.VideoFormat = m.Value;
    }
 
    //get the video format
    re = new Regex("(\d{2,3})x(\d{2,3})");
    m = re.Match(input.RawInfo);
    if (m.Success)
    {
        int width = 0; int height = 0;
        int.TryParse(m.Groups[1].Value, out width);
        int.TryParse(m.Groups[2].Value, out height);
        input.Width = width;
        input.Height = height;
    }
    input.infoGathered = true;
}

Finally, do the conversion

So, here is the conversion meat and preview imaging.

//Note the ouputpackage object output.  The output package class is detailed below.
//this overload does much the same as the one above does, in that, it offers the ability
//to input a memory stream vs. a filename or our videofile input class.
public OutputPackage ConvertToFLV(MemoryStream inputFile, string Filename)
{
    string tempfile = Path.Combine(this.WorkingPath, System.Guid.NewGuid().ToString() + Path.GetExtension(Filename));
    FileStream fs = File.Create(tempfile);
    inputFile.WriteTo(fs);
    fs.Flush();
    fs.Close();
    GC.Collect();
 
    VideoFile vf = null;
    try
    {
        vf = new VideoFile(tempfile);
    }
    catch (Exception ex)
    {
        throw ex;
    }
 
    OutputPackage oo = ConvertToFLV(vf);
 
    try{
        File.Delete(tempfile);
    } catch(Exception) {
 
    }
 
    return oo;
}
public OutputPackage ConvertToFLV(string inputPath)
{
    VideoFile vf = null;
    try
    {
        vf = new VideoFile(inputPath);
    }
    catch (Exception ex)
    {
        throw ex;
    }
 
    OutputPackage oo = ConvertToFLV(vf);
    return oo;
}
 
//The actually important code, rather than an overload.
public OutputPackage ConvertToFLV(VideoFile input)
{
    //check to see if we have already gathered our info so we know
    //where to get our preview image from.
    if (!input.infoGathered)
    {
        GetVideoInfo(input);
    }
 
    //Create our output object
    OutputPackage ou = new OutputPackage();
 
    //set up the parameters for getting a previewimage
    string filename = System.Guid.NewGuid().ToString() + ".jpg";
    int secs;
 
    //divide the duration in 3 to get a preview image in the middle of the clip
    //instead of a black image from the beginning.
    secs = (int)Math.Round(TimeSpan.FromTicks(input.Duration.Ticks / 3).TotalSeconds, 0);
 
    string finalpath = Path.Combine(this.WorkingPath, filename);
 
    //These are the parameters for setting up a preview image that must be passed to ffmpeg.
    //Note that we are asking for a jpeg image at our specified seconds.
    string Params = string.Format("-i {0} {1} -vcodec mjpeg -ss {2} -vframes 1 -an -f rawvideo", input.Path, finalpath, secs);
    string output = RunProcess(Params);
 
    ou.RawOutput = output;
 
    //Ok, so hopefully we now have a preview file.  If the file
    //did not get created properly, try again at the first frame.
    if (File.Exists(finalpath))
    {
        //load that file into our output package and attempt to delete the file
        //since we no longer need it.
        ou.PreviewImage = LoadImageFromFile(finalpath);
        try
        {
            File.Delete(finalpath);
        }
        catch (Exception) { }
    } else { //try running again at frame 1 to get something
        Params = string.Format("-i {0} {1} -vcodec mjpeg -ss {2} -vframes 1 -an -f rawvideo", input.Path, finalpath, 1);
        output = RunProcess(Params);
 
        ou.RawOutput = output;
 
        if (File.Exists(finalpath)) {
            ou.PreviewImage = LoadImageFromFile(finalpath);
            try
            {
                File.Delete(finalpath);
            }
            catch (Exception) { }
        }
    }
 
    finalpath = Path.Combine(this.WorkingPath, filename);
    filename = System.Guid.NewGuid().ToString() + ".flv";
 
    //Now we are going to actually create the converted file.  Note that we are asking for
    //a video at 22khz 64bit.  This can be changed by a couple quick alterations to this line,
    //or by extending out this class to offer multiple different conversions.
    Params = string.Format("-i {0} -y -ar 22050 -ab 64 -f flv {1}", input.Path, finalpath);
    output = RunProcess(Params);
 
    //Check to see if our conversion file exists and then load the converted
    //file into our output package.  If the file does exist and we are able to
    //load it into our output package, we can delete the work file.
    if (File.Exists(finalpath))
    {
        ou.VideoStream = LoadMemoryStreamFromFile(finalpath);
        try
        {
            File.Delete(finalpath);
        }
        catch (Exception) { }
    }
    return ou;
}

Supplementary Classes

Throughout this article, you will have noticed the use of “VideoFile” and “OutputPackage”. These classes are just informational classes that provide simple ways of accessing everything.
Here they are:

public class VideoFile
{
    #region Properties
    private string _Path;
    public string Path
    {
        get
        {
            return _Path;
        }
        set
        {
            _Path = value;
        }
    }
 
    public TimeSpan Duration { get; set; }
    public double BitRate { get; set; }
    public string AudioFormat { get; set; }
    public string VideoFormat { get; set; }
    public int Height { get; set; }
    public int Width { get; set; }
    public string RawInfo { get; set; }
    public bool infoGathered {get; set;}
    #endregion
 
    #region Constructors
    public VideoFile(string path)
    {
        _Path = path;
        Initialize();
    }
    #endregion
 
    #region Initialization
    private void Initialize()
    {
        this.infoGathered = false;
        //first make sure we have a value for the video file setting
        if (string.IsNullOrEmpty(_Path))
        {
            throw new Exception("Could not find the location of the video file");
        }
 
        //Now see if the video file exists
        if (!File.Exists(_Path))
        {
            throw new Exception("The video file " + _Path + " does not exist.");
        }
    }
    #endregion
}
 
public class OutputPackage
{
    public MemoryStream VideoStream { get; set; }
    public System.Drawing.Image PreviewImage { get; set; }
    public string RawOutput { get; set; }
    public bool Success { get; set; }
}

Full Code for the class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;
using System.Diagnostics;
using System.Configuration;
using System.Text.RegularExpressions;
 
namespace ffMpeg
{
    public class Converter
    {
        #region Properties
        private string _ffExe;
        public string ffExe
        {
            get
            {
                return _ffExe;
            }
            set
            {
                _ffExe = value;
            }
        }
 
        private string _WorkingPath;
        public string WorkingPath
        {
            get
            {
                return _WorkingPath;
            }
            set
            {
                _WorkingPath = value;
            }
        }
 
        #endregion
 
        #region Constructors
        public Converter()
        {
            Initialize();
        }
        public Converter(string ffmpegExePath)
        {
            _ffExe = ffmpegExePath;
            Initialize();
        }
        #endregion
 
        #region Initialization
        private void Initialize()
        {
            //first make sure we have a value for the ffexe file setting
            if (string.IsNullOrEmpty(_ffExe))
            {
                object o = ConfigurationManager.AppSettings["ffmpeg:ExeLocation"];
                if (o == null)
                {
                    throw new Exception("Could not find the location of the ffmpeg exe file.  The path for ffmpeg.exe " +
                    "can be passed in via a constructor of the ffmpeg class (this class) or by setting in the app.config or web.config file.  " +
                    "in the appsettings section, the correct property name is: ffmpeg:ExeLocation");
                }
                else
                {
                    if (string.IsNullOrEmpty(o.ToString()))
                    {
                        throw new Exception("No value was found in the app setting for ffmpeg:ExeLocation");
                    }
                    _ffExe = o.ToString();
                }
            }
 
            //Now see if ffmpeg.exe exists
            string workingpath = GetWorkingFile();
            if (string.IsNullOrEmpty(workingpath))
            {
                //ffmpeg doesn't exist at the location stated.
                throw new Exception("Could not find a copy of ffmpeg.exe");
            }
            _ffExe = workingpath;
 
            //now see if we have a temporary place to work
            if (string.IsNullOrEmpty(_WorkingPath))
            {
                object o = ConfigurationManager.AppSettings["ffmpeg:WorkingPath"];
                if (o != null)
                {
                    _WorkingPath = o.ToString();
                }
                else
                {
                    _WorkingPath = string.Empty;
                }
            }
        }
 
        private string GetWorkingFile()
        {
            //try the stated directory
            if (File.Exists(_ffExe))
            {
                return _ffExe;
            }
 
            //oops, that didn't work, try the base directory
            if (File.Exists(Path.GetFileName(_ffExe)))
            {
                return Path.GetFileName(_ffExe);
            }
 
            //well, now we are really unlucky, let's just return null
            return null;
        }
        #endregion
 
        #region Get the File without creating a file lock
        public static System.Drawing.Image LoadImageFromFile(string fileName)
        {
            System.Drawing.Image theImage = null;
            using (FileStream fileStream = new FileStream(fileName, FileMode.Open,
            FileAccess.Read))
            {
                byte[] img;
                img = new byte[fileStream.Length];
                fileStream.Read(img, 0, img.Length);
                fileStream.Close();
                theImage = System.Drawing.Image.FromStream(new MemoryStream(img));
                img = null;
            }
            GC.Collect();
            return theImage;
        }
 
        public static MemoryStream LoadMemoryStreamFromFile(string fileName)
        {
            MemoryStream ms = null;
            using (FileStream fileStream = new FileStream(fileName, FileMode.Open,
            FileAccess.Read))
            {
                byte[] fil;
                fil = new byte[fileStream.Length];
                fileStream.Read(fil, 0, fil.Length);
                fileStream.Close();
                ms = new MemoryStream(fil);
            }
            GC.Collect();
            return ms;
        }
        #endregion
 
        #region Run the process
        private string RunProcess(string Parameters)
        {
            //create a process info
            ProcessStartInfo oInfo = new ProcessStartInfo(this._ffExe, Parameters);
            oInfo.UseShellExecute = false;
            oInfo.CreateNoWindow = true;
            oInfo.RedirectStandardOutput = true;
            oInfo.RedirectStandardError = true;
 
            //Create the output and streamreader to get the output
            string output = null; StreamReader srOutput = null;
 
            //try the process
            try
            {
                //run the process
                Process proc = System.Diagnostics.Process.Start(oInfo);
 
                proc.WaitForExit();
 
                //get the output
                srOutput = proc.StandardError;
 
                //now put it in a string
                output = srOutput.ReadToEnd();
 
                proc.Close();
            }
            catch (Exception)
            {
                output = string.Empty;
            }
            finally
            {
                //now, if we succeded, close out the streamreader
                if (srOutput != null)
                {
                    srOutput.Close();
                    srOutput.Dispose();
                }
            }
            return output;
        }
        #endregion
 
        #region GetVideoInfo
        public VideoFile GetVideoInfo(MemoryStream inputFile, string Filename)
        {
            string tempfile = Path.Combine(this.WorkingPath, System.Guid.NewGuid().ToString() + Path.GetExtension(Filename));
            FileStream fs = File.Create(tempfile);
            inputFile.WriteTo(fs);
            fs.Flush();
            fs.Close();
            GC.Collect();
 
            VideoFile vf = null;
            try
            {
                vf = new VideoFile(tempfile);
            }
            catch (Exception ex)
            {
                throw ex;
            }
 
            GetVideoInfo(vf);
 
            try
            {
                File.Delete(tempfile);
            }
            catch (Exception)
            {
 
            }
 
            return vf;
        }
        public VideoFile GetVideoInfo(string inputPath)
        {
            VideoFile vf = null;
            try
            {
                vf = new VideoFile(inputPath);
            }
            catch (Exception ex)
            {
                throw ex;
            }
            GetVideoInfo(vf);
            return vf;
        }
        public void GetVideoInfo(VideoFile input)
        {
            //set up the parameters for video info
            string Params = string.Format("-i {0}", input.Path);
            string output = RunProcess(Params);
            input.RawInfo = output;
 
            //get duration
            Regex re = new Regex("[D|d]uration:.((\d|:|\.)*)");
            Match m = re.Match(input.RawInfo);
 
            if (m.Success)
            {
                string duration = m.Groups[1].Value;
                string[] timepieces = duration.Split(new char[] { ':', '.' });
                if (timepieces.Length == 4)
                {
                    input.Duration = new TimeSpan(0, Convert.ToInt16(timepieces[0]), Convert.ToInt16(timepieces[1]), Convert.ToInt16(timepieces[2]), Convert.ToInt16(timepieces[3]));
                }
            }
 
            //get audio bit rate
            re = new Regex("[B|b]itrate:.((\d|:)*)");
            m = re.Match(input.RawInfo);
            double kb = 0.0;
            if (m.Success)
            {
                Double.TryParse(m.Groups[1].Value, out kb);
            }
            input.BitRate = kb;
 
            //get the audio format
            re = new Regex("[A|a]udio:.*");
            m = re.Match(input.RawInfo);
            if (m.Success)
            {
                input.AudioFormat = m.Value;
            }
 
            //get the video format
            re = new Regex("[V|v]ideo:.*");
            m = re.Match(input.RawInfo);
            if (m.Success)
            {
                input.VideoFormat = m.Value;
            }
 
            //get the video format
            re = new Regex("(\d{2,3})x(\d{2,3})");
            m = re.Match(input.RawInfo);
            if (m.Success)
            {
                int width = 0; int height = 0;
                int.TryParse(m.Groups[1].Value, out width);
                int.TryParse(m.Groups[2].Value, out height);
                input.Width = width;
                input.Height = height;
            }
            input.infoGathered = true;
        }
        #endregion
 
        #region Convert to FLV
        public OutputPackage ConvertToFLV(MemoryStream inputFile, string Filename)
        {
            string tempfile = Path.Combine(this.WorkingPath, System.Guid.NewGuid().ToString() + Path.GetExtension(Filename));
            FileStream fs = File.Create(tempfile);
            inputFile.WriteTo(fs);
            fs.Flush();
            fs.Close();
            GC.Collect();
 
            VideoFile vf = null;
            try
            {
                vf = new VideoFile(tempfile);
            }
            catch (Exception ex)
            {
                throw ex;
            }
 
            OutputPackage oo = ConvertToFLV(vf);
 
            try{
                File.Delete(tempfile);
            } catch(Exception) {
 
            }
 
            return oo;
        }
        public OutputPackage ConvertToFLV(string inputPath)
        {
            VideoFile vf = null;
            try
            {
                vf = new VideoFile(inputPath);
            }
            catch (Exception ex)
            {
                throw ex;
            }
 
            OutputPackage oo = ConvertToFLV(vf);
            return oo;
        }
        public OutputPackage ConvertToFLV(VideoFile input)
        {
            if (!input.infoGathered)
            {
                GetVideoInfo(input);
            }
            OutputPackage ou = new OutputPackage();
 
            //set up the parameters for getting a previewimage
            string filename = System.Guid.NewGuid().ToString() + ".jpg";
            int secs;
 
            //divide the duration in 3 to get a preview image in the middle of the clip
            //instead of a black image from the beginning.
            secs = (int)Math.Round(TimeSpan.FromTicks(input.Duration.Ticks / 3).TotalSeconds, 0);
 
            string finalpath = Path.Combine(this.WorkingPath, filename);
            string Params = string.Format("-i {0} {1} -vcodec mjpeg -ss {2} -vframes 1 -an -f rawvideo", input.Path, finalpath, secs);
            string output = RunProcess(Params);
 
            ou.RawOutput = output;
 
            if (File.Exists(finalpath))
            {
                ou.PreviewImage = LoadImageFromFile(finalpath);
                try
                {
                    File.Delete(finalpath);
                }
                catch (Exception) { }
            } else { //try running again at frame 1 to get something
                Params = string.Format("-i {0} {1} -vcodec mjpeg -ss {2} -vframes 1 -an -f rawvideo", input.Path, finalpath, 1);
                output = RunProcess(Params);
 
                ou.RawOutput = output;
 
                if (File.Exists(finalpath)) {
                    ou.PreviewImage = LoadImageFromFile(finalpath);
                    try
                    {
                        File.Delete(finalpath);
                    }
                    catch (Exception) { }
                }
            }
 
            finalpath = Path.Combine(this.WorkingPath, filename);
            filename = System.Guid.NewGuid().ToString() + ".flv";
            Params = string.Format("-i {0} -y -ar 22050 -ab 64 -f flv {1}", input.Path, finalpath);
            output = RunProcess(Params);
 
            if (File.Exists(finalpath))
            {
                ou.VideoStream = LoadMemoryStreamFromFile(finalpath);
                try
                {
                    File.Delete(finalpath);
                }
                catch (Exception) { }
            }
            return ou;
        }
        #endregion
    }
 
    public class VideoFile
    {
        #region Properties
        private string _Path;
        public string Path
        {
            get
            {
                return _Path;
            }
            set
            {
                _Path = value;
            }
        }
 
        public TimeSpan Duration { get; set; }
        public double BitRate { get; set; }
        public string AudioFormat { get; set; }
        public string VideoFormat { get; set; }
        public int Height { get; set; }
        public int Width { get; set; }
        public string RawInfo { get; set; }
        public bool infoGathered {get; set;}
        #endregion
 
        #region Constructors
        public VideoFile(string path)
        {
            _Path = path;
            Initialize();
        }
        #endregion
 
        #region Initialization
        private void Initialize()
        {
            this.infoGathered = false;
            //first make sure we have a value for the video file setting
            if (string.IsNullOrEmpty(_Path))
            {
                throw new Exception("Could not find the location of the video file");
            }
 
            //Now see if the video file exists
            if (!File.Exists(_Path))
            {
                throw new Exception("The video file " + _Path + " does not exist.");
            }
        }
        #endregion
    }
 
    public class OutputPackage
    {
        public MemoryStream VideoStream { get; set; }
        public System.Drawing.Image PreviewImage { get; set; }
        public string RawOutput { get; set; }
        public bool Success { get; set; }
    }
}

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原文地址：https://www.cnblogs.com/findcaiyzh/p/3513114.html