我正在使用Asp.Net C＃Framework 4，目前正在开发视频转换应用程序。我也使用ffmpeg将所有上传的格式转换为flv。我首先将上传的文件转换为mpg，然后转换为flv，因为我在尝试从mp4直接转换为flv时遇到了问题。但是ffmpeg一旦完成转换过程到mpg文件就冻结了。当我运行任务管理器并检查进程列表时，它只是站在那里没有CPU资源。当我直接从任务管理器结束ffmpeg进程时，会发生其他进程，从mpg转换为flv和预览文件（jpg）并顺利运行。由于第一个进程冻结，当我尝试从我的网页的文件上传表单上传时，第二个进程无法启动。我感谢你们现在的任何回应。这是我的代码：
string duration = "00:00:00";
//converting video
Process ffmpeg;
ffmpeg = new Process();
// convert to mpg 1st
ffmpeg.StartInfo.Arguments = " -i \"" + Server.MapPath("static/user/vid/") + videolink + "\" -f mpeg -b 300k -ac 2 -ab 128k -ar 44K \"" + Server.MapPath("static/user/vid/") + mpglink + "\"";
ffmpeg.StartInfo.FileName = Page.MapPath("bin/ffmpeg.exe");
ffmpeg.StartInfo.CreateNoWindow = true;
ffmpeg.StartInfo.UseShellExecute = false;
ffmpeg.StartInfo.RedirectStandardOutput = true;
ffmpeg.StartInfo.RedirectStandardError = true;
ffmpeg.Start();
ffmpeg.WaitForExit();
ffmpeg.Close();
// mpg 2 flv
ffmpeg = new Process();
ffmpeg.StartInfo.Arguments = " -i \"" + Server.MapPath("static/user/vid/") + mpglink + "\" -f flv -s 624x352 \"" + Server.MapPath("static/user/vid/") + flvlink + "\"";
ffmpeg.StartInfo.FileName = Page.MapPath("bin/ffmpeg.exe");
ffmpeg.StartInfo.CreateNoWindow = true;
ffmpeg.StartInfo.UseShellExecute = false;
ffmpeg.StartInfo.RedirectStandardOutput = true;
ffmpeg.StartInfo.RedirectStandardError = true;
ffmpeg.Start();
ffmpeg.BeginOutputReadLine();
string error = ffmpeg.StandardError.ReadToEnd();
ffmpeg.WaitForExit();
try
{
duration = error.Substring(error.IndexOf("Duration: ") + 10, 8);
}
catch
{
}
if (ffmpeg.ExitCode != 0)
{
ltrUpload.Text = "<div class=\"resultbox-negative\" id=\"divResult\">Problem occured during upload process. Error code: " + error + "<br>" + "</div>";
return;
}
ffmpeg.Close();
// generate preview image
ffmpeg.StartInfo.Arguments = " -i \"" + Server.MapPath("static/user/vid/") + flvlink + "\" -s 624x352 -ss 00:00:03 -an -vframes 1 -f image2 -vcodec mjpeg \"" + Server.MapPath("static/user/vid/") + flvlink.Replace(".flv", ".jpg") + "\"";
ffmpeg.StartInfo.FileName = Page.MapPath("bin/ffmpeg.exe");
ffmpeg.StartInfo.CreateNoWindow = true;
ffmpeg.StartInfo.UseShellExecute = false;
ffmpeg.StartInfo.RedirectStandardOutput = true;
ffmpeg.StartInfo.RedirectStandardError = true;
ffmpeg.Start();
ffmpeg.WaitForExit();
ffmpeg.Close();
// deleting original file and mpg
FileInfo fi = new FileInfo(Server.MapPath("static/user/vid/") + videolink);
if (fi.Exists) fi.Delete();
fi = new FileInfo(Server.MapPath("static/user/vid/") + mpglink);
if (fi.Exists) fi.Delete();
答案 0 :(得分：3)
我知道这是一个非常古老的问题，但如果有人因Google搜索而到达此处，答案如下：
即使您不需要，也必须读取第一个ffmpeg进程的重定向错误输出。如果您没有读取重定向的错误输出，则会导致死锁，因为您的程序将等待进程完成，但进程会等待读取填充的错误输出流。您可以查找here。
// convert to mpg 1st
ffmpeg.StartInfo.Arguments = " -i \"" + Server.MapPath("static/user/vid/") + videolink + "\" -f mpeg -b 300k -ac 2 -ab 128k -ar 44K \"" + Server.MapPath("static/user/vid/") + mpglink + "\"";
ffmpeg.StartInfo.FileName = Page.MapPath("bin/ffmpeg.exe");
ffmpeg.StartInfo.CreateNoWindow = true;
ffmpeg.StartInfo.UseShellExecute = false;
ffmpeg.StartInfo.RedirectStandardOutput = true;
ffmpeg.StartInfo.RedirectStandardError = true;
ffmpeg.Start();
// Use asynchronous read operations on at least one of the streams.
// Reading both streams synchronously would generate another deadlock.
ffmpeg.BeginOutputReadLine();
string tmpErrorOut = ffmpeg.StandardError.ReadToEnd();
ffmpeg.WaitForExit();
ffmpeg.Close();
因此，您必须像第二个ffmpeg进程一样阅读重定向错误和输出流。
您的生成图片预览部分也一样！
答案 1 :(得分：-1)
private bool ReturnVideo(string fileName)
{
string html = string.Empty;
//rename if file already exists
int j = 0;
string AppPath;
string inputPath;
string outputPath;
string imgpath;
AppPath = Request.PhysicalApplicationPath;
//Get the application path
inputPath = AppPath + "Upload\\Videos\\OriginalVideo";
//Path of the original file
outputPath = AppPath + "Upload\\Videos\\ConvertVideo";
//Path of the converted file
imgpath = AppPath + "Upload\\Videos\\Thumbs";
//Path of the preview file
string filepath = Server.MapPath("../Upload/Videos/OriginalVideo/" + fileName);
while (File.Exists(filepath))
{
j = j + 1;
int dotPos = fileName.LastIndexOf(".");
string namewithoutext = fileName.Substring(0, dotPos);
string ext = fileName.Substring(dotPos + 1);
fileName = namewithoutext + j + "." + ext;
filepath = Server.MapPath("../Upload/Videos/OriginalVideo/" + fileName);
}
try
{
this.fileuploadImageVideo.SaveAs(filepath);
}
catch
{
return false;
}
string outPutFile;
outPutFile = "../Upload/Videos/OriginalVideo/" + fileName;
int i = this.fileuploadImageVideo.PostedFile.ContentLength;
System.IO.FileInfo a = new System.IO.FileInfo(Server.MapPath(outPutFile));
while (a.Exists == false)
{ }
long b = a.Length;
while (i != b)
{ }
string cmd = " -i \"" + inputPath + "\\" + fileName + "\" \"" + outputPath + "\\" + fileName.Remove(fileName.IndexOf(".")) + ".flv" + "\"";
ConvertNow(cmd);
ViewState["fileName"] = fileName.Remove(fileName.IndexOf(".")) + ".wmv";
string imgargs = " -i \"" + inputPath + "\\" + fileName.Remove(fileName.IndexOf(".")) + ".wmv" + "\" -f image2 -ss 1 -vframes 1 -s 280x200 -an \"" + imgpath + "\\" + fileName.Remove(fileName.IndexOf(".")) + ".jpg" + "\"";
ConvertNow(imgargs);
return true;
}
private void ConvertNow(string cmd)
{
string exepath;
string AppPath = Request.PhysicalApplicationPath;
//Get the application path
exepath = AppPath + "ffmpeg.exe";
System.Diagnostics.Process proc = new System.Diagnostics.Process();
proc.StartInfo.FileName = exepath;
//Path of exe that will be executed, only for "filebuffer" it will be "wmvtool2.exe"
proc.StartInfo.Arguments = cmd;
//The command which will be executed
proc.StartInfo.UseShellExecute = false;
proc.StartInfo.CreateNoWindow = true;
proc.StartInfo.RedirectStandardOutput = false;
proc.Start();
while (proc.HasExited == false)
{ }
}
if (fileuploadImageVideo.HasFile)
{
ReturnVideo(this.fileuploadImageVideo.FileName.ToString());
string filename = fileuploadImageVideo.PostedFile.FileName;
fileuploadImageVideo.SaveAs(Server.MapPath("../upload/Video/"+filename));
objfun.Video = filename ;
}