The below code captures console outputs and send it in real time to callback function, so the application can handle it such as displaying its progress by adding to memo, so end user may not think the application is hanging while program performing the command.
type
TArg<T> = reference to procedure(const Arg: T);
.
.
.
procedure CaptureConsoleOutput(const ACommand: String; CallBack: TArg<PAnsiChar>);
const
CReadBuffer = 409600;
var
saSecurity: TSecurityAttributes;
hRead: THandle;
hWrite: THandle;
suiStartup: TStartupInfo;
piProcess: TProcessInformation;
pBuffer: array [0 .. CReadBuffer] of AnsiChar;
dBuffer: array [0 .. CReadBuffer] of AnsiChar;
dRead: DWORD;
dRunning: DWORD;
dAvailable: DWORD;
begin
saSecurity.nLength := SizeOf(TSecurityAttributes);
saSecurity.bInheritHandle := true;
saSecurity.lpSecurityDescriptor := nil;
if CreatePipe(hRead, hWrite, @saSecurity, 0) then
try
FillChar(suiStartup, SizeOf(TStartupInfo), #0);
suiStartup.cb := SizeOf(TStartupInfo);
suiStartup.hStdInput := hRead;
suiStartup.hStdOutput := hWrite;
suiStartup.hStdError := hWrite;
suiStartup.dwFlags := STARTF_USESTDHANDLES or STARTF_USESHOWWINDOW;
suiStartup.wShowWindow := SW_HIDE;
if CreateProcess(nil, PChar(ACommand), @saSecurity, @saSecurity, true, NORMAL_PRIORITY_CLASS, nil, nil, suiStartup,
piProcess) then
try
repeat
dRunning := WaitForSingleObject(piProcess.hProcess, 100);
PeekNamedPipe(hRead, nil, 0, nil, @dAvailable, nil);
if (dAvailable > 0) then
repeat
dRead := 0;
ReadFile(hRead, pBuffer[0], CReadBuffer, dRead, nil);
pBuffer[dRead] := #0;
OemToCharA(pBuffer, dBuffer);
CallBack(dBuffer);
until (dRead < CReadBuffer);
Application.ProcessMessages;
until (dRunning <> WAIT_TIMEOUT);
finally
CloseHandle(piProcess.hProcess);
CloseHandle(piProcess.hThread);
end;
finally
CloseHandle(hRead);
CloseHandle(hWrite);
end;
end;
Example)
var
strDir, strFFMPEG: string;
begin
strDir := GetCurrentDir;
strFFMPEG := '"' + strDir + '\ffmpeg.exe"';
strFFMPEG := strFFMPEG + ' -y -i C:\test.mkv -vcodec h264 -acodec aac -f mp4 C:\test-2.mp4';
Memo1.Lines.Add(strFFMpeg);
CaptureConsoleOutput(strFFMPEG,
procedure(const Line: PAnsiChar)
begin
//Panel1.Caption := String(Line);
Memo1.Lines.Add( String(Line));
end
);
end;