What I need to do
I am building a qt application that run a exe and pipe its output to other exe. (In my case ffmpeg | x265)
What I did
QProcess ffmpeg;
QProcess x265;
ffmpeg.setStandardOutputProcess(&x265);
x265.setProcessChannelMode(QProcess::ForwardedChannels);
ffmpeg.start(ffmpegArgs);
x265.start(x265Args);
if(!ffmpeg.waitForStarted())
return;
bool retval = false;
while ((retval = x265.waitForFinished(-1)))
{}
ffmpeg.close();
x265.close();
Every thing woks fine but the GUI freezes when the process is running.
What I tried to solve the Issue
void Basic::on_btnEncode_clicked()
{
if(fileContainer -> getQueue() -> rowCount() == 0) {
QMessageBox msg;
msg.setText("No Input to Convert");
msg.setIcon(QMessageBox::Information);
msg.exec();
}
QString file;
int bitRate;
QString preset;
QString ffmpegArgs;
QString x265Args;
bitRate = ui->sldBitRate->value();
preset = mapPreset(ui->sldPreset->value());
for(int i = 0; i < fileContainer->getQueue()->rowCount(); ++i)
{
file = QString("\"") + fileContainer->getQueue()->item(i, 0)->text() + QString("\"");
ffmpegArgs = Addons::FFmpegExe() + " -i " + file + " -pix_fmt yuv420p -f yuv4mpegpipe -";
x265Args = Addons::x265Exe() + " --input - --y4m --preset " + preset + " --bitrate " + QString::number(bitRate) + " --output " + QString("\"") + ui->txtDest->text() + "/out.hevc\"";
QProcess *ffmpeg = new QProcess(this);
QProcess *x265 = new QProcess(this);
ffmpeg->setStandardOutputProcess(x265);
x265->setProcessChannelMode(QProcess::ForwardedChannels);
connect(x265, SIGNAL(started()), this, SLOT(processStart()));
connect(ffmpeg, SIGNAL(finished(int, QProcess::ExitStatus)), this, SLOT(deleteLater()));
connect(x265, SIGNAL(finished(int,QProcess::ExitStatus)), this, SLOT(processFinish(int,QProcess::ExitStatus)));
ffmpeg->start(ffmpegArgs);
x265->start(x265Args);
ffmpeg->close();
x265->close();
}
}
void Basic::processStart()
{
qDebug() << "started";
}
void Basic::processFinish(int exitcode, QProcess::ExitStatus staus)
{
qDebug() << "exitcode" << exitcode << "status" << staus;
}
but I always get the output as exitcode 62097 status 1 and nothing happens.
What can I do to run the process so that GUI does not freeze. Please Help.
You are creating the QProcesses on the stack. Meaning that when your function returns, the ffmpeg and x265 objects are destroyed. This also kills those processes.
If you want your process to keep running after your function returns. They must be created on the heap using new:
QProcess * ffmpeg = new QProcess(this);
QProcess * x265 = new QProcess(this);
Now you also need to destruct the ffmpeg and x265 objects yourself, otherwise you would be leaking memory. The following will wait until the processes are finished before their objects are cleaned up.
connect(ffmpeg, SIGNAL(finished(int,QProcess::ExitStatus)), ffmpeg, SLOT(deleteLater()));
connect(x265, SIGNAL(finished(int,QProcess::ExitStatus)), x265, SLOT(deleteLater()));
Related
I am working with a QProcess and have connected QProcess's signal readyReadStandardOutput().
That process normally spits out data to the console regularly, but the readyReadStandardOutput() seems to batch results and only emit every half a minute or so (with all accumulated data).
I want to access the "live feed" of the QProcess so I thought maybe QProcess's superclass QIODevice has some other signals.
Other solutions instead of using bytesWritten are also welcome
Now I'm trying to connect bytesWritten, but it doesn't let me.
Code:
void MainWindow::on_Program_clicked() {
program= new QProcess(this);
QString file = "../folder/program/program.exe";
QString directory = "../folder/program/";
//qint64 pid;
program->setWorkingDirectory(directory);
program->start(file, {""});
program->waitForStarted();
connect(program, SIGNAL(readyReadStandardOutput()), this, SLOT(readOutput()));
//ERROR: "QObject::connect: No such signal QProcess::bytesWritten() in ..\---\mainwindow.cpp:45
connect(program, SIGNAL(bytesWritten()), this, SLOT(myBytesWritten()));
}
void MainWindow::myBytesWritten() {
QProcess *program = dynamic_cast<QProcess *>(sender());
QByteArray outData = program->readAll();
qDebug() << "DEBUG: " + outData;
}
//Works, but only emits a signal every so often, and not every time a new line is written to the console as when I launch the exe normally
void MainWindow::readOutput(){
QProcess *program = dynamic_cast<QProcess *>(sender());
QByteArray outData = program->readAll();
qDebug() << "DEBUG: " + outData;
}
If you want to use the old, deprecated way of connecting signals to slots, you need to also include the parameter list:
connect(program, SIGNAL(bytesWritten(int)), this, SLOT(myBytesWritten()));
Or you can just use the modern, compile-time Qt5 way:
connect(program, &QProcess::bytesWritten, this, &MainWindow::myBytesWritten);
Also note that bytesWritten fires when a write command from YOUR end has succeeded. You don't seem to be sending any input so this will never fire.
I'm using Qt in order to implement an interface allowing to develop for embedded system.
I'm facing a problem: In order to flash program into the embeded system I use QProcess, in order to use the command "make" and "make flash". To make there isn't any problem and the program compiles successfully.
But when I try to do the same thing for "make flash" there is a problem because the console is waiting for user input, he has to press a button on the embedded system.
But QProcess returns standard output only when the script is finished so I don't have the message "press a button".
So my question is: How can I know when QProcess needs user input? Or if it's impossible, how can I open a console dynamically with Qt and start a command?
I tried to what is said here: https://www.qtcentre.org/threads/47538-QProcess-read-from-stdout-lively
And here is my code :
compilator->start("make flash");
compilator->waitForFinished();
QByteArray errors = compilator->readAllStandardError();
QString stringError(errors);
QByteArray message = compilator->readAll();
QString stringMessage(message);
m_logForm->setText("Project path : "
+ pathProject + "\n"
+ "Flash finished with exit code " + QString::number(compilator->exitCode()) + "\n"
+ stringError + "\n"
+ stringMessage + "\n");
Where m_logFrom is a class used to display console report in my interface
[EDIT] I tried what Vladimir said. Unfortunatly I don't have my material so I can't test it but I've done this script (test.bat) in order to test :
set /p answer=Do you want to create it now (Y/N)?
Here is my new code :
QProcess *compilator = new QProcess(this);
connect(compilator, &QProcess::readyReadStandardOutput, [compilator, this](){
QString output =compilator->readAll();
qDebug() << "output: "<< output;
m_logForm->setText("Flash finished with exit code " + QString::number(compilator->exitCode()) + "\n"
+ output + "\n");
});
connect(compilator, &QProcess::readyReadStandardError, [compilator, this](){
QString err = compilator->readAllStandardError();
qDebug() << "error: "<<err;
m_logForm->setText("Flash finished with exit code " + QString::number(compilator->exitCode()) + "\n"
+ err + "\n");
});
m_logForm->setText("Flashing to serial port "+m_Serial + "\n");
compilator->setWorkingDirectory(pathProject);
compilator->start("test.bat");
}
But it do nothing
My test.bat
set /p answer=Do you want to create it now (Y/N)?
echo "user response:" %answer%
pause
The code starts the batch command, reads it output and writes the answer to the process:
QProcess *compilator = new QProcess(this);
connect(compilator, &QProcess::readyReadStandardOutput, [compilator, this]()
{
QString output = compilator->readAllStandardOutput().simplified();
qDebug().noquote() << "output: " << output;
if (output.contains("(Y/N)?", Qt::CaseInsensitive))
{
compilator->write("Y\n"); // write our answer to the process
}
else if (output.contains(". . .", Qt::CaseInsensitive))
{
compilator->write("\n"); // simulate press any key to process
}
});
connect(compilator, &QProcess::readyReadStandardError, [compilator, this]()
{
QString err = compilator->readAllStandardError().simplified();
qWarning().noquote() << "error: " << err;
});
// Handle the finished() signal:
connect(compilator, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished),
[compilator, this](int exitCode, QProcess::ExitStatus exitStatus)
{
qDebug() << "compilator process finished with exit code =" << exitCode
<< "and exit status =" << exitStatus;
});
compilator->start("test.bat");
if (compilator->waitForStarted()) // use to check start errors
{
qDebug() << "compilator process started ok";
}
else
{
qCritical() << "compilator process start FAILED:" << compilator->errorString();
}
I'm a novice in threads and someone advises me to use Qt Concurrent (Qt C++).
I'm trying to run a function in a thread by using Qt Concurrent, my functions runs well but my signal/slot is never emitted.
However for your information if I launch my function without using thread everything works fine.
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
QFutureWatcher<void> *watcher1 = new QFutureWatcher<void>();
connect(watcher1, SIGNAL(finished()), this, SLOT(getSizeFinished()));
QString string = "http://ipv4.download.thinkbroadband.com/50MB.zip";
QFuture<void> future1 = QtConcurrent::run(this, &MainWindow::getRemoteFileSize, string);
watcher1->setFuture(future1);
}
void MainWindow::getSizeFinished()
{
qDebug() << "--- FINISHED ---";
}
void MainWindow::getRemoteFileSize(const QString &url)
{
qDebug() << "Function - getRemoteFileSize";
QNetworkRequest req;
m_netmanager = new QNetworkAccessManager();
req.setUrl(QUrl(url));
m_reply = m_netmanager->get(req);
connect(m_reply, SIGNAL(metaDataChanged()), this, SLOT(remoteHTTPHeader()));
}
void MainWindow::remoteHTTPHeader()
{
qDebug() << "Function - remoteHTTPHeader";
remoteSize = m_reply->header(QNetworkRequest::ContentLengthHeader).toInt();
qDebug() << "Remote File Size: " << remoteSize;
m_reply->deleteLater();
m_netmanager->deleteLater();
qDebug() << "SIZE " << remoteSize;
}
You probably don't need to create a connection in this case, you could call MainWindow::remoteHTTPHeader() right after m_reply = m_netmanager->get(req);.
You might want to check if the reply is effectively finished like so:
if (m_reply->isFinished()) {
remoteHTTPHeader();
} else {
connect(m_reply, &QNetworkReply::finished, this, &MainWindow::remoteHTTPHeader);
}
This way you handle both fast and slow connections. Also notice how I created the connection using function pointers instead of SIGNAL and SLOT macro, this syntax is better since it checks at compile time if the functions exist so you avoid making typos and the like.
I have to get the output of a QProcess while it is running. Therefore I have written the following Code:
CommandExecutor_C::CommandExecutor_C():
mProcessStatus(AI_UNKNOWN),
mOnTdiActiveCallback(),
mTdiProcess(new QProcess)
{
connect(mTdiProcess, SIGNAL(readyReadStandardOutput()), this, SLOT(CheckOutput()));
connect(mTdiProcess, SIGNAL(readyReadStandardError()), this, SLOT(CheckOutput()));
}
void CommandExecutor_C::ExecuteCommand(QString &aCommand)
{
mTdiProcess->start(aCommand, QProcess::Unbuffered | QProcess::ReadWrite);
LOGINFO(FB_TDI,"Launch command: " + aCommand.toStdString());
}
void CommandExecutor_C::CheckOutput()
{
QString StdOut = QString(mTdiProcess->readAllStandardOutput());
QString StdErr = QString(mTdiProcess->readAllStandardError());
mProcessStatus = CheckTdiAutomationInterface(StdOut.toStdString(), StdErr.toStdString());
if(mProcessStatus != AI_UNKNOWN)
{
OnTdiActive(mProcessStatus);
}
}
This works fine if QProcess gets finished but in my case the Process starts an automation interface which should run in background permanently. Therefore I have used "readyReadStandardOutput" and connect it to the slot CheckOutput(). CheckOutput() is getting called just if the process has been finished. Otherwise I am waiting endless.
I have googled a lot about the problem but nothing worked. I am very sure that the output is getting buffered and does just return if the Process has finished. Therefore I have started the Process in Unbuffered-Mode. I have also tried to forward the channels of mTdiProcess. Here the Code:
void CommandExecutor_C::ExecuteCommand(QString &aCommand)
{
mTdiProcess->setProcessChannelMode(QProcess::ForwardedChannels);
mTdiProcess->start(aCommand, QProcess::Unbuffered | QProcess::ReadWrite);
LOGINFO(FB_TDI,"Launch command: " + aCommand.toStdString());
}
But nothing worked. I hope you can help me.
I am using Qt 5.4.2 if that's important.
I usually check the output in regular intervals like this:
bool returnBool = false;
while (returnBool == false)
{
/*! Wait one second if the process finishes. Then read all output to
* stdout and stderr and redo. */
returnBool = process.waitForFinished(1000);
QString outputStdOut = process.readAllStandardOutput();
QString outputStdErr = process.readAllStandardError();
}
I am just trying to create a file with QProcess by the following source code:
void Processmethod()
{
QDialog *ProcessMessage = new QDialog;
Ui::DialogProcessMessage Dialog;
Dialog.setupUi(ProcessMessage);
ProcessMessage->setModal(true);
ProcessMessage->setAttribute(Qt::WA_DeleteOnClose);
ProcessMessage->show();
processmethodONE();
}
void processmethodONE()
{
QString ProcessCommand = "w8 " + blablubli";
Prozess.setWorkingDirectory(Path); //QProcess "Prozess" is globaly defined
Prozess.setStandardOutputFile(Path); //in my class
Prozess.start(ProcessCommand);
QProcess::ExitStatus Status = Prozess.exitStatus();
if (Status == 0)
{
std::cout << "File created!" << std::endl;
}
}
This process creates out of another file which is located in the QString "Path" a new file, let me call it "PROFILE" (PRO for Problem :). The Profile also is created, but is never completed, I guess not even 50% of the file are completed.
Just when using
while(!Prozess.waitForFinished())
{
qApp->processEvents();
std::cerr << "Process Create PROFile running " << std::endl;
}
the file is written completely.
Furthermore I tried to use the QProcess finished(int) Signal to start another method and deleted the while loop (which freezes the whole GUI). I declared it in the constructor with:
connect(&Prozess, SIGNAL(finished(int)), this, (SLOT(processmethodTWO())));
But I guess this could not work because the first process isn't finished completely. Where is the problem?
There is no warranty that right after Prozess.start(ProcessCommand); process will be finished, so calling "Prozess.exitStatus();" right after it will give you "false positive". You certainly will have to wait until process is finished. You may either do it with with while loop, that you suggested or with QEventLoop
// ...
Prozess.setStandardOutputFile(Path); //in my class
QEventLoop loop;
connect(&Prozess, SIGNAL(error(QProcess::ProcessError)), &loop, SLOT(quit()));
connect(&Prozess, SIGNAL(finished(int, QProcess::ExitStatus)), &loop, SLOT(quit()));
Prozess.start();
loop.exec();
// Now your process status should be valid:
QProcess::ExitStatus Status = Prozess.exitStatus();