I tried hard to find a solution for the follwing requirement under C++/Visual Studio:
It's simple: For purpose of alarming I have to play a number of wav sounds from files sequentially in an endless loop, each separated by a short delay:
sound-1 ...sound-2 ... sound-n ... sound-1 ... sound-2 ...
At any time it should be possible to cancel this sequence of sounds.
I tried to play around with PlaySound(), but the problem is, that I cannot stop the sounds properly once they are running.
https://msdn.microsoft.com/en-us/library/Dd743680(v=VS.85).aspx
When a sound is played asynchronously by flag, it can be stopped by specifying a NULL for parameter 1, but then I can't know when sound-1 is finished before sound-2 is started. In fact, starting sound-2 would interrupt sound-1.
In synchroneous mode however, interruption of a sound is not possible.
To be able to cancel sounds I tried to put PlaySound into a Poco::Thread, but how to cancel a thread? It is not foreseen to cancel a thread...Using Poco::Task instaed gives an unhandled exception at 0x01002d62 ... upon cancelling, so it doesn't work either.
What would be the preferred solution for that?
Is there a better solution?
Thanks!
They're all WAV files, you know how long they last. When you start playing sound1, store the time it will end. There's no need to guess.
Related
I have an executable program that performs latency measurements. C++ pseudo-code below:
void main(){
lock_priority();
start_measurements();
work();
end_measurements();
}
The work() creates multiple threads and takes a long time to complete, so ideally I'd like to minimize the executable console when the process is running, just to save screen space. This, however, reduces the output latency by around 50% compared to when not minimized.
I'd like to implement the lock_priority() function so that even when minimized, the process does not go into PROCESS_MODE_BACKGROUND_BEGIN mode.
What I've tried so far
SetPriorityClass(GetCurrentProcess(), REALTIME_PRIORITY_CLASS); - did not work
Created a thread that every few seconds calls the function above - it did work, but, scientifically speaking, "it looks ugly"
I have tried to find a method to attach a callback to the SetPriorityClass() function so that after it finishes if the PriorityClass was anything but REALTIME_PRIORITY_CLASS, it'd re-set it again (or at least set PROCESS_MODE_BACKGROUND_END priority). This sounds like a perfect solution, but I could not find anything in the docs about this.
I discovered there is a way to set the processor to prefer foreground/background tasks (reference) - however even if this was possible to be configured through code, I still need a way to bind this theoretical function to the priority change.
Any help would be very appreciated!
How about redirecting the programm output from console to a file or just buffer it, like here:
Redirect both cout and stdout to a string in C++ for Unit Testing
This way, you don't have any console latency at all - if this is alright for your testing.
I have a performance-sensitive program that I would like to run as stably as possible, thus I'm wanting to disable/suspend MsMpEng.exe, among a few others, to hopefully attain that on Windows 10 when my program starts. When the program finishes, I'd like to restore normal previous function.
I have tried directly suspending the process using resmon.exe (Resource Monitor), and it suspends... but 20-30 seconds later, the entire system just stops. I assume this is some form of self-protect... so at the very least, I'd have to suspend and resume in a timed loop.
Thoughts? Is it even worth the trouble?
EDIT: Gave it some thought and some test cases, and just adjusting process priority isn't quite enough, but it's better than nothing. I'll just recommend people disable their virus protection if they encounter slow downs unless anyone else has any suggestions.
If you've ever used XNA game studio 4 you are familiar with the update method. By default the code within is processed at 60 times per second. I have been struggling to recreate such an effect in c++.
I would like to create a method where it will only process the code x amount of times per second. Every way I've tried it processes all at once, as loops do. I've tried for loops, while, goto, and everything processes all at once.
If anyone could please tell me how and if I can achieve such a thing in c++ it would be much appreciated.
With your current level of knowledge this is as specific as I can get:
You can't do what you want with loops, fors, ifs and gotos, because we are no longer in the MS-DOS era.
You also can't have code running at precisely 60 frames per second.
On Windows a system application runs within something called an "event loop".
Typically, from within the event loop, most GUI frameworks call the "onIdle" event, which happens when an application is doing nothing.
You call update from within the onIdle event.
Your onIdle() function will look like this:
void onIdle(){
currentFrameTime = getCurrentFrameTime();
if ((currentFrameTime - lastFrameTime) < minUpdateDelay){
sleepForSmallAmountOfTime();//using Sleep or anything.
//Delay should be much smaller than minUPdateDelay.
//Doing this will reduce CPU load.
return;
}
update(currentFrameTime - lastFrameTime);
lastFrameTime = currentFrameTime;
}
You will need to write your own update function, your update function should take amount of time passed since last frame, and you need to write a getFrameTime() function using either GetTickCount, QueryPerformanceCounter, or some similar function.
Alternatively you could use system timers, but that is a bad idea compared to onIdle() event - if your app runs too slowly.
In short, there's a long road ahead of you.
You need to learn some (preferably cross-platform) GUI framework, learn how to create a window, the concept of an event loop (can't do anything without it today), and then write your own "update()" and get a basic idea of multithreading programming and system events.
Good luck.
As you are familiar with XNA then i assume you also are familiar with "input" and "draw". What you could do is assign independant threads to these 3 functions and have a timer to see if its time to run a thread.
Eg the input would probably trigger draw, and both draw and input would trigger the update method.
-Another way to handle this is my messages events. If youre using Windows then look into Windows messages loop. This will make your input, update and draw event easier by executing on events triggered by the OS.
Got a large C++ function in Linux that calls a whole lot of other functions, making up an algorithm. At various points given certain bad inputs, the algorithm can get "stuck" and go on forever. Adding a timeout seems appropriate as all potential "stuck" points cannot be predicted. But despite scouring the Internet for timeout examples I've only found how to apply timeouts when either the thing your timing is a separate thread or it's reading inputs. My code is a single thread and does not modify file descriptors, so not coming up with any luck. Do I basically have no choice but to thread it?
I am not sure about the situation, actually server applications or embedded applications often run for years in background without stopping. I think one option is to let your program run in background and log to a file(or screen) timely, and, if you really want to stop the program after certain time, you can use timeout command or a script to kill your program after that time, say, timeout 15s your-prog.
I'm working in a software built in C++ using C++ Builder which is freezing once a month.
I'm looking in the code but it is too big to find it.
The freezes make the UI gets all white. I tried to simulate this error with some proposital bad codes (null pointers, while(1) and this kind of stuff) but never got the same blank UI.
I ran a What's Hang when it's stopped but I got nothing with it.
Someone knows what can I do in the next time to get more informations which could help me find the reason of the freezing?
A blank (white) UI generally occurs when a UI paint message is queued but not processed. Simply blocking the message queue from processing new messages is not enough if you don't do something within the UI to trigger a repaint in the first place.
As for troubleshooting the original problem - you should be looking for any code in the main thread that runs longs loop without processing new messages, or long waits on waitable objects using WaitForSingleObject() or WaitForMultipleOBjects() instead of MsgWaitForMultipleObjects(), calls to TThread::WaitFor() for threads that do not terminate in a timely manner, etc.
It is hard to troubleshoot this kind of problem without knowing what steps the user performs to lead up to the frozen UI so you know what code to start looking at.