Did anybody experience MPMusicPlayerController's nowPlayingItem method being stuck after iOS 11 upgrade? It gets SIGSTOP eventually after couple of seconds.
Yes. When my MPMusicPlayerControllerNowPlayingItemDidChangeNotification is called, the MPMusicPlayerController.nowPlayingItem is usually nil-- but only when playing a song from Apple Music (even if the song has already been downloaded to the device).
My workaround is to manually call my MPMusicPlayerControllerNowPlayingItemDidChangeNotification method again after one second. By then, the MPMusicPlayerController.nowPlayingItem is usually non-nil.
Of course, this makes my UI look quite unresponsive and sluggish.
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I am in the process of building a mobile game with Corona SDK, which is based on Lua. Until now i didn't need any help but this time I can't seem to find the cause, and I've been searching for it for hours.
It's one of those timer problems, where, after leaving, removing, and revisiting the scene, items that are spawned within a loop just multiply themselves every relaunch. More specificly, everytime a "forbidden" collision happens, which leads to the relaunch, according to my onCollision function.
What I already corrected after hours of strenuous research :
--the code inside the onCollision function is now inside the "began" phase,
so that can't cause the multiplication
--the scene phases are also correctly used
--transitions and timers are all canceled right before the relaunch
Since the code would be too long for you to look through, I'd rather ask for some hints :
What do you have in mind can cause such problems, besides what I already mentioned.
I appreciate every answer! Thanks alot.
The above comments are valid, it is going to be hard to diagnose the problem without being able to look at the code.
In the past, I have found it very helpful to name all my objects when dealing with collisions, so when a collision happens I know what objects caused it and it is very helpful for debugging purposes.
It looks like you have an issue with how you are starting the scene and deallocating resources when the scene ends. You may want to start/stop physics when the scene leaves and comes back, but without code I can't give a concrete answer.
There are other questions on StackOverflow which are close to what I want to know, like Webkit GTK :: How to detect when a download has finished?, but I think I'm asking something a bit different:
In general, in the event-driven C Webkit-GTK API there are a lot of events which may relate to the idea of when some document is finished "loading". The problem is the documentation is pretty sparse, and the idea of "finished loading" isn't necessarily clear, because it can refer to a lot of things. Does "finished loading" mean that the document is finished downloading? That it's finished creating the DOM tree? That it's finished downloading including all other resources (like CSS, JS and image files?)
Relevant signals are signal::notify::load-status, document-load-finished, and resource-load-finished.
The load-status signal fires everytime the load status changes, so you need to manually call webkit_web_view_get_load_status and check the status each time. Even so, when the status finally is WEBKIT_LOAD_FINISHED, I'm not sure what that means - does it mean WebKit is done downloading the resource, or that it's finished creating the DOM tree, or what?
Question:
What is the difference between the various "finished" signals, and is there any signal that is equivalent to the standard Javascript DOM event window.onload?
I believe the document-load-finished signal is what you are looking for as it seems (in my opinion) to match more closely what you are trying to test for.
One idea to test which is the correct way to do this would be to test the various ways there are to test if a document has "loaded" manually. I.e. Try the one I linked to above, and output a string to the Terminal when the value is true. If the value is true before the page has completely displayed all of its contents, chances are that it's not the one you're after. Then move on to the next, until you've got the right one.
Other than that, I'm not really sure what else you can do, since as you mentioned, the definition isn't very clear. It's times like these I wish Gtk documentation was a little more verbose.
I'm trying to make a guitar practice website, and a critical functionality is to loop over very short mp3 files (a few seconds long), with absolutely zero gap in between. For example, it could a 4-measures-long chord progression, and I want to allow the user to loop over it seamlessly.
I tried using the HTML5 <audio> tag with the loop attribute. Google Chrome gives a small gap between the loops, but big enough to be totally unacceptable for my purpose. I haven't tested the other browsers, but I believe it won't work.
A possible workaround is to use ffmpeg to stream repetitions the same audio as an mp3. However, this costs a lot of bandwidth.
For myself I use Audacity to loop without gaps, but unfortunately Audacity doesn't have a web version.
So, do you have any ideas how I may loop over an mp3 in a browser with zero gap? I prefer non-Flash solutions, but if nothing else works I'll use Flash.
Edit:
Thank you for all your suggestions. Flash turns out to work decently. I've made a toy demo at http://vmlucid.lcm.hk/~netvope/audio/flash.html. To my surprise (I use to associate Flash with resource hog and browser crashes only), Flash and ActionScript are rather well designed and easy to use. It took me only 3 hours on my first Flash project :)
Have a look at this page. Listening for a while using Google Chrome 7, I found Method 1 works decently, while Method 3 gives the best results, though it's a bit of a hack. Ultimately, all browsers work differently, especially since HTML5 isn't finalized yet. If possible, you should opt for a Flash version, which I would think would give you the best loop.
in flash AS3 you can extract sound data with computeSpectrum() and give it to your Sound object exactly when it's needed (SampleDataEvent is fired).
I am not sure how well this will work, but if you knew your loop lasted 800 milliseconds - you could have the browser call the play method every 800ms... it still wouldn't be guaranteed to be perfect though. I don't think the browser is natively capable of delivering reliable audio looping at this point.
setInterval(function(){
document.getElementById("loop").play();
}, 800);
Rumor has it the best way to do pull this off in the most gapless fashion to use to multiple audio tags and alternate between them.
Or check out this utility: http://www.compuphase.com/mp3/mp3loops.htm I used it successfully for my flash projects when music had to be looped without gaps, and 99% of the time it worked. It takes WAV as an input.
Basically it is a kind of front-end for LAME mp3 encoder, which uses such settings as to prevent the gaps appearing. It won't work on very short sound effects (less than 0.5 second I believe).
Afterward all you have to do is use:
var sound:Sound = new MySoundEffect();
sound.play(0, 1000);
and it will loop one thousand times.
Is there a (or, do you have your own) preferred way to do background processing in slices on the UI thread in Windows Forms? Like OnIdle() in MFC?
In native Windows programming you could roll your own message loop to do this, but Application.Run() doesn't give us access to the message loop.
The Application.Idle event gives us no way to trigger it repeatedly.
I guess you could call native PostMessage() with P/Invoke (since there's no managed version) to post yourself a private "WM_IDLE" message, and override WndProc() to catch it. I don't know how this would get along with Application.Run().
So far I've used a short Timer for this, but I'm afraid I may be losing cycles sleeping, especially since the actual Timer resolution is coarser than the nominal 1 ms minimum.
The best option I've seen is to use a modified version of the Managed DirectX Render Loop designed by Tom Miller. By adding a call to Thread.Sleep() inside the render loop, you can pull your CPU usage down dramatically.
This does require a P/Invoke call to track that the application is still idle, but as long as it's idle, you can make a "timer" that fires continuously during the idle phases, and use that to do your processing.
That being said, on modern systems, you almost always have extra cores. I would suggest just doing the processing on a true background thread.
I thought of my own possible answer, inspired by Reed's talk of multithreading. I may have a way to retrigger Application.Idle:
Create a hidden form, let's call it formRetrigger.
In Application.Idle, launch my Retrigger() method on a thread pool thread.
Retrigger() calls formRetrigger.InvokeOnClick() (or any of the other "Control.Invoke" methods). I expect this to launch another message through Application's queue, causing Idle to get triggered again.
This is an odd one. I am making a app that is kind of a game, and I wanted to have a shooting starburst effect. I made it one evening and it all worked well, until I noticed that my browser was eating over 300 megs of ram, eating 1 meg every 5 seconds, mainly when the starburst would happen.
Here is an example stripped down to just the starburst:
http://www.sizzln.com/example.htm
First thought, I am not removing the objects or still have references somewhere. I am placing each generated star into a Canvas, but I am removing old starts every 3 seconds. I do have a lot of DoubleAnimations as well, but I even have a callback to set everything to null.
Here is the weird part, if I convert it to WPF it doesnt happen, if I run it inside of Silverlight Spy 3, it doenst happen. If I take a Heap Dump using WinDbg and SOS.dll, it reports that it should only be using between 1.8 and 3 MBs of ram.
I have the GC running every 3 seconds to cleanup, but it never has any effect. I can see in the heapdump that many objects are now deleted, and I always get back to 1.8 meg or so after a GC, but the memory shown in Task Manager just keeps going up.
I dont know what to do, I think I am carefully removing the objects unless my Heap is not being honest.
Are you running Vista or Win7? It sounds like the OS is not reclaiming memory, as it shouldn't unless it needs to.
It may also be that the Silverlight GC doesn't free its buffers, on the assumption that the memory may need to be reallocated soon.
In either case, it doesn't sound like anything to worry about, as long as the profiler says your program only uses 1.8MB after the GC runs.
I just briefly looked over your code. You have a lot of places where you hook into events (+=), but never unhook (-=). These are hard references and therefore won't ever be collected if they are ultimately connected to a root object.
OK I am going to sorta answer my own question. Silveright doesn't have the handy "BeginAnimation" method, so I found online a quick way to add an extension to do basically the same thing, it did this by creating a storyboard and starting it.
However, it just stayed there, I dont exactly know what it was being connected to either. Calling Stop() on it after it finishes fixed my memory issue.
One odd side effect is I have to be careful when I call the stop method, when creating so many storyboards it seemed to get a bit confused and it would cause some of the objects to reappear, even after they were removed from the control.