Simple question:
I have an AVPlayer property called player (could be any strong property, its just AVPlayer for example's sake).
If it has already been allocated (and is not nil) and I re-allocate it without setting it to nil:
self.player = [[AVDelegatingPlayer alloc] initWithURL:[NSURL URLWithString:urlString]];
Are there memory implications for this in an ARC environment?
Take a look at clang source code for storing an object into a __strong variable.
https://github.com/llvm-mirror/clang/blob/master/lib/CodeGen/CGObjC.cpp#L2108-L2119
// Retain the new value.
newValue = EmitARCRetain(type, newValue);
// Read the old value.
llvm::Value *oldValue = EmitLoadOfScalar(dst, SourceLocation());
// Store. We do this before the release so that any deallocs won't
// see the old value.
EmitStoreOfScalar(newValue, dst);
// Finally, release the old value.
EmitARCRelease(oldValue, dst.isARCPreciseLifetime());
So your code would be compiled as the following.
id newValue = [[AVDelegatingPlayer alloc] initWithURL:[NSURL URLWithString:urlString]];
id oldValue = self.player;
self.player = newValue;
[oldValue release];
Related
I have integrated the NDI SDK from NewTek in the current version 5 into my Qt6.3 widget project.
I copied and included the required DLLs and header files from the NDI SDK installation directory into my project.
To test my build environment I tried to compile a simple test program based on the example from "..\NDI 5 SDK\Examples\C++\NDIlib_Recv".
That was also successful.
I was therefore able to receive or access data from my NDI source.
There is therefore a valid frame in the video_frame of the type NDIlib_video_frame_v2_t. Within the structure I can also query correct data of the frame such as the size (.xres and .yres).
The pointer p_data points to the actual data.
So far so good.
Of course, I now want to display this frame on the Qt6 GUI. In other words, the only thing missing now is the conversion into an appropriate format so that I can display the frame with QImage, QPixmap, QLabel, etc.
But how?
So far I've tried calls like this:
curFrame = QImage(video_frame.p_data, video_frame.xres, video_frame.yres, QImage::Format::Format_RGB888);
curFrame.save("out.jpg");
I'm not sure if the format is correct either.
Here's a closer look at the mentioned frame structure within the Qt debug session:
my NDI video frame in the Qt Debug session, after receiving
Within "video_frame" you can see the specification video_type_UYVY.
This may really be the format as it appears at the source!?
Fine, but how do I get this converted now?
Many thanks and best regards
You mean something like this? :)
https://github.com/NightVsKnight/QtNdiMonitorCapture
Specifically:
https://github.com/NightVsKnight/QtNdiMonitorCapture/blob/main/lib/ndireceiverworker.cpp
Assuming you connect using NDIlib_recv_color_format_best:
NDIlib_recv_create_v3_t recv_desc;
recv_desc.p_ndi_recv_name = "QtNdiMonitorCapture";
recv_desc.source_to_connect_to = ...;
recv_desc.color_format = NDIlib_recv_color_format_best;
recv_desc.bandwidth = NDIlib_recv_bandwidth_highest;
recv_desc.allow_video_fields = true;
pNdiRecv = NDIlib_recv_create_v3(&recv_desc);
Then when you receive a NDIlib_video_frame_v2_t:
void NdiReceiverWorker::processVideo(
NDIlib_video_frame_v2_t *pNdiVideoFrame,
QList<QVideoSink*> *videoSinks)
{
auto ndiWidth = pNdiVideoFrame->xres;
auto ndiHeight = pNdiVideoFrame->yres;
auto ndiLineStrideInBytes = pNdiVideoFrame->line_stride_in_bytes;
auto ndiPixelFormat = pNdiVideoFrame->FourCC;
auto pixelFormat = NdiWrapper::ndiPixelFormatToPixelFormat(ndiPixelFormat);
if (pixelFormat == QVideoFrameFormat::PixelFormat::Format_Invalid)
{
qDebug().nospace() << "Unsupported pNdiVideoFrame->FourCC " << NdiWrapper::ndiFourCCToString(ndiPixelFormat) << "; return;";
return;
}
QSize videoFrameSize(ndiWidth, ndiHeight);
QVideoFrameFormat videoFrameFormat(videoFrameSize, pixelFormat);
QVideoFrame videoFrame(videoFrameFormat);
if (!videoFrame.map(QVideoFrame::WriteOnly))
{
qWarning() << "videoFrame.map(QVideoFrame::WriteOnly) failed; return;";
return;
}
auto pDstY = videoFrame.bits(0);
auto pSrcY = pNdiVideoFrame->p_data;
auto pDstUV = videoFrame.bits(1);
auto pSrcUV = pSrcY + (ndiLineStrideInBytes * ndiHeight);
for (int line = 0; line < ndiHeight; ++line)
{
memcpy(pDstY, pSrcY, ndiLineStrideInBytes);
pDstY += ndiLineStrideInBytes;
pSrcY += ndiLineStrideInBytes;
if (pDstUV)
{
// For now QVideoFrameFormat/QVideoFrame does not support P216. :(
// I have started the conversation to have it added, but that may take awhile. :(
// Until then, copying only every other UV line is a cheap way to downsample P216's 4:2:2 to P016's 4:2:0 chroma sampling.
// There are still a few visible artifacts on the screen, but it is passable.
if (line % 2)
{
memcpy(pDstUV, pSrcUV, ndiLineStrideInBytes);
pDstUV += ndiLineStrideInBytes;
}
pSrcUV += ndiLineStrideInBytes;
}
}
videoFrame.unmap();
foreach(QVideoSink *videoSink, *videoSinks)
{
videoSink->setVideoFrame(videoFrame);
}
}
QVideoFrameFormat::PixelFormat NdiWrapper::ndiPixelFormatToPixelFormat(enum NDIlib_FourCC_video_type_e ndiFourCC)
{
switch(ndiFourCC)
{
case NDIlib_FourCC_video_type_UYVY:
return QVideoFrameFormat::PixelFormat::Format_UYVY;
case NDIlib_FourCC_video_type_UYVA:
return QVideoFrameFormat::PixelFormat::Format_UYVY;
break;
// Result when requesting NDIlib_recv_color_format_best
case NDIlib_FourCC_video_type_P216:
return QVideoFrameFormat::PixelFormat::Format_P016;
//case NDIlib_FourCC_video_type_PA16:
// return QVideoFrameFormat::PixelFormat::?;
case NDIlib_FourCC_video_type_YV12:
return QVideoFrameFormat::PixelFormat::Format_YV12;
//case NDIlib_FourCC_video_type_I420:
// return QVideoFrameFormat::PixelFormat::?
case NDIlib_FourCC_video_type_NV12:
return QVideoFrameFormat::PixelFormat::Format_NV12;
case NDIlib_FourCC_video_type_BGRA:
return QVideoFrameFormat::PixelFormat::Format_BGRA8888;
case NDIlib_FourCC_video_type_BGRX:
return QVideoFrameFormat::PixelFormat::Format_BGRX8888;
case NDIlib_FourCC_video_type_RGBA:
return QVideoFrameFormat::PixelFormat::Format_RGBA8888;
case NDIlib_FourCC_video_type_RGBX:
return QVideoFrameFormat::PixelFormat::Format_RGBX8888;
default:
return QVideoFrameFormat::PixelFormat::Format_Invalid;
}
}
For my iPhone application I set up a data model for Core Data. It contains one entity Words and its attributes are language : String, length : Integer16 and word : String.
I prefilled my model's SQLite database with a word list (200k items) writing a separate iPhone application using the identical data model and coping the filled database to the main application.
Now using NSFetchedRequest I can query for managed objects as I like, but the results come in slow. I use the following method:
- (NSString *)getRandomWordLengthMin:(int)minLength max:(int)maxLength
{
NSString *word = #"";
MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Words"
inManagedObjectContext:context];
[fetchRequest setEntity:entity];
NSString *predicateString = #"length >= %d AND length <= %d";
NSPredicate *predicate = [NSPredicate predicateWithFormat:predicateString,
minLength, maxLength];
[fetchRequest setPredicate:predicate];
NSError *error = nil;
int entityCount = [context countForFetchRequest:fetchRequest error:&error];
[fetchRequest setFetchLimit:1];
if(entityCount != 0)
{
[fetchRequest setFetchOffset:arc4random()%entityCount];
}
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
if([fetchedObjects count] != 0)
{
Words * test = [fetchedObjects objectAtIndex:0];
word = [NSString stringWithFormat:#"%#", [test word]];
}
return word;
}
Using an SQLite editor I already set an index manually on column zLength, but this didn't bring any speedup. Where is the bottleneck?
EDIT:
I figured out that getting int entityCount = ... is slow. But even getting all objects and then selecting one random word is slow:
Words * test = [fetchedObjects objectAtIndex:arc4random()%[fetchedObjects count]];
You are effectively running two fetches here, one to get the fetch count and then one to fetch the actual object. That will slow things down.
Your predicate is "backwards." Compound predicates evaluate the first expression e.g. length >= %d and then evaluate the second e.g. length <= %d only against the results of the first. Therefore you should put the test that eliminates the most objects first. In this case, length <= %d probably eliminates more objects so it should come first in the predicate.
Since you don't actually need the entire Words managed object but just the word string, you can set the fetch return type to NSDictionaryResultType and then set the property to fetch to just the word attribute. That will speed things up considerably.
Part of your problem here is that Core Data is designed to managed a structured object graph and you are using a random/unstructured graph so you are cutting against the grain of Core Data's optimizations.
Do not use the SQLite editor to edit the SQLite backing store for a Core Data storage. The internals of the database is private and subject to change.
Instead go the the model editor in Xcode and simply put a checkmark on the "indexed" option for the entity attribute you want indexed.
Not sure but maybe this predicate is easier to optimize:
NSString *predicateString = #"length BETWEEN (%d, %d)";
I have a Mac OS X Document based app that has multiple NSViewControllers that I switch between and each view displays data from plist files in NSTableViews based on the user selections in the previous NSViewController's NSTableView. The problem I have is that I can't figure out what function can be called, every time a NSViewController gets loaded, to read the correct data from a file to display in the NSTableView. For UIViewControllers I used the function family of viewDidLoad, viewWillAppear, but I haven't been able to find the corresponding functions for NSViewController.
Currently I am using awakeFromNib, which works fine, but only the first time the NSViewController gets loaded. I've tried loadView, but that collapses the NSView. I assume that I need to do more setup to use loadView.
I'm using the View Swapping code from Hillegass's book Cocoa Programming for MAC OS X which switches ViewControllers with the following code:
- (void)displayViewController:(ManagingViewController *)vc
curBox: (NSBox *)windowBox
{
// End editing
NSWindow *w = [windowBox window];
BOOL ended = [w makeFirstResponder:w];
if (!ended) {
NSBeep();
return;
}
NSView *v = [vc view];
NSSize currentSize = [[windowBox contentView] frame].size;
NSSize newSize = [v frame].size;
float deltaWidth = newSize.width - currentSize.width;
float deltaHeight = newSize.height - currentSize.height;
NSRect windowFrame = [w frame];
windowFrame.size.height += deltaHeight;
windowFrame.origin.y -= deltaHeight;
windowFrame.size.width += deltaWidth;
[windowBox setContentView:nil];
[w setFrame:windowFrame
display:YES
animate:YES];
[windowBox setContentView:v];
// Put the view controller in the responder chain
[v setNextResponder:vc];
[vc setNextResponder:windowBox];
}
and puts the NSView Controller in the responder chain.
Is there some function I can call to setup the view every time I swap NSViewControllers? Can I check that a NSViewController has become the firstResponder?
This post provided the answer.
I added the following code:
- (void)viewWillLoad {
}
- (void)viewDidLoad {
}
- (void)loadView {
[self viewWillLoad];
[super loadView];
[self viewDidLoad];
}
and at the beginning of displayViewController I added
[vc loadView]
I am trying to simply update the entity object and I get this error.. All the googling on the error I did takes me to complex explanations... can anyone put it simply?
I am working of of this simple tutorial
http://aspalliance.com/1919_ASPNET_40_and_the_Entity_Framework_4__Part_2_Perform_CRUD_Operations_Using_the_Entity_Framework_4.5
else
{
//UPDATE
int iFid = Int32.Parse(fid.First().fid.ToString());
oFinancial.fid = iFid;
oFinancial.mainqtr = currentQuarter;
oFinancial.mainyear = currentYear;
oFinancial.qtr = Int32.Parse(currentQuarter);
oFinancial.year = Int32.Parse(currentYear);
oFinancial.updatedate = DateTime.Now;
// ObjectStateEntry ose = null;
// if (!dc.ObjectStateManager.TryGetObjectStateEntry(oFinancial.EntityKey, out ose))
// {
dc.financials.Attach(oFinancial);
// }
dc.ObjectStateManager.ChangeObjectState(oFinancial, System.Data.EntityState.Modified);
}
dc.SaveChanges();
here is what is higher up in the code that I use simple to get me the primary key value.. probably a better way but it works.
var fid = from x in dc.financials
where iPhaseID == x.phaseid &&
strTaskID == x.ftaskid &&
strFundType == x.fundtype &&
iCurrentQuarter == x.qtr &&
iCurrentYear == x.year
select x;
If the oFinancial object came from your dc and you never manually detached it, then there is no reason to call the Attach method or to mess with the ObjectStateManager. As long as the dc knows about the object (which it does unless you detach it), then the ObjectStateManager will keep track of any changes you make and update them accordingly when you call dc.SaveChanges().
EDIT: Here's a refactored version of what you posted, hope it helps:
else {
//UPDATE
// as long as oFinancial was never detatched after you retrieved
// it from the "dc", then you don't have to re-attach it. And
// you should never need to manipulate the primary key, unless it's
// not generated by the database, and you don't already have another
// object in the "dc" with the same primary key value.
int iFid = Int32.Parse(fid.First().fid.ToString());
oFinancial.fid = iFid;
oFinancial.mainqtr = currentQuarter;
oFinancial.mainyear = currentYear;
oFinancial.qtr = Int32.Parse(currentQuarter
oFinancial.year = Int32.Parse(currentYear);
oFinancial.updatedate = DateTime.Now;
}
dc.SaveChanges();
One other thing: if iFid is the primary key, then you shouldn't mess with it as long as this object came from the dc. I believe the problem is that you're resetting the primary key (iFid) to the same value of another object within the dc, and EF4 is barking because you can't have two rows with the same primary key value in a table.
In the big picture I want to create a frame based application in Bada that has a single UI control - a label. So far so good, but I want it to display a number of my choosing and decrement it repeatedly every X seconds. The threading is fine (I think), but I can't pass the label pointer as a class variable.
//MyTask.h
//...
result Construct(Label* pLabel, int seconds);
//...
Label* pLabel;
//MyTask.cpp
//...
result
MyTask::Construct(Label* pLabel, int seconds) {
result r = E_SUCCESS;
r = Thread::Construct(THREAD_TYPE_EVENT_DRIVEN);
AppLog("I'm in da constructor");
this->pLabel = pLabel;
this->seconds = seconds;
return r;
}
//...
bool
Threading::OnAppInitializing(AppRegistry& appRegistry)
{
// ...
Label* pLabel = new Label();
pLabel = static_cast<Label*>(pForm->GetControl(L"IDC_LABEL1"));
MyTask* task = new MyTask();
task->Construct(&pLabel); // HERE IS THE ERROR no matching for Label**
task->Start();
// ...
}
The problem is that I have tried every possible combination of *, &, and just plain pLabel, known in Combinatorics...
It is not extremely important that I get this (it is just for training) but I am dying to understand how to solve the problem.
Have you tried:
task->Construct(pLabel, 0);
And by that I want to point out that you are missing the second parameter for MyTask::Construct.
No, I haven't. I don't know of a second parameter. But this problem is solved. If I declare a variable Object* __pVar, then the constructor should be Init(Object* pVar), and if I want to initialize an instance variable I should write
Object* pVar = new Object();
MyClass* mClass = new MyClass();
mClass->Construct(pVar);