QTKit，打开输入设备？

Question

我试图在以下内容中向QTCaptureSession添加两个输入：

mainSession = [[QTCaptureSession alloc] init];

BOOL success;
NSError* error;

QTCaptureDevice *videoDevice = [QTCaptureDevice defaultInputDeviceWithMediaType:@"QTMediaTypeVideo"];
success = [videoDevice open:&error];

QTCaptureDevice *audioDevice = [QTCaptureDevice defaultInputDeviceWithMediaType:@"QTMediaTypeSound"];
success = [audioDevice open:&error];

//video = [[QTCaptureDeviceInput alloc] initWithDevice:videoDevice];
//success = [mainSession addInput:video error:&error];

//audio = [[QTCaptureDeviceInput alloc] initWithDevice:audioDevice];
//success = [mainSession addInput:audio error:&error];

output = [[QTCaptureMovieFileOutput alloc] init];
success = [mainSession addOutput:output error:&error];

[output setDelegate:self];

[movieView setCaptureSession:mainSession];

[mainWindow makeKeyAndOrderFront:NSApp];

[mainSession startRunning];

我已经确定注释掉的部分是错误的来源：

[QTCaptureDeviceInput initWithDevice:]-不能使用未打开的设备来减少设备输入。

在开放的方法之后，我探索了我的“成功”变量，是的。那么，为什么这个方法认为设备没有打开呢？

Answer 1

如果你还没有找到答案的话，我认为你的问题实际上就在你所指出的两条线上。我查看了苹果的文档，发现QTMediaTypeSound和QTMediaTypeVideo是常量，而不是应该手动传入的字符串。例如，一个快速的NSLog()语句显示，QTMediaTypeVideo常量实际上等于"vide“。

简而言之，您的代码应该是：

mainSession = [[QTCaptureSession alloc] init];

BOOL success;
NSError* error;

QTCaptureDevice *videoDevice = [QTCaptureDevice defaultInputDeviceWithMediaType:QTMediaTypeVideo];
success = [videoDevice open:&error];

QTCaptureDevice *audioDevice = [QTCaptureDevice defaultInputDeviceWithMediaType:QTMediaTypeSound];
success = [audioDevice open:&error];

video = [[QTCaptureDeviceInput alloc] initWithDevice:videoDevice];
success = [mainSession addInput:video error:&error];

audio = [[QTCaptureDeviceInput alloc] initWithDevice:audioDevice];
success = [mainSession addInput:audio error:&error];

output = [[QTCaptureMovieFileOutput alloc] init];
success = [mainSession addOutput:output error:&error];

[output setDelegate:self];

[movieView setCaptureSession:mainSession];

[mainWindow makeKeyAndOrderFront:NSApp];

[mainSession startRunning];