Question

我试图让Apple的AVScreenShack example project在OS X 10.8.2上运行。

当我运行应用程序并触发录制（调用startRecording）时，会发生一系列奇怪的事件：

应用程序继续使用~40％的CPU（可能需要在应用程序窗口中显示视频预览）
委托方法captureOutput:didStartRecordingToOutputFileAtURL:fromConnections: 从不调用

当我触发stopRecording时：

应用程序继续使用~40％CPU
“即将停止”NSLog调用显示captureMovieFileOutput对象带有有效文件URL（指向桌面上的临时文件）
委托方法captureOutput:didFinishRecordingToOutputFileAtURL:fromConnections:error: 从不调用
即使在几分钟后，桌面上也没有创建文件

我在输出控制台中看不到任何错误。有没有什么方法可以进一步有效地调试它？

相关代码如下。我没有修改它（但在这里省略了不必要的部分）。

- (BOOL)createCaptureSession:(NSError **)outError
{
    NSLog(@"createCaptureSession start");

    /* Create a capture session. */
    self.captureSession = [[AVCaptureSession alloc] init];

    // ...

    /* Add the main display as a capture input. */
    display = CGMainDisplayID();
    self.captureScreenInput = [[AVCaptureScreenInput alloc]
                               initWithDisplayID:display];
    if ([self.captureSession canAddInput:self.captureScreenInput]) {
        [self.captureSession addInput:self.captureScreenInput];
    } else {
        return NO;
    }

    /* Add a movie file output + delegate. */
    captureMovieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
    [captureMovieFileOutput setDelegate:self];
    if ([self.captureSession canAddOutput:captureMovieFileOutput]) {
        [self.captureSession addOutput:captureMovieFileOutput];
    } else {
        return NO;
    }

    /* Register for notifications of errors during the capture session so we
       can display an alert. */
    [[NSNotificationCenter defaultCenter]
     addObserver:self
     selector:@selector(captureSessionRuntimeErrorDidOccur:)
     name:AVCaptureSessionRuntimeErrorNotification
     object:self.captureSession];

    NSLog(@"createCaptureSession finish w/o errors");

    return YES;
}

- (void)captureOutput:(AVCaptureFileOutput *)captureOutput
didStartRecordingToOutputFileAtURL:(NSURL *)fileURL
      fromConnections:(NSArray *)connections {
    NSLog(@"starting output");
    NSLog(@"%@", captureMovieFileOutput.outputFileURL);
}


/* Informs the delegate when all pending data has been written to the output file. */
- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error
{
    NSLog(@"didFinish");

    if (error) 
    {
        [self presentError:error];
        return;
    }

    [[NSWorkspace sharedWorkspace] openURL:outputFileURL];
}

- (void)windowControllerDidLoadNib:(NSWindowController *)aController
{
    [super windowControllerDidLoadNib:aController];

    NSLog(@"about to start running the session %@", self.captureSession);
    /* Start the capture session running. */
    [self.captureSession startRunning];
}

/* Called when the user presses the 'Start' button to start a recording. */
- (IBAction)startRecording:(id)sender
{
    NSLog(@"startRecording");

    char *tempNameBytes = tempnam([[@"~/Desktop/" stringByStandardizingPath]
                                   fileSystemRepresentation], "AVScreenShack_");
    NSString *tempName = [[NSString alloc]
                          initWithBytesNoCopy:tempNameBytes
                          length:strlen(tempNameBytes)
                          encoding:NSUTF8StringEncoding
                          freeWhenDone:YES];

    /* Starts recording to a given URL. */
    [captureMovieFileOutput
     startRecordingToOutputFileURL:[NSURL fileURLWithPath:[tempName stringByAppendingPathExtension:@"mov"]]
     recordingDelegate:self];
}

/* Called when the user presses the 'Stop' button to stop a recording. */
- (IBAction)stopRecording:(id)sender
{
    NSLog(@"about to stop from URL: %@", captureMovieFileOutput.outputFileURL);

    [captureMovieFileOutput stopRecording];
}

/* Called when the document is closed. */
- (void)close
{
    NSLog(@"about to stop from URL: %@", captureMovieFileOutput.outputFileURL);

    /* Stop the capture session running. */
    [self.captureSession stopRunning];

    [super close];
}

以上程序的日志输出如下。请注意，“didFinish”日志调用从未进行过，也没有“开始输出”。

2013-04-20 16:00:01.908 AVScreenShack[8950:303] createCaptureSession start
2013-04-20 16:00:01.912 AVScreenShack[8950:303] createCaptureSession finish w/o errors
2013-04-20 16:00:02.131 AVScreenShack[8950:303] about to start running the session <AVCaptureSession: 0x100618e70 [AVCaptureSessionPresetHigh]>
2013-04-20 16:00:10.936 AVScreenShack[8950:303] startRecording
2013-04-20 16:00:10.936 AVScreenShack[8950:303] Minimum Frame Duration: 0.066667, Crop Rect: {{0, 0}, {0, 0}}, Scale Factor: 1.000000, Capture Mouse Clicks: No, Capture Mouse Cursor: Yes, Remove Duplicate Frames: Yes
2013-04-20 16:00:15.648 AVScreenShack[8950:303] about to stop from URL: file://localhost/Users/jon/Desktop/AVScreenShack_Y2DUaA.mov

AVScreenShack示例无法保存文件

0 个答案: