连续调用startRecordingToOutputFileURL:

Question

Apple文档似乎表明,在将视频录制到文件时,应用程序可以动态更改URL,没有任何问题.但我看到了一个问题.当我尝试这个时,录制代表被调用错误...

这项行动无法完成.(OSStatus错误-12780.)信息字典是:{AVErrorRecordingSuccessfullyFinishedKey = 0; }

("can not"中的时髦单引号来自日志记录[error localizedDescription])

这是代码,基本上是对WWDC10 AVCam示例的调整:

1)开始录音.每隔几秒钟启动计时器以更改输出URL

- (void) startRecording
{
    // start the chunk timer
    self.chunkTimer = [NSTimer scheduledTimerWithTimeInterval:5
                                                       target:self
                                                     selector:@selector(chunkTimerFired:)
                                                     userInfo:nil
                                                      repeats:YES];

    AVCaptureConnection *videoConnection = [AVCamCaptureManager connectionWithMediaType:AVMediaTypeVideo fromConnections:[[self movieFileOutput] connections]];
    if ([videoConnection isVideoOrientationSupported]) {
        [videoConnection setVideoOrientation:[self orientation]];
    }

    if ([[UIDevice currentDevice] isMultitaskingSupported]) {
        [self setBackgroundRecordingID:[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{}]];
    }

    NSURL *fileUrl = [[ChunkManager sharedInstance] nextURL];
    NSLog(@"now recording to %@", [fileUrl absoluteString]);
    [[self movieFileOutput] startRecordingToOutputFileURL:fileUrl recordingDelegate:self];
}

2)当计时器触发时,更改输出文件名而不停止记录

- (void)chunkTimerFired:(NSTimer *)aTimer {

    if ([[UIDevice currentDevice] isMultitaskingSupported]) {
        [self setBackgroundRecordingID:[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{}]];
    }

    NSURL *nextUrl = [self nextURL];
    NSLog(@"changing capture output to %@", [[nextUrl absoluteString] lastPathComponent]);

    [[self movieFileOutput] startRecordingToOutputFileURL:nextUrl recordingDelegate:self];
}

注意:[self nextURL]生成文件URL,如file-0.mov,file-5.mov,file-10.mov等.

3)每次文件更改时都会调用此函数,并且每次调用都是错误的...

- (void)              captureOutput:(AVCaptureFileOutput *)captureOutput
didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL
                    fromConnections:(NSArray *)connections
                              error:(NSError *)error
{
    id delegate = [self delegate];
    if (error && [delegate respondsToSelector:@selector(someOtherError:)]) {
        NSLog(@"got an error, tell delegate");
        [delegate someOtherError:error];
    }

    if ([self backgroundRecordingID]) {
        if ([[UIDevice currentDevice] isMultitaskingSupported]) {
            [[UIApplication sharedApplication] endBackgroundTask:[self backgroundRecordingID]];
        }
        [self setBackgroundRecordingID:0];
    }

    if ([delegate respondsToSelector:@selector(recordingFinished)]) {
        [delegate recordingFinished];
    }
}

当这个运行时,file-0被写入,然后我们在将url更改为file-5之后立即看到错误-12780,文件-10被写入,然后是错误,然后好的,依此类推.

看来,动态更改URL不起作用,但它会停止写入,允许下一个URL更改工作.

任何帮助将非常感激.

Answer 1

谢谢大家,对此进行了审核和好评.这是来自Apple DTS的一句话......

我与我们的AV基金会工程师进行了交谈,这肯定是一个错误,因为这种方法没有按照文档所说的那样做("在进行另一次录制时,你不需要在调用此方法之前调用stopRecording.").请使用Apple Bug Reporter(http://developer.apple.com/bugreporter/)提交错误报告,以便团队进行调查.确保并在报告中包含您的最小项目.

我已将此作为错误11632087向Apple提交