可以同时使用AVCaptureVideoDataOutput和AVCaptureMovieFileOutput吗？ [英] Can use AVCaptureVideoDataOutput and AVCaptureMovieFileOutput at the same time?

问题描述

我想用我的代码同时录制视频和抓取帧。

I want to record video and grab frames at the same time with my code.

我正在使用 AVCaptureVideoDataOutput 获取抓取框架和 AVCaptureMovieFileOutput 用于视频录制。但是无法工作并且在同时工作时获得错误代码-12780但个人。

I am using AVCaptureVideoDataOutput for grab frames and AVCaptureMovieFileOutput for video recording. But can't work and get the error code -12780 while working at the same time but individual.

我搜索了这个问题但得不到答案。有没有人有相同的经历或解释？
一段时间我真的很烦。

I searched this problem but get no answer. Did anyone have the same experience or explain? It's really bother me for a while time.

谢谢。

推荐答案

我无法回答具体问题放，但我已成功录制视频并同时使用以下框架抓取框架：

I can't answer the specific question put, but I've been successfully recording video and grabbing frames at the same time using:

• AVCaptureSession 和 AVCaptureVideoDataOutput 将帧路由到我自己的代码


• AVAssetWriter ， AVAssetWriterInput 和 AVAssetWriterInputPixelBufferAdaptor 将帧写入H.264编码的电影文件

• AVCaptureSession and AVCaptureVideoDataOutput to route frames into my own code
• AVAssetWriter, AVAssetWriterInput and AVAssetWriterInputPixelBufferAdaptor to write frames out to an H.264 encoded movie file

没有调查音频。我最终从捕获会话中获取 CMSampleBuffers ，然后将它们推入像素缓冲适配器。

That's without investigating audio. I end up getting CMSampleBuffers from the capture session and then pushing them into the pixel buffer adaptor.

编辑：所以我的代码看起来或多或少都是这样的，你没有遇到过任何问题，并且忽略了范围问题：

so my code looks more or less like, with the bits you're having no problems with skimmed over and ignoring issues of scope:

/* to ensure I'm given incoming CMSampleBuffers */
AVCaptureSession *captureSession = alloc and init, set your preferred preset/etc;
AVCaptureDevice *captureDevice = default for video, probably;

AVCaptureDeviceInput *deviceInput = input with device as above, 
                                    and attach it to the session;

AVCaptureVideoDataOutput *output = output for 32BGRA pixel format, with me as the
                                   delegate and a suitable dispatch queue affixed.

/* to prepare for output; I'll output 640x480 in H.264, via an asset writer */
NSDictionary *outputSettings =
    [NSDictionary dictionaryWithObjectsAndKeys:

            [NSNumber numberWithInt:640], AVVideoWidthKey,
            [NSNumber numberWithInt:480], AVVideoHeightKey,
            AVVideoCodecH264, AVVideoCodecKey,

            nil];

AVAssetWriterInput *assetWriterInput = [AVAssetWriterInput 
                                   assetWriterInputWithMediaType:AVMediaTypeVideo
                                                  outputSettings:outputSettings];

/* I'm going to push pixel buffers to it, so will need a 
   AVAssetWriterPixelBufferAdaptor, to expect the same 32BGRA input as I've
   asked the AVCaptureVideDataOutput to supply */
AVAssetWriterInputPixelBufferAdaptor *pixelBufferAdaptor =
           [[AVAssetWriterInputPixelBufferAdaptor alloc] 
                initWithAssetWriterInput:assetWriterInput 
                sourcePixelBufferAttributes:
                     [NSDictionary dictionaryWithObjectsAndKeys:
                          [NSNumber numberWithInt:kCVPixelFormatType_32BGRA], 
                           kCVPixelBufferPixelFormatTypeKey,
                     nil]];

/* that's going to go somewhere, I imagine you've got the URL for that sorted,
   so create a suitable asset writer; we'll put our H.264 within the normal
   MPEG4 container */
AVAssetWriter *assetWriter = [[AVAssetWriter alloc]
                                initWithURL:URLFromSomwhere
                                fileType:AVFileTypeMPEG4
                                error:you need to check error conditions,
                                      this example is too lazy];
[assetWriter addInput:assetWriterInput];

/* we need to warn the input to expect real time data incoming, so that it tries
   to avoid being unavailable at inopportune moments */
assetWriterInput.expectsMediaDataInRealTime = YES;

... eventually ...

[assetWriter startWriting];
[assetWriter startSessionAtSourceTime:kCMTimeZero];
[captureSession startRunning];

... elsewhere ...

- (void)        captureOutput:(AVCaptureOutput *)captureOutput 
    didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer 
           fromConnection:(AVCaptureConnection *)connection
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

    // a very dense way to keep track of the time at which this frame
    // occurs relative to the output stream, but it's just an example!
    static int64_t frameNumber = 0;
    if(assetWriterInput.readyForMoreMediaData)
        [pixelBufferAdaptor appendPixelBuffer:imageBuffer
                         withPresentationTime:CMTimeMake(frameNumber, 25)];
    frameNumber++;
}

... and, to stop, ensuring the output file is finished properly ...

[captureSession stopRunning];
[assetWriter finishWriting];

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