AVCaptureSession和AVCaptureMovieFileOutput帧时间戳 [英] AVCaptureSession and AVCaptureMovieFileOutput frame timestamp

问题描述

我正在使用AVCaptureSession和AVCaptureMovieFileOutput录制电影。我还记录加速度数据并尝试将加速度数据与视频对齐。

I am recording a movie with AVCaptureSession and AVCaptureMovieFileOutput. I am also recording acceleration data and trying to align the acceleration data with the video.

我正在试图找到一种方法来获取视频文件录制开始的时间。我正在做以下事情：

I am trying to figure out a way to get the time the video file recording started. I am doing the following:

currentDate = [NSDate date];
[output startRecordingToOutputFileURL:fileUrl recordingDelegate:self];

然而，根据我的测试，视频录制在调用startRecordingToOutputFileURL之前0.12秒开始。我假设这是因为各种视频缓冲区已经充满了添加到文件中的数据。

However, according to my tests, the video recording starts 0.12 seconds before the call to startRecordingToOutputFileURL is made. I'm assuming this is because the various video buffers are already full of data which get added to the file.

无论如何都要获得第一帧的实际NSDate视频？

Is there anyway to get the actual NSDate of the first frame of the video?

推荐答案

如果我的问题正确，你想知道记录第一帧的时间戳。你可以尝试

if i get your question correctly, you want to know the timestamp of when the first frame is recorded. you could try

CMTime captureStartTime = nil;

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection { 

      if !captureStartTime{ 
         captureStartTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
      }
  // do the other things you want
 }

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