ios - 如何使用 AVAssetWriter 保存录制的视频？

Question

我尝试了许多其他博客和堆栈溢出。我没有得到解决方案，我可以创建带有预览的自定义相机。我需要带有自定义帧的视频，这就是我使用 AVAssetWriter 的原因。但我无法将录制的视频保存到文档中。我试过这样

-(void) initilizeCameraConfigurations {

if(!captureSession) {

    captureSession = [[AVCaptureSession alloc] init];
    [captureSession beginConfiguration];
    captureSession.sessionPreset = AVCaptureSessionPresetHigh;
    self.view.backgroundColor = UIColor.blackColor;
    CGRect bounds = self.view.bounds;
    captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:captureSession];
    captureVideoPreviewLayer.backgroundColor = [UIColor clearColor].CGColor;
    captureVideoPreviewLayer.bounds = self.view.frame;
    captureVideoPreviewLayer.connection.videoOrientation = AVCaptureVideoOrientationPortrait;
    captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    captureVideoPreviewLayer.position = CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds));
    [self.view.layer addSublayer:captureVideoPreviewLayer];
    [self.view bringSubviewToFront:self.controlsBgView];
}


// Add input to session
NSError *err;
videoCaptureDeviceInput  = [AVCaptureDeviceInput deviceInputWithDevice:videoCaptureDevice error:&err];

if([captureSession canAddInput:videoCaptureDeviceInput]) {
    [captureSession addInput:videoCaptureDeviceInput];
}

docPathUrl = [[NSURL alloc] initFileURLWithPath:[self getDocumentsUrl]];

assetWriter = [AVAssetWriter assetWriterWithURL:docPathUrl fileType:AVFileTypeQuickTimeMovie error:&err];
NSParameterAssert(assetWriter);
//assetWriter.movieFragmentInterval = CMTimeMakeWithSeconds(1.0, 1000);

NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                               AVVideoCodecH264, AVVideoCodecKey,
                               [NSNumber numberWithInt:300], AVVideoWidthKey,
                               [NSNumber numberWithInt:300], AVVideoHeightKey,
                               nil];




 writerInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
 writerInput.expectsMediaDataInRealTime = YES;
 writerInput.transform = CGAffineTransformMakeRotation(M_PI);

 NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:kCVPixelFormatType_32BGRA], kCVPixelBufferPixelFormatTypeKey,
 [NSNumber numberWithInt:300], kCVPixelBufferWidthKey,
 [NSNumber numberWithInt:300], kCVPixelBufferHeightKey,
 nil];

 assetWriterPixelBufferInput = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary];


 if([assetWriter canAddInput:writerInput]) {
 [assetWriter addInput:writerInput];
 }

     // Set video stabilization mode to preview layer
AVCaptureVideoStabilizationMode stablilizationMode = AVCaptureVideoStabilizationModeCinematic;
if([videoCaptureDevice.activeFormat isVideoStabilizationModeSupported:stablilizationMode]) {
    [captureVideoPreviewLayer.connection setPreferredVideoStabilizationMode:stablilizationMode];
}


// image output
stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil];
[stillImageOutput setOutputSettings:outputSettings];
[captureSession addOutput:stillImageOutput];

[captureSession commitConfiguration];
if (![captureVideoPreviewLayer.connection isEnabled]) {
    [captureVideoPreviewLayer.connection setEnabled:YES];
}
[captureSession startRunning];

}
-(IBAction)startStopVideoRecording:(id)sender {

if(captureSession) {
    if(isVideoRecording) {
        [writerInput markAsFinished];

        [assetWriter finishWritingWithCompletionHandler:^{
            NSLog(@"Finished writing...checking completion status...");
            if (assetWriter.status != AVAssetWriterStatusFailed && assetWriter.status == AVAssetWriterStatusCompleted)
            {
                // Video saved
            } else
            {
                NSLog(@"#123 Video writing failed: %@", assetWriter.error);
            }

        }];

    } else {

        [assetWriter startWriting];
        [assetWriter startSessionAtSourceTime:kCMTimeZero];
        isVideoRecording = YES;

    }
}
}
-(NSString *) getDocumentsUrl {

NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
docPath = [[docPath stringByAppendingPathComponent:@"Movie"] stringByAppendingString:@".mov"];
if([[NSFileManager defaultManager] fileExistsAtPath:docPath]) {
    NSError *err;
    [[NSFileManager defaultManager] removeItemAtPath:docPath error:&err];
}
NSLog(@"Movie path : %@",docPath);
return docPath;


}


@end

如果有任何问题，请纠正我。先感谢您。

Answer 1

您没有说实际出了什么问题，但是您的代码有两件事看起来有问题:

docPath = [[docPath stringByAppendingPathComponent:@"Movie"] stringByAppendingString:@".mov"];

看起来它会创建一个像这样的不受欢迎的路径 @"/path/Movie/.mov" ，当你想要这个时:

docPath = [docPath stringByAppendingPathComponent:@"Movie.mov"];

你的时间表是错误的。您的 Assets 编写器从时间 0 开始，但 sampleBuffer从 CMSampleBufferGetPresentationTimestamp(sampleBuffer) > 0 开始，所以改为这样做:

-(void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
    if(firstSampleBuffer) {
        [assetWriter startSessionAtSourceTime:CMSampleBufferGetPresentationTimestamp(sampleBuffer)];
    }

    [writerInput appendSampleBuffer:sampleBuffer];

}