如何从AVCapture保存影片

Question

在过去的几天里，我一直在尝试弄明白AVCapture，并且正在努力保存一段视频。我的理解是你调用[movieFileOutput startRecordingToOutputFileURL:outputURL recordingDelegate:self];，然后你可以调用[movieFileOutput stopRecording];，然后它应该调用委托方法-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error{。在那之后，我应该能够用像UISaveVideoAtPathToSavedPhotosAlbum([outputFileURL path] ,nil,nil,nil);这样的东西来保存电影，但显然我没有正确地这样做。当我启动会话，然后执行startRecordingToOutputFile时，它会立即调用委托didFinishRecording。我不知道为什么。下面是我的代码：

-(void)viewDidAppear:(BOOL)animated{
        [super viewDidAppear:animated];
        session = [[AVCaptureSession alloc] init];
        [session beginConfiguration];
        session.sessionPreset = AVCaptureSessionPresetMedium;

        AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
    captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    captureVideoPreviewLayer.frame = self.imagePreview.bounds; //UIView *imagePreview
    [self.imagePreview.layer addSublayer:captureVideoPreviewLayer];

    AVCaptureDevice *device = [self getCamera];
    NSError *error = nil;
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (!input) {
        // Handle the error appropriately.
        NSLog(@"ERROR: trying to open camera: %@", error);
    }

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectoryPath = [paths objectAtIndex:0];

    movieFileOutput = [[AVCaptureMovieFileOutput alloc] init];

    NSString *archives = [documentsDirectoryPath stringByAppendingPathComponent:@"archives"];
    NSString *outputpathofmovie = [[archives stringByAppendingPathComponent:@"Test"] stringByAppendingString:@".mp4"];
    NSURL *outputURL = [[NSURL alloc] initFileURLWithPath:outputpathofmovie];

    [session addInput:input];
    [session addOutput:movieFileOutput];
    [session commitConfiguration];
    [session startRunning];
    [movieFileOutput startRecordingToOutputFileURL:outputURL recordingDelegate:self];
    [NSTimer timerWithTimeInterval:7 target:self selector:@selector(stopRun) userInfo:nil repeats:NO];
    /*
    [self initializeCamera];
     */
}
 -(void)stopRun{
        [movieFileOutput stopRecording];
    }

-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error{
    NSLog(@"capture done url: %@",outputFileURL);
    UISaveVideoAtPathToSavedPhotosAlbum([outputFileURL path] ,nil,nil,nil);
}

-(AVCaptureDevice*)getCamera{
    NSArray *devices = [AVCaptureDevice devices];
    AVCaptureDevice *frontCamera;
    AVCaptureDevice *backCamera;
    for (AVCaptureDevice *device in devices) {
        NSLog(@"Device name: %@", [device localizedName]);
        if ([device hasMediaType:AVMediaTypeVideo]) {
            if ([device position] == AVCaptureDevicePositionBack) {
                NSLog(@"Device position : back");
                backCamera = device;
            }
            else {
                NSLog(@"Device position : front");
                frontCamera = device;
            }
        }
    }
    return frontCamera;
}

很抱歉，它太长了。我希望这些代码能对其他人有用。

Answer 1

免责声明:我不是Objective C程序员，距离我开始阅读这门语言本身只有15天的时间。

我不得不做一些类似的事情。这是下面的代码，它适用于我。我在developer.apple.com中从不同的堆栈溢出问题和示例中获得了它。我已经注释掉了我的工作原型不需要的代码。你可以玩玩它。

-(void) saveRecordingLocally
{
    dispatch_async([self sessionQueue], ^{
        if (![[self movieFileOutput] isRecording])
        {
            if ([[UIDevice currentDevice] isMultitaskingSupported])
            {
                // Setup background task. This is needed because the captureOutput:didFinishRecordingToOutputFileAtURL: callback is not received until AVCam returns to the foreground unless you request background execution time. This also ensures that there will be time to write the file to the assets library when AVCam is backgrounded. To conclude this background execution, -endBackgroundTask is called in -recorder:recordingDidFinishToOutputFileURL:error: after the recorded file has been saved.
                [self setBackgroundRecordingID:[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil]];
            }

            // Update the orientation on the movie file output video connection before starting recording.
//          [[[self movieFileOutput] connectionWithMediaType:AVMediaTypeVideo] setVideoOrientation:[[(AVCaptureVideoPreviewLayer *)[[self previewView] layer] connection] videoOrientation]];

            // Turning OFF flash for video recording
            //[AVCamViewController setFlashMode:AVCaptureFlashModeOff forDevice:[[self videoDeviceInput] device]];

            // Start recording to a temporary file.
            NSString *outputFilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:[@"movie" stringByAppendingPathExtension:@"mov"]];
            [[self movieFileOutput] startRecordingToOutputFileURL:[NSURL fileURLWithPath:outputFilePath] recordingDelegate:self];
        }
    });
}

//delegate
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error
{
    NSLog(@"OutputFileUrl %@", outputFileURL);
    if(error){
        NSLog(@"ERROR : %@", error);
    }
    UIBackgroundTaskIdentifier backgroundRecordingID = [self backgroundRecordingID];
    [self setBackgroundRecordingID:UIBackgroundTaskInvalid];
    [[[ALAssetsLibrary alloc] init] writeVideoAtPathToSavedPhotosAlbum:outputFileURL completionBlock:^(NSURL *assetURL, NSError *error) {
        if (error)
            NSLog(@"%@", error);

        [[NSFileManager defaultManager] removeItemAtURL:outputFileURL error:nil];

        if (backgroundRecordingID != UIBackgroundTaskInvalid)
            [[UIApplication sharedApplication] endBackgroundTask:backgroundRecordingID];
    }];
}