基于AVFoundation實作視頻錄制的兩種方式

• 一、前言
• 二、方案一：AVCaptureSession + AVCaptureMovieFileOutput
  • 1.創建AVCaptureSession
  • 2.設定音頻、視頻輸入
  • 3.設定檔案輸出源
  • 4.添加視頻預覽層
  • 5. 開始采集
  • 6. 開始錄制
  • 7.停止錄制
  • 8.停止采集
• 三、方案二：AVCaptureSession + AVAssetWriter

一、前言

AVCaptureSession 是 AVFoundation 的核心類，用于管理捕獲物件 AVCaptureInput 的視頻和音頻的輸入，協調捕獲的輸出 AVCaptureOutput，

AVCaptureOutput 的輸出有兩種方法：

• 一種是直接以 movieFileUrl 方式輸出；
• 一種是以原始資料流 data 的方式輸出

流程對比圖如下：

下面詳細講解兩種錄制視頻的方案：

二、方案一：AVCaptureSession + AVCaptureMovieFileOutput

1.創建AVCaptureSession

//匯入 AVFoundation.framework 
#import <AVFoundation/AVFoundation.h>

//宣告屬性
@property (nonatomic, strong) AVCaptureSession *captureSession;

//懶加載 AVCapturesession
- (AVCaptureSession *)captureSession {
    if (!_captureSession) {
        _captureSession = [[AVCaptureSession alloc] init];
        
        //設定解析度
        if ([_captureSession canSetSessionPreset:AVCaptureSessionPresetHigh]) {
            [_captureSession setSessionPreset:AVCaptureSessionPresetHigh];
        }
    }
    return _captureSession;
}

注意：AVCaptureSession 的呼叫是會阻塞執行緒的，建議單獨開辟子執行緒處理，

2.設定音頻、視頻輸入

//宣告屬性
@property (nonatomic, strong) AVCaptureDeviceInput *videoInput;
@property (nonatomic, strong) AVCaptureDeviceInput *audioInput;


//設定視頻，音頻輸入源
- (void)setCaptureDeviceInput {
    //1. 視頻輸入源
    //獲取視頻輸入設備， 默認后置攝像頭
    AVCaptureDevice *videoCaptureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    
    NSError *error = nil;
    self.videoInput = [AVCaptureDeviceInput deviceInputWithDevice:videoCaptureDevice error:&error];
    
    if ([self.captureSession canAddInput:self.videoInput]) {
        [self.captureSession addInput:self.videoInput];
    }
    
    
    //2. 音頻輸入源
    AVCaptureDevice *audioCaptureDevice = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio] firstObject];
    self.audioInput = [AVCaptureDeviceInput deviceInputWithDevice:audioCaptureDevice error:&error];
    if ([self.captureSession canAddInput:self.audioInput]) {
        [self.captureSession addInput:self.audioInput];
    }
    
}

3.設定檔案輸出源

//宣告屬性
@property (nonatomic, strong) AVCaptureMovieFileOutput *movieFileOutput;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *previewLayer;


//設定檔案輸出源
- (void)setDeviceFileOutput {
    
    //初始化檔案輸出物件
    self.movieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
    
    //捕獲會話中特定捕獲輸入物件和捕獲輸出物件之間的連接
    AVCaptureConnection *captureConnection = [self.movieFileOutput connectionWithMediaType:AVMediaTypeVideo];
    
    //設定防抖
    if ([captureConnection isVideoStabilizationSupported]) {
        captureConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeAuto;
    }
    
    //預覽圖層和視頻方向保持一致
    captureConnection.videoOrientation = [self.previewLayer connection].videoOrientation;
    
    //添加檔案輸出源
    if ([self.captureSession canAddOutput:self.movieFileOutput]) {
        [self.captureSession addOutput:self.movieFileOutput];
    }
    
}

4.添加視頻預覽層

- (void)setVideoPreviewLayer {
    self.previewLayer.frame = [UIScreen mainScreen].bounds;
    
    [self.superView.layer addSubLayer:self.previewLayer];
}


- (AVCaptureVideoPreviewLayer *)previewLayer {
    if (!_previewLayer) {
        _previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
        _previewLayer.masksToBounds = YES;
        _previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;//填充模式
    }
    return _previewLayer;
}

5. 開始采集

//宣告屬性
@property (nonatomic, strong) dispatch_queue_t sessionQueue;

//開始采集
- (void)startCapture {
	self.sessionQueue = dispatch_queue_create("com.capturesession.queue", DISPATCH_QUEUE_CONCURRENT);

    if (![self.captureSession isRunning]) {
        __weak __typeof(self) weakSelf = self;
        
        dispatch_async(self.sessionQueue, ^{
            [weakSelf.captureSession startRunning];
        });
        
    }
}

6. 開始錄制

//開始錄制
- (void)startRecord {
    
    [self.movieFileOutput startRecordingToOutputFileURL:[self createVideoPath] recordingDelegate:self];
}

當實際的錄制開始或停止時，系統會有代理回呼，當開始錄制之后，這時可能還沒有真正寫入，真正開始寫入會回呼下面代理，停止錄制也是如此，所以如果你需要對錄制視頻起始點操作，建議通過系統的回呼代理：

//實作協議 <AVCaptureFileOutputRecordingDelegate>中的方法


#pragma mark _ AVCaptureFileOutputRecordingDelegate

//起始點 - 開始錄制
- (void)captureOutput:(AVCaptureFileOutput *)output didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray<AVCaptureConnection *> *)connections {
    
}

//結束錄制
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error
{
    NSLog(@"視頻錄制完成. 檔案路徑：%@",[outputFileURL absoluteString]);
}

7.停止錄制

//停止錄制
- (void)stopRecord {
    if ([self.movieFileOutput isRecording]) {
        [self.movieFileOutput stopRecording];
    }
}

8.停止采集

//停止采集
- (void)stopCapture {
    if ([self.captureSession isRunning]) {
        __weak __typeof(self) weakSelf = self;
        dispatch_async(self.sessionQueue, ^{
            [weakSelf.captureSession stopRunning];
            weakSelf.captureSession = nil;
        });
    }
}

三、方案二：AVCaptureSession + AVAssetWriter

方案二及更多內容，請訪問： 基于AVFoundation實作視頻錄制的兩種方式

本文來自博客園，作者：reyzhang，轉載請注明原文鏈接：https://www.cnblogs.com/reyzhang/p/16646673.html

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