一、前言
AVCaptureSession 是 AVFoundation 的核心类，用于管理捕获对象 AVCaptureInput 的视频和音频的输入，协调捕获的输出 AVCaptureOutput。
AVCaptureOutput 的输出有两种方法：
- 一种是直接以 movieFileUrl 方式输出；
- 一种是以原始数据流 data 的方式输出
流程对比图如下：
下面详细讲解录制视频的方案：
二、AVCaptureSession AVCaptureMovieFileOutput
1.创建AVCaptureSession
//导入 AVFoundation.framework
#import <AVFoundation/AVFoundation.h>
//声明属性
@property (nonatomic, strong) AVCaptureSession *captureSession;
//懒加载 AVCapturesession
- (AVCaptureSession *)captureSession {
if (!_captureSession) {
_captureSession = [[AVCaptureSession alloc] init];
//设置分辨率
if ([_captureSession canSetSessionPreset:AVCaptureSessionPresetHigh]) {
[_captureSession setSessionPreset:AVCaptureSessionPresetHigh];
}
}
return _captureSession;
}注意：AVCaptureSession 的调用是会阻塞线程的，建议单独开辟子线程处理。2.设置音频、视频输入
//声明属性
@property (nonatomic, strong) AVCaptureDeviceInput *videoInput;
@property (nonatomic, strong) AVCaptureDeviceInput *audioInput;
//设置视频，音频输入源
- (void)setCaptureDeviceInput {
//1. 视频输入源
//获取视频输入设备， 默认后置摄像头
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. 音频输入源
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.设置文件输出源
//声明属性
@property (nonatomic, strong) AVCaptureMovieFileOutput *movieFileOutput;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *previewLayer;
//设置文件输出源
- (void)setDeviceFileOutput {
//初始化文件输出对象
self.movieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
//捕获会话中特定捕获输入对象和捕获输出对象之间的连接
AVCaptureConnection *captureConnection = [self.movieFileOutput connectionWithMediaType:AVMediaTypeVideo];
//设置防抖
if ([captureConnection isVideoStabilizationSupported]) {
captureConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeAuto;
}
//预览图层和视频方向保持一致
captureConnection.videoOrientation = [self.previewLayer connection].videoOrientation;
//添加文件输出源
if ([self.captureSession canAddOutput:self.movieFileOutput]) {
[self.captureSession addOutput:self.movieFileOutput];
}
}4.添加视频预览层
- (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. 开始采集
//声明属性
@property (nonatomic, strong) dispatch_queue_t sessionQueue;
//开始采集
- (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. 开始录制
//开始录制
- (void)startRecord {
[self.movieFileOutput startRecordingToOutputFileURL:[self createVideoPath] recordingDelegate:self];
}当实际的录制开始或停止时，系统会有代理回调。当开始录制之后，这时可能还没有真正写入，真正开始写入会回调下面代理，停止录制也是如此，所以如果你需要对录制视频起始点操作，建议通过系统的回调代理：
//实现协议 <AVCaptureFileOutputRecordingDelegate>中的方法
#pragma mark _ AVCaptureFileOutputRecordingDelegate
//起始点 - 开始录制
- (void)captureOutput:(AVCaptureFileOutput *)output didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray<AVCaptureConnection *> *)connections {
}
//结束录制
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error
{
NSLog(@"视频录制完成. 文件路径：%@",[outputFileURL absoluteString]);
}7.停止录制
//停止录制
- (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;
});
}
}
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