前段时间项目要求需要在聊天模块中加入类似微信的小视频功能，这边博客主要是为了总结遇到的问题和解决方法，希望能够对有同样需求的朋友有所帮助。
效果预览：
这里先罗列遇到的主要问题：
1.视频剪裁 微信的小视频只是取了摄像头获取的一部分画面
2.滚动预览的卡顿问题 AVPlayer播放视频在滚动中会出现很卡的问题
接下来让我们一步步来实现。
Part 1 实现视频录制
1.录制类WKMovieRecorder实现
创建一个录制类WKMovieRecorder，负责视频录制。
@interface WKMovieRecorder : NSObject
+ (WKMovieRecorder*) sharedRecorder;
- (instancetype)initWithMaxDuration:(NSTimeInterval)duration;
@end
定义回调block
/**
* 录制结束
*
* @param info 回调信息
* @param isCancle YES:取消 NO:正常结束
*/
typedef void(^FinishRecordingBlock)(NSDictionary *info, WKRecorderFinishedReason finishReason);
/**
* 焦点改变
*/
typedef void(^FocusAreaDidChanged)();
/**
* 权限验证
*
* @param success 是否成功
*/
typedef void(^AuthorizationResult)(BOOL success);
@interface WKMovieRecorder : NSObject
//回调
@property (nonatomic, copy) FinishRecordingBlock finishBlock;//录制结束回调
@property (nonatomic, copy) FocusAreaDidChanged focusAreaDidChangedBlock;
@property (nonatomic, copy) AuthorizationResult authorizationResultBlock;
@end
定义一个cropSize用于视频裁剪
@property (nonatomic, assign) CGSize cropSize;
接下来就是capture的实现了，这里代码有点长，懒得看的可以直接看后面的视频剪裁部分
录制配置：
@interface WKMovieRecorder ()
<
AVCaptureVideoDataOutputSampleBufferDelegate,
AVCaptureAudioDataOutputSampleBufferDelegate,
WKMovieWriterDelegate
>
{
AVCaptureSession* _session;
AVCaptureVideoPreviewLayer* _preview;
WKMovieWriter* _writer;
//暂停录制
BOOL _isCapturing;
BOOL _isPaused;
BOOL _discont;
int _currentFile;
CMTime _timeOffset;
CMTime _lastVideo;
CMTime _lastAudio;
NSTimeInterval _maxDuration;
}
// Session management.
@property (nonatomic, strong) dispatch_queue_t sessionQueue;
@property (nonatomic, strong) dispatch_queue_t videoDataOutputQueue;
@property (nonatomic, strong) AVCaptureSession *session;
@property (nonatomic, strong) AVCaptureDevice *captureDevice;
@property (nonatomic, strong) AVCaptureDeviceInput *videoDeviceInput;
@property (nonatomic, strong) AVCaptureStillImageOutput *stillImageOutput;
@property (nonatomic, strong) AVCaptureConnection *videoConnection;
@property (nonatomic, strong) AVCaptureConnection *audioConnection;
@property (nonatomic, strong) NSDictionary *videoCompressionSettings;
@property (nonatomic, strong) NSDictionary *audioCompressionSettings;
@property (nonatomic, strong) AVAssetWriterInputPixelBufferAdaptor *adaptor;
@property (nonatomic, strong) AVCaptureVideoDataOutput *videoDataOutput;
//Utilities
@property (nonatomic, strong) NSMutableArray *frames;//存储录制帧
@property (nonatomic, assign) CaptureAVSetupResult result;
@property (atomic, readwrite) BOOL isCapturing;
@property (atomic, readwrite) BOOL isPaused;
@property (nonatomic, strong) NSTimer *durationTimer;
@property (nonatomic, assign) WKRecorderFinishedReason finishReason;
@end
