前言：本系列文章旨在为刚接触短视频的新人开发提供方便，写的不好的地方，还请各路大神指教。众所周知，开发音视频相关的项目是有很大难度的，基于OpenCV、OpenGL、ffmpeg等众多框架，iOS下又涉及到GPUImage、AVFoundation等框架，语言层面上涉及C、C++语言，可谓非一个人能完成的工作。
正文：
核心思路：使用AVFoundation下的拍摄比较繁琐，而GPUImage封装了这一层，因此我们可以直接使用GPUImage完成拍摄功能。
具体步骤
1.新建工程 在 infoplist文件设置麦克风 相机 相册 图片等权限
<!-- 相册 -->
<key>NSPhotoLibraryUsageDescription</key>
<string>App需要您的同意,才能访问相册</string>
<!-- 相机 -->
<key>NSCameraUsageDescription</key>
<string>App需要您的同意,才能访问相机</string>
<!-- 麦克风 -->
<key>NSMicrophoneUsageDescription</key>
<string>App需要您的同意,才能访问麦克风</string>
<!-- 图片 -->
<key>NSPhotoLibraryAddUsageDescription</key>
<string>App需要您的同意,才能保存图片到您的相册</string>
2.基于GPUImage 建议用cocoapods导GPUImage，GPUImage引入后，修改以下部分：
1. GPUImageMovieWriter.h文件中添加isNeedBreakAudioWhiter属性
@property (nonatomic, assign) BOOL isNeedBreakAudioWhiter;
2. GPUImageMovieWriter.m文件中第377行代码修改如下：
if (CMTIME_IS_INVALID(startTime))
{
if (_isNeedBreakAudioWhiter) {
}else{
runSynchronouslyOnContextQueue(_movieWriterContext, ^{
if ((audioInputReadyCallback == NULL) && (assetWriter.status != AVAssetWriterStatusWriting))
{
[assetWriter startWriting];
}
[assetWriter startSessionAtSourceTime:currentSampleTime];
startTime = currentSampleTime;
});
}
}
3. GPUImageMovieWriter初始化时设置 isNeedBreakAudioWhiter =YES;
3.初始化相机及filterView,filterView是处理美颜的，大家可以处理成不同的美颜效果
//录制相关 AVCaptureSessionPreset1280x720视频分辨率 AVCaptureDevicePositionBack后置摄像头
videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPreset1280x720
cameraPosition:AVCaptureDevicePositionBack];
if ([videoCamera.inputCamera lockForConfiguration:nil]) {
//自动对焦
if ([videoCamera.inputCamera isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]) {
[videoCamera.inputCamera setFocusMode:AVCaptureFocusModeContinuousAutoFocus];
}
//自动曝光
if ([videoCamera.inputCamera isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
[videoCamera.inputCamera setExposureMode:AVCaptureExposureModeContinuousAutoExposure];
}
//自动白平衡
if ([videoCamera.inputCamera isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance]) {
[videoCamera.inputCamera setWhiteBalanceMode:AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance];
}
[videoCamera.inputCamera unlockForConfiguration];
}
//输出方向为竖屏
videoCamera.outputImageOrientation = UIInterfaceOrientationPortrait;
//防止允许声音通过的情况下，避免录制第一帧黑屏闪屏
[videoCamera addAudioInputsAndOutputs];
videoCamera.horizontallyMirrorFrontFacingCamera = YES;
videoCamera.horizontallyMirrorRearFacingCamera = NO;
//显示view
filterView =[[GPUImageView alloc]initWithFrame:[UIScreen mainScreen].bounds];
[self.view addSubview:filterView];
//组合
// filter = [[GPUImageBilateralFilter alloc] init];
// [videoCamera addTarget:filter];
// [filter addTarget:filterView];
[videoCamera addTarget:filterView];
//相机开始运行
[videoCamera startCameraCapture];
4.初始化moviewriter
videoURL即视频文件的存储URL
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *videoPath = [[paths objectAtIndex:0] stringByAppendingPathComponent@"tets.MOV"];
unlink([path UTF8String]);
videoURL =[NSURL fileURLWithPath:path];
需要注意的是要调用unlink方法，否则写入可能会失败。
//写入
movieWriter = [[GPUImageMovieWriter alloc] initWithMovieURL:videoURL size:CGSizeMake(720.0, 1280.0)];
//设置为liveVideo
movieWriter.isNeedBreakAudioWhiter =YES;
movieWriter.encodingLiveVideo = YES;
movieWriter.shouldPassthroughAudio =YES;
// [filter addTarget:movieWriter];
[videoCamera addTarget:movieWriter];
//设置声音
videoCamera.audioEncodingTarget = movieWriter;
5.开始录制与暂停
开始录制
[movieWriter startRecording];
停止录制
[movieWriter finishRecording];
[filter removeTarget:movieWriter];
videoCamera.audioEncodingTarget = nil;
自此，我们就可以完成一个简单的视频录制功能了，下几篇文章我会讲到其中注意事项以及切换前后摄像头、闪光灯、断点拍摄、视频合成等相关功能。
