使用AVFoundation录制视频，以及碰到的一些问题
2018-05-09 本文已影响663人
kikido
最近在项目中碰到一个需求：
播放一段事先录制好的音频文件，客户回答音频里面出现的问题，整个过程使用手机录制视频，完成后上传至服务器。
这里面有几个需求点：
- 录制的时候不能锁屏
- 能够手动对焦
- 能够切换摄像头（我只完成了在录制前能够摄像头）
- 横拍或者竖排，视频要求都是正的(无论有没有锁定竖屏方向)
在这里我是使用AVFoundation框架的AVCaptureSession + AVCaptureMovieFileOutput 来录制视频。好了，下面我会介绍一下自己项目里面的部分代码，并说明下我碰到过的一些麻烦，让有需要的同学们能少踩点坑。。。
遇到的坑
此文档篇幅有点长，怕没有耐心的同学直接走了。。。所有我现在这里放上本文的Demo地址：Demo地址，以及说明遇到的坑
设置AVCaptureMovieFileOutput，需要设置它的movieFragmentInterval属性为kCMTimeInvalid，不然录制的视频超过10秒就会没有声音
使用CMMotionManager时，需要将其设置为全局变量或者私有属性。在调用它的方法
- (void)startAccelerometerUpdatesToQueue:(NSOperationQueue *)queue withHandler:(CMAccelerometerHandler)handler __TVOS_PROHIBITED;时，在block里面的self需设置为__weak修饰的self，不然会引起循环引用导致无法dealloc。
[self.motionManager startAccelerometerUpdatesToQueue:[NSOperationQueue currentQueue] withHandler:^(CMAccelerometerData * _Nullable accelerometerData, NSError * _Nullable error) {
__strong typeof(weakSelf) strongSelf = weakSelf;
if (!error) {
[strongSelf outputData:accelerometerData.acceleration];
} else {
NSLog(@"error = %@",error);
}
}];
可以使用NSTimer的
[_recordTimer setFireDate:[NSDate distantPast]];和[_recordTimer setFireDate:[NSDate distantFuture]];,实现定时器的暂停与继续
几个类
首先导入头文件#import <AVFoundation/AVFoundation.h>
导入头文件后我们需要创建几个相机必须的属性
//AVCaptureSession对象来执行输入设备和输出设备之间的数据传递
@property (nonatomic, strong) AVCaptureSession *captureSession;
//输入设备源
@property (nonatomic, strong) AVCaptureDeviceInput *captureDeviceInput;
//视频输出流
@property (nonatomic, strong) AVCaptureMovieFileOutput *captureMovieFileOutput;
//相机拍摄预览图层
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;
AVCaptureSession: 控制输入和输出设备之间的数据传递
AVCaptureDeviceInput: 调用所有的输入硬件。例如摄像头和麦克风
AVCaptureMovieFileOutput: 用于输出视频
AVCaptureVideoPreviewLayer：镜头捕捉到得预览图层
一个AVCaptureSession对象可以管理多个输入输出设备，如下图所示
输入输出设备之间的关系
接下来就是初始化所有的对象，可以放在viewDidLoad方法中进行
CMMotionManager
先#import <CoreMotion/CoreMotion.h>，然后将其设为私有变量或者属性，只是临时初始化得到一个实例时不起作用的。通过这个类管理的加速器属性，可以判断出设备的方向，从而设置AVCaptureConnection的方向，使用户在横拍或者竖的情况下，视频要求都是正的。
//运动管理器 初始化
self.motionManager = [[CMMotionManager alloc] init];
//加速器每2秒采集一次数据
self.motionManager.accelerometerUpdateInterval = 2.;
//避免循环引用
__weak typeof(self) weakSelf = self;
[self.motionManager startAccelerometerUpdatesToQueue:[NSOperationQueue currentQueue] withHandler:^(CMAccelerometerData * _Nullable accelerometerData, NSError * _Nullable error) {
__strong typeof(weakSelf) strongSelf = weakSelf;
if (!error) {
[strongSelf outputData:accelerometerData.acceleration];
} else {
NSLog(@"error = %@",error);
}
}];
/**
更新设备方向
@param data 加速器
*/
-(void)outputData:(CMAcceleration)data
{
UIInterfaceOrientation orientation;
if(data.x >= 0.75){
orientation = UIInterfaceOrientationLandscapeLeft;
}
else if (data.x<= -0.75){
orientation = UIInterfaceOrientationLandscapeRight;
}
else if (data.y <= -0.75){
orientation = UIInterfaceOrientationPortrait;
}
else if (data.y >= 0.75){
orientation = UIInterfaceOrientationPortraitUpsideDown;
}
else{
return;
}
self.videoOrientation = orientation;
}
AVCaptureSession
- (AVCaptureSession *)captureSession
{
// 录制5秒钟视频 高画质10M,压缩成中画质 0.5M
// 录制5秒钟视频 中画质0.5M,压缩成中画质 0.5M
// 录制5秒钟视频 低画质0.1M,压缩成中画质 0.1M
if (_captureSession == nil) {
//设置分辨率
_captureSession = [[AVCaptureSession alloc] init];
if ([_captureSession canSetSessionPreset:AVCaptureSessionPresetHigh]) {
_captureSession.sessionPreset =AVCaptureSessionPresetHigh;
}
}
return _captureSession;
}
AVCaptureDevice(相机以及麦克风)
//获得输入设备
//取得后置摄像头
AVCaptureDevice *captureDevice = [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];
if (!captureDevice) {
NSLog(@"取得后置摄像头时出现问题");
return;
}
//获取音频输入设备
AVCaptureDevice *audioCaptureDevice = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio] firstObject];
AVCaptureDeviceInput
使用输入设备AVCaptureDevice初始化AVCaptureDeviceInput对象。
NSError *error = nil;
//根据输入设备初始化设备输入对象，用于获得输入数据
_captureDeviceInput = [[AVCaptureDeviceInput alloc]initWithDevice:captureDevice error:&error];
if (error) {
NSLog(@"取得设备输入对象时出错，错误原因：%@",error.localizedDescription);
return;
}
//获取音频输入设备
AVCaptureDevice *audioCaptureDevice = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio] firstObject];
//创建音频输入源
NSError *tError;
AVCaptureDeviceInput *audioCaptureDeviceInput = [[AVCaptureDeviceInput alloc]initWithDevice:audioCaptureDevice error:&tError];
if (tError) {
NSLog(@"取得设备输入对象时出错，错误原因：%@",tError.localizedDescription);
return;
}
AVCaptureMovieFileOutput
初始化输出数据管理对象，如果要拍照就初始化AVCaptureStillImageOutput对象；如果拍摄视频就初始化AVCaptureMovieFileOutput对象。
需要注意的是：
需要设置movieFragmentInterval属性为kCMTimeInvalid，不然录制的视频超过十秒就会没有声音
//初始化设备输出对象，用于获得输出数据
_captureMovieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
//需要设置movieFragmentInterval，不然视频超过十秒就会没有声音
_captureMovieFileOutput.movieFragmentInterval = kCMTimeInvalid;
添加输入源，输出源到会话中
//将视频输入添加到会话中
if ([self.captureSession canAddInput:_captureDeviceInput]) {
[_captureSession addInput:_captureDeviceInput];
}
//将音频输入源添加到会话中
if ([self.captureSession canAddInput:audioCaptureDeviceInput]) {
[_captureSession addInput:audioCaptureDeviceInput];
}
AVCaptureConnection *captureConnection = [_captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
//视频防抖 是在 iOS 6 和 iPhone 4S 发布时引入的功能。到了 iPhone 6，增加了更强劲和流畅的防抖模式，被称为影院级的视频防抖动。相关的 API 也有所改动 (目前为止并没有在文档中反映出来，不过可以查看头文件）。防抖并不是在捕获设备上配置的，而是在 AVCaptureConnection 上设置。由于不是所有的设备格式都支持全部的防抖模式，所以在实际应用中应事先确认具体的防抖模式是否支持
if ([captureConnection isVideoStabilizationSupported ]) {
captureConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeAuto;
}
//将设备输出添加到会话中
if ([_captureSession canAddOutput:_captureMovieFileOutput]) {
[_captureSession addOutput:_captureMovieFileOutput];
}
AVCaptureVideoPreviewLayer
- (AVCaptureVideoPreviewLayer *)captureVideoPreviewLayer
{
if (_captureVideoPreviewLayer == nil) {
_captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
//填充模式
_captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
_captureVideoPreviewLayer.frame = self.view.bounds;
}
return _captureVideoPreviewLayer;
}
//创建视频预览层，用于实时展示摄像头状态
//将视频预览层添加到界面中
[self.view.layer insertSublayer:self.captureVideoPreviewLayer atIndex:0];
开始录制
在viewWillAppear，viewDidDisappear方法里开启和关闭session, 捕捉摄像内容到AVCaptureVideoPreviewLayer上
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:YES];
[self.session startRunning];
}
- (void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:YES];
[self.session stopRunning];
}
将录制的视频输出到指定文件
//开始结束录制
- (void)startOrEndAction:(UIButton *)sender
{
sender.selected = !sender.selected;
if (sender.selected) {
//录制状态
if (!self.captureMovieFileOutput.isRecording) {
//开始定时器
[self startTimeLabel];
[sender setTitle:@"结束录制" forState:UIControlStateNormal];
//将视频的输出方向与设备方向保持一致
AVCaptureConnection *connection = [self.captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
connection.videoOrientation = self.videoOrientation;
[self.captureMovieFileOutput startRecordingToOutputFileURL:self.fileUrl recordingDelegate:self];
}
} else {
//结束录制状态
[sender setTitle:@"开始录制" forState:UIControlStateNormal];
//停止录制
[self.captureMovieFileOutput stopRecording];
//关闭定时器
[self.recordTimer invalidate];
self.recordTimer = nil;
}
}
代理
当我们开始和结束录制都是有监听方法的，AVCaptureFileOutputRecordingDelegate这个代理里面就有我们想要做的。
#pragma mark - AVCaptureFileOutputRecordingDelegate
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections
{
NSLog(@"开始录制...");
}
-(void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error
{
NSLog(@"视频录制完成");
[self stopTimeLabel];
NSFileManager *fileManager = [[NSFileManager alloc] init] ;
float filesize = -1.0;
if ([fileManager fileExistsAtPath:self.fileUrl.path]) {
NSDictionary *fileDic = [fileManager attributesOfItemAtPath:self.fileUrl.path error:nil];//获取文件的属性
unsigned long long size = fileDic.fileSize;
filesize = 1*size;
}
NSLog(@"视频大小 %lfM", filesize / 1024 / 1024);
}
至此相机的拍照功能已经完成~
私有方法
/**
* 取得指定位置的摄像头
*
* @param position 摄像头位置
*
* @return 摄像头设备
*/
-(AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition )position{
NSArray *cameras= [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *camera in cameras) {
if ([camera position]==position) {
return camera;
}
}
return nil;
}
/**
切换摄像头
@param sender 按钮
*/
- (void)switchCameraClicked:(UIButton *)sender
{
AVCaptureDevice *currentDevice = [self.captureDeviceInput device];
AVCaptureDevicePosition currentPosition = [currentDevice position];
[self removeNotificationFromCaptureDevice:currentDevice];
AVCaptureDevice *toChangeDevice;
AVCaptureDevicePosition toChangePosition = AVCaptureDevicePositionFront;
if (currentPosition==AVCaptureDevicePositionUnspecified || currentPosition==AVCaptureDevicePositionFront) {
toChangePosition=AVCaptureDevicePositionBack;
}
toChangeDevice = [self getCameraDeviceWithPosition:toChangePosition];
if (!toChangeDevice) {
NSLog(@"切换摄像头失败");
return;
}
[self addNotificationToCaptureDevice:toChangeDevice];
//获得要调整的设备输入对象
AVCaptureDeviceInput *toChangeDeviceInput = [[AVCaptureDeviceInput alloc]initWithDevice:toChangeDevice error:nil];
//改变会话的配置前一定要先开启配置，配置完成后提交配置改变
[self.captureSession beginConfiguration];
//移除原有输入对象
[self.captureSession removeInput:self.captureDeviceInput];
//添加新的输入对象
if ([self.captureSession canAddInput:toChangeDeviceInput]) {
[self.captureSession addInput:toChangeDeviceInput];
self.captureDeviceInput = toChangeDeviceInput;
}else{
[self.captureSession addInput:self.captureDeviceInput];
}
//提交会话配置
[self.captureSession commitConfiguration];
}
/**
* 改变设备属性的统一操作方法
*
* @param propertyChange 属性改变操作
*/
-(void)changeDeviceProperty:(PropertyChangeBlock)propertyChange{
AVCaptureDevice *captureDevice= [self.captureDeviceInput device];
NSError *error;
//注意改变设备属性前一定要首先调用lockForConfiguration:调用完之后使用unlockForConfiguration方法解锁
if ([captureDevice lockForConfiguration:&error]) {
propertyChange(captureDevice);
[captureDevice unlockForConfiguration];
}else{
NSLog(@"设置设备属性过程发生错误，错误信息：%@",error.localizedDescription);
}
}
/**
* 设置聚焦模式
*
* @param focusMode 聚焦模式
*/
-(void)setFocusMode:(AVCaptureFocusMode )focusMode{
[self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
if ([captureDevice isFocusModeSupported:focusMode]) {
[captureDevice setFocusMode:focusMode];
}
}];
}
/**
* 设置聚焦点
*
* @param point 聚焦点
*/
-(void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{
[self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
if ([captureDevice isFocusModeSupported:focusMode]) {
[captureDevice setFocusMode:AVCaptureFocusModeAutoFocus];
}
if ([captureDevice isFocusPointOfInterestSupported]) {
[captureDevice setFocusPointOfInterest:point];
}
if ([captureDevice isExposureModeSupported:exposureMode]) {
[captureDevice setExposureMode:AVCaptureExposureModeAutoExpose];
}
if ([captureDevice isExposurePointOfInterestSupported]) {
[captureDevice setExposurePointOfInterest:point];
}
}];
}
/**
* 添加点按手势，点按时聚焦
*/
-(void)addGenstureRecognizer{
UITapGestureRecognizer *tapGesture=[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapScreen:)];
[self.viewContainer addGestureRecognizer:tapGesture];
}
-(void)tapScreen:(UITapGestureRecognizer *)tapGesture{
CGPoint point= [tapGesture locationInView:self.viewContainer];
//将UI坐标转化为摄像头坐标
CGPoint cameraPoint= [self.captureVideoPreviewLayer captureDevicePointOfInterestForPoint:point];
[self setFocusCursorWithPoint:point];
[self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:cameraPoint];
}
/**
* 设置聚焦光标位置
*
* @param point 光标位置
*/
-(void)setFocusCursorWithPoint:(CGPoint)point{
self.focusImage.center = point;
self.focusImage.transform = CGAffineTransformMakeScale(1.5, 1.5);
self.focusImage.alpha = 1.0;
[UIView animateWithDuration:.2 animations:^{
self.focusImage.transform = CGAffineTransformIdentity;
} completion:^(BOOL finished) {
[UIView animateWithDuration:1.0 animations:^{
self.focusImage.alpha = 0;
}];
}];
}
结尾
到这主要的基本都讲了了，详细点说的话代码有点多会显得很乱。所以如果对录制视频感兴趣的同学，可以在我的github上下载这个Demo：Demo地址
好久没写东西了，写的不好见谅有错误请指出哈~~~如果对你有帮助的话请点个赞吧！
