视音频的录制可以通过AVFoundation或GPUImage来实现，但是目前几乎所有的小视频应用都会有滤镜功能，所以大都采用GPUImage框架来开发，不过GPUImage并没有视音频的剪辑、拼接功能，而且GPUImage的录制也是在AVFoundation上进行的封装，所以学习AVFoundation还是很有必要的。
AVFoundation录制视频需要用到的类:
-
AVCaptureSession: 类似于管理器
-
AVCaptureVideoPreviewLayer: 用于展示摄像头采集到的数据
-
AVCaptureInput: 输入(允许使用摄像头、麦克风设备)
-
AVCaptureOutput: 输出(输出视频、音频数据)
-
AVCaptureMovieFileOutput
-
AVAssetWriter
AVCaptureMovieFileOutput代码简单，可以很快速的封装好一个录制框架，缺点是无法采集录制过程中的数据，类似微信小视频，快速录制并发送；
AVAssetWriter代码相对复杂，并且貌似不能重新录制，录制完一个视频后需要销毁该对象，重新创建才能再次录制，优点是能实时采集到录制过程中的图片帧数据，便于在视频实时通讯中使用；
GPUImage录制视频的话，它的底层也是使用AVAssetWriter进行录制的，并且已经封装好，所以使用起来也很方便，而且通过GPUImageView可以实时展示滤镜效果，很不错。
视音频数据采集
声明属性
@property(nonatomic,strong) AVCaptureSession *session;
@property(nonatomic,strong) AVCaptureVideoPreviewLayer *previewLayer;
@property(nonatomic,strong) AVCaptureDeviceInput *videoInput;
@property(nonatomic,strong) AVCaptureDeviceInput *audioInput;
- (AVCaptureSession *)session {
if (!_session) {
_session = [[AVCaptureSession alloc] init];
/*
sessionPreset:
AVCaptureSessionPresetHigh: 高分辨率, 最终效果根据设备不同有所差异
AVCaptureSessionPresetMedium: 中等分辨率, 适合Wi-Fi分享. 最终效果根据设备不同有所差异
AVCaptureSessionPresetLow: 低分辨率, 适合3G分享, 最终效果根据设备不同有所差异
AVCaptureSessionPreset640x480: 640x480, VGA
AVCaptureSessionPreset1280x720: 1280x720, 720p HD
AVCaptureSessionPresetPhoto: 全屏照片, 不能用来作为输出视频
*/
if (![_session canSetSessionPreset:AVCaptureSessionPresetMedium]) {
_session.sessionPreset = AVCaptureSessionPresetMedium; //默认中等画质
}
}
return _session;
}
- (AVCaptureDeviceInput *)videoInput {
if (!_videoInput) {
if (_cameraInput == CameraInputBack) {
_videoInput = self.backCameraInput;
}else {
_videoInput = self.frontCameraInput;
}
}
return _videoInput;
}
- (AVCaptureDeviceInput *)audioInput {
if (!_audioInput) {
NSError *error = nil;
AVCaptureDevice *mic = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
_audioInput = [AVCaptureDeviceInput deviceInputWithDevice:mic error:&error];
if (error) {
NSLog(@"获取麦克风失败");
}
}
return _audioInput;
}
//视频预览view
- (AVCaptureVideoPreviewLayer *)previewLayer {
if (!_previewLayer) {
_previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
_previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
}
return _previewLayer;
}
//后置摄像头输入
- (AVCaptureDeviceInput *)backCameraInput {
if (!_backCameraInput) {
NSError *error = nil;
_backCameraInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self backCamera] error:&error];
if (error) {
NSLog(@"获取后置摄像头失败");
}
}
return _backCameraInput;
}
//前置摄像头输入
- (AVCaptureDeviceInput *)frontCameraInput {
if (!_frontCameraInput) {
NSError *error = nil;
_frontCameraInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self frontCamera] error:&error];
if (error) {
NSLog(@"获取前置摄像头失败");
}
}
return _frontCameraInput;
}
//后置摄像头
- (AVCaptureDevice *)backCamera {
return [self getCameraWithPosition:AVCaptureDevicePositionBack];
}
//前置摄像头
- (AVCaptureDevice *)frontCamera {
return [self getCameraWithPosition:AVCaptureDevicePositionFront];
}
//返回指定设备
- (AVCaptureDevice *)getCameraWithPosition:(AVCaptureDevicePosition)position {
#if __IPHONE_10_0
AVCaptureDeviceDiscoverySession *discoverySession = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInWideAngleCamera] mediaType:AVMediaTypeVideo position:position];
NSArray *devices = discoverySession.devices;
#else
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
#endif
for (AVCaptureDevice *device in devices) {
if (device.position == position) {
return device;
}
}
return nil;
}
如何使用
if (//要录制视频) {
[self addDeviceInput:self.videoInput];
}
if (//要录制音频) {
[self addDeviceInput:self.audioInput];
}
- (void)addDeviceInput:(AVCaptureInput *)input {
if ([self.session canAddInput:input]) {
[self.session addInput:input];
}
}
最后一步，开始采集数据，即可完成一个简单相机
[self.session startRunning];
AVCaptureMovieFileOutput的使用
相机已经做好了，接下来就是录制视音频了，我们先创建好AVCaptureMovieFileOutput对象
@property(nonatomic,strong) AVCaptureMovieFileOutput *fileOutput;
@property(nonatomic,strong) AVCaptureConnection *fileConnection;
- (AVCaptureMovieFileOutput *)fileOutput {
if (!_fileOutput) {
_fileOutput = [[AVCaptureMovieFileOutput alloc] init];
}
return _fileOutput;
}
- (AVCaptureConnection *)fileConnection {
if (!_fileConnection) {
_fileConnection = [self.fileOutput connectionWithMediaType:AVMediaTypeVideo];
//开启防抖，如果支持防抖就开启，有的用就用，实测效果还不错
if ([_fileConnection isVideoStabilizationSupported]) {
_fileConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeAuto;
}
}
return _fileConnection;
}
AVCaptureConnection可用来调整预览视频的方向，还能开启防抖功能
接下来就开始录制视频了，首先要遵循代理<AVCaptureFileOutputRecordingDelegate>
开始录制
//开始录制
- (void)startRecording {
NSLog(@"startRecording");
//在session运行后以及不在录制状态时才能进行录制
if ([self.session isRunning] && self.fileOutput.isRecording == NO) {
self.recordStatus = RecordStatusRecording;
unlink([self.fileUrl.path UTF8String]);
[self.fileOutput startRecordingToOutputFileURL:self.fileUrl recordingDelegate:self];
}else {
NSAssert([self.session isRunning], @"session must be running");
}
}
要注意一点，上面传入的fileUrl路径为录制文件的保存路径，请确保该路径不存在已有文件，不然将无法写入
停止录制
- (void)stopRecording {
NSLog(@"stopRecording");
if (self.fileOutput.isRecording == YES) {
[self.fileOutput stopRecording];
}
}
开始录制和停止录制都会回调函数，在这里就可以做回调操作
# pragma mark - AVCaptureFileOutputRecordingDelegate
//开始录制回调函数
- (void)captureOutput:(AVCaptureFileOutput *)output didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray<AVCaptureConnection *> *)connections {
NSLog(@"didStartRecordingToOutputFileAtURL");
}
//结束录制回调函数，注意，[self.session stopRunning]将会停止录制
- (void)captureOutput:(AVCaptureFileOutput *)output didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray<AVCaptureConnection *> *)connections error:(nullable NSError *)error {
NSLog(@"didFinishRecordingToOutputFileAtURL");
}
到这里我们就完成了录制功能，代码很简单对吧
关于暂停录制
关于暂停录制的实现，我还没有发现哪个框架有提供，即便有pause函数，也只是视频暂停，录制过程还是在继续的，所以暂停录制我实现的方案是视频拼接，即每一次视频录制完成都会进行临时存储，在点击完成操作的时候将这些分段视频进行拼接。
AVAssetWriter的使用
这个类相对会麻烦一些，但是它可以在录制过程中回调视频帧，用于网络实时通讯还是很方便的
开始，遵循代理<AVCaptureVideoDataOutputSampleBufferDelegate,AVCaptureAudioDataOutputSampleBufferDelegate>，这两个代理都有一个共同的函数，用于回调录制过程中的视频帧和音频帧
- (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection;
声明属性
/*
设备输出时需要控制在同一个线程内
*/
@property(nonatomic,strong) dispatch_queue_t recordQueue;
@property(nonatomic,strong) AVCaptureVideoDataOutput *videoOutput;
@property(nonatomic,strong) AVCaptureAudioDataOutput *audioOutput;
@property(nonatomic,strong) AVCaptureConnection *fileConnection;
@property(nonatomic,strong) AVAssetWriter *assetWriter;
@property(nonatomic,strong) AVAssetWriterInput *assetWriterVideoInput;
@property(nonatomic,strong) AVAssetWriterInput *assetWriterAudioInput;
@property(nonatomic,strong) NSDictionary *videoWriterSetting; //视频属性
@property(nonatomic,strong) NSDictionary *audioWriterSetting; //音频属性
这次多了一个dispatch_queue_t，因为使用这个类的话，必不可少的会需要解析视频帧，将其转为UIImage，这是耗时操作，所以会需要开辟线程去运行
初始化
- (dispatch_queue_t)recordQueue {
if (!_recordQueue) {
_recordQueue = dispatch_queue_create("media_writer", DISPATCH_QUEUE_SERIAL);
}
return _recordQueue;
}
- (AVCaptureVideoDataOutput *)videoOutput {
if (!_videoOutput) {
_videoOutput = [[AVCaptureVideoDataOutput alloc] init];
_videoOutput.alwaysDiscardsLateVideoFrames = YES; //立即丢弃旧帧，节省内存，默认YES
//这里遇到个坑，在解析每帧数据的时候一直报CGBitmapContextCreate相关错误，加上下面代码就可以了，具体参考https://www.jianshu.com/p/61ca3a917fe5
NSDictionary *videoSettings = @{(id)kCVPixelBufferPixelFormatTypeKey:@(kCVPixelFormatType_32BGRA)};
[_videoOutput setVideoSettings:videoSettings];
[_videoOutput setSampleBufferDelegate:self queue:self.recordQueue];
}
return _videoOutput;
}
- (AVCaptureAudioDataOutput *)audioOutput {
if (!_audioOutput) {
_audioOutput = [[AVCaptureAudioDataOutput alloc] init];
[_audioOutput setSampleBufferDelegate:self queue:self.recordQueue];
}
return _audioOutput;
}
- (AVCaptureConnection *)fileConnection {
if (!_fileConnection) {
_fileConnection = [self.videoOutput connectionWithMediaType:AVMediaTypeVideo];
//开启防抖，如果支持防抖就开启，有的用就用，实测效果还不错
if ([_fileConnection isVideoStabilizationSupported]) {
_fileConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeAuto;
}
}
return _fileConnection;
}
- (AVAssetWriter *)assetWriter {
if (!_assetWriter) {
NSError *error = nil;
NSURL *fileUrl = _currentUrl;
[self removeFilePathIfExist:fileUrl.path];
_assetWriter = [AVAssetWriter assetWriterWithURL:fileUrl fileType:AVFileTypeMPEG4 error:&error];
if (error) {
NSLog(@"writer对象创建失败: %@",error);
}
}
return _assetWriter;
}
- (AVAssetWriterInput *)assetWriterVideoInput {
if (!_assetWriterVideoInput) {
_assetWriterVideoInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:self.videoWriterSetting];
_assetWriterVideoInput.expectsMediaDataInRealTime = YES; //必须设为YES，否则会丢帧
}
return _assetWriterVideoInput;
}
- (AVAssetWriterInput *)assetWriterAudioInput {
if (!_assetWriterAudioInput) {
_assetWriterAudioInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:self.audioWriterSetting];
_assetWriterAudioInput.expectsMediaDataInRealTime = YES;
}
return _assetWriterAudioInput;
}
- (NSDictionary *)videoWriterSetting {
CGFloat videoWidth = CGRectGetWidth(self.containerView.bounds);
CGFloat videoHeight = CGRectGetHeight(self.containerView.bounds);
//写入视频大小
NSInteger numPixels = videoWidth * videoHeight;
//每像素比特
CGFloat bitsPerPixel = 6.0f;
NSInteger bitsPerSecond = numPixels * bitsPerPixel;
/*
码率和帧率设置
AVVideoCodecKey 编码方式：H.264编码
AVVideoExpectedSourceFrameRateKey 帧率：每秒钟多少帧画面
AVVideoAverageBitRateKey 码率：单位时间内保存的数据量,码率: 编码效率, 码率越高,则画面越清晰, 如果码率较低会引起马赛克 --> 码率高有利于还原原始画面,但是也不利于传输)
AVVideoMaxKeyFrameIntervalKey 关键帧（GOPsize)间隔：多少帧为一个GOP,
*/
NSDictionary *compresstionProperties = @{AVVideoAverageBitRateKey:@(bitsPerSecond),
AVVideoExpectedSourceFrameRateKey:@(30),
AVVideoMaxKeyFrameIntervalKey:@(30),
AVVideoProfileLevelKey:AVVideoProfileLevelH264BaselineAutoLevel,
};
return @{AVVideoCodecKey:AVVideoCodecH264,
AVVideoScalingModeKey:AVVideoScalingModeResizeAspectFill,
AVVideoWidthKey:@(videoWidth),
AVVideoHeightKey:@(videoWidth),
AVVideoCompressionPropertiesKey:compresstionProperties,
};
}
- (NSDictionary *)audioWriterSetting {
return @{AVEncoderBitRatePerChannelKey:@(28000),
AVFormatIDKey:@(kAudioFormatMPEG4AAC),
AVNumberOfChannelsKey:@(1),
AVSampleRateKey:@(22050),
};
}
- (void)initializeAssetWriter {
//视频
if (...) {
if ([self.assetWriter canAddInput:self.assetWriterVideoInput]) {
[self.assetWriter addInput:self.assetWriterVideoInput];
}
}
//音频
if (...) {
if ([self.assetWriter canAddInput:self.assetWriterAudioInput]) {
[self.assetWriter addInput:self.assetWriterAudioInput];
}
}
}
可以看到在初始化的时候可以进行高度定制，满足实时通讯或小视频拍摄的需求
开始录制
首先要注意这些操作最好都在同一个线程中处理，为什么不用我多说了吧
- (void)startRecording {
dispatch_async(self.recordQueue, ^{
if (_assetWriter == nil) {
[self initializeAssetWriter];
}
}
}
停止录制
- (void)stopRecording {
dispatch_async(self.recordQueue, ^{
[self stopWrite];
});
}
- (void)stopWrite {
dispatch_async(self.recordQueue, ^{
if (_assetWriter) {
[_assetWriter finishWritingWithCompletionHandler:^{
[self destoryWrite];
}];
}else {
NSLog(@"writer对象为空");
}
});
}
/*
writer对象只能使用一次，再次写入需要重新创建对象，参考链接:
https://stackoverflow.com/questions/4911534/avassetwriter-multiple-sessions-and-the-status-property
*/
- (void)destoryWrite {
dispatch_async(self.recordQueue, ^{
@synchronized(self) {
_assetWriter = nil;
_assetWriterVideoInput = nil;
_assetWriterAudioInput = nil;
NSLog(@"摧毁写入对象~");
}
});
}
在AVAssetWriter初始化之后就会开始回调函数，开始录制的代码我们在该回调函数中写，同样需要保证写入文件的路径是有效的；
//在这里可以获取视频帧，可以在此实现滤镜等效果
- (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
if (sampleBuffer == NULL) {
NSLog(@"empty sampleBuffer");
return;
}
if (connection == [_videoOutput connectionWithMediaType:AVMediaTypeVideo]) {
//视频
if (_assetWriter == nil) {
NSLog(@"_assetWriter 为空.");
[self destoryWrite];
return;
}
if (_assetWriter.status == AVAssetWriterStatusFailed) {
NSLog(@"Error: %@", _assetWriter.error);
[self stopWrite];
return;
}
if (_assetWriter.status == AVAssetWriterStatusUnknown) {
NSLog(@"开始写入");
[_assetWriter startWriting];
[_assetWriter startSessionAtSourceTime:CMSampleBufferGetPresentationTimeStamp(sampleBuffer)];
}
if (_assetWriterVideoInput.readyForMoreMediaData) {
BOOL success = [_assetWriterVideoInput appendSampleBuffer:sampleBuffer]; //如果报错请检查是否已存在文件
if (!success) {
NSLog(@"append sampleBuffer fail~");
@synchronized(self) {
[self stopRecording];
}
}
}
}
if (connection == [_audioOutput connectionWithMediaType:AVMediaTypeAudio]) {
//音频
if (self.assetWriterAudioInput.readyForMoreMediaData) {
BOOL success = [_assetWriterAudioInput appendSampleBuffer:sampleBuffer];
if (!success) {
NSLog(@"append sampleBuffer fail~");
@synchronized(self) {
[self stopRecording];
}
}
}
}
}
CMSampleBufferRef转UIImage
给一个网上找到的方法
//CMSampleBufferRef转UIImage
-(UIImage *)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer{
// 为媒体数据设置一个CMSampleBuffer的Core Video图像缓存对象
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
// 锁定pixel buffer的基地址
CVPixelBufferLockBaseAddress(imageBuffer, 0);
// 得到pixel buffer的基地址
void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
// 得到pixel buffer的行字节数
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
// 得到pixel buffer的宽和高
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
// 创建一个依赖于设备的RGB颜色空间
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// 用抽样缓存的数据创建一个位图格式的图形上下文（graphics context）对象
CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
// 根据这个位图context中的像素数据创建一个Quartz image对象
CGImageRef quartzImage = CGBitmapContextCreateImage(context);
// 解锁pixel buffer
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
// 释放context和颜色空间
CGContextRelease(context); CGColorSpaceRelease(colorSpace);
// 用Quartz image创建一个UIImage对象image
UIImage *image = [UIImage imageWithCGImage:quartzImage scale:1 orientation:UIImageOrientationUp];
// 释放Quartz image对象
CGImageRelease(quartzImage);
return (image);
}
GPUImage录制视频
- GPUImageVideoCamera: GPUImage封装的相机
- GPUImageView: 视图展示
- GPUImageFilterGroup: 滤镜组，
- GPUImageMovieWriter: 视频写入类
声明属性
@property(nonatomic,strong) GPUImageVideoCamera *videoCamera;
@property(nonatomic,strong) GPUImageView *preView;
@property(nonatomic,strong) GPUImageFilterGroup *filterGroup;
@property(nonatomic,strong) GPUImageMovieWriter *movieWriter;
@property(nonatomic,strong) NSMutableArray *filters; //滤镜个数
初始化
- (void)initializedCamera {
//视频源
_videoCamera = [[GPUImageVideoCamera alloc] initWithSessionPreset:AVCaptureSessionPresetHigh cameraPosition:AVCaptureDevicePositionFront];
_videoCamera.outputImageOrientation = UIInterfaceOrientationPortrait;
_videoCamera.horizontallyMirrorFrontFacingCamera = YES;
//解决开始录制时相机闪烁的问题。在初始化时就添加声音输入
[_videoCamera addAudioInputsAndOutputs];
//滤镜组
_filterGroup = [[GPUImageFilterGroup alloc] init];
_filters = @[].mutableCopy;
[self updateCamera];
}
- (void)updateCamera {
[_videoCamera removeAllTargets];
if (_filters.count == 0) {
[_videoCamera addTarget:self.preView];
}else {
[_videoCamera addTarget:_filterGroup];
[_filterGroup addTarget:self.preView];
}
}
- (GPUImageView *)preView {
if (!_preView) {
_preView = [[GPUImageView alloc] init];
_preView.fillMode = kGPUImageFillModePreserveAspectRatioAndFill;
}
return _preView;
}
写入对象GPUImageMovieWriter的创建，GPUImage封装的视频写入函数也是需要重新创建的
- (void)resetMovieWriter {
if (_movieWriter) _movieWriter = nil;
unlink([self.fileUrl.path UTF8String]);
_movieWriter = [[GPUImageMovieWriter alloc] initWithMovieURL:url size:self.preView.bounds.size];
_movieWriter.encodingLiveVideo = YES;
_videoCamera.audioEncodingTarget = _movieWriter;
}
视频采集
因为GPUImage底层进行了封装，所以我们开启摄像头采集的函数不再是[self.session startRunning]了
- (void)startRunning {
[self.videoCamera startCameraCapture]; //开始采集
}
- (void)stopRunning {
[self.videoCamera stopCameraCapture]; //停止采集
}
开始录制
- (void)startRecording {
self.recordStatus = RecordStatusRecording;
NSLog(@"新的录制");
[self resetMovieWriter];
[self addMovieWriter];
_videoCamera.audioEncodingTarget = _movieWriter;
[_movieWriter startRecording];
}
//添加视频写入target
- (void)addMovieWriter {
if (self.filters.count == 0) {
[_videoCamera addTarget:_movieWriter];
}else {
[_filterGroup addTarget:_movieWriter];
}
}
停止录制
- (void)stopRecording {
NSLog(@"暂停录制");
[self removeMovieWriter];
_videoCamera.audioEncodingTarget = nil;
[_movieWriter finishRecording];
}
//移除视频写入target
- (void)removeMovieWriter {
if (self.filters.count == 0) {
[_videoCamera removeTarget:_movieWriter];
}else {
[_filterGroup removeTarget:_movieWriter];
}
}
滤镜
使用GPUImage录制还可以实时添加滤镜功能
//更新滤镜
- (void)updateGPUImageFilters:(NSArray <GPUImageOutput<GPUImageInput> *>*)filters {
NSLog(@"update filters: %@",filters);
if (filters.count == 0) {
[self removeAllFilters];
[self updateCamera];
return;
}
[self removeAllFilters];
_filterGroup = [[GPUImageFilterGroup alloc] init];
for (GPUImageOutput<GPUImageInput> *target in filters) {
[self addGPUImageFilter:target filterGroup:_filterGroup];
}
[_filters addObjectsFromArray:filters];
[_filterGroup useNextFrameForImageCapture];
[self updateCamera];
}
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