access 网站后台,开发公司房产销售合同中必须明确哪些事项?,asp做的网站后台怎么进去,dw网页制作详细步骤景颇族AVCaptureSession配置采集行为并协调从输入设备到采集输出的数据流。要执行实时音视频采集#xff0c;需要实例化采集会话并添加适当的输入和输出。
AVCaptureSession#xff1a;管理输入输出音视频流AVCaptureDevice#xff1a;相机硬件的接口#xff0c;用于控制硬件特性…AVCaptureSession配置采集行为并协调从输入设备到采集输出的数据流。要执行实时音视频采集需要实例化采集会话并添加适当的输入和输出。
AVCaptureSession管理输入输出音视频流AVCaptureDevice相机硬件的接口用于控制硬件特性诸如镜头的位置(前后摄像头)、曝光、闪光灯等。AVCaptureInput配置输入设备提供来自设备的数据AVCaptureOutput管理输出的音视频数据流AVCaptureConnection输入与输出的连接AVCaptureVideoPreviewLayer显示当前相机正在采集的状况AVAssetWriter将媒体数据写入到容器文件
初始化AVCaptureSession
- (AVCaptureSession *)captureSession {if (_captureSession nil){_captureSession [[AVCaptureSession alloc] init];if ([_captureSession canSetSessionPreset:AVCaptureSessionPresetHigh]) {_captureSession.sessionPreset AVCaptureSessionPreset1280x720;}}return _captureSession;
}- (dispatch_queue_t)videoQueue {if (!_videoQueue) {_videoQueue dispatch_queue_create(VideoCapture, DISPATCH_QUEUE_SERIAL);}return _videoQueue;
}
添加视频输入
- (AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition )position {AVCaptureDeviceDiscoverySession *deviceDiscoverySession [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:[AVCaptureDeviceTypeBuiltInWideAngleCamera] mediaType:AVMediaTypeVideo position:position];for (AVCaptureDevice *device in deviceDiscoverySession.devices) {if ([device position] position) {return device;}}return nil;
}- (void)setupVideoInput {AVCaptureDevice *captureDevice [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];if (!captureDevice){NSLog(captureDevice failed);return;}NSError *error nil;self.videoInput [[AVCaptureDeviceInput alloc] initWithDevice:captureDevice error:error];if (error) {NSLog(videoInput error:%, error);return;}if ([self.captureSession canAddInput:self.videoInput]) {[self.captureSession addInput:self.videoInput];}
}添加音频输入
- (void)setupAudioInput {AVCaptureDevice *captureDevice [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];NSError *error nil;self.audioInput [[AVCaptureDeviceInput alloc] initWithDevice:captureDevice error:error];if (error) {NSLog(audioInput error:%, error);return;}if ([self.captureSession canAddInput:self.audioInput]) {[self.captureSession addInput:self.audioInput];}
}
添加视频输出
- (void)setupVideoOutput {self.videoOutput [[AVCaptureVideoDataOutput alloc] init];self.videoOutput.alwaysDiscardsLateVideoFrames YES;[self.videoOutput setSampleBufferDelegate:self queue:self.videoQueue];if ([self.captureSession canAddOutput:self.videoOutput]) {[self.captureSession addOutput:self.videoOutput];}
}添加音频输出
- (void)setupAudioOutput {self.audioOutput [[AVCaptureAudioDataOutput alloc] init];[self.audioOutput setSampleBufferDelegate:self queue:self.videoQueue];if ([self.captureSession canAddOutput:self.audioOutput]) {[self.captureSession addOutput:self.audioOutput];}
}
设置视频预览
- (void)setupCaptureVideoPreviewLayer:(UIView *)previewView {_captureVideoPreviewLayer [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];CALayer *layer previewView.layer;_captureVideoPreviewLayer.frame previewView.bounds;_captureVideoPreviewLayer.videoGravity AVLayerVideoGravityResizeAspect;_captureVideoPreviewLayer.videoGravity AVLayerVideoGravityResizeAspectFill;_captureVideoPreviewLayer.connection.videoOrientation AVCaptureVideoOrientationLandscapeRight;[layer insertSublayer:_captureVideoPreviewLayer atIndex:0];
}开始和结束采集会话
- (void)startSession {if (![self.captureSession isRunning]) {[self.captureSession startRunning];}
}- (void)stopSession{if ([self.captureSession isRunning]) {[self.captureSession stopRunning];}
}初始化AVAssetWriter将音视频保存到视频文件
- (void)setUpWriter {if (self.videoURL nil) {return;}self.assetWriter [AVAssetWriter assetWriterWithURL:self.videoURL fileType:AVFileTypeMPEG4 error:nil];NSInteger numPixels kScreenWidth * kScreenHeight;CGFloat bitsPerPixel 12.0;NSInteger bitsPerSecond numPixels * bitsPerPixel;NSDictionary *compressionProperties { AVVideoAverageBitRateKey : (bitsPerSecond),AVVideoExpectedSourceFrameRateKey : (15),AVVideoMaxKeyFrameIntervalKey : (15),AVVideoProfileLevelKey : AVVideoProfileLevelH264BaselineAutoLevel };self.videoCompressionSettings { AVVideoCodecKey : AVVideoCodecTypeH264,AVVideoWidthKey : (width * 2),AVVideoHeightKey : (height * 2),AVVideoScalingModeKey : AVVideoScalingModeResizeAspect,AVVideoCompressionPropertiesKey : compressionProperties };_assetWriterVideoInput [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:self.videoCompressionSettings];_assetWriterVideoInput.expectsMediaDataInRealTime YES;self.audioCompressionSettings { AVEncoderBitRatePerChannelKey : (28000),AVFormatIDKey : (kAudioFormatMPEG4AAC),AVNumberOfChannelsKey : (1),AVSampleRateKey : (22050) };_assetWriterAudioInput [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:self.audioCompressionSettings];_assetWriterAudioInput.expectsMediaDataInRealTime YES;if ([_assetWriter canAddInput:_assetWriterVideoInput]){[_assetWriter addInput:_assetWriterVideoInput];}else{NSLog(AssetWriter videoInput append Failed);}if ([_assetWriter canAddInput:_assetWriterAudioInput]){[_assetWriter addInput:_assetWriterAudioInput];}else{NSLog(AssetWriter audioInput Append Failed);}_canWrite NO;
}
AVCaptureVideoDataOutputSampleBufferDelegate和AVCaptureAudioDataOutputSampleBufferDelegate音视频处理
#pragma mark - AVCaptureVideoDataOutputSampleBufferDelegate|AVCaptureAudioDataOutputSampleBufferDelegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {autoreleasepool{if (connection [self.videoOutput connectionWithMediaType:AVMediaTypeVideo]) {synchronized(self){[self appendSampleBuffer:sampleBuffer ofMediaType:AVMediaTypeVideo];}}if (connection [self.audioOutput connectionWithMediaType:AVMediaTypeAudio]) {synchronized(self) {[self appendSampleBuffer:sampleBuffer ofMediaType:AVMediaTypeAudio];}}}
}- (void)appendSampleBuffer:(CMSampleBufferRef)sampleBuffer ofMediaType:(NSString *)mediaType {if (sampleBuffer NULL){NSLog(empty sampleBuffer);return;}autoreleasepool{if (!self.canWrite mediaType AVMediaTypeVideo){[self.assetWriter startWriting];[self.assetWriter startSessionAtSourceTime:CMSampleBufferGetPresentationTimeStamp(sampleBuffer)];self.canWrite YES;}if (mediaType AVMediaTypeVideo){if (self.assetWriterVideoInput.readyForMoreMediaData){BOOL success [self.assetWriterVideoInput appendSampleBuffer:sampleBuffer];if (!success){NSLog(assetWriterVideoInput appendSampleBuffer fail);synchronized (self){[self stopVideoRecorder];}}}}if (mediaType AVMediaTypeAudio){if (self.assetWriterAudioInput.readyForMoreMediaData){BOOL success [self.assetWriterAudioInput appendSampleBuffer:sampleBuffer];if (!success){NSLog(assetWriterAudioInput appendSampleBuffer fail);synchronized (self){[self stopVideoRecorder];}}}}}
}
停止视频录制
- (void)stopVideoRecorder {__weak __typeof(self)weakSelf self;if(_assetWriter _assetWriter.status AVAssetWriterStatusWriting) {[_assetWriter finishWritingWithCompletionHandler:^{weakSelf.canWrite NO;weakSelf.assetWriter nil;weakSelf.assetWriterAudioInput nil;weakSelf.assetWriterVideoInput nil;}];}
}
