【如何快速的開發(fā)一個(gè)完整的iOS直播app】(采集篇)

轉(zhuǎn)載自簡(jiǎn)書@袁崢Seemygo:http://www.jianshu.com/p/c71bfda055fa

前言

　　開發(fā)一款直播app，首先需要采集主播的視頻和音頻，然后傳入流媒體服務(wù)器，本篇主要講解如何采集主播的視頻和音頻，當(dāng)前可以切換前置后置攝像頭和焦點(diǎn)坐標(biāo)。

基本知識(shí)介紹

• AVFoundation:音視頻數(shù)據(jù)采集需要用AVFoundation框架.

• AVCaptureDevice:硬件設(shè)備，包括麥克風(fēng)、攝像頭，通過(guò)該對(duì)象可以設(shè)置物理設(shè)備的一些屬性（例如相機(jī)聚焦、白平衡等）

• AVCaptureDeviceInput:硬件輸入對(duì)象，可以根據(jù)AVCaptureDevice創(chuàng)建對(duì)應(yīng)的AVCaptureDeviceInput對(duì)象，用于管理硬件輸入數(shù)據(jù)。

• AVCaptureOutput:硬件輸出對(duì)象，用于接收各類輸出數(shù)據(jù)，通常使用對(duì)應(yīng)的子類AVCaptureAudioDataOutput（聲音數(shù)據(jù)輸出對(duì)象）、　　AVCaptureVideoDataOutput（視頻數(shù)據(jù)輸出對(duì)象）

• AVCaptureConnection:當(dāng)把一個(gè)輸入和輸出添加到AVCaptureSession之后，AVCaptureSession就會(huì)在輸入、輸出設(shè)備之間建立連接,而且通過(guò)AVCaptureOutput可以獲取這個(gè)連接對(duì)象。

• AVCaptureVideoPreviewLayer:相機(jī)拍攝預(yù)覽圖層，能實(shí)時(shí)查看拍照或視頻錄制效果，創(chuàng)建該對(duì)象需要指定對(duì)應(yīng)的AVCaptureSession對(duì)象，因?yàn)锳VCaptureSession包含視頻輸入數(shù)據(jù)，有視頻數(shù)據(jù)才能展示。

• AVCaptureSession:協(xié)調(diào)輸入和輸出之間傳遞數(shù)據(jù)?
  
  • 系統(tǒng)作用：可以操作硬件設(shè)備
  • 工作原理：讓App與系統(tǒng)之間產(chǎn)生一個(gè)捕獲會(huì)話，相當(dāng)于App與硬件設(shè)備有聯(lián)系了， 我們只需要把硬件輸入對(duì)象和輸出對(duì)象添加到會(huì)話中，會(huì)話就會(huì)自動(dòng)把硬件輸入對(duì)象和輸出產(chǎn)生連接，這樣硬件輸入與輸出設(shè)備就能傳輸音視頻數(shù)據(jù)。
  • 現(xiàn)實(shí)生活場(chǎng)景：租客（輸入錢），中介（會(huì)話），房東（輸出房），租客和房東都在中介登記，中介就會(huì)讓租客與房東之間產(chǎn)生聯(lián)系，以后租客就能直接和房東聯(lián)系了。

捕獲音視頻步驟:官方文檔

• 1.創(chuàng)建AVCaptureSession對(duì)象
• 2.獲取AVCaptureDevicel錄像設(shè)備（攝像頭），錄音設(shè)備（麥克風(fēng)），注意不具備輸入數(shù)據(jù)功能,只是用來(lái)調(diào)節(jié)硬件設(shè)備的配置。
• 3.根據(jù)音頻/視頻硬件設(shè)備(AVCaptureDevice)創(chuàng)建音頻/視頻硬件輸入數(shù)據(jù)對(duì)象(AVCaptureDeviceInput)，專門管理數(shù)據(jù)輸入。
• 4.創(chuàng)建視頻輸出數(shù)據(jù)管理對(duì)象（AVCaptureVideoDataOutput），并且設(shè)置樣品緩存代理(setSampleBufferDelegate)就可以通過(guò)它拿到采集到的視頻數(shù)據(jù)
• 5.創(chuàng)建音頻輸出數(shù)據(jù)管理對(duì)象（AVCaptureAudioDataOutput），并且設(shè)置樣品緩存代理(setSampleBufferDelegate)就可以通過(guò)它拿到采集到的音頻數(shù)據(jù)
• 6.將數(shù)據(jù)輸入對(duì)象AVCaptureDeviceInput、數(shù)據(jù)輸出對(duì)象AVCaptureOutput添加到媒體會(huì)話管理對(duì)象AVCaptureSession中,就會(huì)自動(dòng)讓音頻輸入與輸出和視頻輸入與輸出產(chǎn)生連接.
• 7.創(chuàng)建視頻預(yù)覽圖層AVCaptureVideoPreviewLayer并指定媒體會(huì)話，添加圖層到顯示容器layer中
• 8.啟動(dòng)AVCaptureSession，只有開啟，才會(huì)開始輸入到輸出數(shù)據(jù)流傳輸。

// 捕獲音視頻 - (void)setupCaputureVideo {// 1.創(chuàng)建捕獲會(huì)話,必須要強(qiáng)引用，否則會(huì)被釋放AVCaptureSession *captureSession = [[AVCaptureSession alloc] init];_captureSession = captureSession;// 2.獲取攝像頭設(shè)備，默認(rèn)是后置攝像頭AVCaptureDevice *videoDevice = [self getVideoDevice:AVCaptureDevicePositionFront];// 3.獲取聲音設(shè)備AVCaptureDevice *audioDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];// 4.創(chuàng)建對(duì)應(yīng)視頻設(shè)備輸入對(duì)象AVCaptureDeviceInput *videoDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:nil];_currentVideoDeviceInput = videoDeviceInput;// 5.創(chuàng)建對(duì)應(yīng)音頻設(shè)備輸入對(duì)象AVCaptureDeviceInput *audioDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:audioDevice error:nil];// 6.添加到會(huì)話中// 注意“最好要判斷是否能添加輸入，會(huì)話不能添加空的// 6.1 添加視頻if ([captureSession canAddInput:videoDeviceInput]) {[captureSession addInput:videoDeviceInput];}// 6.2 添加音頻if ([captureSession canAddInput:audioDeviceInput]) {[captureSession addInput:audioDeviceInput];}// 7.獲取視頻數(shù)據(jù)輸出設(shè)備AVCaptureVideoDataOutput *videoOutput = [[AVCaptureVideoDataOutput alloc] init];// 7.1 設(shè)置代理，捕獲視頻樣品數(shù)據(jù)// 注意：隊(duì)列必須是串行隊(duì)列，才能獲取到數(shù)據(jù)，而且不能為空dispatch_queue_t videoQueue = dispatch_queue_create("Video Capture Queue", DISPATCH_QUEUE_SERIAL);[videoOutput setSampleBufferDelegate:self queue:videoQueue];if ([captureSession canAddOutput:videoOutput]) {[captureSession addOutput:videoOutput];}// 8.獲取音頻數(shù)據(jù)輸出設(shè)備AVCaptureAudioDataOutput *audioOutput = [[AVCaptureAudioDataOutput alloc] init];// 8.2 設(shè)置代理，捕獲視頻樣品數(shù)據(jù)// 注意：隊(duì)列必須是串行隊(duì)列，才能獲取到數(shù)據(jù)，而且不能為空dispatch_queue_t audioQueue = dispatch_queue_create("Audio Capture Queue", DISPATCH_QUEUE_SERIAL);[audioOutput setSampleBufferDelegate:self queue:audioQueue];if ([captureSession canAddOutput:audioOutput]) {[captureSession addOutput:audioOutput];}// 9.獲取視頻輸入與輸出連接，用于分辨音視頻數(shù)據(jù)_videoConnection = [videoOutput connectionWithMediaType:AVMediaTypeVideo];// 10.添加視頻預(yù)覽圖層AVCaptureVideoPreviewLayer *previedLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession];previedLayer.frame = [UIScreen mainScreen].bounds;[self.view.layer insertSublayer:previedLayer atIndex:0];_previedLayer = previedLayer;// 11.啟動(dòng)會(huì)話 [captureSession startRunning]; }// 指定攝像頭方向獲取攝像頭 - (AVCaptureDevice *)getVideoDevice:(AVCaptureDevicePosition)position {NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];for (AVCaptureDevice *device in devices) {if (device.position == position) {return device;}}return nil; }#pragma mark - AVCaptureVideoDataOutputSampleBufferDelegate // 獲取輸入設(shè)備數(shù)據(jù)，有可能是音頻有可能是視頻 - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {if (_videoConnection == connection) {NSLog(@"采集到視頻數(shù)據(jù)");} else {NSLog(@"采集到音頻數(shù)據(jù)");} }

視頻采集額外功能一（切換攝像頭）

• 切換攝像頭步驟
  • 1.獲取當(dāng)前視頻設(shè)備輸入對(duì)象
  • 2.判斷當(dāng)前視頻設(shè)備是前置還是后置
  • 3.確定切換攝像頭的方向
  • 4.根據(jù)攝像頭方向獲取對(duì)應(yīng)的攝像頭設(shè)備
  • 5.創(chuàng)建對(duì)應(yīng)的攝像頭輸入對(duì)象
  • 6.從會(huì)話中移除之前的視頻輸入對(duì)象
  • 7.添加新的視頻輸入對(duì)象到會(huì)話中

// 切換攝像頭 - (IBAction)toggleCapture:(id)sender {// 獲取當(dāng)前設(shè)備方向AVCaptureDevicePosition curPosition = _currentVideoDeviceInput.device.position;// 獲取需要改變的方向AVCaptureDevicePosition togglePosition = curPosition == AVCaptureDevicePositionFront?AVCaptureDevicePositionBack:AVCaptureDevicePositionFront;// 獲取改變的攝像頭設(shè)備AVCaptureDevice *toggleDevice = [self getVideoDevice:togglePosition];// 獲取改變的攝像頭輸入設(shè)備AVCaptureDeviceInput *toggleDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:toggleDevice error:nil];// 移除之前攝像頭輸入設(shè)備 [_captureSession removeInput:_currentVideoDeviceInput];// 添加新的攝像頭輸入設(shè)備 [_captureSession addInput:toggleDeviceInput];// 記錄當(dāng)前攝像頭輸入設(shè)備_currentVideoDeviceInput = toggleDeviceInput;}

視頻采集額外功能二（聚焦光標(biāo)）

• 聚焦光標(biāo)步驟
  • 1.監(jiān)聽屏幕的點(diǎn)擊
  • 2.獲取點(diǎn)擊的點(diǎn)位置，轉(zhuǎn)換為攝像頭上的點(diǎn)，必須通過(guò)視頻預(yù)覽圖層（AVCaptureVideoPreviewLayer）轉(zhuǎn)
  • 3.設(shè)置聚焦光標(biāo)圖片的位置，并做動(dòng)畫
  • 4.設(shè)置攝像頭設(shè)備聚焦模式和曝光模式(注意：這里設(shè)置一定要鎖定配置lockForConfiguration,否則報(bào)錯(cuò))

// 點(diǎn)擊屏幕，出現(xiàn)聚焦視圖 - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {// 獲取點(diǎn)擊位置UITouch *touch = [touches anyObject];CGPoint point = [touch locationInView:self.view];// 把當(dāng)前位置轉(zhuǎn)換為攝像頭點(diǎn)上的位置CGPoint cameraPoint = [_previedLayer captureDevicePointOfInterestForPoint:point];// 設(shè)置聚焦點(diǎn)光標(biāo)位置 [self setFocusCursorWithPoint:point];// 設(shè)置聚焦 [self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:cameraPoint]; }/*** 設(shè)置聚焦光標(biāo)位置** @param point 光標(biāo)位置*/ -(void)setFocusCursorWithPoint:(CGPoint)point{self.focusCursorImageView.center=point;self.focusCursorImageView.transform=CGAffineTransformMakeScale(1.5, 1.5);self.focusCursorImageView.alpha=1.0;[UIView animateWithDuration:1.0 animations:^{self.focusCursorImageView.transform=CGAffineTransformIdentity;} completion:^(BOOL finished) {self.focusCursorImageView.alpha=0;}]; }/*** 設(shè)置聚焦*/ -(void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{AVCaptureDevice *captureDevice = _currentVideoDeviceInput.device;// 鎖定配置 [captureDevice lockForConfiguration:nil];// 設(shè)置聚焦if ([captureDevice isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {[captureDevice setFocusMode:AVCaptureFocusModeAutoFocus];}if ([captureDevice isFocusPointOfInterestSupported]) {[captureDevice setFocusPointOfInterest:point];}// 設(shè)置曝光if ([captureDevice isExposureModeSupported:AVCaptureExposureModeAutoExpose]) {[captureDevice setExposureMode:AVCaptureExposureModeAutoExpose];}if ([captureDevice isExposurePointOfInterestSupported]) {[captureDevice setExposurePointOfInterest:point];}// 解鎖配置 [captureDevice unlockForConfiguration]; }

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轉(zhuǎn)載于:https://www.cnblogs.com/XYQ-208910/p/5859337.html

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