1. AVFoundation 中重要的类
- AVCaptureSession 音视频会话
- AVCaptureDevice 音视频设备
- AVCaptureDeviceInput 音视频输入
- AVCaptureVideoDataOutput 视频输出
- AVCaptureAudioDataOutput 音频输出
- AVCaptureVideoPreviewLayer 预览图层
- AVCaptureConnection 输入输出连接
- AVCaptureVideoDataOutputSampleBufferDelegate 视频输出代理
- AVCaptureAudioDataOutputSampleBufferDelegate 音频输出代理
2. 采集音视频思路
- 创建音视频会话AVCaptureSession
- 设置视频信息
- 设置音频信息
- 创建预览图层
- 开启捕捉
- 处理代理输出
3. 详细配置步骤
1. 创建音视频会话 AVCaptureSession
- 创建 AVCaptureSession
- 设置分辨率
2. 设置视频信息
- 创建视频输入 AVCaptureDevice -> AVCaptureDeviceInput
- 添加视频输入设备 AVCaptureDeviceInput - > AVCaptureSession
- 创建视频输出设备 AVCaptureVideoDataOutput
- 设置视频输出相关参数
4.1 设置视频输出格式 YUV420
4.2 是否丢弃延时帧 setAlwaysDiscardsLateVideoFrames
4.3 设置视频输出代理和串行队列
4.4 添加视频输出设备 AVCaptureVideoDataOutput -> AVCaptureSession - 创建视频连接 AVCaptureVideoDataOutput -> AVCaptureConnection
- 设置视频方向 AVCaptureConnection->
- 判断是否支撑视频稳定 preferredVideoStabilizationMode
3. 设置音频信息
- 创建音频输入 AVCaptureDevice -> AVCaptureDeviceInput
- 添加音频输入设备 AVCaptureDeviceInput -> AVCaptureSession
- 创建音频输出设备 AVCaptureAudioDataOutput
3.1 设置音频输出代理和串行队列
3.2 添加音频输出设备到会话AVCaptureAudioDataOutput -> AVCaptureSession - 创建音频连接 AVCaptureAudioDataOutput -> AVCaptureConnection
4. 创建预览图层
- 创建预览图层 AVCaptureConnection -> AVCaptureVideoPreviewLayer
- 设置预览图层显示模式-> 全屏
5. 开启捕捉
- AVCaptureConnection -> startRunning
6. 处理代理输出
- 音视频输出代理
- (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
7. 总结
1. 视频
- 添加视频输入设备 AVCaptureSession -> AVCaptureDeviceInput
- 添加视频输出设备 AVCaptureSession -> AVCaptureVideoDataOutput
- 建立视频连接 AVCaptureVideoDataOutput -> AVCaptureConnection
- 视频输出到代理 AVCaptureConnection -> delegate
2. 音频
- 添加音频输入设备 AVCaptureSession -> AVCaptureDeviceInput
- 添加音频输出设备 AVCaptureSession -> AVCaptureAudioDataOutput
- 建立视频连接 AVCaptureVideoDataOutput -> AVCaptureConnection
- 音频输出到代理 AVCaptureConnection -> delegate
3. 队列
- 会话异步串行队列 -> AVCaptureSession
- 视频输出异步串行队列 -> AVCaptureVideoDataOutput
- 音频输出异步串行队列 - > AVCaptureAudioDataOutput
通过给视频会话AVCaptureSession添加音视频输入输出设备，并且建立连接后，采集的数据就会输出到代理方法里面，且Session 音频 视频输出都要放在异步串行队列里面
4.具体代码实现
1.头文件及属性
#import <AVFoundation/AVFoundation.h>
@interface VideoCaptureView ()
<AVCaptureVideoDataOutputSampleBufferDelegate, AVCaptureAudioDataOutputSampleBufferDelegate>
// 会话
@property (nonatomic, strong) AVCaptureSession * captureSession;
// 会话的串行队列
@property (nonatomic, strong) dispatch_queue_t captureSessionQueue;
// 视频输入设备
@property (nonatomic, strong) AVCaptureDeviceInput * activeDeviceInput;
// 视频连接
@property (nonatomic, strong) AVCaptureConnection * videoConnection;
// 音频连接
@property (nonatomic, strong) AVCaptureConnection * audioConnection;
// 音频数据输出
@property (nonatomic, strong) AVCaptureAudioDataOutput * audioDataOutput;
// 视频数据输出
@property (nonatomic, strong) AVCaptureVideoDataOutput * videoDataOutput;
- 创建Session会话
- (void)setupCaptureSession {
// 1.创建AVCaptureSession
AVCaptureSession * session = [[AVCaptureSession alloc] init];
self.captureSession = session;
// 2.设置分辨率 分辨率与编码时候的宽和高有关系
if ([session canSetSessionPreset:AVCaptureSessionPresetHigh]) {
session.sessionPreset = AVCaptureSessionPresetHigh;
}
// 3. 创建Session队列
self.captureSessionQueue = dispatch_queue_create("captureSession queue", DISPATCH_QUEUE_SERIAL);
}
2.设置视频信息
- (void)setupVideo {
// 1. 创建视频输入设备 AVCaptureDevice -> AVCaptureDeviceInput
AVCaptureDevice * device = nil;
if (@available (iOS 10, *)) {
device = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInWideAngleCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionBack];
} else {
device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
}
// 创建视频输入AVCaptureDeviceInput
NSError * error = nil;
AVCaptureDeviceInput * videoInput = [[AVCaptureDeviceInput alloc] initWithDevice:device error:&error];
if (error != nil) {
NSLog(@"init AVCaptureDeviceInput failed");
}
self.activeDeviceInput = videoInput;
// 2.AVCaptureSession 添加视频输入设备
if ([self.captureSession canAddInput:videoInput]) {
[self.captureSession addInput:videoInput];
}
// 3. 创建视频输出设备
AVCaptureVideoDataOutput * videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];
self.videoDataOutput = videoDataOutput;
// 4. 设置视频输出格式 YUV420
videoDataOutput.videoSettings = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange] forKey:(id)kCVPixelBufferPixelFormatTypeKey];
// 5. 是否丢弃延时帧
[videoDataOutput setAlwaysDiscardsLateVideoFrames:YES];
// 6. 设置视频输出代理和队列
dispatch_queue_t videoQueue = dispatch_queue_create("video output queue", DISPATCH_QUEUE_SERIAL);
[videoDataOutput setSampleBufferDelegate:self queue:videoQueue];
// 7. 添加视频输出设备
if ([self.captureSession canAddOutput:videoDataOutput]) {
[self.captureSession addOutput:videoDataOutput];
}
// 8. 设置视频输出连接AVCaptureConnection
AVCaptureConnection * connection = [videoDataOutput connectionWithMediaType:AVMediaTypeVideo];
self.videoConnection = connection;
// 9. 设置视频输出方向
[connection setVideoOrientation:AVCaptureVideoOrientationPortrait];
// 10. 判断是否支撑视频稳定 可以显著提高视频的质量 只会在录制视频文件涉及到
if ([connection isVideoStabilizationSupported]) {
connection.preferredVideoStabilizationMode = YES;
}
}
- 设置音频信息
- (void)setupAudio {
// 1. 创建视频输入设备 AVCaptureDevice -> AVCaptureDeviceInput
AVCaptureDevice * device = nil;
if (@available (iOS 10, *)) {
device = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInMicrophone mediaType:AVMediaTypeAudio position:AVCaptureDevicePositionUnspecified];
} else {
device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
}
// 创建音频输入AVCaptureDeviceInput
NSError * error = nil;
AVCaptureDeviceInput * audioInput = [[AVCaptureDeviceInput alloc] initWithDevice:device error:&error];
if (error != nil) {
NSLog(@"init AVCaptureDeviceInput failed");
}
// 2.添加音频输入设备
if ([self.captureSession canAddInput:audioInput]) {
[self.captureSession addInput:audioInput];
}
// 3. 创建音频输出设备
AVCaptureAudioDataOutput * audioDataOutput = [[AVCaptureAudioDataOutput alloc] init];
self.audioDataOutput = audioDataOutput;
// 4. 设置音频代理和队列
dispatch_queue_t audioQueue = dispatch_queue_create("audio output queue", DISPATCH_QUEUE_SERIAL);
[audioDataOutput setSampleBufferDelegate:self queue:audioQueue];
// 5. 添加音频输出设备
if ([self.captureSession canAddOutput:audioDataOutput]) {
[self.captureSession addOutput:audioDataOutput];
}
// 6.设置音频输出连接
AVCaptureConnection * audioConnection = [audioDataOutput connectionWithMediaType:AVMediaTypeAudio];
self.audioConnection = audioConnection;
}
- 设置预览图层
// 创建预览图层
- (void)setupPreviewLayer {
AVCaptureVideoPreviewLayer * previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
previewLayer.frame = self.bounds;
// 全屏
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.layer addSublayer:previewLayer];
}
5.开启结束捕捉音视频
// 开始
- (void)startRunningCaptureSession {
dispatch_async(self.captureSessionQueue, ^{
if (!self.captureSession.isRunning) {
[self.captureSession startRunning];
}
});
}
// 结束
- (void)stopRunningCaptureSession {
dispatch_async(self.captureSessionQueue, ^{
if (self.captureSession.isRunning) {
[self.captureSession stopRunning];
}
});
}
6.音视频数据处理
- (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
// 判断音频还是视频
// 视频
if ([connection isEqual:self.videoConnection]) {
NSLog(@"video sampleBuffer%@", sampleBuffer);
}
// 音频
if ([connection isEqual:self.audioConnection]) {
NSLog(@"audio sampleBuffer%@", sampleBuffer);
}
// 视频
if ([output isEqual:self.videoDataOutput]) {
}
// 音频
if ([output isEqual:self.audioDataOutput]) {
}
}
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