借助LFLiveKit实现AR推流功能

LFLiveKit中的相机是通过GPUImage实现的，并没有AR功能；如果想实现AR直播的功能又想使用LFLiveKit的推流功能，可以通过对LFLiveKit进行改造来实现AR直播功能。

LFLiveKit中图像信息的主要来源是封装了GUPImage的LFVideoCapture类，其获取到图像资源之后以CVPixelBufferRef的格式返回给LFLiveSession，LFLiveSession是主要的数据交换中心，那么就可以通过修改LFLiveSession中的视频采集对象就可以实现具有AR功能的LFLiveKit。

#import "ViewController.h"
#import <ARKit/ARKit.h>
#import <Metal/Metal.h>
#import <Metal/MTLTexture.h>
#import "PFDelegate.h"
#import "PFHardwareVideoEncoder.h"
#import "PFLiveKit.h"

@interface ViewController ()<ARSCNViewDelegate, ARSessionDelegate, ARSessionObserver, PFLiveSessionDelegate>

@property (nonatomic, strong) ARSCNView * scnView;
@property (nonatomic, strong) SCNScene * scene;
@property (nonatomic, strong) SCNNode * sunNode;
@property (nonatomic, strong) ARSession * session;
@property (nonatomic, strong) ARWorldTrackingConfiguration * config;
@property (nonatomic, strong) PFLiveSession * videoSession;
@property (nonatomic, assign) BOOL isPushing;

@property (weak, nonatomic) IBOutlet UIButton *liveingBtn;

@end

#define ScreenSize [UIScreen mainScreen].bounds.size

@implementation ViewController


- (void)viewDidLoad {
    [super viewDidLoad];
    [self loadScnView];
    [self configEncoderSession];
    [self configView];
}

- (void)loadScnView
{
    self.scnView = [[ARSCNView alloc] initWithFrame:CGRectMake(0, 0, ScreenSize.width, ScreenSize.height)];
    [self.view addSubview:self.scnView];
//    self.scnView.allowsCameraControl = YES;
    self.scnView.showsStatistics = YES;
    self.scnView.delegate = self;

    
    self.session = [[ARSession alloc] init];
    self.scnView.session = self.session;
    self.scnView.session.delegate = self;
    self.session.delegate = self;
    
    [self loadMode];
    
    self.config = [[ARWorldTrackingConfiguration alloc] init];
    self.config.planeDetection = ARPlaneDetectionHorizontal;    // 设置主要监测平面
    self.config.lightEstimationEnabled = YES;   // 是否支持现实光照补给
    self.config.providesAudioData = YES;    // 配置支持音频
    [self.session runWithConfiguration:self.config];
    
}

- (void)configView
{
    [self.view bringSubviewToFront:self.liveingBtn];
    
    [self.liveingBtn addTarget:self action:@selector(begainLiveVideo:) forControlEvents:UIControlEventTouchUpInside];
}


- (void)configEncoderSession
{
    PFLiveAudioConfiguration *audioConfiguration = [PFLiveAudioConfiguration new];  //
     // 设置音频相关
    audioConfiguration.numberOfChannels = 1;  // 设置声道数
    audioConfiguration.audioBitrate = PFLiveAudioBitRate_128Kbps;  // 设置音频的码率
    audioConfiguration.audioSampleRate = PFLiveAudioSampleRate_44100Hz;  //音频采样率
    
    // 配置编解码
    PFLiveVideoConfiguration *videoConfiguration = [PFLiveVideoConfiguration new];
    videoConfiguration.videoSize = CGSizeMake(720, 1280);  // 视频尺寸
    videoConfiguration.videoBitRate = 800*1024;  //视频码率，比特率 Bit Rate或叫位速率，是单位时间内视频（或音频）的数据量，单位是 bps (bit per second，位每秒），一般使用 kbps（千位每秒）或Mbps（百万位每秒）。
    videoConfiguration.videoMaxBitRate = 1000*1024;  // 最大码率
    videoConfiguration.videoMinBitRate = 500*1024;  // 最小码率
    videoConfiguration.videoFrameRate = 15;  //  帧率，即fps
    videoConfiguration.videoMaxKeyframeInterval = 30;  // 最大关键帧间隔，可设定为 fps 的2倍，影响一个 gop 的大小
    videoConfiguration.outputImageOrientation = UIInterfaceOrientationPortrait;  //视频输出方向
    videoConfiguration.sessionPreset = PFCaptureSessionPreset360x640;  //视频分辨率(都是16：9 当此设备不支持当前分辨率，自动降低一级)
    
    self.videoSession = [[PFLiveSession alloc] initWithAudioConfiguration:audioConfiguration videoConfiguration:videoConfiguration];
    
    self.videoSession.delegate = self;
    self.videoSession.showDebugInfo = NO;
}

- (void)loadMode
{
    SCNSphere * sunSphere = [SCNSphere sphereWithRadius:0.2];
    sunSphere.firstMaterial.multiply.contents = @"art.scnassets/earth/sun.jpg";
    sunSphere.firstMaterial.diffuse.contents = @"art.scnassets/earth/sun.jpg";
    sunSphere.firstMaterial.multiply.intensity = 0.5;
    sunSphere.firstMaterial.lightingModelName = SCNLightingModelConstant;
    
    self.sunNode = [[SCNNode alloc] init];
    self.sunNode.geometry = sunSphere;
    
    self.sunNode.position = SCNVector3Make(0, 0, -2);
 
    [self.scnView.scene.rootNode addChildNode:self.sunNode];

    SCNAction * act = [SCNAction repeatActionForever:[SCNAction rotateByX:0 y:1 z:0 duration:1]];
    [_sunNode runAction:act];
}

- (void)session:(ARSession *)session didOutputAudioSampleBuffer:(CMSampleBufferRef)audioSampleBuffer
{
    [self.videoSession captureOutputAudioData:audioSampleBuffer];
}

- (void)renderer:(id<SCNSceneRenderer>)renderer updateAtTime:(NSTimeInterval)time
{
    if (renderer.currentRenderPassDescriptor.colorAttachments[0].texture == nil) {
        return;
    }
    CVPixelBufferRef pixelBuffer = nil;
    if (renderer.currentRenderPassDescriptor.colorAttachments[0].texture.iosurface == nil) {
        return;
    }
    CVPixelBufferCreateWithIOSurface(kCFAllocatorDefault, renderer.currentRenderPassDescriptor.colorAttachments[0].texture.iosurface, nil, &pixelBuffer);
    // 通过该方法将获取的资源传递给LFLiveKit
    [self.videoSession captureOutputPixelBuffer:pixelBuffer];
}

- (void)begainLiveVideo:(UIButton *)sender
{
    if (self.isPushing == YES) {
        [self.videoSession stopLive];
        self.isPushing = NO;
        [sender setTitle:@"开始直播" forState:UIControlStateNormal];
    } else {
        PFLiveStreamInfo *stream = [PFLiveStreamInfo new];
        stream.url = @"rtmp://192.168.2.160:1935/rtmplive/demo";
        [self.videoSession startLive:stream];
        self.isPushing = YES;
        [sender setTitle:@"关闭直播" forState:UIControlStateNormal];
    }
}

效果图：