截屏实时录制

  _seam = dispatch_semaphore_create(0); //创建一个信号量

把UIImage转换成CVPixelBufferRef

- (CVPixelBufferRef)pixelBufferFromCGImage:(CGImageRef)image size:(CGSize)size {
    
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                           
                           [NSNumber numberWithBool:YES],kCVPixelBufferCGImageCompatibilityKey,
                           
                           [NSNumber numberWithBool:YES],kCVPixelBufferCGBitmapContextCompatibilityKey,nil];
    
    CVPixelBufferRef pxbuffer = NULL;
    
    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault,size.width,size.height,kCVPixelFormatType_32ARGB,(__bridge CFDictionaryRef) options,&pxbuffer);
    
    NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
    
    CVPixelBufferLockBaseAddress(pxbuffer,0);
    
    void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
    
    NSParameterAssert(pxdata !=NULL);
    
    CGColorSpaceRef rgbColorSpace=CGColorSpaceCreateDeviceRGB();
    
    //    当你调用这个函数的时候，Quartz创建一个位图绘制环境，也就是位图上下文。当你向上下文中绘制信息时，Quartz把你要绘制的信息作为位图数据绘制到指定的内存块。一个新的位图上下文的像素格式由三个参数决定：每个组件的位数，颜色空间，alpha选项
    
    CGContextRef context = CGBitmapContextCreate(pxdata,size.width,size.height,8,4*size.width,rgbColorSpace,kCGImageAlphaPremultipliedFirst);
    
    NSParameterAssert(context);
    
    
    CGContextDrawImage(context,CGRectMake(0,0,CGImageGetWidth(image),CGImageGetHeight(image)), image);
    
    // 释放色彩空间
    
    CGColorSpaceRelease(rgbColorSpace);
    
    // 释放context
    
    CGContextRelease(context);
    
    // 解锁pixel buffer
    
    CVPixelBufferUnlockBaseAddress(pxbuffer,0);
    
    return pxbuffer;
    
}

创建视频文件

/// 视频编码
-(void)recordVideoCodel
{
    self.theVideoPath = [self videoSavingPath:self.videoName];
    //定义视频的大小320 480 倍数
    
    CGSize size = CGSizeMake(320,480); // 192 256
    NSError *error = nil;
    
    __block AVAssetWriter *videoWriter = [[AVAssetWriter alloc]initWithURL:[NSURL fileURLWithPath:self.theVideoPath]fileType:AVFileTypeQuickTimeMovie error:&error];
    NSParameterAssert(videoWriter);
    
    if(error) {
        NSLog(@"error =%@",[error localizedDescription]);
        return;
    }

    //mp4的格式设置 编码格式 宽度 高度
    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:AVVideoCodecTypeH264, AVVideoCodecKey,
                                   [NSNumber numberWithInt:size.width], AVVideoWidthKey,
                                   [NSNumber numberWithInt:size.height], AVVideoHeightKey, nil];
    
    AVAssetWriterInput *writerInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
    
    NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithInt:kCVPixelFormatType_32ARGB],kCVPixelBufferPixelFormatTypeKey,nil];
    //    AVAssetWriterInputPixelBufferAdaptor提供CVPixelBufferPool实例,
    //    可以使用分配像素缓冲区写入输出文件。使用提供的像素为缓冲池分配通常
    //    是更有效的比添加像素缓冲区分配使用一个单独的池
    AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary];
    
    NSParameterAssert(writerInput);
    
    NSParameterAssert([videoWriter canAddInput:writerInput]);
    
    if([videoWriter canAddInput:writerInput]){
        
        NSLog(@"11111");
        
    }else{
        
        NSLog(@"22222");
        
    }

    [videoWriter addInput:writerInput];
    
    [videoWriter startWriting];
    [videoWriter startSessionAtSourceTime:kCMTimeZero];
    
    dispatch_queue_t dispatchQueue = dispatch_queue_create("mediaInputQueue", NULL);
    int __block frame = 0;
    __weak typeof(self)weakSelf = self;
    //开始写视频帧
    [writerInput requestMediaDataWhenReadyOnQueue:dispatchQueue usingBlock:^{
        while ([writerInput isReadyForMoreMediaData]) {
            if (_end) { //结束标记
                [writerInput markAsFinished];
                if (videoWriter.status == AVAssetWriterStatusWriting) {
                    NSCondition *cond = [[NSCondition alloc]init];
                    [videoWriter finishWritingWithCompletionHandler:^{
                        [cond lock];
                        [cond signal];
                        [cond unlock];
                    }];
                    [cond wait];
                    [cond unlock];
                    if (weakSelf.videoUrl) {
                        weakSelf.videoUrl(weakSelf.theVideoPath);
                    }//保存视频方法
                }
                break;
            }
            dispatch_semaphore_wait(_seam, DISPATCH_TIME_FOREVER);
            if (_imageBuffer) {
                //写入视频帧数据
                if (![adaptor appendPixelBuffer:_imageBuffer withPresentationTime:CMTimeMake(frame, 25)]) {
                    NSLog(@"success视频数据写入失败");
                }else{
                    NSLog(@"success视频数据写入成功");
                    frame++;
                }
                NSLog(@"--------->写入数据");
                //释放buffer
                CVPixelBufferRelease(_imageBuffer);
                CVPixelBufferRelease(_imgBuffer);
                _imgBuffer = NULL;
                _imageBuffer = NULL;
            }
        }
    }];
    
}

图片实时写入

/// 帧数据写入
/// @param image 图片帧
-(void)framedataWriting:(UIImage *)image
{
    CGSize size = CGSizeMake(320,480); // 192 256
    _imgBuffer = (CVPixelBufferRef)[self pixelBufferFromCGImage:[image CGImage] size:size];   //图片数据转入视频流bufferref
    CVPixelBufferLockBaseAddress(_imgBuffer, 0);
    _imageBuffer = CVPixelBufferRetain(_imgBuffer);
    CVPixelBufferUnlockBaseAddress(_imgBuffer, 0);
    //发送 写帧 信号
    dispatch_semaphore_signal(_seam);
    NSLog(@"--------->发送数据");
}

结束录制

/// 结束录制
-(void)endrecordVideo
{
    self.end = YES;
    dispatch_semaphore_signal(_seam);
}

目前长时间录制CPU 使用率到140%最高。内存控制在40M左右。 录制一个小时 手机微微有点发热，各位大佬看看有没有更好的方法实现长时间录制