代码 tips

摄像头的一些关键词

曝光

白平衡

测光

调焦

防抖

采集帧率设置

先判断摄像头支持的帧率

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- (BOOL)supportsVideoFrameRate:(NSInteger)videoFrameRate
{
    if (!_device) {
        return NO;
    }
    
    AVCaptureDeviceFormat* format = [_device activeFormat];
    NSArray *videoSupportedFrameRateRanges = [format videoSupportedFrameRateRanges];
    for (AVFrameRateRange *frameRateRange in videoSupportedFrameRateRanges) {
        if ( (frameRateRange.minFrameRate <= videoFrameRate) && (videoFrameRate <= frameRateRange.maxFrameRate) ) {
            return YES;
        }
    }
    
    return NO;
}

然后设置最大、最小的帧间间隔

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- (void)doSetFrameRate:(int32_t)frameRate
{
    if (![self supportsVideoFrameRate:frameRate]) {
        //   NSLog(@"CameraCaptureFilter not support framerate %d", newFrameRate);
        return;
    }
    AVCaptureDevice *videoDevice = _device;
    
    if ([videoDevice lockForConfiguration:NULL]) {
        [videoDevice setActiveVideoMinFrameDuration:CMTimeMake(1, frameRate)];
        [videoDevice setActiveVideoMaxFrameDuration:CMTimeMake(1, frameRate)];
        
        [videoDevice unlockForConfiguration];
        _frameRate = frameRate;
        _cameraJustChanged = YES;
    }
}