最近在研究视频录制，网上找的demo都设置不了帧数，这样就不能通过设置低帧数的方法来达到减小文件大小的目的，网上demo都是这样设置帧数的，以设置最大帧数10为例
//初始化视频输入
NSDictionary*compressionSettings = [NSDictionarydictionaryWithObjectsAndKeys:
[NSNumbernumberWithInteger:300*1000],AVVideoAverageBitRateKey,
[NSNumbernumberWithInteger:10],AVVideoExpectedSourceFrameRateKey,
[NSNumbernumberWithInteger:10],AVVideoMaxKeyFrameIntervalKey,
AVVideoProfileLevelH264HighAutoLevel,AVVideoProfileLevelKey,
nil,nil];
然而你会发现录制出来的还是30帧
正确做法是通过CMTimeperferTimescale来设置，而且得在 添加视频输出和添加音频输出之后设置才有效
//4.1设置采集帧率
CMTimeperferTimescale =CMTimeMake(1,15);
BOOLisSupport =NO;
//获取视频输入设备(摄像头)
AVCaptureDevice*device=[selfbackCamera];//取得后置摄像头
for(AVFrameRateRange*supportFrameindevice.activeFormat.videoSupportedFrameRateRanges) {
int32_tminv =CMTimeCompare(perferTimescale, supportFrame.minFrameDuration);
int32_tmaxv =CMTimeCompare(perferTimescale, supportFrame.maxFrameDuration);
if(maxv <=0&&minv >=0) {
isSupport =YES;
break;
}
}
if(isSupport) {
[devicelockForConfiguration:nil];
device.activeVideoMaxFrameDuration= perferTimescale;
device.activeVideoMinFrameDuration= perferTimescale;
[deviceunlockForConfiguration];
}
