AVFoundation总结

1, Using Assets ［自己理解为：数据的来源］ 
这个资源可以来自自己的ipod媒体库或图片也可以时文件 
creating> AVURLAsset *ansset = [[AVURLSset alloc] initwithURL:url  options:nil]; 
2.获得一个视频的图像 
使用AVASsetImageGenerator类来实现 
用来生成图像序列 
3.Playback 
我们在播放视频时可以使用AVPlayer和AVQueuePlayer播放AVPlayer是AVQueuePlayer的父类 
a先创建一个路径 
b可以使用AVPlayerItem加载路径 
c使用AVPlayer播放文件 
当然我们还可以控制它的播放速度 
使用rate属性它是一个介于0.0－－1.0之间的数 
 
我们也可以播放多个项目 
NSArray *items  = // 设置一个播放的组合 
AVQueuePlayer ＊queueplayer ＝ ［［AVQueuePlayer> if([session canSetSessionPreset:AVCaptureSessionPrese 1280x720]){ 
session.sessionPreset = AVCaptureSessionPreset 1280x720; 
}else{ 
// Handle> fo(AVCaptureDevice *device in device){ 
NSLogO("Device> nslog(@"Device postion :back"); 
}else{ 
NSLog(@"Device> NsMutableArray *torchDevices =  [[NSMutableArray alloc]init];  
for(AVCaptureDevice *device> [session beginConfiguration]; 
 
[session> AVCaptureDeviceInput *captureDeviceInput = <#Get a capture device input#>;  
// 检查是否适用 
if ([captureSession> AVCaptureMovieFileOutput *movieInput = <#Create and configure a movie output#>;  
if ([captureSession> CMTime maxDuration = <#Create a CMTime to represent the maximum duration#>; aMovieFileOutput.maxRecordedDuration = maxDuration;  
aMovieFileOutput.minFreeDiskSpaceLimit = <#An> NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey, nil]; [stillImageOutput setOutputSettings:outputSettings]; 
13 重力模式 
The>     for ( AVCaptureDevice *device in devices ) 
       >             return device; 
   >     for ( AVCaptureDeviceInput *input in inputs ) { 
        AVCaptureDevice *device =>             AVCaptureDevice *newCamera = nil; 
            AVCaptureDeviceInput *newInput =>                 newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack]; 
           >             newInput = [AVCaptureDeviceInput deviceInputWithDevice:newCamera error:nil]; 
 
            // beginConfiguration ensures that pending changes are not applied immediately 
            [self.session beginConfiguration]; 
 
            [self.session removeInput:input]; 
            [self.session addInput:newInput]; 
 
            // Changes take effect once the outermost commitConfiguration is invoked. 
            [self.session commitConfiguration]; 
            break; 
        } 
    }  
}