我在调用相机视图录制视频前，实现了一个覆盖视图。
pickerController.cameraOverlayView =myOverlay;
在录制视频并通过电子邮件等方式分享后，将视频录制并保存到相册中都正常工作。
如果我使用“高质量”作为视频质量，则录制的视频文件大小会变得非常大。例如，如果我以高质量录制30秒的视频，则录制的视频文件大小约为30-40 MB。
pickerController.videoQuality = UIImagePickerControllerQualityTypeHigh;
如何像苹果内置视频录制一样，在分享前对高质量录制的视频进行压缩编程？
请指导我解决这个问题。
谢谢！
更新：
这是我最近尝试的方法，但仍然没有成功：我想要压缩通过didFinishPickingMediaWithInfo获取的已记录视频，并将其存储在同一个照片相册的实际视频路径中，而不是任何其他地方。当我从照片库中选择相同的视频时，测试发现该视频已被压缩到非常小的大小，但是通过didFinishPickingMediaWithInfo拍摄并传输的相同视频并没有被压缩，尽管我使用了下面的AVAssetExportSession代码。
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];
if ([mediaType isEqualToString:(NSString *)kUTTypeMovie])
{
NSURL *videoURL = [info objectForKey:UIImagePickerControllerMediaURL];
NSString *urlPath = [videoURL path];
if ([[urlPath lastPathComponent] isEqualToString:@"capturedvideo.MOV"])
{
if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum (urlPath))
{
[self copyTempVideoToMediaLibrary :urlPath];
}
else
{
NSLog(@"Video Capture Error: Captured video cannot be saved...didFinishPickingMediaWithInfo()");
}
}
else
{
NSLog(@"Processing soon to saved photos album...else loop of lastPathComponent..didFinishPickingMediaWithInfo()");
}
}
[self dismissModalViewControllerAnimated:YES];
}
- (void)copyTempVideoToMediaLibrary :(NSString *)videoURL {
dispatch_queue_t mainQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(mainQueue, ^{
ALAssetsLibrary *library = [[[ALAssetsLibrary alloc] init] autorelease];
ALAssetsLibraryWriteVideoCompletionBlock completionBlock = ^(NSURL *assetURL, NSError *error) {
NSLog(@"Saved URL: %@", assetURL);
NSLog(@"Error: %@", error);
if (assetURL != nil) {
AVURLAsset *theAsset = [AVURLAsset URLAssetWithURL:[NSURL URLWithString:videoURL] options:nil];
NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:theAsset];
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:theAsset presetName:AVAssetExportPresetLowQuality];
[exportSession setOutputURL:[NSURL URLWithString:videoURL]];
[exportSession setOutputFileType:AVFileTypeQuickTimeMovie];
[exportSession exportAsynchronouslyWithCompletionHandler:^ {
switch ([exportSession status]) {
case AVAssetExportSessionStatusFailed:
NSLog(@"Export session faied with error: %@", [exportSession error]);
break;
default:
//[self mediaIsReady];
break;
}
}];
}
};
[library writeVideoAtPathToSavedPhotosAlbum:[NSURL URLWithString:videoURL] completionBlock:completionBlock];
});
}