调用系统UIImagePickerController录像并保存到指定的文件夹

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#pragma mark - 录像
- (void)recodVideo{

    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        UIImagePickerController* pickerView = [[UIImagePickerController alloc] init];
        pickerView.sourceType = UIImagePickerControllerSourceTypeCamera;
        NSArray* availableMedia = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera];
        pickerView.mediaTypes = [NSArray arrayWithObject:availableMedia[1]];
        pickerView.videoQuality = UIImagePickerControllerQualityTypeMedium;
        [self pushVieCtr:pickerView];
        //    pickerView.videoMaximumDuration = 60;
        pickerView.delegate = self;
        [pickerView release];

    }

}

#pragma mark - UIImagePickerControllerDelegate
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    _videoURL = [info[UIImagePickerControllerMediaURL] retain];
    NSLog(@"_videoURL = %@",_videoURL);

    [picker.flipboardNavigationController popViewController];
   [self encodeVideoOrientation:_videoURL];
    NSLog(@"_videoURL.absoluteString %@",_videoURL.path);

    //    NSString *videoPath = _videoURL.path;
    //    if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(videoPath)) {
    //        UISaveVideoAtPathToSavedPhotosAlbum(videoPath, self, NULL, NULL);
    //    }
}

- (void)encodeVideoOrientation:(NSURL *)anOutputFileURL
{

    _alert = [[UIAlertView alloc] init];
    [_alert setTitle:@"Waiting.."];

    UIActivityIndicatorView* activity = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    activity.frame = CGRectMake(140,
                                80,
                                CGRectGetWidth(_alert.frame),
                                CGRectGetHeight(_alert.frame));
    [_alert addSubview:activity];
    [activity startAnimating];
    [activity release];
    [_alert show];
    [_alert release];
    _startDate = [[NSDate date] retain];


    AVURLAsset * videoAsset = [[AVURLAsset alloc]initWithURL:anOutputFileURL options:nil];

    AVAssetExportSession * assetExport = [[AVAssetExportSession alloc] initWithAsset:videoAsset
                                                                          presetName:AVAssetExportPresetMediumQuality];
    NSDateFormatter* formater = [[NSDateFormatter alloc] init];
    [formater setDateFormat:@"yyyy-MM-dd-HH:mm:ss"];
    _mp4Path = [[NSHomeDirectory() stringByAppendingFormat:@"/Documents/videos/%@.mp4", [formater stringFromDate:[NSDate date]]] retain];
    [formater release];

    assetExport.outputURL = [NSURL fileURLWithPath: _mp4Path];
    assetExport.shouldOptimizeForNetworkUse = YES;
    assetExport.outputFileType = AVFileTypeMPEG4;
    assetExport.videoComposition = [self getVideoComposition:videoAsset];
    [assetExport exportAsynchronouslyWithCompletionHandler:^{
        switch ([assetExport status]) {
            case AVAssetExportSessionStatusFailed:
            {
                NSLog(@"AVAssetExportSessionStatusFailed!");
                [_alert dismissWithClickedButtonIndex:0 animated:NO];
                [self performSelectorOnMainThread:@selector(converFailed:) withObject:assetExport waitUntilDone:NO];
                break;
            }

            case AVAssetExportSessionStatusCancelled:
                NSLog(@"Export canceled");
                [_alert dismissWithClickedButtonIndex:0
                                             animated:YES];
                break;
            case AVAssetExportSessionStatusCompleted:
                NSLog(@"Successful!");
                [self performSelectorOnMainThread:@selector(convertFinish) withObject:nil waitUntilDone:NO];
                break;
            default:
                break;
        }
        [assetExport release];
    }];

}

#pragma mark - 解决录像保存角度问题

-(AVMutableVideoComposition *) getVideoComposition:(AVAsset *)asset
{
    AVAssetTrack *videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    AVMutableComposition *composition = [AVMutableComposition composition];
    AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
    CGSize videoSize = videoTrack.naturalSize;
    BOOL isPortrait_ = [self isVideoPortrait:asset];
    if(isPortrait_) {
        NSLog(@"video is portrait ");
        videoSize = CGSizeMake(videoSize.height, videoSize.width);
    }
    composition.naturalSize     = videoSize;
    videoComposition.renderSize = videoSize;
    // videoComposition.renderSize = videoTrack.naturalSize; //
    videoComposition.frameDuration = CMTimeMakeWithSeconds( 1 / videoTrack.nominalFrameRate, 600);

    AVMutableCompositionTrack *compositionVideoTrack;
    compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:videoTrack atTime:kCMTimeZero error:nil];
    AVMutableVideoCompositionLayerInstruction *layerInst;
    layerInst = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
    [layerInst setTransform:videoTrack.preferredTransform atTime:kCMTimeZero];
    AVMutableVideoCompositionInstruction *inst = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    inst.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration);
    inst.layerInstructions = [NSArray arrayWithObject:layerInst];
    videoComposition.instructions = [NSArray arrayWithObject:inst];
    return videoComposition;
}

-(BOOL) isVideoPortrait:(AVAsset *)asset
{
    BOOL isPortrait = FALSE;
    NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
    if([tracks    count] > 0) {
        AVAssetTrack *videoTrack = [tracks objectAtIndex:0];

        CGAffineTransform t = videoTrack.preferredTransform;
        // Portrait
        if(t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0)
        {
            isPortrait = YES;
        }
        // PortraitUpsideDown
        if(t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0)  {

            isPortrait = YES;
        }
        // LandscapeRight
        if(t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0)
        {
            isPortrait = FALSE;
        }
        // LandscapeLeft
        if(t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0)
        {
            isPortrait = FALSE;
        }
    }
    return isPortrait;
}