A simple Objective-C class for creating a reversed (silent) version of a video file. Reversal occurs in its own thread, input frames are read in passes to reduce memory usage, and a delegate can be called upon completion or error.
Create an instance of the class, set any custom reader settings, and call the main method with the inputPath of the video to be reversed, and the outputPath where the finished result will reside:
NSString *inputPath = [[NSBundle mainBundle] pathForResource:@"input" ofType:@"mov"];
// create a path for our reversed output video
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
outputPath = [documentsPath stringByAppendingFormat:@"/reversed.mov"];
// get instance of our reverse video class
CSVideoReverse *reverser = [[CSVideoReverse alloc] init];
reverser.delegate = self;
// if custom reader settings are desired
reverser.readerOutputSettings = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange], kCVPixelBufferPixelFormatTypeKey, nil];
// now start the reversal process
[reverser reverseVideoAtPath:inputPath outputPath:outputPath];Then implement the delegate method of the class to get the result:
#pragma mark CSVideoReverseDelegate Methods
- (void)didFinishReverse:(bool)success withError:(NSError *)error {
if (!success) {
NSLog(@"%s error: %@", __FUNCTION__, error.localizedDescription);
}
else {
// show the reversed video located at outputPath
}
}Build the XCode project at example/CSVideoReverse.xcodeproj to see it in action with reverse video playback - you may want to sub in your own .mov or .mp4 file in example/CSVideoReverse/ViewController.m. At some point, I'll add a UIImagePickerController so you can simply choose from Camera Roll instead of having to reference an asset within the app bundle itself.
All source code is licensed under the MIT-License.