Creating Thumbnail from Video - Improving Speed Performance - AVAsset - iPhone [duplicate] - iphone

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Grabbing First Frame of a Video - Thumbnail Resolution - iPhone
(1 answer)
Closed 3 years ago.
I am using code based on the code in the following thread to generate a video thumbnail :
Getting a thumbnail from a video url or data in iPhone SDK
My code is as follows :
if (selectionType == kUserSelectedMedia) {
NSURL * assetURL = [info objectForKey:UIImagePickerControllerReferenceURL];
AVURLAsset *asset=[[AVURLAsset alloc] initWithURL:assetURL options:nil];
AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
generator.appliesPreferredTrackTransform=TRUE;
[asset release];
CMTime thumbTime = CMTimeMakeWithSeconds(0,30);
//NSLog(#"Starting Async Queue");
AVAssetImageGeneratorCompletionHandler handler = ^(CMTime requestedTime, CGImageRef im, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error){
if (result != AVAssetImageGeneratorSucceeded) {
NSLog(#"couldn't generate thumbnail, error:%#", error);
}
//NSLog(#"Updating UI");
selectMediaButton.hidden = YES;
selectedMedia.hidden = NO;
cancelMediaChoiceButton.hidden = NO;
whiteBackgroundMedia.hidden = NO;
//Convert CGImage thumbnail to UIImage.
UIImage * thumbnail = [UIImage imageWithCGImage:im];
int checkSizeW = thumbnail.size.width;
int checkSizeH = thumbnail.size.height;
NSLog(#"Image width is %d", checkSizeW);
NSLog(#"Image height is %d", checkSizeH);
if (checkSizeW >=checkSizeH) {
//This is a landscape image or video.
NSLog(#"This is a landscape image - will resize automatically");
}
if (checkSizeH >=checkSizeW) {
//This is a portrait image or video.
selectedIntroHeight = thumbnail.size.height;
}
//Set the image once resized.
selectedMedia.image = thumbnail;
//Set out confirm button BOOL to YES and check if we need to display confirm button.
mediaReady = YES;
[self checkIfConfirmButtonShouldBeDisplayed];
//[button setImage:[UIImage imageWithCGImage:im] forState:UIControlStateNormal];
//thumbImg=[[UIImage imageWithCGImage:im] retain];
[generator release];
};
CGSize maxSize = CGSizeMake(320, 180);
generator.maximumSize = maxSize;
[generator generateCGImagesAsynchronouslyForTimes:[NSArray arrayWithObject:[NSValue valueWithCMTime:thumbTime]] completionHandler:handler];
}
}
The issue is that there is a delay of about 5-10 seconds in generating the thumbnail image. Is there anyway that I could improve the speed of this code and generate the thumbnail quicker ?
Thank you.

Answer 1

This is a generic code, you should just pass a path for the media file and set the ratio between 0 and 1.0.
+ (UIImage*)previewFromFileAtPath:(NSString*)path ratio:(CGFloat)ratio
{
AVAsset *asset = [AVURLAsset assetWithURL:[NSURL fileURLWithPath:path]];
AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc]initWithAsset:asset];
CMTime duration = asset.duration;
CGFloat durationInSeconds = duration.value / duration.timescale;
CMTime time = CMTimeMakeWithSeconds(durationInSeconds * ratio, (int)duration.value);
CGImageRef imageRef = [imageGenerator copyCGImageAtTime:time actualTime:NULL error:NULL];
UIImage *thumbnail = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return thumbnail;
}

Answer 2

Swift solution:
func previewImageForLocalVideo(url:NSURL) -> UIImage?
{
let asset = AVAsset(URL: url)
let imageGenerator = AVAssetImageGenerator(asset: asset)
imageGenerator.appliesPreferredTrackTransform = true
var time = asset.duration
//If possible - take not the first frame (it could be completely black or white on camara's videos)
time.value = min(time.value, 2)
do {
let imageRef = try imageGenerator.copyCGImageAtTime(time, actualTime: nil)
return UIImage(CGImage: imageRef)
}
catch let error as NSError
{
print("Image generation failed with error \(error)")
return nil
}
}