ALAsset thumbnail at specific timestamp - iphone

Question

I'm working working on an iPhone application for uploading video files to a specific platform, and one feature I would really love is to be able to present, say, ten different thumbnails for the same video for the user to pick from.
The problem is, that ALAsset only provides a thumbnail method, which just returns the default thumbnail. I have read through the ALAssetRepresentation and ALAsset documentation and I can't seem to find a way to get a thumbnail for a specific timestamp.
I guess one option would be to use something along the lines of libav to get thumbnails but that seems a little "over the top" for something like this. Can anyone help me on this one?
Best regards,
Nick

Answer 1

i think this will help you , and
you can also see through this prompt
Video File thumbnail timestamp missing in ALAsset
{
if ([theAsset valueForProperty:ALAssetPropertyType] == ALAssetTypeVideo) {
// Black semi-transparent background at the bottom of the item
CGRect containerFrame = CGRectMake(0, frame.size.height - AGIPC_ITEM_HEIGHT, frame.size.width, AGIPC_ITEM_HEIGHT);
UIView *containerForMovieInfo = [[[UIView alloc] initWithFrame:containerFrame] autorelease];
containerForMovieInfo.backgroundColor = [UIColor blackColor];
containerForMovieInfo.alpha = 0.7f;
// Movie icon on left side
CGRect movieFrame = CGRectMake(4, 60, 26, 15);
UIImageView *movieImageView = [[[UIImageView alloc] initWithFrame:movieFrame] autorelease];
if (IS_IPAD()) {
movieImageView.image = [UIImage imageNamed:#"AGIPC-Movie-iPad"];
} else {
movieImageView.image = [UIImage imageNamed:#"AGIPC-Movie-iPhone"];
}
[containerForMovieInfo addSubview:movieImageView];
// Movie duration on right side
if ([theAsset valueForProperty:ALAssetPropertyDuration] != ALErrorInvalidProperty) {
NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];
[formatter setDateFormat:#"mm:ss"];
CGRect durationFrame = CGRectMake(frame.size.width - 26 - 4, 60, 26, 15);
UILabel *durationView = [[[UILabel alloc] initWithFrame:durationFrame] autorelease];
durationView.backgroundColor = [UIColor clearColor];
durationView.textColor = [UIColor whiteColor];
durationView.text = [formatter stringFromDate:[NSDate dateWithTimeIntervalSince1970:[[theAsset valueForProperty:ALAssetPropertyDuration] doubleValue]]];
durationView.font = [UIFont systemFontOfSize:10];
[containerForMovieInfo addSubview:durationView];
}
[self addSubview:containerForMovieInfo];
}
}
last but not least, you must creat the image of the camera on your own.

Answer 2

// Get URL from ALAsset* asset:
NSURL* assetURL = [asset valueForProperty:ALAssetPropertyAssetURL];
// Create AVURLAsset using this URL (assetOptions is optional):
NSDictionary* assetOptions = nil;
// assetOptions = #{AVURLAssetPreferPreciseDurationAndTimingKey : #(YES)};
AVAsset* avAsset = [[AVURLAsset alloc] initWithURL:assetURL options:assetOptions];
// Create generator:
AVAssetImageGenerator* generator = [[AVAssetImageGenerator alloc] initWithAsset:avAsset];
generator.appliesPreferredTrackTransform = YES;
// Create array with CMTimes of thumbnails using your own logic.
// (Use +(NSValue*)valueWithCMTime:(CMTime)time to add CMTime in array).
NSArray* times = [self generateThumbnailTimesForVideo:avAsset];
// Generate thumbnail images asynchronously:
[generator generateCGImagesAsynchronouslyForTimes:times
completionHandler:^(CMTime requestedTime,
CGImageRef image,
CMTime actualTime,
AVAssetImageGeneratorResult result,
NSError* error)
{
// This block is performed for each CMTime in times array.
UIImage* thumbnail = [[UIImage alloc] initWithCGImage:image];
}
];
Synchronous method to get thumbnail at any time is
// PS: SYNC method:
CGImageRef imgRef = [generator copyCGImageAtTime:time actualTime:NULL error:&error];
UIImage* thumbnail = [[UIImage alloc] initWithCGImage:image];