iOS: AVPlayer - getting a snapshot of the current frame of a video - ios

Question

I have spent the whole day and went through a lot of SO answers, Apple references, documentations, etc, but no success.
I want a simple thing: I am playing a video using AVPlayer and I want to pause it and get the current frame as UIImage. That's it.
My video is a m3u8 file located on the internet, it is played normally in the AVPlayerLayer without any problems.
What have I tried:
AVAssetImageGenerator. It is not working, the method copyCGImageAtTime:actualTime: error: returns null image ref. According to the answer here AVAssetImageGenerator doesn't work for streaming videos.
Taking snapshot of the player view. I tried first renderInContext: on AVPlayerLayer, but then I realized that it is not rendering this kind of "special" layers. Then I found a new method introduced in iOS 7 - drawViewHierarchyInRect:afterScreenUpdates: which should be able to render also the special layers, but no luck, still got the UI snapshot with blank black area where the video is shown.
AVPlayerItemVideoOutput. I have added a video output for my AVPlayerItem, however whenever I call hasNewPixelBufferForItemTime: it returns NO. I guess the problem is again streaming video and I am not alone with this problem.
AVAssetReader. I was thinking to try it but decided not to lose time after finding a related question here.
So isn't there any way to get a snapshot of something that I am anyway seeing right now on the screen? I can't believe this.

Answer 1

AVAssetImageGenerator is the best way to snapshot a video, this method return asynchronously a UIImage :
import AVFoundation
// ...
var player:AVPlayer? = // ...
func screenshot(handler:#escaping ((UIImage)->Void)) {
guard let player = player ,
let asset = player.currentItem?.asset else {
return
}
let imageGenerator = AVAssetImageGenerator(asset: asset)
imageGenerator.appliesPreferredTrackTransform = true
let times = [NSValue(time:player.currentTime())]
imageGenerator.generateCGImagesAsynchronously(forTimes: times) { _, image, _, _, _ in
if let img = image {
handler(UIImage(cgImage: img))
}
}
}
(It's Swift 4.2)

Answer 2

AVPlayerItemVideoOutput works fine for me from an m3u8. Maybe it's because I don't consult hasNewPixelBufferForItemTime and simply call copyPixelBufferForItemTime? This code produces a CVPixelBuffer instead of a UIImage, but there are answers that describe how to do that.
This answer mostly cribbed from here
#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
#interface ViewController ()
#property (nonatomic) AVPlayer *player;
#property (nonatomic) AVPlayerItem *playerItem;
#property (nonatomic) AVPlayerItemVideoOutput *playerOutput;
#end
#implementation ViewController
- (void)setupPlayerWithLoadedAsset:(AVAsset *)asset {
NSDictionary* settings = #{ (id)kCVPixelBufferPixelFormatTypeKey : #(kCVPixelFormatType_32BGRA) };
self.playerOutput = [[AVPlayerItemVideoOutput alloc] initWithPixelBufferAttributes:settings];
self.playerItem = [AVPlayerItem playerItemWithAsset:asset];
[self.playerItem addOutput:self.playerOutput];
self.player = [AVPlayer playerWithPlayerItem:self.playerItem];
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player];
playerLayer.frame = self.view.frame;
[self.view.layer addSublayer:playerLayer];
[self.player play];
}
- (IBAction)grabFrame {
CVPixelBufferRef buffer = [self.playerOutput copyPixelBufferForItemTime:[self.playerItem currentTime] itemTimeForDisplay:nil];
NSLog(#"The image: %#", buffer);
}
- (void)viewDidLoad {
[super viewDidLoad];
NSURL *someUrl = [NSURL URLWithString:#"http://qthttp.apple.com.edgesuite.net/1010qwoeiuryfg/sl.m3u8"];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:someUrl options:nil];
[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:#"tracks"] completionHandler:^{
NSError* error = nil;
AVKeyValueStatus status = [asset statusOfValueForKey:#"tracks" error:&error];
if (status == AVKeyValueStatusLoaded)
{
dispatch_async(dispatch_get_main_queue(), ^{
[self setupPlayerWithLoadedAsset:asset];
});
}
else
{
NSLog(#"%# Failed to load the tracks.", self);
}
}];
}
#end