问题
I am using AVFoundation's AVPlayer to play 2 video clips made from 1 longer video (so the end of the first matches the beginning of the second)
When the first video ends and the user taps, I create a new AVPlayer and assign it to my PlayerView, and start playing the second clip.
This all works, however, there is a prominent screen "flicker".
My assumption is that this is caused by the player view removing the first clip and then showing the second clip.
What I need is for this flicker to no appear, so that going between the two clips is seamless.
Do anyone know if there is a way to stop this flickr, either via the AVPlayer* classes, or a way to "fake" it by doing something to make it so this isn't visible.
Thanks
Below is the code of my load and play method:
- (void)loadAssetFromFile
{
NSURL *fileURL = nil;
switch (playingClip)
{
case 1:
fileURL = [[NSBundle mainBundle] URLForResource:@"wh_3a" withExtension:@"mp4"];
break;
case 2:
fileURL = [[NSBundle mainBundle] URLForResource:@"wh_3b" withExtension:@"mp4"];
break;
case 3:
fileURL = [[NSBundle mainBundle] URLForResource:@"wh_3c" withExtension:@"mp4"];
break;
case 4:
fileURL = [[NSBundle mainBundle] URLForResource:@"wh_3d" withExtension:@"mp4"];
break;
default:
return;
break;
}
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:fileURL options:nil];
NSString *tracksKey = @"tracks";
[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:tracksKey] completionHandler:
^{
// The completion block goes here.
NSError *error = nil;
AVKeyValueStatus status = [asset statusOfValueForKey:tracksKey error:&error];
if (status == AVKeyValueStatusLoaded)
{
self.playerItem = [AVPlayerItem playerItemWithAsset:asset];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerItemDidReachEnd:) name:AVPlayerItemDidPlayToEndTimeNotification object:playerItem];
self.player = [AVPlayer playerWithPlayerItem:playerItem];
[playerView setPlayer:player];
[self.player seekToTime:kCMTimeZero];
[self play];
}
else {
// Deal with the error appropriately.
NSLog(@"The asset's tracks were not loaded:\n%@", [error localizedDescription]);
}
}];
}
回答1:
You do not need to re-create AVPlayer for this task. You can just have multiple AVPlayerItems and then switch which one is current via [AVPlayer replaceCurrentItemWithPlayerItem:item].
Also, you can observe for when current item has changed with the code below.
static void* CurrentItemObservationContext = &CurrentItemObservationContext;
... After creating a player, register the observer:
[player1 addObserver:self
forKeyPath:kCurrentItemKey
options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
context:CurrentItemObservationContext];
...
- (void)observeValueForKeyPath:(NSString*) path
ofObject:(id)object
change:(NSDictionary*)change
context:(void*)context {
if (context == CurrentItemObservationContext) {
AVPlayerItem *item = [change objectForKey:NSKeyValueChangeNewKey];
if (item != (id)[NSNull null]) {
[player1 play];
}
}
}
回答2:
There are two workaround that I found. To me both approaches worked and I prefer the second one.
First, as @Alex Kennberg mentioned, create two set of AVPlayerLayer and AVPlayer. and switching them when you switch between videos. Be sure to set background color to clear color.
Second, use UIImageView as the owner view of AVPlayerLayer. Create thumbnail image of a video and set it to the imageview before switching the video. Be sure to set the view mode correctly.
回答3:
I tried this and it worked for me.
if (layerView1.playerLayer.superlayer) {
[layerView1.playerLayer removeFromSuperlayer];
}
But I am also allocating my own AVPlayerLayer instead of using IB to do it.
回答4:
After too many tries without success, I finally found a solution, not the best one, but works
My entry code bellow, have a look at the loadVideo method
#import "ViewController.h"
#import <AVKit/AVKit.h>
@interface ViewController ()<UIGestureRecognizerDelegate>
@property (nonatomic, strong) NSArray *videos;
@property (nonatomic, assign) NSInteger videoIndex;
@property (nonatomic, strong) AVPlayer *player;
@property (nonatomic, strong) AVPlayerLayer *playerLayer;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor blackColor];
self.videos = @[@"1.mp4", @"2.mp4", @"3.mp4", @"4.mp4", @"5.mp4", @"6.mp4"];
self.videoIndex = 0;
[self loadVideo];
[self configureGestures:self.view]; //changes video on swipe
}
-(void)prevZoomPanel{
if(self.videoIndex <= 0){
NSLog(@"cant go prev");
return;
}
self.videoIndex -= 1;
[self loadVideo];
}
-(void)nextZoomPanel{
if(self.videoIndex >= self.videos.count - 1){
NSLog(@"cant go next");
return;
}
self.videoIndex += 1;
[self loadVideo];
}
#pragma mark - Load Video
-(void)loadVideo{
NSURL * bundle = [[NSBundle mainBundle] bundleURL];
NSURL * file = [NSURL URLWithString:self.videos[self.videoIndex] relativeToURL:bundle];
NSURL * absoluteFile = [file absoluteURL];
AVPlayerItem *item = [AVPlayerItem playerItemWithURL:absoluteFile];
//*************
//DO NOT USE '[self.player replaceCurrentItemWithPlayerItem:item]', it flashes, instead, initialize the instace again.
//Why is replaceCurrentItemWithPlayerItem flashing but playerWithPlayerItem is NOT?
// if you want to see the diferente, uncomment the code above
self.player = [AVPlayer playerWithPlayerItem:item];
// if (self.player == nil) {
// self.player = [AVPlayer playerWithPlayerItem:item];
// }else{
// [self.player replaceCurrentItemWithPlayerItem:item];
// }
//*************
//create an instance of AVPlayerLayer and add it on self.view
//afraid of this
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player];
playerLayer.videoGravity = AVLayerVideoGravityResizeAspect;
playerLayer.frame = self.view.layer.bounds;
[self.view.layer addSublayer:playerLayer];
//*************
//play the video before remove the old AVPlayerLayer instance, at this time will have 2 sublayers
[self.player play];
NSLog(@"sublayers before: %zd", self.view.layer.sublayers.count);
//*************
//remove all sublayers after 0.09s, to avoid the flash, 0.08 still flashing.
//TODO: tested on iPhone X, need to test on slower iPhones to check if the time is enough.
//Why do I need to wait to remove? Is that safe? What if I swipe a lot too fast, faster than 0.09s ?
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.09 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
NSArray* sublayers = [NSArray arrayWithArray:self.view.layer.sublayers];
NSInteger idx = 0;
for (CALayer *layer in sublayers) {
if (idx < self.view.layer.sublayers.count && self.view.layer.sublayers.count > 1) {
//to avoid memory crash, need to remove all sublayer but keep the top one.
[layer removeFromSuperlayer];
}
idx += 1;
}
NSLog(@"sublayers after: %zd", self.view.layer.sublayers.count);
});
//*************
//the code bellow is the same of the above, but with no delay
//uncomment the code bellow AND comment the code above to test
// NSArray* sublayers = [NSArray arrayWithArray:self.view.layer.sublayers];
// NSInteger idx = 0;
//
// for (CALayer *layer in sublayers) {
//
// if (idx < self.view.layer.sublayers.count && self.view.layer.sublayers.count > 1) {
//
// //to avoid memory crash, need to remove all sublayer but keep the top one.
// [layer removeFromSuperlayer];
// }
// idx += 1;
// }
//*************
//App's memory usage is about 14MB constantly, didn't increase on videos change.
//TODO: need to test with more than 100 heavy videos.
}
-(void)configureGestures:(UIView *)view{
UISwipeGestureRecognizer *right = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(userDidSwipeScreen:)];
right.direction = UISwipeGestureRecognizerDirectionRight;
right.delegate = self;
[view addGestureRecognizer:right];
UISwipeGestureRecognizer *left = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(userDidSwipeScreen:)];
left.direction = UISwipeGestureRecognizerDirectionLeft;
left.delegate = self;
[view addGestureRecognizer:left];
}
- (void)userDidSwipeScreen:(UISwipeGestureRecognizer *)swipeGestureRecognizer{
switch (swipeGestureRecognizer.direction) {
case UISwipeGestureRecognizerDirectionLeft: [self nextZoomPanel];break;
case UISwipeGestureRecognizerDirectionRight:[self prevZoomPanel];break;
default: break;
}
}
@end
回答5:
I found a very simple solution (maybe too simple for some people, but for me it worked): In Interface Builder I set the background color of my view (which gets the video layer attached to) to black. So it's just 'flashing' black now...
来源：https://stackoverflow.com/questions/7238200/switching-videos-in-avplayer-creates-flash-when-changing