Play video in Mac OS X 10.7 - objective-c

Question

What is the simplest way to play a video programmatically with Objective-C in Mac OS X 10.7 (Lion)? And if I want to support OS X 10.6 (Snow Leopard) too?
I noticed that iOS AV Foundation was introduced to OS X 10.7. Unfortunately the documentation seems to be written for iOS and I found it confusing.

Answer 1

Here's a NSView subclass that plays a video given a URL, using AV Foundation (thus Mac OS X 10.7 upwards only). Based on the AVSimplePlayer sample code.
Header:
#interface RMVideoView : NSView
#property (nonatomic, readonly, strong) AVPlayer* player;
#property (nonatomic, readonly, strong) AVPlayerLayer* playerLayer;
#property (nonatomic, retain) NSURL* videoURL;
- (void) play;
#end
Implementation:
static void *RMVideoViewPlayerLayerReadyForDisplay = &RMVideoViewPlayerLayerReadyForDisplay;
static void *RMVideoViewPlayerItemStatusContext = &RMVideoViewPlayerItemStatusContext;
#interface RMVideoView()
- (void)onError:(NSError*)error;
- (void)onReadyToPlay;
- (void)setUpPlaybackOfAsset:(AVAsset *)asset withKeys:(NSArray *)keys;
#end
#implementation RMVideoView
#synthesize player = _player;
#synthesize playerLayer = _playerLayer;
#synthesize videoURL = _videoURL;
- (id)initWithFrame:(NSRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.wantsLayer = YES;
_player = [[AVPlayer alloc] init];
[self addObserver:self forKeyPath:#"player.currentItem.status" options:NSKeyValueObservingOptionNew context:RMVideoViewPlayerItemStatusContext];
}
return self;
}
- (void) dealloc {
[self.player pause];
[self removeObserver:self forKeyPath:#"player.currentItem.status"];
[self removeObserver:self forKeyPath:#"playerLayer.readyForDisplay"];
[_player release];
[_playerLayer release];
[_videoURL release];
[super dealloc];
}
- (void) setVideoURL:(NSURL *)videoURL {
_videoURL = videoURL;
[self.player pause];
[self.playerLayer removeFromSuperlayer];
AVURLAsset *asset = [AVAsset assetWithURL:self.videoURL];
NSArray *assetKeysToLoadAndTest = [NSArray arrayWithObjects:#"playable", #"hasProtectedContent", #"tracks", #"duration", nil];
[asset loadValuesAsynchronouslyForKeys:assetKeysToLoadAndTest completionHandler:^(void) {
dispatch_async(dispatch_get_main_queue(), ^(void) {
[self setUpPlaybackOfAsset:asset withKeys:assetKeysToLoadAndTest];
});
}];
}
#pragma mark - KVO
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if (context == RMVideoViewPlayerItemStatusContext) {
AVPlayerStatus status = [[change objectForKey:NSKeyValueChangeNewKey] integerValue];
switch (status) {
case AVPlayerItemStatusUnknown:
break;
case AVPlayerItemStatusReadyToPlay:
[self onReadyToPlay];
break;
case AVPlayerItemStatusFailed:
[self onError:nil];
break;
}
} else if (context == RMVideoViewPlayerLayerReadyForDisplay) {
if ([[change objectForKey:NSKeyValueChangeNewKey] boolValue]) {
self.playerLayer.hidden = NO;
}
} else {
[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
}
}
#pragma mark - Private
- (void)onError:(NSError*)error {
// Notify delegate
}
- (void)onReadyToPlay {
// Notify delegate
}
- (void)setUpPlaybackOfAsset:(AVAsset *)asset withKeys:(NSArray *)keys {
for (NSString *key in keys) {
NSError *error = nil;
if ([asset statusOfValueForKey:key error:&error] == AVKeyValueStatusFailed) {
[self onError:error];
return;
}
}
if (!asset.isPlayable || asset.hasProtectedContent) {
[self onError:nil];
return;
}
if ([[asset tracksWithMediaType:AVMediaTypeVideo] count] != 0) { // Asset has video tracks
_playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player];
self.playerLayer.frame = self.layer.bounds;
self.playerLayer.autoresizingMask = kCALayerWidthSizable | kCALayerHeightSizable;
self.playerLayer.hidden = YES;
[self.layer addSublayer:self.playerLayer];
[self addObserver:self forKeyPath:#"playerLayer.readyForDisplay" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew context:RMVideoViewPlayerLayerReadyForDisplay];
}
// Create a new AVPlayerItem and make it our player's current item.
AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset];
[self.player replaceCurrentItemWithPlayerItem:playerItem];
}
#pragma mark - Public
- (void) play {
[self.player play];
}
#end

Answer 2

"Simplest" depends on exactly what you're trying to do. If you want more control (e.g., rendering the movie as an OpenGL texture) or less (e.g., a completely independent window that you can just pop up and ignore), there might be different answers.
But for most use cases, if you want 10.6+ support, the simplest way to show a movie is QTKit. See the article "Using QTKit for Media Playback" in the Xcode documentation for a good starting point.