AVAUdioPlayer - changing current URL - ios

In my audio player app, if I hit the fast forward button - the player must find the next song in the playlist and play it. What I do is I get the URL from the next song, and try to put it in the background (background is an instance of AVAudioPlayer*) url field, but that property is read only. So what I'm actually doing - I'm calling the initWithContentsOfURL method (again) to set the URL like this :
[self.background initWithContentsOfURL:
[[_playlist.collection objectAtIndex:currentIndex] songURL] error:nil];
Is this legit? I mean, the compiler tells me that the expression result is unused, but it actually works.
Is there another way of doing it? Thanks ;-)

For playing more than one URL, or effectively changing the URL, use the subclass AVQueuePlayer.
AVQueuePlayer is a subclass of AVPlayer you use to play a number of items in sequence.
Example:
NSString *fooVideoPath = [[NSBundle mainBundle] pathForResource:#"tommy" ofType:#"mov"];
NSString *barVideoPath = [[NSBundle mainBundle] pathForResource:#"pamela" ofType:#"mp4"];
AVPlayerItem *fooVideoItem = [AVPlayerItem playerItemWithURL:[NSURL fileURLWithPath:fooVideoPath]];
AVPlayerItem *barVideoItem = [AVPlayerItem playerItemWithURL:[NSURL fileURLWithPath:barVideoPath]];
self.queuePlayer = [AVQueuePlayer queuePlayerWithItems:[NSArray arrayWithObjects:fooVideoItem, barVideoItem,nil]];
[self.queuePlayer play];
// things happening...
[self.queuePlayer advanceToNextItem];

Have checked 4 Apple samples, they are using AVAudioPlayer to play one song only. However, your result looks very interesting and impressive! Please let us know, are you stopping the playback before reinitializing object with the same address, are you starting the new audio session ?
As for me, I'd not put the playback and app stability in a risk doing something not mentioned in the documentation but , but to be on the bright side would use the AVAudioPlayer class as it seems the most right, which gives us:
use the error variable to track the possible errors
stop the playing AVAudioPlayer instance, initialize a new instance of AVAudioPlayer and set it to the property letting an old-one to be deallocated automatically.
And you probably know yourself, that
self.background = [self.background initWithContentsOfURL::
will remove the warning for you.

Related

Finding the parent AVPlayer of an AVPlayerItem

I have an AVPlayerItem that I have been able to grab from my UIWebView (visiting a website with an AVPlayer/video-file in the HTML) using some AVPlayer callbacks in my ViewController.
I need to access the AVPlayer that has that item set as its AVPlayerItem.
As of now I am doing this by calling [TheAVPlayerItem valueForKey:#"player"]; but this is undocumented and not guaranteed to work in the future.
I'm looking for a more authoritative way of achieving this. I'd even be happy with literally starting at the UIWebView and looping down through all subviews (or sub-objects?) and grabbing any AVPlayer then checking if it has its AVPlayerItem set to my AVPlayerItem.... alas I don't know how to do that. But I have included my attempt at doing so:
//[TheAVPlayerItem valueForKey:#"player"];//undocumented and prone to breaking.
for (NSObject *anObject in [myWebView subviews]) {
if ([anObject isKindOfClass:[AVPlayer class]]) {
NSLog(#"Found an AVPlayer, now check if AVPlayerItem is a match");//never called
} else {
}
}
Of course the NSLog was never called.

Audio overlap issue

I'm developing a iOS app using objective-c. When the application is launched a background music is played. The background music should continue playing when the user clicks help button. Also when the user goes back to the main screen from the help screen the background music should be continuously playing.
For me a new background music is getting played along with the old background music when I navigate from help to main menu. So, I am hearing two background music now.
Could anyone help me in solving this issue?
Regards,
Bharathi.
Your problem could be solved if you retained a reference to your audio player in your UIApplicationDelegate (or some other singleton that's kept around).
//in the .h
#property (nonatomic, strong) AVAudioPlayer *player;
//in the .m
- (void) playMusic
{
if (self.player == nil) {
NSString *path = [NSString stringWithFormat:#"%#/music.mp3", [[NSBundle mainBundle] resourcePath]];
NSURL *soundUrl = [NSURL fileURLWithPath:path];
self.player = [[AVAudioPlayer alloc] initWithContentsOfURL:soundUrl error:nil];
}
if (!self.player.isPlaying) {
[self.player play];
}
}
That way you can call it wherever you need with a:
[(MyAppDelegate*)[UIApplication sharedApplication].delegate playMusic];
Though it might be to your advantage to keep around a SoundsManager class as a singleton in order to handle all the sounds that you'll need to track if you're going to need more than just this one.

Play multiple audio files in sequence as one

I'm trying to implement an Audio Player to play multiple files as if they were a single one. However, the initial buffer time should be only the first part's duration, and the other files should be loaded in sequence.
For example:
File1:
Part1 - 0:35s
Part2 - 0:47s
Part3 - 0:07s
The File1 should be played as if it had 1:29, but we'd only wait (at most) until Part1 is loaded to start playing.
I've had a look at AVAsset, but it doesn't seem to solve the problem. I also thought of implementing it using AVAudioPlayer and doing all the logic myself.
Has anyone had this issue before?
Thanks!
You can use AVQueuePlayer for achieving this. You need to create AVPlayerItem using your files url and then need to initialize the AVQueuePlayer using it's queuePlayerWithItems: method.
AVPlayerItem *firstItem = [[AVPlayerItem alloc] initWithURL:firstPartURL];
AVPlayerItem *secondItem = [[AVPlayerItem alloc] initWithURL:secondPartURL];
AVPlayerItem *thirdItem = [[AVPlayerItem alloc] initWithURL:thirdPartURL];
NSArray *itemsToPlay = [NSArray arrayWithObjects:firstItem, secondItem, thirdItem, nil];
AVQueuePlayer *qPlayer = [AVQueuePlayer queuePlayerWithItems:itemsToPlay];
[qPlayer play];

ios SystemSound will not respond to volume buttons

Ive used SystemSound in my app in order to play simple sound effects. In addition to this I play a musicvideo through the MPMoviePlayerController - now when I turn the volume up/down the music from the video responds as intended (lowering the volume up/down).
But the system sounds that are played does not respond to the volume. Im playing the system sounds when the user taps certain areas in the app. Heres a snippet of my code for that:
- (void)handleTap:(UITapGestureRecognizer *)recognizer {
SystemSoundID completeSound = nil;
//yellow folder in xcode doesnt need subdirectory param
//blue folder (true folder) will need to use subdirectory:#"dirname"
NSURL *sound_path = [[NSBundle mainBundle] URLForResource: target_sound_filename withExtension: #"wav"];
AudioServicesCreateSystemSoundID((__bridge CFURLRef)sound_path, &completeSound);
AudioServicesPlaySystemSound(completeSound);
}
PS. I doublechecked that my "Settings->Sounds->Ringer and Alerts->Change With Buttons" is set to ON (as I read on some other SO answers that leaving this option OFF will cause systemsound to not respond to the volume buttons)
Further the reason for using systemsound is that it gave the most accurate and responsive results when playing multiple sounds (like in a game).
Id prefer to not use OpenAL if possible (even through 3rd party sound libraries like Finch or CocosDenshion)
Any ideas?
Use the AVAudioPlayer class for playing sounds that are controlled by the user's volume settings (non-system sounds).
You can retain instances of AVAudioPlayer for each sound file that you use regularly and simply call the play method. Use prepareToPlay to preload the buffers.
Cheers to Marcus for suggesting that i could retain instances of AVAudioPlayer for each sound file and use prepareToPlay to preload the sounds. It might be to help for others looking for the same solution so here is how I did it (feel free to comment if anyone have suggestions for improvements)
//top of viewcontroller.m
#property (nonatomic, strong) NSMutableDictionary *audioPlayers;
#synthesize audioPlayers = _audioPlayers;
//on viewDidLoad
self.audioPlayers = [NSMutableDictionary new];
//creating the instances and adding them to the nsmutabledictonary in order to retain them
//soundFile is just a NSString containing the name of the wav file
NSString *soundFile = [[NSBundle mainBundle] pathForResource:s ofType:#"wav"];
AVAudioPlayer *audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:soundFile] error:nil];
//audioPlayer.numberOfLoops = -1;
[audioPlayer prepareToPlay];
//add to dictonary with filename (omit extension) as key
[self.audioPlayers setObject:audioPlayer forKey:s];
//then i use the following to play the sound later on (i have it on a tap event)
//get pointer reference to the correct AVAudioPlayer instance for this sound, and play it
AVAudioPlayer *foo = [self.audioPlayers objectForKey:target_sound_filename];
[foo play];
//also im not sure how ARC will treat the strong property, im setting it to nil in dealloc atm.
-(void)dealloc {
self.audioPlayers = nil;
}

How to play movie with a URL using a custom NSURLProtocol?

As you know,play a movie with MPMoviePlayerController object using
[[MPMoviePlayerController alloc] initWithContentURL: aURL];
now ,i want to achieve a custom NSURLProtocol in which i will decrypt a movie source that had be encrypt by AlgorithmDES.
Is that possibility? thanks for giving any ideas.need you help~
UPDATE: I spoke to Apple about this and it's not possible to use MPMoviePlayerController with a NSURLProtocol subclass at the moment!
Hej,
I am not sure but it could be possible. I am currently working on something similar but haven't got it fully working. What I have found out is that MPMoviePlayerController interacts with my custom NSURLProtocol subclass BUT it seems to be important to take the HTTPHeaders of the NSURLRequest into account because they define a range of bytes the MPMoviePlayerController needs.
If you dump them in your NSURLProtocol subclass you will get something like this twice for the start:
2011-01-16 17:00:47.287 iPhoneApp[1177:5f03] Start loading from request: {
Range = "bytes=0-1";
}
So my GUESS is that as long as you can provide the correct range and return a mp4 file that can be played by the MPMoviePlayerController it should be possible!
EDIT: Here is a interesting link: Protecting resources in iPhone and iPad apps
The solution is to proxy requests through a local HTTP server. I have accomplished this using CocoaHTTPServer.
Look at the HTTPAsyncFileResponse example.
There is one more solution as of iOS 7. You can use a AVAssetResourceLoaderDelegate for AVAssetResourceLoader. But this will only work with AVPlayer then.
There is a demo project by apple called AVARLDelegateDemo have a look at it and you should find what you need. (I think linking to it isn't a good idea, so just search for it in the Developer Library on developer.apple.com) Then use any custom URL scheme (without declaring a NSURLProtocol) and handle that URL scheme in the AVAssetResourceLoaderDelegate.
If there is a huge interest I could provide a proof of concept gist.
#property AVPlayerViewController *avPlayerVC;
#property NSData *yourDataSource
// initialise avPlayerVC
NSURL *dummyURL = [NSURL URLWithString:#"foobar://dummy.mov"];// a non-reachable URL will force the use of the resourceLoader
AVURLAsset *asset = [AVURLAsset assetWithURL:dummyURL];
[asset.resourceLoader setDelegate:self queue:dispatch_get_global_queue(QOS_CLASS_USER_INTERACTIVE, 0)];
AVPlayerItem *item = [AVPlayerItem playerItemWithAsset:asset];
self.avPlayerVC.player = [AVPlayer playerWithPlayerItem:item];
self.avPlayerVC.player.actionAtItemEnd = AVPlayerActionAtItemEndNone;
// implement AVAssetResourceLoaderDelegate
- (BOOL)resourceLoader:(AVAssetResourceLoader *)resourceLoader shouldWaitForLoadingOfRequestedResource:(AVAssetResourceLoadingRequest *)loadingRequest {
loadingRequest.contentInformationRequest.contentType = (__bridge NSString *)kUTTypeQuickTimeMovie;
loadingRequest.contentInformationRequest.contentLength = self.yourDataSource.length;
loadingRequest.contentInformationRequest.byteRangeAccessSupported = YES;
NSRange range = NSMakeRange((NSUInteger)loadingRequest.dataRequest.requestedOffset, loadingRequest.dataRequest.requestedLength);
[loadingRequest.dataRequest respondWithData:[self.yourDataSource subdataWithRange:range]];
[loadingRequest finishLoading];
return YES;
}
Notice the use of a dummy URL to force AVPlayer to use the AVAssetResourceLoaderDelegate methods instead of accessing the URL directly.

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