IOS: AVAudioPlayer - ios

Question

In my app I have 52 mp3 and when I load my view controller I alloc all 52 mp3 in this way:
NSString *pathFrase1 = [NSString stringWithFormat:#"%#/%#",[[NSBundle mainBundle] resourcePath],[NSString stringWithFormat:#"a%d_1a.mp3",set]];
NSURL *filePath1 = [NSURL fileURLWithPath:pathFrase1 isDirectory:NO];
f1 = [[AVAudioPlayer alloc] initWithContentsOfURL:filePath1 error:nil];
[f1 prepareToPlay];
but it's very slow when I open viewcontroller, then is there a way to alloc mp3 when I use it? and release its AVAudioPlayer??

Answer 1

It's a little more complicated to handle, but instead of using AVAudioPlayer, use AVPlayer. AVPlayer is designed to play AVAssets, which can be preloaded files. Specifically, you'll want to use a subclass of AVAsset called AVURLAssets, which can load up your URL: Loading AVAsset. You can then use AVAsset to create an AVPlayerItem. An AVPlayerItem is a lightweight wrapper that AVPlayer uses to keep track of play state for an AVAsset. The nice thing about using AVPlayer is that it can play an AVMutableComposition, which itself can contain multiple AVAssets. AVPlayer can also play a queue of AVAssets and provide you with information on when it is beginning to play a new AVAsset, and which one. If you load your MP3's into a bunch of AVURlAssets you can load them and keep them around, creating AVPlayerItem & AVPlayer only when you want to play one (or more) of the MP3's.
AVAudioPlayer is designed to play single files, but it uses AVAssets (and probably AVPlayer) behind the scenes. It's nice for simple situations, but anything more complex and you really want to use AVPlayer.
I should also point out that AVPlayerItem & AVPlayer are light weight objects. They don't take long at all to instantiate. It's loading the AVAsset that takes all the time. So you can feel free to create and destroy AVPlayerItem & AVPlayer objects as you need.
Finally, AVAsset and AVPlayer sometimes rely on blocks for notifications. So, for example, you may need to use c-blocks when loading up AVURLAsset to get notification on when an Asset if fully loaded. Just be aware that those blocks aren't called on the main thread. So if you try to update any UI elements or do any animations from that block it won't work right. You need to dispatch another block on to the main thread to do this, for example: dispatch_async(dispatch_get_main_queue(),^{....update UI element code....});. For more information about about dispatching blocks see Apple's Concurrency Programming Guide and Block Programming Guide.

Answer 2

Sure, but there will be a delay as the AVAudioPlayer is allocated and prepared for playing. Can you predict what will play and when? If so, maybe you can load a couple of seconds before you need a particular mp3 to play.
An alternative, which may not work depending on your timing requirements, is the following:
- (void)prepareAudioPlayer {
static int index = -1;
index = index + 1;
if (index < [[self FileNames] count]) {
NSError *err = nil;
NSString *audioFilePath = #""; // Figure out how to get each file name here
NSURL *audioFileURL = [NSURL fileURLWithPath:audioFilePath];
AVAudioPlayer *player = [[AVAudioPlayer alloc] initWithContentsOfURL:audioFileURL error:&err];
if (err) {
NSLog(#"Audio Player Error: %#", [err description]);
}
[player prepareToPlay];
// Add this player to the "AudioPlayers" array
[[self AudioPlayers] addObject:player];
// Recurse until all players are loaded
[self prepareAudioPlayer];
}
}
This solution requires properties of FileNames and AudioPlayers.
Once this is set up, you could do something like the following (probably in viewDidLoad):
// Make the file name array
[self setFileNames:[NSMutableArray array]];
// Initiate the audio player loading
[self performSelectorInBackground:#selector(prepareAudioPlayer) withObject:nil];
Later, when you need to play a particular file, you can find the index of the file name in the FileNames array and the call play on the AVAudioPlayer for that index in the AudioPlayers array.
This seems like maybe not the best way to do things, but it might work if you require it this way.

Answer 3

Here is the using method , If the sound is playing, current Time is the offset of the current playback position, measured in seconds from the start of the sound. If the sound is not playing, current Time is the offset of where playing starts upon calling the play method, measured in seconds from the start of the sound.
By setting this property you can seek to a specific point in a sound file or implement audio fast-forward and rewind functions.
The value of this property increases monotonically while an audio player is playing or paused.
If more than one audio player is connected to the audio output device, device time continues incrementing as long as at least one of the players is playing or paused.
If the audio output device has no connected audio players that are either playing or paused, device time reverts to 0.
Use this property to indicate “now” when calling the play AtTime: instance method. By configuring multiple audio players to play at a specified offset from deviceCurrent Time, you can perform precise synchronization—as described in the discussion for that method.To learn more visit..enter link description here