I built an iPhone app using AudioServices to play short sounds. The first time a sound is played, there's a delay of half a second or so while the sound loads before it plays. This definitely makes for an awkward user experience.
Is there a way to preload sounds for AudioServices to play, or do I need to switch to audioQueues or some other method of playing sounds?
Thanks,
Maha
This is a well known problem. Everything in AudioServices is initialized lazily.
I think that your best choice is between Core Audio or OpenAL. OpenAL might be overkill, but it has a simple API. The oalTouch example is a good place to start.
Core Audio is a bit more raw, but it's well documented. The iPhone's OpenAL SDK is built on top of it.
Related
I'm using the SimpleAudioEngine for cocos2d and when one track finished I would like to play another.
It only allows one background music to be preloaded at a time though. Would it be ridiculous to 'join' 2 .mp3s using audacity and then just convert to .caf and preload the whole thing?
Certainly not ridiculous, but be wary about how much memory your sounds require.
Also, why the conversion to .caf? You can play .mp3s. Is this just for compression?
I need to play sounds (~5 seconds each) throughout my iphone application. When they're triggered, they need to play immediately.
For the moment I'm using AudioServices and (as you probably know) the first time you play a sound it lags, then every time there after it's perfect. Is there some code available that's clever enough to preload an AudioServices sound (by playing it silently maybe?). I've read adjusting the system volume programmatically will get your app rejected, so that's not an option. Seems AudioServices isn't made for volume correction from what I can see.
I've looked into OpenAL and while feasible seems a little over kill. AVAudioPlayer seems like a little bit of a better option, I'm using that for background music at present. Extending my music player to handle a 'sound board' might be my last resort.
On the topic of OpenAL, does anyone know of a place with a decent (app store friendly) OpenAL wrapper for the iPhone?
Thanks in advance
Finch could be perfect for you. It’s a tiny wrapper around OpenAL with very low latency and simple API. See also all SO questions tagged ‘Finch’.
If you use an AVAudioPlayer, you can call prepareToPlay when you initialize the object to reduce the delay between calling play and having the audio start.
I am playing sounds in loop in my app. So it should continue playing through out the app. but sometimes it stops after playing sound for 3/4 times.I don't understand whats happening.
I am using audio-toolbox framework for playing sound. creating audio queue and then playing sounds in loop. I am also playing sound from ipod library using mediaplayer. Same thing happening with song from ipod.
I have set [musicPlayer setRepeatMode: MPMusicRepeatModeOne]; but still it stops after 3/4 times.
How exactly are you playing the sound? Show us the code. Do you use System Sound Services? They are not meant to play longer sounds, quote Audio Toolbox Reference:
You can use System Sound Services to
play short (30 seconds or less)
sounds.
This could be the source of your problem. But until you show us the code we can’t but guess.
I have a performance-intensive iPhone game I would like to add sounds to. There seem to be about three main choices: (1) AVAudioPlayer, (2) Audio Queues and (3) OpenAL. I’d hate to write pages of low-level code just to play a sample, so that I would like to use AVAudioPlayer. The problem is that it seems to kill the performace – I’ve done a simple measuring using CFAbsoluteTimeGetCurrent and the play message seems to take somewhere from 9 to 30 ms to finish. That’s quite miserable, considering that 25 ms == 40 fps.
Of course there is the prepareToPlay method that should speed things up. That’s why I wrote a simple class that keeps several AVAudioPlayers at its disposal, prepares them beforehand and then plays the sample using the prepared player. No cigar, still it takes the ~20 ms I mentioned above.
Such performance is unusable for games, so what do you use to play sounds with a decent performance on iPhone? Am I doing something wrong with the AVAudioPlayer? Do you play sounds with Audio Queues? (I’ve written something akin to AVAudioPlayer before 2.2 came out and I would love to spare that experience.) Do you use OpenAL? If yes, is there a simple way to play sounds with OpenAL, or do you have to write pages of code?
Update: Yes, playing sounds with OpenAL is fairly simple.
AVAudioPlayer is very marginal for game audio. Tackling AudioQueue or OpenAL by adapting one of the examples is definitely the way to go. latency is much more controllable that way.
If you're calling play on the main thread, try running it on a separate thread. What I ended up doing is:
#include <dispatch/dispatch.h>
dispatch_queue_t playQueue = dispatch_queue_create("com.example.playqueue", NULL);
AVAudioPlayer* player = ...
dispatch_async(playQueue, ^{
[player play];
});
which fixed the worst of the framerate stuttering I was experiencing.
I use OpenAL and the classes that came with the CrashLanding sample code. It's worked fine so far to play samples and play looped music all at the same time. I'm currently learning how to release the memory I've allocated for a sound (.wav file) when, for example, I want to play some intro music just once.
Use CocosDenshion – it’s free, easy, and works. It wraps AVAudioPlayer for background tracks and OpenAL for sounds.
Do you want to check the buffering with the implementation you're using? It might be somehow related to the 20ms delay you're experiencing. i.e., try to play around with the buffer size.
Is there an easy way to control the playback speed/tempo of a sound file loop played using Audio Queue Services? For example, if a game is playing background music, I want to make the BGM speed up as time runs out, but without changing the pitch of the music. Thx!
There's no trivial way to do this that I know of. On the Mac, you'd presumably use Audio Units to do this, but I think the support for those is limited on the iPhone SDK.
You can do some processing during your AudioQueue playback callback, between AudioFileReadPackets() and AudioQueueEnqueueBuffer() but I think speed-shifting without changing the tone will require rather a lot of CPU time.
It'd probably be easier to have more than one recording of the music, and switch files during a silent passage of the music.