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.
Related
I have a recording that has some unuseful voices at the beginning, and at the end.
How can I play just the middle part of the sound?
I have AL_SEC_OFFSET, that is suitable for the entry point, I already use it, but what about the endpoint?
Is there any smart OpenAL settings for this? Hopeso.
Thanks.
There could be a workaround that fires a timer that stops playing before end.
Any simplier?
OpenAL doesn't have built-in support for stopping playback at a specific sample point. A timer is your best bet in this case, even though it will be somewhat inaccurate.
If you want sample-perfect stopping, you could just load the middle part of the audio file into an ALBuffer rather than the entire thing. I have some code which does that here:
https://github.com/kstenerud/ObjectAL-for-iPhone/blob/master/ObjectAL/ObjectAL/Support/OALAudioFile.m#L188
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 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.
I'm using Media Player Framework to access the user's music library on iPhone. I would like to set the playback starting position so that I can start playing a song from 30 second mark, for example.
I have trouble finding out how to do this. The MPMediaPlayerController only offers beginSeekingForward but that's not quite what I'm looking for as it simply accelerates the playback speed.
There is probably something really simple that I'm missing.
MPMusicPlayerController's property currentPlaybackTime is a writeable property, so adjusting the playback starting point can be done with player.currentPlaybackTime = 30.0
You can use player.currentPlaybackTime to set the time, before you start playing and playback will start at your desired point.
UPDATE
2009 me had some real problems. He didn't really understand properties and missed the fact that MPMusicPlayerController.currentPlaybackTime is writable! And he was angry. Angry because iOS3.0 had promised iPod Library "Access" and instead delivered MPMusicPlayerController. He had been hoping for speedy access to the music packet data upon which he would have built many fascinating and magical audio applications. Luckily, iOS4.1's AVAssetReader came along 1 year later and he was finally able to stop hating.
WRONG 2009 ANSWER
Nope, this API is deliberately crippled, which is why you don't see any functions for
opening, or streaming from, the media file.
Your only hope is lowering the volume and calling beginSeekingForward until currentPlaybackTime returns >= 30s.
Enjoy!
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.