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AVAudioPlayer - Drop in Framerate
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Closed 4 years ago.
I'm writing a game for iphone, and without background music it runs smoothly at 30 fps. But if I add music (using AudioQueues or AVAudioPlayer, both give similar effect), framerate periodically drops to 10 (about once per second), and then returns to 30. Music is mp3#128kps, 44kHz. It degrades performance not constantly, but at certain moments in time, which causes very jerky gameplay. Did anyone meet such problem? Is there any way to make cpu load for mp3 decoding/playing back more uniform? I'd rather have constanly 29 fps than 30 fps most of the time, and 10 once per second.
Maybe you could increase the priority of your rendering thread? Or take it into a different Run Loop (if that is how you're doing animation).
Couple of thoughts:
1) It might be work trying converting your files into another format and see if you still have this issue. I have had great success with using CAF files, just run afconvert over them.
afconvert -f caff -d ima4 <your mp3 file>
2) Also, is there any connection between the slowdown and track changes? I have often seen similar things when changing tracks (or restarting tracks). I think it has to do with the load it takes to read the file from 'disk'.
This is most probably caused by using the AmbientSound audio session category, see this question. You can easily solve the problem by switching to the SoloAmbientSound category.
You need to profile your app.
I'm getting 60fps regardless of bitrate.
It would be best if you showed us your code. Have you checked into the audio buffer options, it might not be optimal for what you need. Are you comfortable with audio Units?
Related
I am working on an app that allows the user to create a sort of dub. There is an audio file playing, and the user can tap at certain moments to insert sound (kind of like a censor button.) I'm wondering how to go about capturing the final product.
Capturing audio directly from the iPhone seems the easiest route, as the user already hears the finished product as it is made. However, I can't find anything on how to do this. If not possible, are there any suggestions?
The best way would probably be to be using the AV Foundation framework for mixing and then buffering the audio as well as playing it. This would allow for a high abstraction level while guaranteeing both played back and saved audio to be equal.
Apart from that: from a How can I achieve this with minimum code-perspective, without more information about your setup, the question is way too broad and/or opinion-based.
You will have to work with buffers. Don't know right now how it is done in Swift but you can implement it in Obj-C and then bridge it out.
You can refer to this answers here in StackOverflow (They are a bit old)
https://stackoverflow.com/a/11218339/2683201
https://stackoverflow.com/a/10101877/2683201
and a project also exists (but is in Obj-C)
https://github.com/alexbw/novocaine
Mainly the idea for your case would be to have 2 separated buffers and your sound effect.
Then, you will be playing from buffer A (your music) and copying played data into buffer B (final Output) unless you are playing the effect. In wich case you will be copying the effect data into your buffer B.
Other option is to do it offline:
Play your music (or audio) and keep a timer running synced with the elapsed time of your "to be censored audio".
Save the timestamp of when you start and end tapping the censor button (for example).
Overlap buffer A with your effect in those recorded (start-end) timestamps.
Save the buffer as a file (or do whatever you need to do with it)
UPDATE:
You should take a look into the Apple implementation of something like this:
https://developer.apple.com/library/ios/samplecode/AVAEMixerSample/Introduction/Intro.html
I am wondering if it is possible to play several little audio files on iPhone. I created a sound file of 25µs but I can't play it on Simulator or on the Device.
So I created several files 25µs, 50µs and 100µs but even if I use NSArray or NSMutableArray with ÀVQueuePlayer`I couldn't play it!
Do someone know the minimum time to play a sound or if what I am doing is possible?
Thank you for your answers
PS : My project is to communicate with other device on the audio
What makes you think it is not being played ? 25µs is 25 millionth of a second long !
I suggest you start playing a clip which is audible, then cut its length in half
and repeat until it becomes inaudible. Is your intention to have the other device listen ? you could get your play/listen loop working with audible clips then drill down.
I have large looping background music files of up to 10 minutes length. The sounds are looped perfectly and if the player introduces no delay you would not notice where the loop point is.
Can AVAudioPlayer play them without that the user will hear a gap caused by latency or other problems with looping?
You might be hearing a delay because your music is compressed (mp3 for example). AVAudioPlayer has to decode the mp3 as it streams. If you had the same music in an uncompressed format, it would take significantly more disk space, but would loop seamlessly.
As long as you don't stop/start it at the end and you set numberOfLoops to a negative integer, it should work.
I had problems trying to create seamless loops. I tried using the numberOfLoops property, with no success. I tried switching to uncompressed audio files, with no success. I even tried switching to an AVAudioQueuePlayer, queued with multiple instances of the same asset, with no success. In the end I solved the problem by creating two instances of AVAudioPlayer (player1 & player2) and switching between them. I began playback of player1 and used player2's prepareToPlay method, and the play(atTime time:) method setting the TimeInterval to player1.deviceCurrentTime - player1.currentTime + player1.duration.
I then used the delegate method audioPlayerDidFinishPlaying to prepare player1 to restart playback after player2 was done. To be honest, I don't know why this approach worked and simply setting numberOfLoops to -1 did not. But it may work for you also
I have been facing this since so many days but I have not reach to any conclusion.
My problem is : I want to play an mp3 file but not simply by clicking on a play button.
It is this way I want to play it.
*There is a slider that I can drag using finger, I want that the mp3 should play with the frequency with which I am dragging the finger (or speed with which I am dragging my finger, so that it will give an effect of fast forwarding (funny type of voice)) or if I drag slider slowyly the output will be slow *
The problem is the output of the sound is not coming out smooth. its very distorted and disturbed voice.
I want the outuput to be smoother.
Please help. Any suggestions please. Presently I am using AVAudioPlayer and passing the time value based upon slider input to play the file. (It does not seems to be feasible though).
I feel that it is possible using openAL only and no other way. Because using openAL we can modify the frequency of the sound file (pitch)
CAN SOME ONE PLEASE REFER ME A LINK TO openAL implementation for iPhone . I have never played a sound file using openAL
Help!!
You won't be able to do it with AVAudioPlayer, as it does not support pitch operations.
You can load and decode the entire track into memory for playback with OpenAL (which supports pitch), or you can do realtime loading/decoding and pitch changing using Audio Units (MUCH lower level, and more complicated, though).
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.