I've been trying to play music in my SpriteKit game and used the AVAudioPlayerNode
class to do so via AVAudioPCMBuffer
s. Every time I exported my OS X project, it would crash and give me an error regarding audio playback. After banging my head against the wall for the last 24 hours I decided to re-watch WWDC session 501 (see 54:17). My solution to this problem was what the presenter used, which is to break the frames of the buffer into smaller pieces to break up the audio file being read.
NSError *error = nil;
NSURL *someFileURL = ...
AVAudioFile *audioFile = [[AVAudioFile alloc] initForReading: someFileURL commonFormat: AVAudioPCMFormatFloat32 interleaved: NO error:&error];
const AVAudioFrameCount kBufferFrameCapacity = 128 * 1024L;
AVAudioFramePosition fileLength = audioFile.length;
AVAudioPCMBuffer *readBuffer = [[AvAudioPCMBuffer alloc] initWithPCMFormat: audioFile.processingFormat frameCapacity: kBufferFrameCapacity];
while (audioFile.framePosition < fileLength) {
AVAudioFramePosition readPosition = audioFile.framePosition;
if (![audioFile readIntoBuffer: readBuffer error: &error])
return NO;
if (readBuffer.frameLength == 0) //end of file reached
break;
}
My current problem is that the player only plays the last frame read into the buffer. The music that I'm playing is only 2 minutes long. Apparently, this is too long to just read into the buffer outright. Is the buffer being overwritten every time the readIntoBuffer:
method is called inside the loop? I'm such a noob at this stuff...how can I get the entire file played?
If I can't get this to work, what is a good way to play music (2 different files) across multiple SKScene
s?
This is the solution that I came up with. It's still not perfect, but hopefully it will help someone who is in the same predicament that I've found myself in. I created a singleton class to handle this job. One improvement that can be made in the future is to only load sound effects and music files needed for a particular SKScene at the time they are needed. I had so many issues with this code that I don't want to mess with it now. Currently, I don't have too many sounds, so it's not using an excessive amount of memory.
Overview
My strategy was the following:
The music dictionary is compose of an array of AVAudioPCMBuffers, an array of timestamps for when those buffers should be played in queue, a AVAudioPlayerNode and the sample rate of the original audio file
Create an AVAudioEngine and get the main mixer from the engine and attach all AVAudioPlayerNodes to the mixer (as per usual)
-(void) playSfxFile:(NSString*)file;
and it plays a sound-(void) playMusicFile:(NSString*)file;
and it will schedule the buffers to play in order that they were created. I couldn't find a good way to get the music to repeat once completed within myAudioEngine
class so I decided to get the scene to check in itsupdate:
method whether or not the music was playing for a particular file and if not, play it again (not a very slick solution, but it works)AudioEngine.h
AudioEngine.m