Does the scheduleFile(_:at:completionHandler:) execute the handler before or AFTER the audio file has finished playing? Does it execute it before or after stopping the player/engine?
On Apple's documentation it says this:
Called after the player has scheduled the buffer for playback on the
render thread or the player is stopped
Source
Related
In AudioKit there is this method for AKPlayer:
#objc dynamic public func play(at audioTime: AVAudioTime?)
I want the same for stop method because I want to be able to stop the player at any time when the user hits the stop button. I am making a music app and I need to stop the sound in X time which is calculated based on BPM and etc.
Here is how I start my AKPlayer:
drums.play(at: AVAudioTime.now() + timeToClosestBeatGrid)
I want the same API with stop:
drums.stop(at: AVAudioTime.now() + timeToClosestBeatGrid) // this api doesnt exist :(((
I tried using endTime property by setting it but it does not seem to do anything...
How may I accomplish this?
PS: I am not looking for a Timer solution this is because a timer is not 100% accurate. I want my stop method to be 100% accurate just like play method
The most accurate way to schedule events in AudioKit is by using AKSequencer. The sequencer can be connected to a callback instrument, which is a node that passes the events to an user-defined function.
In your case, you would add an event at the time where you want the player to stop. In your callback function, you would stop the player as a response to that event.
This is an outline of what should be done:
Create a track to contain the stop event, using AKSequencer's addTrack method. Connect this track to an AKCallbackInstrument. Please see this answer on how to connect an AKCallbackInstrument to an AKSequencer track.
Add the stop event to the track, at the time position where you want the music to stop. As you will be interpreting the event yourself with a callback function, it doesn't really matter what type of event you use. You could simply use a Note On.
In the callback function, stop the player when that event is received.
This is what your callback function would look like:
func stopCallback(status:UInt8, note:MIDINoteNumber, vel:MIDIVelocity) -> () {
guard let status = AKMIDIStatus(byte: status),
let type = status.type,
type == .noteOn else { return }
drums.stop()
}
According to AudioKit documentation, you can try using the schedule(at:) method:
You can call this to schedule playback in the future or the player will call it when play() is called to load the audio data
After the play() method you should declare this schedule(at:) with an offset AVAudioTime.now() + timeToClosestBeatGrid and specify .dataPlayedBack as completion callback type, because this completion is called when (from docs)...
The buffer or file has finished playing
and now (in completion block) you can call drums.stop()
But... If the .stop() method should be called whenever the button is pressed, why not use some form of delay (Timer or DispatchQueue) with the value timeToClosestBeatGrid as the offset?
I have an AVAudioPlayerNode object that is linked with an AVAudioEngine. I used the schedule method to load them in the queue. How can I know the state of the playback and when a single file start and finish to play?
This is the code I use for scheduling :
playerNode.scheduleFile(file, at: audioTime) {
// Completion
}
I want to play the recorded audio directly to speaker when headset is plugged in an iOS device.
What I did is calling AudioUnitRender in AURenderCallback func so that the audio data is writed to AudioBuffer structure.
It works well if the "IO buffer duration" is not set or set to 0.020seconds. If the "IO buffer duration" is set to a small value (0.005 etc.) by calling setPreferredIOBufferDuration, AudioUnitRender() will return an error:
kAudioUnitErr_CannotDoInCurrentContext (-10863).
Any one can help to figure out why and how to resolve it please? Thanks
Just wanted to add that changing the output scope sample rate to match the input scope sample rate of the input to the OSx kAudioUnitSubType_HALOutput Audio Unit that I was using fixed this error for me
The buffer is full so wait until a subsequent render pass or use a larger buffer.
This same error code is used by AudioToolbox, AudioUnit and AUGraph but only documented for AUGraph.
To avoid spinning or waiting in the render thread (a bad idea!), many
of the calls to AUGraph can return:
kAUGraphErr_CannotDoInCurrentContext. This result is only generated
when you call an AUGraph API from its render callback. It means that
the lock that it required was held at that time, by another thread. If
you see this result code, you can generally attempt the action again -
typically the NEXT render cycle (so in the mean time the lock can be
cleared), or you can delegate that call to another thread in your app.
You should not spin or put-to-sleep the render thread.
https://developer.apple.com/reference/audiotoolbox/kaugrapherr_cannotdoincurrentcontext
When I use <AudioToolbox/AudioServices.h> to implement a recording function, sometimes there will be unsuccessful recording. The reason is AudioQueueStart returned value -66681. The document says:
The audio queue has encountered a problem and cannot start
I found documents but I have no idea about that.
I am using the MPMoviePlayerController to play an audio stream. To verify that there isn't a problem with playback, I set a movie playback error timer and I implement moviePreloadDidFinish. When moviePreloadDidFinish is called, I check the loadState for MPMovieLoadStatePlaythroughOK. If it is not called and my timer expires, I assume the download has failed.
- (void) moviePreloadDidFinish:(NSNotification*)notification
{
if (self.moviePlayer.loadState & MPMovieLoadStatePlaythroughOK) {
NSLog(#"The movie or mp3 finished loading and will now start playing");
// cancel movie playback error timer.
}
}
Occasionally, I do not receive this notification, yet audio keeps playing until my movie playback error timer expires (30 seconds). Does the absence of this moviePreloadDidFinish imply that the download of the audio stream is going to fail soon? If not, is there a better way to programmatically determine that there is a playback problem?