A client of mine wants to continually record audio and when he clicks submit he wants to submit the last 10 seconds only. So he wants a continual recording and only keeping the last x seconds.
I would think this requires something like a circular buffer, but (as a somewhat newbie for iOS) it looks like AVAudioRecorder can only write to a file.
Are there any options for me to implement this?
Can anyone give a pointer?
I would use the Audio Queue Services. This will allow you isolate certain parts of the buffer. Here is the guide to it: http://developer.apple.com/library/ios/#documentation/MusicAudio/Conceptual/AudioQueueProgrammingGuide/AQRecord/RecordingAudio.html#//apple_ref/doc/uid/TP40005343-CH4-SW1
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Hello I am trying to create a simple push-notification system similar to this common use case:
1. The user gets a chest and can either watch an ad to skip the wait time or wait one hours for the chest to open. The app sends an upstream request which sets up a downstream push notification that shall be delivered in one hour to let the user know the chest is ready.
2a. The user then waits an hour, gets a push notification (outside of the app) to open their chest and they do!
or
2b. They wait 20 minutes then decide to watch the ad. The app sends an upstream request which cancels the pending push notification which would have otherwise been delivered in 40 minutes.
Okay awesome so that is the problem and I am having a hard time understanding how to do this. I have looked over the documentation for each of these programs but they seem designed for downstream push notifications. It just seems odd there is no built-in support for this use case. It seems like such a common use case.
I so far found 3 solutions that will integrate into my cross-platform Unity setup and provide services for free or super-cheap:
Amazon Simple Notification Service (SNS)
Google Firebase Cloud Messaging (FCM)
OneSignal
Amazon seems to group clients into "Topics" so I guess I would be setting up a one-device-topic and essentially. I can subscribe and unsubscribe from them but it doesn't seem to support a topic with a 60 minute delay.
2a. Create a topic: https://docs.aws.amazon.com/sns/latest/dg/sns-tutorial-create-topic.html (it would just include the current device)
2b. Subscribe to it
2c. Send a message to it https://docs.aws.amazon.com/sns/latest/dg/sns-tutorial-publish-message-with-attributes.html
So basically I can add attributes to my message but it would seem I need to implement the server-side code to read a delay attribute then somehow queue a message for delay. Maybe I am missing something?
For Firebase I pretty much see the same thing as Amazon. There are topics https://firebase.google.com/docs/cloud-messaging/android/topic-messaging and a means to send upstream messages https://firebase.google.com/docs/cloud-messaging/android/send-with-console but with the messages I don't see anyway here to get the time delay https://firebase.google.com/docs/cloud-messaging/unity/topic-messaging I see conditions towards the bottom of that article but I don't know if it is meant for this use case.
OneSignal has the easiest to scroll-through API. I'll refer to some strings that you can CTRL-F by using the format ("Create Notif") because everything is on this one page: https://documentation.onesignal.com/reference
So basically I can ("Send to Specific Devices") which I guess would be the sending device, then I can ("Schedule notification for future delivery.") using the send_after parameter. And finally, if need be, I can ("Cancel notification"). So this appears to be everything I need. I'm currently looking at this option and trying to figure out how to actually get this working.
So there is my progress over the last few hours researching each of these options. I am hoping you can help me better understand how I may be misunderstanding the above options as this seems to me a very common use-case. Perhaps I am just not googling the question correctly. Any help appreciated.
Whenever there's a likelihood that you'll need to cancel a significant percent of the notifications you send, you should use local notifications. That way you can easily schedule and cancel them locally without making any network requests. Also, this solution works for offline devices which is great for games (played on planes, etc...)
SoundBunny does exactly what I need, the ability to mute/unmute and change the volume of the audio, on demand, at an individual application level. Unfortunately I can't control it via AppleScript as it's not scriptable.
What other options do I have?
I found a way to mute a particular audio queue based on a reference to it by using :
AudioQueueSetParameter(audioQueue, kAudioQueueParam_Volume, 0);
The problem is that I can't find a way to retrieve all audio queues currently in use by other applications(don't know if that's possible). I only found documentation how to create and manipulate one.
After searching for a very long time for a way to play notification noises only through the headphones (when plugged in), on a stream separate from STREAM_MUSIC, in a way that could interrupt and be completely audible over any background music, Android finally came out with the AudioAttributes API. By using the following code, I'm able to achieve exactly what I want for notifications, at least in API 21 or higher (STREAM_MUSIC is the best option I've found for lower versions):
AudioAttributes audioAttributes = new AudioAttributes.Builder()
.setUsage(AudioAttributes.USAGE_ASSISTANCE_SONIFICATION)
.setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
.build();
Unfortunately, there doesn't appear to be any way to adjust the volume of the sonification in my app's settings. I currently use the AudioManager in the following way, but it only allows volume adjustments to streams, and none of STREAM_ALARM, STREAM_NOTIFICATION, STREAM_RING, or STREAM_MUSIC applies to whatever routing strategy is used for the sonification:
audioManager.setStreamVolume(AudioManager.STREAM_NOTIFICATION, originalVolume, 0);
Does anyone have any suggestion on how to set the volume corresponding to the AudioAttributes output? Keep in mind that the audio is actually played in a BroadcastReceiver that's used for the actual notification, and the audio setting would be specified in just some settings Activity.
Well, it appears that I missed a critical table in the API documentation:
https://source.android.com/devices/audio/attributes.html
It seems that STREAM_SYSTEM is the equivalent of what I was attempting to do with AudioAttributes. Basically, using the code I have above is sufficient for API 21 and forward, and use of STREAM_SYSTEM does everything necessary for the AudioManager and APIs prior to 21.
I successfully use WasapiLoopbackCapture() for recording audio played on system, but I'm looking for a way to record what the user would actually hear through the speakers.
I'll explain: If a certain application plays music, WASAPI Loopback shall intercept music samples, even if Windows main volume-control is set to 0, meaning: even if no sound is actually heard through audio-card's output-jack (speakers/headphone/etc).
I'd like to intercept the audio actually "reaching" the output-jack (after ALL mixers on the audio-path have "done their job").
Is this possible using NAudio (or other infrastructure)?
A code-sample or a link to a such could come in handy.
Thanks much.
No, this is not directly possible. The loopback capture provided by WASAPI is the stream of data being sent to the audio hardware. It is the hardware that controls the actual output sound, and this is where the volume level is applied to change the output signal strength. Apart from some hardware- and driver-specific options - or some interesting hardware solutions like loopback cables or external ADC - there is no direct method to get the true output data.
One option is to get the volume level from the mixer and apply it as a scaling factor on any data you receive from the loopback stream. This is not a perfect solution, but possibly the best you can do without specific hardware support.
Using the iPhone and objective C, is there a way to stall or perform a timing loop to allow for the GPS to catch up and return a valid set of coordinates?
Currently, the application runs too quickly and the GPS cannot supply the coordinates fast enough...
Since you said you're on iPhone, you're using CLLocationManager. Just set a delegate on the manager and wait for the locationManager:didUpdateToLocation:fromLocation: message to know when the GPS data is ready.
Assuming your GPS polling is running in a different thread to the User Interface, you can call the static NSThread functions sleepForTimeInterval or sleepUntilDate from the thread that is waiting for the GPS data.
If your mobile application is using GPS, your application should be prepared for location updates, even if your application doesn't track movements..
A common case would be where the user put your application in background and activate it later on a completely different location.
On iOS, create an implementation of CLLocationManagerDelegate like Anomie wrote. And use the timestamp of the update to evaluate the freshness of the location.
Don't sleep & poll like other people suggested.
Either block to wait for data or don't update anything if no data received. There is of course usleep(), but without showing code and specifically how your loop is executed and by what mechanism (threaded or not) we can only answer in general terms.