i have an app that's creating an audio context and then decoding multiple audio files to get audio buffers on page load (on component mount in react) ,
everything is going as expected , handling errors and all .
but there's one that i don't know its source :
InvalidStateError: An attempt was made to use an object that is not, or is no longer, usable
after some research i found out that the audio context is starting with a state of suspended , and that's what's causing the problem .
is that gonna affect the app or not ?
Related
I am developing an Android app that gets data from Movesense using the GATT profile from the sample app GATT Sensor Data App here.
I followed the tutorial available here. Building the app and getting the DFU worked fine. I can get IMU, HR and temperature data with no issues.
Now I'd like add a tap detection feature to my app. I understand that I have to subscribe to 'System/States', but first I need to be able to receive the system state data.
I understand that I need a modified DFU for that, but I don't understand what changes I should make in which files of the gatt_sensordata_app before rebuilding and generating the new DFU.
What changes should I make in order to broadcast /System/State data?
(I usually just deal with Android so apologies for the very basic question.)
I tried adding #include "system_states/resources.h" to GATTSensorDataClient.cpp but I don't know how to continue.
The normal data straming in the gatt_sensordata_app uses the sbem-encoding code that the build process generates when building the firmware. However /System/States is not among the paths that the code can serialize. Therefore the only possibility is to implement the States-support to the firmware.
Easiest way is to do as follows:
In your python app call data subscription with "/System/States/3" (3 == DOUBLE_TAP)
Add a special case to the switch in onNotify which matches the localResourceId to the WB_RES::LOCAL::SYSTEM_STATES_STATEID::LID
In that handler, return the data the way you want. Easiest is to copy paste the "default" handler but replace the code between getSbemLength() & writeToSbemBuffer(...) calls with your own serialization code
Full disclosure: I work for the Movesense team
I'm trying to reload a kext in an Objective-C OSX application I'm writing. The KextManager API seems to be what I should use (docs here)
Calling KextManagerUnloadKextWithIdentifier() works flawlessly, but when I go to load the same kext shortly after using KextManagerLoadKextWithIdentifier() I get this console error:
com.apple.kextd[12]: Request from non-root process 'App Name' (euid 501) to load /path/to/kext - not allowed.
The docs for both methods both state "The calling process must have an effective user id of 0 (superuser)", yet unload works and load does not? Surely they should both behave the same?
Now since device enumeration is present in chrome, i know i can select a device during "getUserMedia" negotiation. I was also wondering whether i could switch devices during the middle of a call (queue up a local track and switch tracks or do i have to renegotiate the stream)? I am not sure if this is something that is still blocked or now is "allowable"
I have tried to make a new track, but i can't figure out how to switch the track on the go. I know this was previously impossible, but was wondering now if it is possible?
Even i have the same requirement. I have to record the video using MediaRecorder. For this I am using navigator.getUserMedia with constraints of audio and video. You can pass the video or audio tracks dynamically by getting the available devices from navigator.mediaDevices.enumerateDevices() and attaching the respective device to constraints and calling navigator.getUserMedia with new constraints again. The point to be noted when doing this is, you have to kill the existing tracks using track.stop() method.
You can see my example here.
StreamTrack's readyState is getting changed to ended, just before playing the stream (MediaStream - MediaStreamTrack - WebRTC)
In Firefox, you can use the RTPSender object to call replaceTrack() to replace a track on the fly (with no renegotiation). This should eventually be supported by other browsers as part of the spec.
Without replaceTrack(), you can remove the old stream, add a new one, deal with onnegotiationnedded, and let the client process the change in streams.
See the replaceTrack() test in the Mozilla source: https://developer.mozilla.org/en-US/docs/Web/API/RTCRtpSender/replaceTrack
Have you tried calling getUserMedia() when you want to change to a different device?
There's an applyConstraints() method in the Media Capture and Streams spec that makes it possible to change constraints on the fly, but it hasn't been implemented yet:
dev.w3.org/2011/webrtc/editor/getusermedia.html#the-model-sources-sinks-constraints-and-states
dev.w3.org/2011/webrtc/editor/getusermedia.html#methods-1
I write some photos to the photo library using UIImageWriteToSavedPhotosAlbum() and at the same time I display the contents of this asset group (ALAssetsGroupSavedPhotos) using enumerateAssetsUsingBlock: and friends. Sometimes the assets returned by enumerating the group become sort of “invalid”, meaning that the defaultRepresentation call returns nil, although the asset is still in memory.
I noticed that this seems to happen after the photo library gets modified by the UIImageWriteToSavedPhotosAlbum() call. Is this a documented behaviour? How can I prevent it? Reloading the assets is not a feasible option, as the user might already be somewhere deeper in the UI working with the asset.
this is an unfortunate, but documented behavior. For reference:
"ALAssetsLibraryChangedNotification Sent when the contents of the
assets library have changed from under the app that is using the data.
When you receive this notification, you should discard any cached
information and query the assets library again. You should consider
invalid any ALAsset, ALAssetsGroup, or ALAssetRepresentation objects
you are referencing after finishing processing the notification."
So what you have to do is to register an observer for ALAssetsLibraryChangedNotification. (And there is a bug in regarding this notification on iOS 5.X, see Open Radar.)
When you receive the notification you have to reenumerate all groups and assets. There is at the moment no other way. This is very unfortunate from a GUI perspective and we can only hope Apple improves this mechanism in the future.
Cheers,
Hendrik
Our code was written based on the example from Google Gears' own docs. We're using an unmanaged resource store. So we declare the files in an array, create the store, and capture all the files.
Trouble is, the capturing process hangs. It always hangs on a random file (no discernible pattern has emerged), and when you reload the page, it always successfully captures.
We're capturing 48 files. It seems to have nothing to do with the files themselves, as it hangs on every file type. I've seen it hang on the 6th file or the 47th. Windows and Mac. FF, IE, and Safari.
We are not using a WorkerPool, and I'm thinking this may be necessary. Any other ideas why it would hang?
I discovered that the problem was in the scope of the variable. The code we had used from Google's own example had the creation of the store, and the capture happening in separate functions, and since we were downloading so many files along the way, the object was getting destroyed by the browser's own trash collector.
That's why the callback was producing no errors, and it was instead just hanging.