I am developing an WP8 app witch uses background audio agent. i have taken the background audio players sample. i have added the following method to audioplayer.cs
public static void playTrackAtIndex(int index)
{
currentTrackNumber = index;
BackgroundAudioPlayer.Instance.Track = _playList[currentTrackNumber];
}
after it is called the song at the specified index (let's say 5) will play, but when i pres skipnext in my ap or in the UVC currentTrackNumber is 0!. Please, any help is apreciated
it turns out you don't have any control over the lifecycle of the background audio agent, so at any time it may be killed and then instanced by the foreground app or the Background audio player. So the only whey to make the agent work is to design it as it will always be killed and instanced (use sql lite or files with a lock, or always check what backgoundaudioplayer is playing when your agent is called, so your agent will "remember" where it was before getting killed
Related
In my Corona SDK project, I have a composer scene called "menu.lua" (created with composer.newScene()) that is the first scene, called by main.lua file. I have a background track only for this scene, loaded in scene:create() with audio.loadSound() in a local variable. When I load another scene (let's suppose it's a "credit" scene, static, with no music, sounds, animations, timers, etc.) and then come back to menu scene, audio is still played, but with a lower volume.
Audio is played in loop on channel 2, I use audio.play() in scene:show "did" phase. I use audio.fadeOut() in scene:hide "will" phase, and stop it with audio.stop() in "did" phase, then dispose it with audio.dispose() in scene:destroy.
In "menu.lua" file
local composer=require("composer")
local scene=composer.newScene()
local theme --this is the variable for audio
function scene:create(event)
local sceneGroup=self.view
theme=audio.loadSound("sfx/theme_short.mp3")
end
function scene:show(event)
local sceneGroup=self.view
if event.phase=="will"
audio.play(theme,{loops=-1,channel=2})
end
end
function scene:hide(event)
local sceneGroup=self.view
if event.phase=="will" then
audio.fadeOut(theme,{500})
end
elseif event.phase=="did" then
audio.stop(2)
end
end
function scene:destroy(event)
local sceneGroup=self.view
audio.dispose(theme)
end
The other scene (let's suppose it's "credits.lua") is called by a button with a "tap" event attached. In "credits.lua" I use this function to go back to "menu.lua" scene (function is called with a "tap" event attached to a button)
local function goMenu()
composer.removeScene("menu")
composer.gotoScene("menu","slideUp",500)
return true
end
I've already tried to play audio in scene:show "did" phase and in scene:create, but the problem persists. The problem happens with all the scenes, all static (3 in total). Any idea?
You should replace
audio.fadeOut(theme,{500})
with
audio.fadeOut( { channel=2, time=500 } )
since you use wrong syntax.
See audio.fadeOut()
Make sure you read the "Gotcha" section of the docs:
When you fade the volume, you are changing the volume of the channel. This value is persistent and it's your responsibility to reset the volume on the channel if you want to use the channel again later (see audio.setVolume()).
You're responsible for setting the channel volume back because fadeOut changes the volume of the channel.
I'm making a gym management web app that handles sign-ins. Members have a barcode on a tag that they scan when they arrive to the gym.
I've heard that most barcode scanners simply act as a keyboard. This would require the scanning-in page to be open and in the foreground when a barcode is scanned.
If it's just a keyboard, how would I send the barcode scanner input to a single background process running on the computer, and have it ignore by all processes that may be in focus?
You're right that most scanner can support HID in keyboard emulation, but that's just the start.
If you want to have a bit more control over the data you can use a scanners that support the OPOS driver model.
Take a look at Zebra's Windows SDK to have a overview of the things that you can do. It may be a better solution than try to steal the barcode data coming in the OS as a keyboard entry to the foreground app.
Disclaimer: I work for Zebra Technologies
Other Barcode scanner vendor support a similar driver model.
I found an interesting post with a simple solution:
On the form constructor
InitializeComponent():
this.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.Form1_KeyPress);
Handler & supporting items:
DateTime _lastKeystroke = new DateTime(0);
List<char> _barcode = new List<char>(10);
private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
// check timing (keystrokes within 100 ms)
TimeSpan elapsed = (DateTime.Now - _lastKeystroke);
if (elapsed.TotalMilliseconds > 100)
_barcode.Clear();
// record keystroke & timestamp
_barcode.Add(e.KeyChar);
_lastKeystroke = DateTime.Now;
// process barcode
if (e.KeyChar == 13 && _barcode.Count > 0) {
string msg = new String(_barcode.ToArray());
MessageBox.Show(msg);
_barcode.Clear();
}
}
Credits: #ltiong_sh
Original post: Here
Use RawInput API (https://www.codeproject.com/Articles/17123/Using-Raw-Input-from-C-to-handle-multiple-keyboard#_Toc156395975) and check device ID for incoming keystrokes. Different devices have different IDs. You can also block keystrokes from scanner from reaching your application and interfering with input fields.
One thing you might want to add is option for user to identity which device is used as a barcode scanner. I did it by asking user to test-scan barcode with scanner on first application startup or in settings.
Works with any barcode scanner which outputs keystrokes.
i`m using mediaElement to play background music in my app. And that works just fine.
Problem is when the user minimize the application. When the application resume there is no sound... I can play other sounds in my application but cant play that background music any more.
First i have this code to stop all background music at first time app open:
if (Microsoft.Xna.Framework.Media.MediaPlayer.State == MediaState.Playing)
{
Microsoft.Xna.Framework.Media.MediaPlayer.Pause();
FrameworkDispatcher.Update();
}
xaml code of that mediaElement
<MediaElement AutoPlay="True" Source="/Dodaci/pozadina.mp3" x:Name="muzika_pozadina" MediaEnded="pustiPonovo" Loaded="pustiPonovo" />
and the cs code
private void pustiPonovo(object sender, RoutedEventArgs e)
{
muzika_pozadina.Play();
}
sound is about 300kb size.
So, how can i resume that sound playing after the user resume the application?
When your App is put into Dormant State (when you hit Start buton for example), the MediaElement is stopped. Then after you return to your App (and it wasn't Tombstoned), the Page is not Initialized once again, which means that your MediaElement is not loaded once again, so your Music doesn't start once again.
It depends on your purpose and code how it can be returned. In very simple example when you don't need to remember music last position you can just set source of your MediaElement once again in OnNavigatedTo() event:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
if (e.NavigationMode == NavigationMode.Back)
muzika_pozadina.Source = new Uri("/Dodaci/pozadina.mp3", UriKind.RelativeOrAbsolute);
}
As you have set your MediaElement.AutoPlay to true - it should start automatically (because of that you probably also don't need your Loaded event pustiPonovo).
In more complicated cases you can take an advantage of Activation and Deactivation events of your App - returning to MediaElement from Dormant/Tombstoned case is well explained here in the article.
You should also read about Fast App Resume in case User decides to return to your App by Tile instead of Launchers-Choosers.
I haven't tried above code, but hopefully it will do the job.
I am trying to stop sound when user exits the application by pressing Hang up key in Series 60. But the application goes to background and the sound still plays.
I want to stop the sound when user clicks the Hang up key of the device. I called the stop() method of Player. I also called the stop() method at hidNotify();
{
Player p;
p.start();
p.stop();
}
The AMS calls (or should call) the destroyApp() method of the MIDlet when the user exits.
Try putting your p.stop() command in there. (And other clean-up code too).
I made a streaming music player and it works fine in the foreground.
But in the background iOS4, it doesn't play the next song automatically. ( remote control works )
The reason is AudioQueueStart return -12985.
I already check the audio session. it just fine. I use AudioQueueStart when it start to play the music.
How can you remove AudioQueueStart?
- (void)play
{
[self setupAudioQueueBuffers]; // calcluate the size to use for each audio queue buffer, and calculate the // number of packets to read into each buffer
OSStatus status = AudioQueueStart(self.queueObject, NULL);
}
I read the answer in the web about the AudioQueueStart fail subject.
One thing to check is that the AudioSession is active first.
In my case, I had previously set the session to inactive between song changes before starting a new song:AudioSessionSetActive(false);
Once I removed this AudioQueueStart works just fine from the background.
In my experience, the -12985 message occurs because another app already has an audio session active when you try to start playback in your app. Options are to 1) instruct the user to close the other app, or 2) set mix mode (see kAudioSessionProperty_OverrideCategoryMixWithOthers).
The disadvantage of mix mode is if you depend on lock screen art or remote controls, they won't work with mix mode set.
I also faced with such problem week ago. I've spent two days to find solution and I found it. May be this link will help (it is official answer): http://developer.apple.com/library/ios/#qa/qa1668/_index.html
Make sure that you activate session from applicationDidEnterBackground task handler. Now my application can play sound in background.
See this.
You probably need to include the following:
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
Towards the bottom there is a reiteration of the how important that line is. As it is not mentioned in any of the three main audio audio guides (AVFoundation, AudioSession, or AudioQueue) it can easily be missed.
I have the same problem.
I registry the AudioSessionInterruptionListener, pause the audio when phone call, resume it after the call end. but get -12985 error code when call AudioQueueStart to resume.
My solution is that I try to call AudioQueueStart after 0.02s.
I don't know the reason.
On iOS7, AudioQueueStart was returning '!int' ('tni!'), though i'm sure no one would be surprised to find that it's not documented in the docs or headers. It was the same issue, though, and the same fix (setting the audio session to active in the background task handler) worked for me.