{"id":127,"date":"2008-09-11T15:34:57","date_gmt":"2008-09-11T20:34:57","guid":{"rendered":"http:\/\/vgable.com\/blog\/2008\/09\/11\/detecting-if-headphones-are-plugged-in\/"},"modified":"2008-11-10T16:35:10","modified_gmt":"2008-11-10T21:35:10","slug":"detecting-if-headphones-are-plugged-in","status":"publish","type":"post","link":"https:\/\/vgable.com\/blog\/2008\/09\/11\/detecting-if-headphones-are-plugged-in\/","title":{"rendered":"Detecting if Headphones are Plugged In"},"content":{"rendered":"

I found many posts on mailing lists asking the question of how to detect if something is plugged into the headphones jack, but no complete answer. So here’s how I do it.<\/p>\n

Docs & Tools<\/strong><\/p>\n

Use the CoreAudio.framework<\/a>, specifically CoreAudio\/CoreAudio.h<\/code><\/a> Unfortunately it’s a bit confusing sometimes<\/a>, but the documentation is still very complete (if complex).<\/p>\n

HALLab (\/Developer\/Examples\/CoreAudio\/HAL\/HALLab\/<\/code> if you have the developer tools installed) is the most complex bit of relevant CoreAudio sample code, and when built it’s a useful utility for poking-around with to boot.<\/p>\n

How To Do It<\/strong><\/p>\n

Whenever something is plugged into the headphones jack, CoreAudio changes the data source for the output device, from internal speakers to headphones. Use AudioDeviceGetProperty(outputDeviceID, 0, 0, kAudioDevicePropertyDataSource, &size, &dataSource);<\/code> to examine the 32-bit ID of the data source, which is best thought of as a 4 character code<\/a>. If dataSource<\/code> is 'ispk'<\/code>, sound is played through internal speakers, if it is 'hdpn'<\/code>, sound is playing through the headphones jack. I’m not sure what happens if you have speakers plugged in that use a different output source, like USB, FireWire, or optical out.<\/p>\n

A word of caution, do not use the promising-looking AudioDevice Property kAudioDevicePropertyJackIsConnected<\/code> it does not work on all systems (specifically it didn’t work in 10.4, and I have not tested it under Leopard).<\/p>\n

Change Notifications<\/strong><\/p>\n

If you want to be notified when something is plugged\/unplugged in the headphones jack, listen for a kAudioDevicePropertyDataSource<\/code> change to the output audio device. Here is the code I use to test if a computer is using it’s internal speakers:<\/p>\n

Sample Code:<\/strong><\/p>\n


\n\/\/Returns YES if the default sound output device
\/\/is using external speakers to play sound.
- (BOOL) usingInternalSpeakers
{
   AudioDeviceID deviceID;
   UInt32 size = sizeof(deviceID);
   OSStatus err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultSystemOutputDevice, &size, &deviceID);
   NSCAssert((err == noErr), @\"AudioHardwareGetProperty failed to get the kAudioHardwarePropertyDefaultSystemOutputDevice property\");
   \/\/To be notified when something is plugged\/unplugged into the headphones jack
   \/\/listen for a kAudioDevicePropertyDataSource or kAudioDevicePropertyDataSources notification on deviceID
   
   \/\/Check if headphones are plugged in right now:
   UInt32 dataSource;
   size = sizeof(dataSource);
   err = AudioDeviceGetProperty(deviceID, 0, 0, kAudioDevicePropertyDataSource, &size, &dataSource);
   NSCAssert((err == noErr), @\"AudioDeviceGetProperty failed to get the kAudioDevicePropertyDataSource property\");
   
   \/\/'ispk' => internal speakers
   \/\/'hdpn' => headphones
   return dataSource == 'ispk';
}
\n<\/code><\/p>\n","protected":false},"excerpt":{"rendered":"

I found many posts on mailing lists asking the question of how to detect if something is plugged into the headphones jack, but no complete answer. So here’s how I do it. Docs & Tools Use the CoreAudio.framework, specifically CoreAudio\/CoreAudio.h Unfortunately it’s a bit confusing sometimes, but the documentation is still very complete (if complex). […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,4,13],"tags":[223,172,79],"class_list":["post-127","post","type-post","status-publish","format-standard","hentry","category-macosx","category-programming","category-sample-code","tag-audiohardwaregetproperty","tag-coreaudio","tag-fourcharcode"],"_links":{"self":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts\/127","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/comments?post=127"}],"version-history":[{"count":0,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts\/127\/revisions"}],"wp:attachment":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/media?parent=127"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/categories?post=127"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/tags?post=127"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}