HdmiCECSpike

Investigation on HDMI-CEC technology for CTV (leanback)

GoogleTV observations:

CTV & GoogleTV HDMI-CEC is enabled:

!- when I turn off the TV (even when TV Input Source is another) - Activity.onStop (the app is minimized), the Activity is still alive (but stopped)

!- when I switch TV Input Source from GoogleTV HDMI - no any message

- when I launch a spike app:
		Added device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Added device (1): name: Chromecast, type: 21 - TYPE_BUS, sink: true, source: false
		Added device (2): name: Chromecast, type: 15 - TYPE_BUILTIN_MIC, sink: false, source: true
		Added device (3): name: Chromecast, type: 15 - TYPE_BUILTIN_MIC, sink: false, source: true
		Broadcast, extraAudioPlugState: 1 - PLUGGED

- when I switch TV Input Source to GoogleTV HDMI:
		Removed device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 0 - UNPLUGGED
		Added device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 1 - PLUGGED

- when I disconnected HDMI:
		Broadcast, extraAudioPlugState: 0 - UNPLUGGED
		Removed device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false

- when I connected HDMI back again:
		Added device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 1 - PLUGGED
		Broadcast, extraAudioPlugState: 0 - UNPLUGGED
		Removed device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Added device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 1 - PLUGGED


CTV HDMI-CEC is disabled, GoogleTV HDMI-CEC is enabled or disabled:

!- when I turn off the TV - no any signal or message

!- when I switch TV Input Source from GoogleTV HDMI - no any message

- when I turn on the TV:
		Removed device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 0 - UNPLUGGED
		Added device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 1 - PLUGGED

- when I disconnected HDMI:
		Broadcast, extraAudioPlugState: 0 - UNPLUGGED
		Removed device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false

- when I connected HDMI back again:
		Added device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 1 - PLUGGED

- when I switch TV Input Source to GoogleTV HDMI:
		Removed device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 0 - UNPLUGGED
		Added device (0): name: Chromecast, type: 9 - TYPE_HDMI, sink: true, source: false
		Broadcast, extraAudioPlugState: 1 - PLUGGED

FireTV 4K Max observations:

CTV & FireTV HDMI-CEC is enabled (the only difference with GoogleTV):

!- when I switch TV Input Source from FireTV HDMI (only when another HDMI Input was selected, not analogue or digital TV):
		Broadcast, extraAudioPlugState: 0 - UNPLUGGED
		Removed device (0): name: AFTKA, type: 9 - TYPE_HDMI, sink: true, source: false

Summary:

CTV & GoogleTV HDMI-CEC is enabled: - need a 5 sec throttle while listening for the HDMI events - there is no events when another TV Input Source is switched to - in fact we need only listen to for RemovedDevice or UNPLUGGED events

CTV HDMI-CEC is disabled, GoogleTV HDMI-CEC is enabled (or disabled): - we still can get notifications when HDMI is disconnected - we still can get notifications when GoogleTV Input Source is activated

For Android 6 (API 23) and above we need to use audioManager.registerAudioDeviceCallback(audioDeviceCallback, null)
For android 5 (API 21-22) we need to use BroadcastReceiver with IntentFilter().apply { addAction(ACTION_HDMI_AUDIO_PLUG) }

Conclusion:

(POWER OFF - HDMI-CEC) The main difference when HDMI-CEC is enabled (on both CTV + Stick) from disabled is reaction to power-off button, the App Activity goes in onStop (CREATED state), so the player is destroyed in any case
(CHANGE INPUT - only FireTV) We can detect when the TV Input Source is changed to another one only for FireTV and only if another HDMI device was selected (not a analogue or digital TV), and it is not HDMI-CEC feature
(DISCONNECT HDMI) Even without HDMI-CEC technology the app is still available to listen for events when HDMI is disconnected and check the HDMI connection state (connected/disconnected)
(CONNECT HDMI) Even without HDMI-CEC technology the app is still available to listen for events when HDMI is connected and check the HDMI connection state (connected/disconnected)
(ACTIVATED INPUT) We can determine if the INPUT SOURCE was activated again

ultraon/HdmiCECSpike

HdmiCECSpike