Android - send HDMI CEC commands to TV - minix - libCEC

Question

i\'m working on a Minix NEO X8-H (Android media center, 4.4.2) and i need to send HDMI-CEC command to TV: when my App receives a call i want to change automatically the TV Sourc

Answer 1

My two cents on the issue:

Chapter I: Compassion

I went through all the trouble you went, too, especially with libCEC, so I'd like to describe the only way I got any interaction going between an Android TV box and the TV connected to it with HDMI cable.

Chapter II: Cooking low and slow

Send a request for connected device's power status echo 0x40 0x8F > /sys/class/cec/cmd

To get the response, you can:

1. read the "registry" cat /sys/class/cec/dump_reg

2. wait and look for the response in logcat

// Example:
02-06 16:33:10.568  4012  4105 D CEC     : [cec_rx_loop]msg:04 90 00
02-06 16:33:10.570  4012  4105 D HdmiCecExtend: onCecMessageRx
02-06 16:33:10.657  4012  4012 W HDMI    : [1]:Unhandled cec command:<Report Power Status> src: 0, dst: 4, params: 00
02-06 16:33:10.762  4012  4104 D CEC     : [cec_send_message][4 -> 0]len:3, body:00 90 00 , result:success

Magic numbers (codes) explanation:

40 - Playback device #1
04 - TV device #1
On - 90 00
Off - 00 00 // in registry or no response at all in logcat

Other available codes can be constructed or read on Cec-O-Matic or amlogic.

Chapter III: New hope

I still have to try and get to Android's HdmiControlService but I still don't know how, probably through Java reflection. You can see HdmiCecExtend: onCecMessageRx so the API is available on the device, but you cannot use it in Android Studio, as far as I know, it's only available to Android TV vendors.

Will update if anything comes along.

Answer 2

First of all, very impressive reverse engineering work!

Secondly, I'm facing a similar issue (but with a non Minix product). Have you tried upgrading to a newer firmware, such as this one:

http://minixforum.com/threads/x8-x8-plus-x8-h-official-firmware-004a-not-for-x8-h-plus.5567/

I am suggesting this as a possible solution, because one of the issues it fixes is this:

Fixed HDMI-CEC multi devices issues

This means the device is not only a "slave", but also a "master" (i.e. can send commands to other hdmi devices).

Please note that as stated in the link, it is not intended for the plus version.

Good luck!