In article ,
TheM wrote:

I always wondered how the mute works?

In every case I know, MUTE is treated just like any other button on
the remote. The remote usually transmits an IR packet which (when
decoded) says "Device ID NNN, button MMM has been pressed".

It's up to the IR receiver logic, and the microcontroller in the TV,
to decode the modulated IR burst, pull out the device ID and "realize"
that the ID is that of the TV set, pull out the button ID and
"realize" that this means "mute", and do whatever is necessary.

I'd like to be able to universally mute
any TV (usefull).

Unless your remote control is capable of firing a 50-calibre plastic
slug through through the TV screen, that's not going to happen :-)

Every manufacturer can choose its own IR-modulation schema and command
packet format (although there are a few very popular variants), device
IDs, and button IDs. There is no universal standard.

Now the question is whether there are two different signals
for mute on and mute off or is it just a Flip/Flop kind of thing.

Almost always a flip-flop, just like the POWER button. The remote
control doesn't have any way of knowing whether the TV is on or off,
muted or unmuted, etc.

In some remote-control dialects, there are different variants of some
command codes (I think they're called "discrete" codes but I may be
misremebering). For instance, the POWER code is used by the normal
power-on/off pushbutton on the remote, and is a toggle... and there
are separate POWER ON and POWER OFF codes as well. The POWER ON code
would turn on the power if it's off, and would have no effect if the
TV is already on.

These discrete codes usually aren't programmed directly to a
pushbutton on the remote. Rather, they're used when composing a
complex "macro" sequence of commands, on a programmable remote. One
might set up a special-purpose button which means "Turn on the TV if
it's off, turn on the DVD player if it's off, select the DVD input on
the TV, dim the room lights to 50%, wait 10 seconds, send a PLAY
command to the DVD player." Using a discrete-ON (e.g.) command
ensures that the sequence will work correctly regardless of whether
the device is on or off.

I've never seen a remote which has discrete MUTE and UNMUTE
commands... it's always been a toggle. Some devices may support this,
but I haven't run into one myself as far as I know.



--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!