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Volume control for external audio output

Posted: Sun Jan 31, 2010 1:43 pm
by nbd
Hello. At least my TV (UE40B7070) is not able to adjust the external audio output volume (when I choose the audio to be played through external speakers from audio menu, I think it's the same for most of the Sammys)

This is a big disappointment for me, and I've asked from CNET Samsung forums if Samsung would provide external audio volume control through FW upgrade, but they replied it's not going to happen.

I was hoping that maybe that would be possible with SamyGO. At least the TV is receiving the Vol +/- commands from remote control, since the light blinks, so it could be that the function that handles Vol +/- has some kind of if-statement to disregard those commands while external speakers are chosen. Maybe there is room for injection code that would adjust the outgoing audio signal.

Re: Volume control for external audio output

Posted: Tue Feb 02, 2010 11:03 pm
by antapetr
I see the reason why Samsung not going to add support you asked. It is because with external audio playback TV passes sound as bit-stream without touching it. If this is PCM sound it is not difficult to add volume control but if this is AC3 sound there is a lot of decoding and coding which will bring some sound lag. These arguments stands only for optical audio output but I don't see a big reason to connect through analog output because you will get only stereo channels and with optical and AC3 you can get all 6.

Re: Volume control for external audio output

Posted: Wed Feb 03, 2010 1:51 pm
by nbd
Yes, valid reasons.

My own solution is to build IR interpreter, a simple micro controller device with 2 IR leds, one for receiving remote control signals, one for sending signals out. The micro controller is responsible for detecting Samsung remote control's Vol+/- and sending them out as my AV amplifier's vol+/- commands.

And no, I don't want to go the Harmony way (or any other learning controls), because that really does not fully resolve my problem, since the TV is not located at the same direction as the AV amplifier, and I want to use the Sammy's RC.

Would there be option to attach USB IR device to the TV and control it from the firmware/software? I'll open separate thread for it.

Re: Volume control for external audio output

Posted: Sat Feb 06, 2010 3:33 pm
by andbir
Would not the volume +/- commands be sent through Anynet+/HDMI-CEC to the amplifier? I suppose that at least a Samsung amplifier would intercept the signal and adjust the volume. I haven't bought a new ampilfier yet still on my surround-amp from 1998 so no HDMI connectivity in this one so no personal experience from this yet.

Re: Volume control for external audio output

Posted: Sat Feb 06, 2010 6:55 pm
by nbd
That had crossed my mind, but I don't have a Samsung amplifier either. I was about to buy HDMI-CEC aware amplifier but I didn't. But my experience with Anynet+ is not so promising; I have Samsung BD player and it performs only basic commands through the TV's IR receiver - play,stop,ff,rew and up/down/right/left arrows while in the menu - more advanced commands like disc menu, subtitles, audio, are not forwarded to the player. I complained about this to the CNET Samsung forums.

Re: Volume control for external audio output

Posted: Wed May 19, 2010 12:26 pm
by nbd
Btw, I found one USB IR device that works with the TV without firmware mods. Also succeeded building a software that sends vol +/- commads to my amplifier when TV remote vol +/- is pressed.

Re: Volume control for external audio output

Posted: Wed Mar 14, 2012 2:21 pm
by shakham
I know this thread is pretty old...
nbd....can you provide more details as to what you did?

Re: Volume control for external audio output

Posted: Thu Mar 15, 2012 12:49 am
by erdem_ua
I don't use external sound dua lack of any sound system...
But it comes to my mind, if you could enter "Debug Menu" you can look what you can make with PC speaker related debug functions...
Details of entering debug menu of TV (not service menu, debug menu is something that you can reach only from ExLink port.) is available on wiki pages.

Re: Volume control for external audio output

Posted: Thu Mar 15, 2012 9:56 am
by nbd
I bought an Iguana IR device and compiled its drivers for the TV. Then I was able to send IR commands from TV's shell. After that I hacked around and got to the point where remote control Vol+ / Vol- was sending those IR commands.

I compiled LIRC for the TV, but found out much easier way to communicate with the Iguana IR device (just a binary) and since I had the needed IR pulse commads already available, I decided to skip unnecessary dependencies to get it more robust, but the LIRC method would be more universal.

However the vol change response rate was too low, as I was only able to detect the Vol+ / Vol- events (not the key being held down), so vol change meant hitting the key repeatedly and still it was too slow to be usable.

Then I lost interest on the subject, mainly because it was easier to use amplifiers own remote, and also I wanted that the TV's own speaker is on use (for the sake of my sanity, by not needing to explain to my kids & wife how the system "works")

Also at the time I wasn't able to find elegant method. But now there is possibility to detect key down and key release events, so it could be fine tuned so that while key is down, constant stream of IR messages would be sent, making the amplifier much more responsive. Also LIRC could be used, since it can easily handle key down / key release method.

Feel free to ask more.