SamyGO

Hello,
several times already i was thinking about making some dynamic light effects for my TV. As usual after 1 week i got another thought and forgot about that. Now, after i saw how cheap the LED stripes became on ebay the dreams are back, but now with a different way of controlling it.

In the past I was thinking about grabbing the SCART signal in proper way with a microcontroller and control with PWM the LED Stripes ( i read it somewhere, i think it was mikrocontroller.net ). But now i got a C650 TV and had following thoughts:
what if it was possible to grab the picture buffer from the TV -> pass the picture to the internal DSP or CPU or whatever -> calculate there the dominating colors of the borders and then send the values over TV's RS232/ UART to a microcontroller which interprets the signal and controls the LED stripes.

Could it work?
Does the internal CPU/DSP have enought power to calculate the colors?
Does the firmware need to be hacked or is it possible to run the app from the USB Stick for example?

As you see i am not really informed about all possibilities of SamyGo and the internal life of the TV. A quick search in the forum was not satisfying enough to me so i decided to ask.


Thx & Greets

maxmustermann

Hi, welcome to SamyGO

Yes, we have some success on A and B series, i suggest you to read this topic.
Noone reported about C series, but with help of our devels you could be the first

There is very interested open source project for Windows/Linux/MacOS for Ambilight. It's called Light Pack.

More info:
http://lightpack.googlecode.com
http://pixelkit.ru

I think it's not too hard to do such calculations from PVR stream capture at B series...
Later we could do it same for C series too.
We could build a program for supporting LightPack devices...

Hello and thank you for the interesting answers. Its very nice to hear that there is at least a theoretical chance to build such a thing. Also the project lightpack is very interesting with the expection that a external equipment is needed to feed the microcontroller with data. I am dreaming about a light effects which a working independent of what i am using, if that is a TV signal or HDMI or internal media player

@erdem_ua wold that require a modded firmware or could that be an external program on a USB-Stick? (I have seen some "screen capture" applications here, would it go this way or something complitely different ?) because i think that a modded firmware would scare a lot of people ( including me ) because I have no idea at the moment how easy it is to brick my TV. I mean, do i just need to forget a semicolon in the sourcecode and the TV is dead or does "bricking" require a lot more mistakes to be made before it cant be undone. Of cource a light pack support would be cool since it is a open source project and everyone could try his own luck in developing the lights itself based on the light control signal coming from the TV

No firmware change required. We just needed to build a program that calculates those colors from transport stream. But that approach definitelly doesn't work with HDMI/scart inputs and analog TV. Just possible with Digital Input and PVR enabled platforms. Also we need to find person who wanted to do this job

erdem_ua wrote:...But that approach definitelly doesn't work with HDMI/scart inputs and analog TV. Just possible with Digital Input and PVR enabled platforms...

well that very pity, i didnt even try to enable PVR in my TV because of lacking a usecase (i never record because i am watching mostly internet streams with "Online Video Player" ( NetPlayer ) or media from my HDD and the TV broadcastings rarely deserve it to be recorded ) so i thought the PVR function can record everything what comes to the screen, no matter which source...maybe i should try to enable PVR on my TV first and try to run some application from here before i continue dreaming ( i remember there were some hints that with the latest firmware some ways of hacking are not available anymore, that will be the first thing to check

erdem_ua wrote:We just needed to build a program that calculates those colors from transport stream.

Capturing DVB-T/C/S transport stream (or just video PES) - sure, why not. But: decoding MPEG2/MPEG4 video on 600MHz ARM CPU in real time? I really doubt it..
For MPEG4 1920x1080@i50 video: downright impossible, IMO.

maxmustermann wrote: what if it was possible to grab the picture buffer from the TV -> pass the picture to the internal DSP or CPU or whatever ->

Broadly speaking, it should be possible to capture picture[s] from TV memory [frame]buffers, regardless of the signal source. I did some preliminary research on that subject for B-Series; see viewtopic.php?f=3&t=346 thread for details (last ~5 posts or so). I think it's quite similar in C-Series Valencia/T-VAL* models..

and then send the values over TV's RS232/ UART

USB and/or LAN output (or additional 3.50$ USB <-> RS232 dongle) will be better/easier/cheaper choice, IMO.

Could it work?

I think so (at least for T-CH* B-Series, and T-VAL* C-Series TVs). Quite a lot of work required, though .

Does the internal CPU/DSP have enought power to calculate the colors?

Good question. Most likely, some kind of YCbCr -> RGB real-time conversion will be unavoidable.. But, (considering that we only need to process image borders): I think so .

sbav1 wrote:

Does the internal CPU/DSP have enought power to calculate the colors?

Good question. Most likely, some kind of YCbCr -> RGB real-time conversion will be unavoidable.. But, (considering that we only need to process image borders): I think so .

Also we don't needed to calculate those values for each frame. Instead I believe ~15-20 FPS is enough to have good illumination...