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chromecast, another product only half finished

Dr_Doggy

Well-Known Member
ok , so i got one of these , and now i can cast the image from my phone to my tv ... whoopy doo. my phone has a screen already.

what i am looking for is the transmitter side of things , I would like a device that I can plug to the hdmi output of my blueray player where it will take the signal and turn it to a casting source that i can send to the tv

so far all i can find are HDMI transmitter/receiver but all these i believe are built so you can use multi receivers, but only 1 transmitter, hence why i want to use the casting networks, so when i have 5 of these and 5 chrome casts i can say "hey google play blueray 3 to tv2" (a future layer to the project)

but the sound of hdmi input circuitry is over my head already, if i was smart i could use a pi/ard to receive the hdmi then code it to wifi cast protocol, so not a overly complex device but anyone feel brave to try to walk me through this or how i can do it?
1)hdmi decoder to uC
2)convert to cast protocol
are the challenges i will be facing and have no idea what to begin with to even capture the input,

also if anyone wants my idea to build one then post the link from kickstarter so i can just buy one i would be happy with that too!!?

i contacted google about this, they dont mind that it doesnt work
 

Nigel Goodwin

Super Moderator
Most Helpful Member
but the sound of hdmi input circuitry is over my head already, if i was smart i could use a pi/ard to receive the hdmi then code it to wifi cast protocol, so not a overly complex device but anyone feel brave to try to walk me through this or how i can do it?
1)hdmi decoder to uC
2)convert to cast protocol
I presume you're having a laugh?
 

rjenkinsgb

Well-Known Member
Most Helpful Member
HDMI runs at up to 18 GIGABITS per second...
If you can build anything from scratch that works with that, good luck!


The sane approach is to use an HDMI matrix switch.

Connect the inputs to your various sources and the outputs to the TVs.
You can then select any source on any TV.

Examples: https://www.alibaba.com/showroom/hdmi-matrix-4x8.html

You can get cheap HDMI extenders that work over cat5e/cat6 ethernet cables for longer runs to TVs etc.
 

Dr_Doggy

Well-Known Member
yes the extenders would be great , but you need to link the receiver to transmitter , so it helps when you have several tv's ... but the other side of that it is only one transmitter, and eliminates the option of selecting which feeds from a single tv
some of them even use the actual ethernet so splitting and routing can be done from common router

i have 5 tv's in my home and 4 devices to share among them, to do the same with hdmi extender i would need 4 transmitters and 20 receivers ... cos of the receiver limits. and then extra hdmi support for the tv since each tv only has 3 hdmi ports

which is why im looking at the chrome cast as it supports casting , I am also looking at things called mirror casting, screen casting and dlna, not sure the difference between all these but they all share the fact that i can send a video feed from my cell phone/PC to the tv

... but back to the point of all i can tx with is my phone/pc
... ya im serious, i really need one.. pushing the input button is too much work now adays

but i am surprised that if a pi can output why cant it input just as fast?
also i dont need 4k, just 1080!

and actually, the transmitter on the hdmi extender can input ok, and then it just encodes to its own network stream encoding ... then technically my device has been proven as feasible ...... but to complete it my way we just need to change the encoding a bit to meet the casting criteria

do i make sense? i just cant understand why they dont exist already!?
 

gophert

Well-Known Member
Most Helpful Member
ok , so i got one of these , and now i can cast the image from my phone to my tv ... whoopy doo. my phone has a screen already.

what i am looking for is the transmitter side of things , I would like a device that I can plug to the hdmi output of my blueray player where it will take the signal and turn it to a casting source that i can send to the tv

so far all i can find are HDMI transmitter/receiver but all these i believe are built so you can use multi receivers, but only 1 transmitter, hence why i want to use the casting networks, so when i have 5 of these and 5 chrome casts i can say "hey google play blueray 3 to tv2" (a future layer to the project)

but the sound of hdmi input circuitry is over my head already, if i was smart i could use a pi/ard to receive the hdmi then code it to wifi cast protocol, so not a overly complex device but anyone feel brave to try to walk me through this or how i can do it?
1)hdmi decoder to uC
2)convert to cast protocol
are the challenges i will be facing and have no idea what to begin with to even capture the input,

also if anyone wants my idea to build one then post the link from kickstarter so i can just buy one i would be happy with that too!!?

i contacted google about this, they dont mind that it doesnt work

HDMI in the US is a standard that specifically forbids broadcasting / routing a signal to multiple devices. Also, it is quite difficult to do since HDM
I is a communications protocol, not just a coaxial cable sending a television signal down the line. A device name and acknowledgements must be made. Therefore, you need to make a buffer of the signal, send it, get ack that data packet received and repeat.

The setup at Costco/Walmart/Bestbuy/Target are specifically licensed for TV demonstration uses only. Recently they've been made more broadly available. A 1 to 8 splitter is about $600 at Bestbuy and a 1 to 2 splitter is $70.

You'll need to split the signal before you transmit. Wireless transmitters are available - more commonly used in conference rooms in businesses. Not a perfect science there. Posts of meetings have been delayed because of hdmi technology - often because each laptop seems to have a different connector and people keep walking off with the set of adapters.


 

Dr_Doggy

Well-Known Member
this again would work great for a single transmitter:

check out the wire diagram in photo 5 with the router,.. not the same as using cat as just an extention cord(if thats what others do?):

but would need 4x of them for all 4 of my feeds, there is no reason why adding feed switching to this 80$ device should be so hard/expensive
 

rjenkinsgb

Well-Known Member
Most Helpful Member
HDMI is raw, uncompressed RGB video data in serial form.

1920 x 1080 at 60Hz = 1920 x 1080 x 3 x 60 = 373 Megabytes of data per second or near enough three gigabits per second.
That means seriously specialised design just at the PCB level, even using off-the-shelf ICs.


These units you link to re-code and compress the video for transfer; they only support up to HDMI version 1.3 and use H264 video compression to reduce the bandwidth needed down to just 10 Mbit, according to the info. They are not "full quality" HDMI devices.



I am also looking at things called mirror casting, screen casting and dlna,
DLNA is a totally different thing and most smart TVs are DLNA compatible.

You need a DLNA media server, which is a program on a computer or smartphone that has access to stored media - video, movies, music or whatever.

Any device with a DLNA client can find the server over the network/WiFi and play the media on it.
Most also have the ability to send it to a different device to be played on that instead, eg. I can be watching something on my phone and transfer it to the TV.

That does not need any chromecast or such, if the TV has DLNA capability.
 

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