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Sending audio to LKV373 HDMI extenders (2021)

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Re: Sending audio to LKV373 HDMI extenders (2021)

#3
People are amazing. I love this. Adore it. A thread of various awesome enterprising hackers, searching for truth, and using observability & tools to uncover meaning. Then bend reality to their whims & desires. This is the best human spirit. It's a pity technology so often obstructs rather than builds this human mastery. Alas! Never-the-less, humanity persisted. Against the throws of corporate-controlled limiting tech. Break out that wireshark & conquer in the name of freedom! Become great! Be unbounded.

I have huge respect for the Chromecast ecosystem, but there's so many weird prickly points for it. For a while I had a chromecast plugged in to a computer which then variously resent the output. This looks like a great way to do the same but simpler/dumber. One of the specific flaws of Chromecast is that if you stream a video, it can only go to a single device. Meaning my whole home audio does no good. Something like this could help me work-around that limitation. It's great how absurdly flexible these devices are, but it sucks enormous egg that Chromecast apps will only stream in the first place to signed Chromecast devices; this whole thing should be a non-issue I can software workaround. But a hardware workaround like this is adequate.

Re: Sending audio to LKV373 HDMI extenders (2021)

#5
post #4

I didn't even know HDMI extenders over IP existed! I wouldn't use it for TV/movies, because the re-compressed picture can't look all that great. But I could imagine plenty of uses for something like that!

Why do you assume the signal is being recompressed or in any other way manipulating the image?

Re: Sending audio to LKV373 HDMI extenders (2021)

#6
post #5
post #4

I didn't even know HDMI extenders over IP existed! I wouldn't use it for TV/movies, because the re-compressed picture can't look all that great. But I could imagine plenty of uses for something like that!

Why do you assume the signal is being recompressed or in any other way manipulating the image?

Because a 1080p60 video stream is about 3Gb/sec on the wire uncompressed like happens over HDMI. 1920w * 1080h * 3colorbytes * 8bits/byte * 60fps = 2,985,984,000 bits/sec.

Re: Sending audio to LKV373 HDMI extenders (2021)

#7
post #5
post #4

I didn't even know HDMI extenders over IP existed! I wouldn't use it for TV/movies, because the re-compressed picture can't look all that great. But I could imagine plenty of uses for something like that!

Why do you assume the signal is being recompressed or in any other way manipulating the image?

Well, for one, the fact that it's streaming frames as motion JPEG...

Re: Sending audio to LKV373 HDMI extenders (2021)

#8
There was some effort to reverse engineer those devices [1] so that one could use for example either transmitters or receivers paired with normal PCs and not just connecting them straight each other. There are also newer models around, though I'm not aware of any reverse engineering efforts so far.

If you want to tinker with them, please leave some writeup of the results. Beware that there are both HDMI over IP and aesthetically very similar, but often cheaper, HDMI over Ethernet cable adapters. The 2nd ones contain no brain and can't do any IP encapsulation, they're essentially just level translators using CATx cable to carry the HDMI signals, and of course aren't compatible with any network devices, switches, etc. For that use, you want HDMI to IP transmitters and receivers, which should be clearly marked as capable of working in a network environment. Check carefully the features before buying, because some among the stupid level translators sold on the usual channels are marked as HDMI over IP, which they clearly are not.

1 - https://blog.danman.eu/reverse-engineering-lenkeng-hdmi-over...

Re: Sending audio to LKV373 HDMI extenders (2021)

#9
post #7
post #5

Earlier quoted context omitted.

Why do you assume the signal is being recompressed or in any other way manipulating the image?

Well, for one, the fact that it's streaming frames as motion JPEG...

Where do you see that? I quickly glanced at the Amazon listing, and saw nothing about this. I could have glanced too quickly and missed it, but it just seems like a totally strange thing for it to do.

Re: Sending audio to LKV373 HDMI extenders (2021)

#10
post #6
post #5

Earlier quoted context omitted.

Why do you assume the signal is being recompressed or in any other way manipulating the image?

Because a 1080p60 video stream is about 3Gb/sec on the wire uncompressed like happens over HDMI. 1920w * 1080h * 3colorbytes * 8bits/byte * 60fps = 2,985,984,000 bits/sec.

Okay, but the original signal is not RAW uncompressed either. It's just a serial signal, so converting that into IP packets is pretty much all I'm assuming this is doing and then converting those back to an HDMI formatted signal on the other end. The only thing different about this unit from others is that it's actually turning them into actual network traffic to connect to an existing network.
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