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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 ima
by jaywalk 3y ago
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!
- dylan604 3y agoWhy do you assume the signal is being recompressed or in any other way manipulating the image?
- duskwuff 3y agoWell, for one, the fact that it's streaming frames as motion JPEG...
- monocasa 3y agoBecause 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.
- dylan604 3y agoOkay, 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.
- monocasa 3y ago> Okay, but the original signal is not RAW uncompressed either. HDMI is in fact the RAW color values, uncompressed. Each of the color channels are serial, but that doesn't really change anything about the raw bitrate.
- jacquesm 3y agoI suspect that just delta compression would reduce the required number of bits considerably.
- duskwuff 3y agoLossless compression isn't a good fit for real-time video. Being able to get some compression ratio on a "typical" image means your stream will drop out when the user has an image on screen which doesn't compress well.
- Clamchop 3y agoJust to throw a little more hair-splitting, we're not talking about raw data, either, raw being a term of art for unprocessed or minimally processed data read from a device (like an image sensor). It usually can't be displayed without some interpreting. HDMI video signal is uncompressed but not raw.
- metaphor 3y agoMuch closer to 5 Gbps when you factor in horizontal/vertical blanking + TMDS 8b10b encoding.
- mnd999 3y agoThat’s very doable on a 10gb Ethernet network which is becoming more and more normal.
- monocasa 3y agoIt's going to be a while before 10Gb ethernet is available on devices that cost ~$30/pair.
- toast0 3y agoYou're right, but used dual port 10g ethernet cards do go for about $30/each... Of course, that doesn't get you hdmi encode/decode, and not new.
- metaphor 3y agoIrrelevant. The hardware under scrutiny is a chinesium HDMI over IP extender with 1 Gbps Ethernet PHY at best.
- mnd999 3y agoStupidity with a hint of racism. Nice.
- monocasa 3y agoFor sure, I'd simply expect even a simple non-compresing bridge to strip a lot of the 'dead air' and expansion at the physical layer. Just wanted to show that even best case of simply the color value bits leaves you with ten pounds of potatoes to fit into a five pound bag.
- mrb 3y agoA hypothetical HDMI-to-IP converter would certainly ignore hblank/vblank, and 8b10b encoding is only used on the HDMI link, not Ethernet. So parent's point stands: 1080p60 could be done in 3 Gbit/s.
- belthesar 3y agoYou can look at the protocol analysis in the post to see that it's sending MJPEG
- bobsmooth 3y agoYou can do HDMI over a lot of things. They all work by encoding the video stream, usually h264, and sending it over the network. Check out HDBaseT which does video, ethernet, USB and power over a single cat5e cable.
- blahlabs 3y agoNot sure if you gave heard of NDI before? Its a broadcast quality low latency protocol for video/audio over 1Gb links