$ ping -s 1450 192.168.11.10
PING 192.168.11.10 (192.168.11.10): 1450 data bytes
1458 bytes from 192.168.11.10: icmp_seq=0 ttl=255 time=0.646 ms
1458 bytes from 192.168.11.10: icmp_seq=1 ttl=255 time=0.478 ms
1458 bytes from 192.168.11.10: icmp_seq=2 ttl=255 time=0.469 msFor raw 720p RGBA you'd send: 1280 * 720 * 32 = 29,491,200 bits but obviously you're not going to do that. Suddenly you're not only sending data but also encoding / decoding it.
..though 802.11ad is supposed to be out early 2014, and that maxes out around 7 gig, and has cooperation from the HDMI consortium to use it for streaming. I wonder if some kind of some kind of ultra-high-speed wireless dongle is in Steambox's future..
It doesn't matter, that's the point. Your MTU is almost certainly 1500 bytes. You are sending 1500 byte packets at the most. That does not cause latency. If you want to argue that we're incapable of encoding or decoding video with acceptable latency go right ahead, but doing it in response to me correcting a misconception about network latency doesn't make much sense.
The main lag comes from encoding/decoding. If you do it naively you encode frame-per-frame (encoding slices is more difficult), and the encoder does not only outputs iframes: you get partial frames that depend on both previous and future frames. Also the decoder does not always output frames in order. So you have to expect something around ~10 frames of latency, maybe less if you optimize everything well enough. That still means easily more than 100ms of lag.
The network is really not the main issue here.
1. Essentially equivalent to streaming, or
2. Essentially equivalent to normal CPU->GPU communication but over the network (and, thus, needing the bandwidth that local CPU->GPU communication has if you want to avoid slowing things down -- GigE wouldn't seem to be enough, much less WiFi, even if you consider only bandwidth and not latency.)
I mean, a 720p60Hz stream in 4:2:0 (12 bits per pixel) still amounts to 663Mbits/s. You won't get that out of a gigabit link realistically (at least not over IP). Of course you could use a lightweight compression algorithm, but you'll have to divide this bandwidth by at least 5 to make it manageable for the average home network I'd say (I have absolutely nothing to back that last number, but 100Mbits/s doesn't look too scary...). And that's only for 720p remember.
I think if you plan to stream HD video over the network you have to encode and be clever about it.
I just got more than that using scp with no compression. Yes, you absolutely can get that realistically from gigE.
Also, you have to remember that steam won't control the encoding end of the pipeline (and if the "steambox" is third party hardware with steamOS installed, no control at all on the hardware). Which means that in the end the observed latency will depend a lot on the hardware and drivers of the desktop PC and there isn't much Valve can do about that.
So in the end I'm sure it'll be more than fine to play Civilization or Torchlight, MMOs and most RPGs but maybe not Counter Strike or Quake III.
My HDhomerun ATSC receiver certainly has no problem shoving a couple megabits of high def video over ethernet. Nor does my mythtv setup, or even just plain old NFS shares to watch videos.
I don't think the importance of this can be understated.
What is the precedence on which you base your belief that, whatever protocol Valve has come up with to replicate the video stream, it will be open? I'm not that much into gaming, but Steam is a closed-source software that includes mandatory DRM for the games, it doesn't really set a precedent of openness and interoperability.
Second, keep in mind that they've already announced streaming inside the LAN. Having mobile apps would be a natural extension of that. (Note I didn't say that it would be open, I said they will probably release mobile apps).
That streaming is also completely not a threat to their system.
As you say, if the streaming feature works well, this is a huge win. At the very least, it should save me from running 60+ feet of HDMI/USB cables which was my original plan.
Old Way) I have to spend all the money for equally good hardware. I also need a copy of Windows.
New Way) Just get something that can render YouTube videos well. I now have a second Gaming PC. No copy of Windows!