I love how on computerphile, they have the 2 guests filming themselves then gather the video file, instead of having 1 person recording its screen

Being a sound engineer, the last few months have been one long shadenfreude. It is a know fact that people do not notice sound until it isn't there. Same goes for sound engineers, what they do isn't noticed until they aren't there anymore to take care of everything in advance.. Talk shows etc have been below youtuber quality.. Untreated, echoic rooms, camera mics used when lapels should be there, background noises coming in, distortion... It is like watching the world after all sound engineers returned back to their home planet..

I love how the editor managed to play with the audio to make it sound like a packet lost

I love how much work goes into these videos to replicate what they are speaking about, "audio quality loss" - bam, audio quality is lower in the video.

Such an odd thing to notice, but I appreciate Dr. Bagley's proper use of radio etiquette. That is, "out" instead of the incorrect but often-used "over and out".

"computerphile is better than cat videos ... we have mice" everyone liked this

Meanwhile, every TV program ever has over 2 seconds latency between the studio and the reporter, even when talking from one room to another.

Dr Bagley has excellent taste in movies, TV shows, and books! I would feel right at home in his library!

20:23 This is where “quality of service” (“QoS”) comes into play. TCP/IP allows for marking packets with indications as to whether timeliness of delivery is more important than reliability of delivery: that is, if a packet is taking too long to be delivered, it might as well be dropped rather than delivered too late to be of use.

- What do we want? - Now! - When do we want it? - Race conditions!

It's interesting how now that you have to do it remotely, your videos kinda feel more "personal" because of you participating with your face and not just off-screen questions like before, @Computerphile. The irony is not lost on me.

"a gigabit symmetrical isn't unheard of these days" [cries in Australian]

Over the last few years my employers have migrated our business from T1s plugged in to proprietary abandonware to VoIP and Asterisk on Linux. Our customers appreciate the better service. The tech support people appreciate the improved reliability. The bosses appreciate the reduced cost. And I appreciate having new toys to play with. :-)

100ms latency is the equivalent of listening to someone 34m away

Clever to illustrate the importance of sound by breaking the video feed when your are talking about it. Your editing is illustrating your point throughout the video and it's very pleasing ! Thx

17:09 Which brings us to the phenomenon known as “buffer bloat”, where all kinds of devices between your end of the connection and mine have large buffers built into them, just to make some problems easier to solve. But of course this adds latency for real-time applications. So there are people trying to persuade makers of these devices to reduce their buffer sizes. Which requires them to write better code to deal with the problems that they were papering over with large buffers before.

Yes! IPv6 FTW! Restoring end-to-end addressing, like the original Internet architects darned well intended!!! One of the tougher problems even in telephone system engineering (let alone Internet conversations), particularly in conference bridges, is something you touched on a little bit, echo cancellation. The company I work for in the US contracts with folks from India. No way to get around the physics of having to transmit an electrical signal that far around the world. We often have to speak up and say, if you're not actively saying something, put yourself on mute. Otherwise, due to the packetizing, buffering, etc. stuff you mentioned, we hear ourselves 0.5 to 0.75 seconds later, and on occasion, repeatedly.

Very interesting. I thought it was so much more straight forward like a streamed movie. I never thought about the need to minimize delay so conversations are easy. This certainly explains why all these zoom meetings are so awkward. It's too much latency. Another element to consider in the process is the power of the hardware being used. This is a huge problem for me when my kids get involved with meetings for school. We are using very low powered PCs and it's a challenge for them to process multiple video streams at once.

RTP is an ancient protocol that was invented to do multicast audio conferencing. It's almost never used for that because 'the internet' doesn't do multicast, It's also redundant for video such as H.264 or MPEG2 transport streams which have packetisation and timing and audio sync built in. RTP is only really used for SIP based VOIP phones and it's a right pain with NAT

Hey hey, we got cat5 and mice!

Skype, TeamSpeak, WhatsApp, Discord, Teams, Zoom are PROPRIETARY! Repeating these flaws result in the same failures. #StallmanWasRight

That was an excellent video - for a topic that encompasses so many technologies, I can't imagine how you could have summarised it better in only 28 minutes!

IPv6, yes, thank you for shouting that out, it really is outrageous how we are still basically v4 and how much trouble it makes. Privacy and all, but the changing ip disconnecting me is not nice, privacy is the only real issue I ever hear and a simpl(ish) request system would bring us back to where we were, but better.

Aside form all else, I'd like to say that I really appreciate the Doctor Who DVD sets back there, from 3 to 8 (? It's kinda hard to make out...). In fact I'm quite jealous! Don't think I wouldn't notice, though! /\ W

I think Dr. Bagley would benefit from a lapel mic. It might reduce echo feedback from the roome he's in.

KZfaq started lagging fiercely just for this video. I felt like they were being cheeky.

9:53 Some people think that stuttering might be caused by a neural analogue to this sort of phenomenon.

Please do more of these networking videos. Perhaps one along the lines of "Why you missed the shot in your online game" Where you consider netcode, latencies, bufferbloat, jitter ETC and have a few recommendations to bring those down.

Video calling technology has really improved during the... uhm... since 2020. It's interesting looking back, how much better coordinated things have become. At least, for the people fortunate enough to work for a transparent, straightforward and honest organization.

Have computerphile done a video about the deployment of IPV6 and the delay? Seeing Steve ending reaction, I think he has opinions ;)

5:46 I like the little "John Malkovich" door on the back wall.

I'm surprised that there has been no mention of SCTP, Stream Control Transmission Protocol, which has been an Internet standard (since 2000) and was designed specifically for telephony over the Internet. It's covered at some length in the classic "UNIX Network Programming" (volume 1, third edition, Stevens, Fenner, and Rudoff). And because it's an IETF standard, it has its share of RFCs as well.

I would have made a distinction between processing latency and transmission latency of the network.

Steven did the Max Headroom (well Sean did with after effects) when e spoke about distorted audio. Loving it.

That looks like a fine collection of Dr Who videos on the shelf. Approved!

Streaming is sensitive to congestion, latency and data loss, which circuit switching, such as ATM, can control much better than packet switching but is more expensive. Packet switching, such as IP, throws more cheap hardware at the problem. A follow up episode should be the cost effectiveness of both approaches for various uses.

The header info seems like it’s larger than those small packets for voip!

You could do a talk or three on peer-to-peer vs centralised distribution, the flavours and pitfalls of (CG)NAT, etc. Just as I hit return the last few seconds told me it's coming. We're on the same wavelength. Jon (on IPv6)

Star Wars background vs. Star Trek Background ?

90% what you talking about here was solved in 2003 with skype quite well. 17 years ago with a significantly less bandwidth and much weaker hardware. I'd love tho hear more about what changed with the network that possibly made it necessary to reinvent or adopt those things, because it is not changed as much as the hardware and bandwidth growth would suggest I think.

Love the Atari Portfolio computer in the background!

8:05 Interestingly, the speed of sound in Earth’s atmosphere at room temperature is almost exactly one millionth of the speed of light.

“A gigabit symmetrical isn’t unheard of these days” if I can get more than 5 mbps download I consider it a victory #dslproblems #middleofnowhere

I feel like in practice the packet size (and therefore buffer sizes) will be handled by (or will strongly depend on) the codec? Like, one frame at a time sounds reasonable for video, sure ; but for audio, I guess codecs can make a smarter choice depending on their internals and their target bitrate? EDIT: Thinking about it, I guess video codecs still operate on some variant of "keyframes" and "deltas", so they too should be able to make a smarter choice there (do I wait for the next keyframe and bundle as many deltas as possible in the current packet, if so how much time do I wait, etc). I would guess the chunk size is very much dynamic in practice? EDIT2: Yeah, this is literally what Dr Steve says at the end. I should watch the entire thing before commenting. :-P

"Saggy ol' cloth cat, baggy and a bit loose at the seams": That man's got one of my favourite children's tv show characters on his shelf! That's all what I care about xD

Interesting that you mention latency; I'm watching this video with cheap Chinese eBay Bluetooth earphones so the audio is out of sync with the video. Good thing I'm only watching the video out of the corner of my eye while I work on the computer. 27:48 - Chris Griffin?

Audio compression about 14 to 1, video compression around 80 to 1 (because so similar to nearby frames)

0:28 I see some interesting books on GCHQ and the like. No copy of _Spycatcher_ ? Is that still banned in the UK?

Video conference calls, don't do it! it's distracting, takes a lot of bandwidth, some have poor image quality with hiccups, and so on... Just use your phone and make someone who has an unlimited plan call everyone to join. The sound is always good and it's not distracting. Next to that, you could also is have everyone open a collaborative document, like google presentations. That a fast way to show everyone documents, notes, ideas etc.. and you can see what other people are looking at and are writing in that presentation, all in real time. Sometimes that works even better than in a real conference room!

I’ve never thought about how complicated video conferencing can be, but the question that came up for me while watching this: could you do a video about how online MP gaming works? Is it more complicated then this? I’d be really interested in the “behind the scenes” look if this

So 2 people standing over 35 meters apart cannot have a normal conversation anymore, since the sound would take more than 100 ms. (ignoring the visual aspect of conversation)

Anyone remember the old timey live news reports with a 2 second delay?

7:35 - *on halving your RTT to determine latency* - This is in fact not true at all. It may and must be assumed to be the case (especially in larger networks such as the Internet) unless otherwise proven that latency in one direction isn't equivalent to latency in another direction. It could and likely is the case that one direction may have queues which are different lengths at any given instant. We must also not assume that routing is synchronous (i.e. the path you take to return traffic could be different from the path that was taken to get to the destination) - which could also mean longer/shorter links, links of different media types, links with different rates and also completely different forwarding devices which may have different queueing delays. Measuring actual one-way latency is an incredibly difficult problem which is impossible in most situations and it shouldn't be glossed over like that. It requires precise instrumentation and synchronization. Source: am network engineer

Wish this video had captioning. For whatever reason, I find it hard to understand exactly what he is saying when he speaks quickly. Most videos have captions; I wonder why this one doesn't?

It might be worth talking about the actual connection topology (peer-to-peer or client-server-client). I would be interested to know if the client received scaled video when the video on their screen is physically small (like when lots of people in a group chat all have their webcams on).

This week there was a release, Tauria, which has e2e crypto for videocalls up to 50 people. Pretty nice.

Has Brady always looked this good, or is that just the quarantine pine taking over...

I enjoy trying to estimate the latency by the echoes of people you hear when noise cancellation inevitably fails. I reckon it goes North of 200 ms each way in bigger group chats. Also, I miss push-to-talk.

What happens when your audio/video is being received by more than one other conference participant? Does multicasting work in practice, so a single copy of the data is transmitted from your machine, and received by multiple recipients? Or do you have to send out multiple copies, one to each recipient?

My usual day sounds just like the real life simulator. 10/10

Please do a video with details on the different ways to handle echoes

5:14 Remember also that many video conferences are held over bandwidth-restricted corporate networks.

I'm really interested in the following - Zoom can show a max of 49 video feeds at once in their gallery view. Other platforms can show a max of 4-10 at once. This is by far one of the killer features that makes Zoom stand out. Both Google and Microsoft have said they're working on increasing the number of video feeds in Meet and Teams, but they're taking a lifetime, and they're only promising like 16 or so at once. My question is - is it really difficult to implement showing 50 video feeds at once? Is there something technically that's preventing Google and Microsoft from following quickly in Zoom's footsteps?

Best channel on KZfaq!

Talk about hypercomputing super Turing machines that solve the halting problem or other undecidable problems

Echo suppression is a pretty well established technology. But feedback, not so much.

I hope in these trying times that everyone living with others is familiar with their router's QoS settings ;)

For the love of God, Steve... Those Doctor Who DVDs come with reversible covers so you and your audience don't have to be annoyed by some spines having the BBC logo in a purple square in one of two totally different places or age certifications. They can look quite nice and uniform. There is no excuse. You are not in Australia. Get your act together! Anyway. Great talk, as usual! Really appreciate you guys :)

Half Sci-fi, half programing and computer science. This bookshelf does not surprise me.

Is that you, Jared Harris?

Good editing skills m8

11:05 I need to stop drinking while at my computer.

Love this channel

Really wish he would have talked more about codecs

This reminds me of Nagle's Algorithm. Which may be a nice topic for Computerphile one day

At the end you say the routing will get v street with IPv6. Could you make a video explaining this? As a slightly tech savvy user, how will IPv6 affect me?

simply a great vid - thx

Why do video streaming services like twitch use a several second buffer instead of trying to do something closer to this?

Can we use timestamps instead of packet sequence numbers?

“the video conferencing problem”, as if there’s only one problem with video conferencing!!

There are VHS tapes hiding behind the DVDs!

Why do no video conferencing systems feed your voice back into your own speakers like the phone system does? It’s so unnatural wearing headphones and trying to talk and not be able to hear your own voice.

The commenting "first" on youtube problem.

So that is how the cameraman looks like.

nice illustrative editing in this one..

How do you keep a lizard from climbing a window? With a gecko canceler.

If you avocating for always having a garbage collector your ruling out a whole class of performance-related problems. While a single hybrid language might be able to replace them all, a constrained language will never be able to be universal.

I have some of those books!

Hahahaha, that last point about IPv6 :-D it's funny how it still is sort of a pipe dream for consumers right now!

I kinda miss lockdown

Yeah, that Echo Cancellation is a very interesting subject

Wondered for a split second why Uwe Boll was in my subscription box

Wait... Is that a 64 telecaster?

Their webcams are better than my main camera...lol

Very interesting. I'm french and quite comfortable with english, but subtitles would have helped a little. Thanks a lot anyway.

Starting to feel like the whole covid19 thing was just an ad campaign for airpods... (all kidding aside i honestly see them EVERYWHERE now in all these staying at home streams/videos etc, and the audio quality of those is so bad man omg why is 90% of america and uk using them?!)

Couple of things: 1 - what was that clicking that was happening throughout the talk? 2 - isn't the other person Heston Blumenthal? ;) Or a cousin?

Doesn't the packet time code make the sequence number redundant?

So how much of this is handed by the pc and how much by the particular video app?

ATM isn't worth talking about unless you tell the story of how the telecoms world changed 20 years ago when data started to exceed voice on backbone networks.