5 ms·

What amazes me is the lack of concern on latency for web streaming. We use the internet (and IP in general) to stream video. At high bitrates (200mbit+) we aim

What amazes me is the lack of concern on latency for web streaming. We use the internet (and IP in general) to stream video. At high bitrates (200mbit+) we aim for sub 100ms end to end, for compressed services we're happy with 500ms, maybe upto a second if it's something like Sydney to London over the internet. I was in a control room a couple of weeks ago watching some football. There were two displays, one end was the feed from the stadium, one was the feed from the web streaming service. There were cheers and then groans from the live end of the room. nearly a minute later someone on the web end started running up the field to score. Of course I knew at that point that it wouldn't be a goal, as not only did the people watching the live stream tell me, but twitter was abuzz. 1 minute end to end delivery latency is shocking for this type of program. Heck 10 seconds is bad enough.

mayneack 8y ago
I stream a lot of sports from home. I would gladly trade delays for stream stability/quality. I frequently have to switch from a legal stream that I pay for to a more robust illegal stream. It would be annoying if there were multiple devices nearby on different delays, but for me in my living room. I don't care if it's 30 seconds or 3 minutes. I've gotten spoiled by twitter feeds a few times, but it's not the end of the world.
Someone1234 8y ago
Interesting factoid, but some press have agreed to intentional latency as a security feature around certain events and dignitaries. The theory being that a sniper or drone operator cannot use the "live TV" footage to know their exact position. In some cases international viewers may see the "live" footage before local ones.
- Harvey-Specter 8y ago
  > The theory being that a sniper or drone operator cannot use the "live TV" footage to know their exact position. How is this helpful in either of these cases? A sniper needs eyes on, a drone operator probably has live video from the drone. I don't see how a TV delay would have any effect.
  - newest_user_ 8y ago
    I'm going to assume the example was a bad one. I could see something like a remotely activated bomb leveraging live TV to inflict the most damage.
    - isostatic 8y ago
      So watch the international feed
jonknee 8y ago
"Live" TV broadcasts are also on a delay, so I guess it's all relative. I had a friend who lived near enough to an NFL stadium that you could hear when something big happened and the TV delay made it impossible to enjoy a home game there.
- isostatic 8y ago
  Very minor delay in the UK -- well under 2 seconds from pitch to TV on DTT in the case of the FA Cup. Sure enough to cause some grief when you can hear the crowd, but not enough to get notifications on twitter or whatever.
  - jonknee 8y ago
    They intentionally delay it ~7 seconds in the US because we're scared of an errant boob or curse word to make the broadcast.
mv4 8y ago
You comment mentions two types of latency: 1. network latency, in milliseconds, that affects stream quality and stability 2. the delay (lag) between real-time capture and what the end user is seeing; this one is usually measured in seconds. A stream needs to be ingested, transcoded, sent from distribution servers to edge servers in each target region - with each step adding to the delay. Minimizing the lag is very hard, because stripping all buffers (to reduce the delay) makes the stream very sensitive to network conditions (which reduces quality). With most commercial CDN providers you will get 5..10 seconds. It can be reduced to 2..3 sec if you know what you're doing. edit: in case anyone is interested - in the second scenario, where we achieved 2..3 sec broadcast lag vs real-time, stream source (ingestion) was in the US, and the viewers were in mainland China. Network latency was over 600 msec. Wasn't easy!
- isostatic 8y ago
  60 seconds in the case of iplayer for the fa cup. 1m20 in the case of BBC News channel right now. HLS tends to be packetised in something like 15 second chunks at the end of the process. I know why there's a delay, I'm just amazed that people aren't concerned about it. The BBC used to offer multicast sources of live TV, which is a far more sensible solution, far more bandwidth efficient and allows end-to-end transmission in the satellite (or even less) range. Wowza did a talk at demuxed last year about how to do "3 second latency end to end at scale", which I found amusing given that TV people have been doing sub millisecond latency at scale for nearly 100 years, so at least some people in the industry recognize the problem (which is mainly for sports events)
  - mv4 8y ago
    As for what TV people have been doing - YES. No matter what anybody says, the Internet just isn't well suited for massive live streaming events. That's what television is for!
  - shittyadmin 8y ago
    I hate that I try to stream a game for my friends and they don't see what I did til 10-15s later. I'm trying to have discussions with them in real time on our voice chat server and any input they give me is inherently dated. Mumble gives extremely low latency, so achieving this kind of thing over the internet isn't exactly impossible, the bandwidth requirements of video would probably make it a bit more iffy, but should still be doable with some random issues. Maybe I just need to get away from the public streaming services which use HLS, switch to UDP streams and sub-1s buffer sizes.
_trampeltier 8y ago
Already since over 20 years, the german TV chanel "RTL" is about 15 seconds later than all other TV chanels on live events like formula 1. But I have no idea why it is.
- LunaSea 8y ago
  Luxembourgish channel
- mv4 8y ago
  There no technical reason for it to be that high. Perhaps I should reach out to them.
bradleybuda 8y ago
In the US we've seen a half-dozen over-the-top TV providers launch in the past couple of years. They all seem to understand that live sports is their core feature, yet none of them tries to compete on latency. I regularly see two or more minutes from reading tweets about a goal or touchdown (from broadcast or cable viewers) until I see that TD live on Sling / PSVue / DirecTV NOW / YouTube TV (I've tried them all). Second-screening live sports is impossible with the OTT apps, and is very likely to drive me back to Comcast. There's a real opportunity for a sports-oriented OTT company to compete on latency, a DVR that actually works, and expansive rights (I never have to guess if I have access to any sporting event).
- mtberatwork 8y ago
  Doesn't "second-screening" while watching a sports event interfere with the act of watching the sports event in the first place?
  - NoNotTheDuo 8y ago
    For games like American Football, there's only 11 actual minutes of action, but it takes 3+ hours to complete the game[0]. That leaves a lot of time to watch a second screen. [0]: https://qz.com/150577/an-average-nfl-game-more-than-100-commercials-and-just-11-minutes-of-play/ https://qz.com/150577/an-average-nfl-game-more-than-100-comm...
  - isostatic 8y ago
    Second screening even in things like drama is very popular. If you're watching a sports game, I can see that having a second stream (perhaps curated) with easy to access stats on that game, or a different angle to what the director thinks you want, or whatever. I don't see the appeal of second stream in drama, but in things like sport, yes

mayneack 8y ago

I stream a lot of sports from home. I would gladly trade delays for stream stability/quality. I frequently have to switch from a legal stream that I pay for to a more robust illegal stream. It would be annoying if there were multiple devices nearby on different delays, but for me in my living room. I don't care if it's 30 seconds or 3 minutes. I've gotten spoiled by twitter feeds a few times, but it's not the end of the world.

Someone1234 8y ago

Interesting factoid, but some press have agreed to intentional latency as a security feature around certain events and dignitaries. The theory being that a sniper or drone operator cannot use the "live TV" footage to know their exact position. In some cases international viewers may see the "live" footage before local ones.

Harvey-Specter 8y ago
> The theory being that a sniper or drone operator cannot use the "live TV" footage to know their exact position. How is this helpful in either of these cases? A sniper needs eyes on, a drone operator probably has live video from the drone. I don't see how a TV delay would have any effect.
- newest_user_ 8y ago
  I'm going to assume the example was a bad one. I could see something like a remotely activated bomb leveraging live TV to inflict the most damage.
  - isostatic 8y ago
    So watch the international feed

jonknee 8y ago

"Live" TV broadcasts are also on a delay, so I guess it's all relative. I had a friend who lived near enough to an NFL stadium that you could hear when something big happened and the TV delay made it impossible to enjoy a home game there.

isostatic 8y ago
Very minor delay in the UK -- well under 2 seconds from pitch to TV on DTT in the case of the FA Cup. Sure enough to cause some grief when you can hear the crowd, but not enough to get notifications on twitter or whatever.
- jonknee 8y ago
  They intentionally delay it ~7 seconds in the US because we're scared of an errant boob or curse word to make the broadcast.

mv4 8y ago

You comment mentions two types of latency: 1. network latency, in milliseconds, that affects stream quality and stability 2. the delay (lag) between real-time capture and what the end user is seeing; this one is usually measured in seconds. A stream needs to be ingested, transcoded, sent from distribution servers to edge servers in each target region - with each step adding to the delay. Minimizing the lag is very hard, because stripping all buffers (to reduce the delay) makes the stream very sensitive to network conditions (which reduces quality). With most commercial CDN providers you will get 5..10 seconds. It can be reduced to 2..3 sec if you know what you're doing. edit: in case anyone is interested - in the second scenario, where we achieved 2..3 sec broadcast lag vs real-time, stream source (ingestion) was in the US, and the viewers were in mainland China. Network latency was over 600 msec. Wasn't easy!

isostatic 8y ago
60 seconds in the case of iplayer for the fa cup. 1m20 in the case of BBC News channel right now. HLS tends to be packetised in something like 15 second chunks at the end of the process. I know why there's a delay, I'm just amazed that people aren't concerned about it. The BBC used to offer multicast sources of live TV, which is a far more sensible solution, far more bandwidth efficient and allows end-to-end transmission in the satellite (or even less) range. Wowza did a talk at demuxed last year about how to do "3 second latency end to end at scale", which I found amusing given that TV people have been doing sub millisecond latency at scale for nearly 100 years, so at least some people in the industry recognize the problem (which is mainly for sports events)
- mv4 8y ago
  As for what TV people have been doing - YES. No matter what anybody says, the Internet just isn't well suited for massive live streaming events. That's what television is for!
- shittyadmin 8y ago
  I hate that I try to stream a game for my friends and they don't see what I did til 10-15s later. I'm trying to have discussions with them in real time on our voice chat server and any input they give me is inherently dated. Mumble gives extremely low latency, so achieving this kind of thing over the internet isn't exactly impossible, the bandwidth requirements of video would probably make it a bit more iffy, but should still be doable with some random issues. Maybe I just need to get away from the public streaming services which use HLS, switch to UDP streams and sub-1s buffer sizes.

_trampeltier 8y ago

Already since over 20 years, the german TV chanel "RTL" is about 15 seconds later than all other TV chanels on live events like formula 1. But I have no idea why it is.

LunaSea 8y ago
Luxembourgish channel
mv4 8y ago
There no technical reason for it to be that high. Perhaps I should reach out to them.

bradleybuda 8y ago

In the US we've seen a half-dozen over-the-top TV providers launch in the past couple of years. They all seem to understand that live sports is their core feature, yet none of them tries to compete on latency. I regularly see two or more minutes from reading tweets about a goal or touchdown (from broadcast or cable viewers) until I see that TD live on Sling / PSVue / DirecTV NOW / YouTube TV (I've tried them all). Second-screening live sports is impossible with the OTT apps, and is very likely to drive me back to Comcast. There's a real opportunity for a sports-oriented OTT company to compete on latency, a DVR that actually works, and expansive rights (I never have to guess if I have access to any sporting event).

mtberatwork 8y ago
Doesn't "second-screening" while watching a sports event interfere with the act of watching the sports event in the first place?
- NoNotTheDuo 8y ago
  For games like American Football, there's only 11 actual minutes of action, but it takes 3+ hours to complete the game[0]. That leaves a lot of time to watch a second screen. [0]: https://qz.com/150577/an-average-nfl-game-more-than-100-commercials-and-just-11-minutes-of-play/ https://qz.com/150577/an-average-nfl-game-more-than-100-comm...
- isostatic 8y ago
  Second screening even in things like drama is very popular. If you're watching a sports game, I can see that having a second stream (perhaps curated) with easy to access stats on that game, or a different angle to what the director thinks you want, or whatever. I don't see the appeal of second stream in drama, but in things like sport, yes