Video: Is Latency Still Hurting Live Streaming?
In this excerpt from a panel at Live Streaming Summit, Ooyala's Paula Minardi and Level 3's Jon Alexander discuss ongoing issues with latency times and buffering and what viewers of live and VOD are inclined to tolerate as acceptable parts of the online video viewing experience.
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Read a complete transcript of this clip:
Jon Alexander: We definitely see latency as one of those kind of emotional subjects, where people always want lower latency. Why would you sign up for higher latency?
On the broadcast side, it's kind of an interesting anecdote, if you talk about the NFL, the propagation of video, a broadcast feed across our networks, it's about 10 milliseconds. If we do an encode on that, it adds about 100 milliseconds of latency. We've been seeing an increased number of broadcasters coming to us now asking for uncompressed feeds. They don't want us to do any kind of compression, even a very lightweight lossless compression, because it adds latency. That is an additional 100 milliseconds of delay on the broadcast side that is something that they are trying to eliminate.
At the same time, they have to have a three-second delay imposed to avoid a Janet Jackson-type event. They are trying to trim off 100 milliseconds on one end, when they are imposing a three-second delay at another end. If you're doing satellite, your roundtrip time up and down is roughly a two-second delay. End-to-end delay, even in television best case, you're looking at 5-6 seconds. A lot less than the 30-40 seconds we typically see with HLS, but still non-zero.
For me, I think the biggest challenge with internet is it is non-deterministic and synchronization between devices isn't there. You could be watching on your phone, I could be watching on my phone and we're not synchronized. I think that's the experience which is more off-putting, rather than someone tweeting what's going to happen in five seconds time.
Paula Minardi: We worked with Nice People at Work, one of our partners, to look at buffering times and how that sort of impacts live and VOD content. It was kind of interesting. What we found is that the buffer ratio is that the buffer time over the session time. When we found that the buffer ratios were less than 0.2% that was kind of ideal for people to hang with the content. If you're watching it on a VOD stream, people hung about 16 times as long, but they dropped off very quickly once that ratio started going up. On the live content, people hung on about 24 times as long.
What it sort of tells us is that maybe they are a little forgiving at this point around getting that experience, because they are valuing that content. I think as time goes on they are going to be a little less forgiving, especially those younger audiences. They are going to just start demanding.
Jon Alexander: We definitely see latency as one of those kind of emotional subjects, where people always want lower latency. Why would you sign up for higher latency?
On the broadcast side, it's kind of an interesting anecdote, if you talk about the NFL, the propagation of video, a broadcast feed across our networks, it's about 10 milliseconds. If we do an encode on that, it adds about 100 milliseconds of latency. We've been seeing an increased number of broadcasters coming to us now asking for uncompressed feeds. They don't want us to do any kind of compression, even a very lightweight lossless compression, because it adds latency. That is an additional 100 milliseconds of delay on the broadcast side that is something that they are trying to eliminate.
At the same time, they have to have a three-second delay imposed to avoid a Janet Jackson-type event. They are trying to trim off 100 milliseconds on one end, when they are imposing a three-second delay at another end. If you're doing satellite, your roundtrip time up and down is roughly a two-second delay. End-to-end delay, even in television best case, you're looking at 5-6 seconds. A lot less than the 30-40 seconds we typically see with HLS, but still non-zero.
For me, I think the biggest challenge with internet is it is non-deterministic and synchronization between devices isn't there. You could be watching on your phone, I could be watching on my phone and we're not synchronized. I think that's the experience which is more off-putting, rather than someone tweeting what's going to happen in five seconds time.
Paula Minardi: We worked with Nice People at Work, one of our partners, to look at buffering times and how that sort of impacts live and VOD content. It was kind of interesting. What we found is that the buffer ratio is that the buffer time over the session time. When we found that the buffer ratios were less than 0.2% that was kind of ideal for people to hang with the content. If you're watching it on a VOD stream, people hung about 16 times as long, but they dropped off very quickly once that ratio started going up. On the live content, people hung on about 24 times as long.
What it sort of tells us is that maybe they are a little forgiving at this point around getting that experience, because they are valuing that content. I think as time goes on they are going to be a little less forgiving, especially those younger audiences. They are going to just start demanding.
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