What Is Output Locking?
Learn more about live sports streaming at Esports & Sports Streaming Summit.
Read the complete transcript of this clip:
Taylor Busch: Output locking when we get a little bit further down, you're going to see that this was actually extremely key for our ability to do seamless switching of origins when there were issues without having any disruption to the end users. So, essentially what output locking is, is it ensures that your media segments and your manifests are all in alignment. So, as you're running independent events on each encoder, output locking will synchronize the output of the TS segments so that they're exactly the same.
So, when you're delivering to multiple origins, if you need to switch between one, theoretically, you go to that other origin, you get that file, and that file is going to contain exactly what would have come from the origin that has failed that you switched from. The way that it works, is, we have to have a consistent timecode coming into the SDI input on the encoder.
We learned quite a bit through this process. Not all time codes were created equal. So, through trial and error with that, and things on the signal and the broadcast side, plus multiple elemental live updates as we really kind of flesh this feature out with that team, we got very comfortable with ensuring that the timecode coming into the encoder was consistent. It was actually synced with the master clock in the broadcast center. And then, from there, we had to also make sure that our backup facility wasn't losing that timecode. It needed the same timecode.
So, depending on how you route your video, so, for example, if you're going to send video over some type of compressed or potentially encrypted pipe, there is the potential that you're going to lose your timecode. So, we had a lot to kind of figure out there. But really, the testing for this was across the board. So, it's not just about being able to start the encoders at different times, or being able to pause an event, or pause an output. We went as far as to try to simulate real network issues. I went into the server room, and I physically pulled cable. I mean, who knows? Anything could happen.
So we routed different sources, some with no timecode, some with a different timecode than the timecode we wanted, and we made sure that basically once the event started, and they were properly locked, there was essentially nothing that could get it off track. And so obviously, if you do do something to pull a cable, for example, when it comes back, it will recover. So, you keep that time code permanently through the duration of the event.
CBS Sports Digital Senior Director of Engineering Taylor Busch discusses Fastly's Media Shield and the role it played in optimizing high-traffic streaming in its Super Bowl stream in this clip from Live Streaming Summit at Streaming Media East 2019.
CBS Sports Digital Senior Director of Engineering Taylor Busch explains what QVBR encoding is, how CBS Sports leveraged it, and the savings it delivered in their Super Bowl stream in this clip from Live Streaming Summit at Streaming Media East 2019.