Video: Streams on a Plane: Why Gogo Chose HEVC/H.265 for In-Flight Streaming
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Read the complete transcript of this clip:
Prem Bangole: At Gogo we’ve always looked closely at the costs associated with encoded video for streaming live TV in-flight. We looked at what we’d been doing with H.264 and wondered if we could encode more efficiently and cost-effectively. We didn’t want to compromise on the quality, because if you’re watching a soccer game or a football game, 你期望高质量. Coincidentally, we were launching the service with GOL, which is a Brazilian carrier. 他们问, "Can you build this product for us," because a lot of people wouldn't fly at certain times based on what their favorite soccer team was doing. If São Paulo was playing Brasilia, some people wouldn't fly between those two segments. So that was a use case where we could put a live TV on a plane.
Here’s where we felt that HEVC could solve our problem. If it lived up to the hype, we could get the same quality as H.264, but with a lower bitrate. We did a file comparison, roughly, and then they kept improving, so it was two to one, and H.265 or HEVC was available today. And new hardware libraries were being built with Intel Quick Sync. 这些都很有帮助. 然而, the challenge was the end devices, like your mobile devices or your laptop--did those have HEVC support? I think they still don't, or if they do in a limited fashion, it's not open source. It doesn't have an open API, because of some licensing challenges.
HEVC really helped us to cut down the bandwidth by 35-40%. 另一个秘密调料, or secret element which we found is the stat mux, 统计复用器, which can be used in conjunction with this encoder. We had this fixed bandwidth allocated, but we were betting on the fact that not every channel would be using a larger bitrate. 有一个体育频道, 就像体育中心一样, where people are talking — you would consume lower bandwidth, so you would borrow the bandwidth from different channels. 统计, your total output bandwidth is the same, but you’re competing based on the channels which are playing, based on the picture quality which is getting encoded.
Then we tried to put it on a plane, and flew. Then we discovered that there are network problems, some pockets where you run out of coverage. 1 to 2% packet loss over a terrestrial network is acceptable. Those are defects, but they really have bad experiences when it comes to live TV. So we had to add this FEC and encryption component, because some content providers were very specific about security. Those two added 5% overhead, but still, I think, in a sense, I think that's really worth it. The FEC was really helpful and decoded, because when it comes to live, timeliness is what matters.
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