New Video System: Update after One Week in Full ServiceDec 20 2013 · 237 comments · Engineering, News, Status, Tech
FIRST: We’re keenly aware and sympathetic to the notion that less latency will make social interaction better. We care very much about interactivity and continue work to deliver less overall latency. We assure you we have not directly imposed any latency on top of what the system currently delivers.
As the new video system has been 100% live for a week, we wanted to provide an update on its performance and address the feedback and concerns some of you have posted.
When we set out to build this new system over a year ago, we did so with the knowledge that the previous system was not scaling to meet our projected growth. As we plan to be here for a long time, our Video team set forth on a mission to build a system that would scale while providing better quality of service over the previous system.
When the new system was ready, we first tested and introduced it on our iOS, Android, and Xbox app experiences (i.e., non-Web). Over the next several months, we gradually implemented it on our site, constantly A/B testing against the previous system. Several weeks before we fully launched it, all of the larger streams were already using the new video system with great success. Everything about the new system was better – scaling, less user reports, less automated reports – with the sole exception of latency.
The new system does indeed have a higher inherent latency than the previous system. This is a result of how the new system delivers and buffers data. At present, we observe latency ranging from 12-40 seconds in most cases.
Can the latency be lowered? Yes, there is room to lower latency, and we’ll continue to engineer ways to do so over the coming months.
The number of times that a video buffered on the site dropped, on average, by two thirds. We’ve seen an increase in users watching in higher resolutions using the new video system. This shows us that not only are video connections more stable, but video is often being seen at higher quality.
Moving forward, we will be constantly working to decrease the latency and to make your video experience better. The new system is more flexible to work with, which will allow for us to do cool things in the future that were not possible with the previous system.
If you experience abnormal issues or have concerns about the system, we’ve set up a feedback document. We’ve been reviewing it on a daily basis and reading your feedback. Feel free to add your feedback here to let us know how your experience has been.
Thanks again for all of your feedback and understanding while we iterate on our new video system. And most of all thanks for using Twitch.
PS for Broadcasters: One way to make sure your stream is optimized to work with our video system is to make sure your broadcast quality is “Excellent.” You can check this on your dashboard. If you need information on how to do this, visit our Broadcast Requirements page.
- Codec: H.264 (x264)
- Mode: [Strict] CBR
- Keyframe Interval: 2 seconds
- Bitrate: 3500 max (1000-3500 recommend for most broadcasters)
- Codec: AAC-LC or MP3, Stereo or Mono
- Maximum bit rate: 160 kbps (AAC), 128 kbps (MP3)
- Sampling frequency: any (AAC), 44.1 KHz (MP3)