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Testing latency

Keeping viewers in sync at low latencies is crucial in many live-streaming contexts, such as online auctions and games.

How to test latency​

To evaluate this, simultaneously test your streaming products - ideally on different networks - and compare the playout when injecting audio or visual cues into the stream. Remember to subject one or more devices to network congestions, or try disabling the internet connection briefly to assess how well playout resumes at the proper pace.

Vindral Live has a demo site where you can test this.

Stability​

Any live streaming technology should be evaluated under real-world network conditions to determine how stable the end-user experience will be. We recommend that you shape your device's network to lower bandwidth, induce packet loss, and increase round trip times to put some pressure on the services you are evaluating. Keep an eye on bitrate switching both when conditions worsen and upon recovery.

Compatibility​

Users need to be able to consume your content no matter what device they are using. When comparing streaming products/services, test on iOS browsers, Android browsers, and native applications simultaneously to ensure that sync and low latency works across the board.

Common issues​

Higher than expected latency​

  • Solution: Ensure correct keyframe interval/GOP settings, disable unnecessary encoding buffering, and use low-latency encoding presets (no bframes, tune low-latency, no 2-pass encoding).
  • Cause: The most common cause is source encoder settings not optimized for low latency.

Frequent Buffering for all viewers​

  • Solution: Increase minBufferTime by 500-1000ms or use maxBufferTime to allow more flexibility. Look at stability metrics in Vindral Portal to see if there are specific patterns or issues on your ISP.
  • Cause: Network conditions from your source require more buffering for stable playback. Consider testing with different ISPs to identify potential issues.

Frequent Buffering for a few viewers​

  • Solution: If you detect a pattern or need Vindral's team to investigate further, consider reaching out for support. Increase minBufferTime slightly if needed or use maxBufferTime for more flexibility so those that need it will have a better experience, at slightly increased latency.
  • Cause: If only a few viewers are affected, it is likely not a source issue but rather a last-mile issue. It may be specific to certain ISPs or network conditions.