Choosing the Optimal Data Rate for Live Streaming
The object of the exercise was to show how output quality was affected by the data rate of the incoming video in a cloud transcoding scenario.
Analysis
This is the time where caveats come into play, and this article won’t be any different. All live events are different and your results will vary by content, and by the encoding presets used for your live encoder at the source and during transcoding. Undoubtedly, higher data rates are always better. However, outbound bandwidth can be quite expensive, particularly at off-site facilities, and blowing the budget on more bandwidth may not deliver much additional noticeable quality.
These results tend to indicate that at 720p, you should be able to produce quite good results at 2-3 Mbps for talking head videos, with 3-4 Mbps sufficient for concert or similar events, though these rules go out the window for really high-motion sporting events. Even for those events, however, once you reach the tipping point, upping the data rate of your source clip will deliver increasingly diminishing returns.