Video stream optimization and analytics provider Conviva has raised a $15 million Series D round, led by Time Warner Investments. With the financing, Conviva has raised $59 million to date. The new funding is earmarked for international expansion and headcount growth.

Conviva's client-side software takes the "pulse" of video streams, and depending on problems detected, will preemptively modify the stream's bit rate and its source, switching CDNs on the fly. The result is a much-improved user experience.  Content providers are able to use the Conviva dashboard to analyze delivery, playback and of their video, along with viewer engagement.  Conviva optimizes streams for Time Warner divisions HBO and Turner Broadcasting, among other customers including ESPN, Netflix, Fox, NBCU and others. In total, Conviva is optimizing over 1 billion streams per month.

To help illustrate the value of its service, Conviva recently published a useful infographic based on data it has collected across its customer base. Key findings included:

- Viewers who experience a single video start-up failure return 54% less.

- A 1% increase in buffering leads to an average decrease of 3 minutes in viewing time.

- In long-form VOD content, viewers watch 32% more video when there's no buffering.

- The average viewing time for a video that buffered was 12.2 minutes per stream; when it didn't buffer the average time was 25.4 minutes.

- For live events, viewers experienced 7.5 buffering events, but when Conviva optimizes it drops to 1.9 events

(Conviva defines "buffering" as 5 seconds or 2% of total length of viewing session)