Industry Perspectives: Finding the Bitrate Sweet Spot

As we continue to move away from analog to a fully digital world, the common perception is that performance and feature sets improve across the board. In fact, there are compromises to be made, and it is the careful balancing of these compromises that are key to the success of any digital project.

In the digital video arena, the over-arching compromise is that of bitrate versus quality. As we increase the compression ratios in the conversion of analog video to digital, we see a reduction in quality of the resultant video. Taken to its extreme, low-bitrate video becomes blocky and stutters, and is out of sync with the accompanying audio. It is at this point the viewer becomes distracted by the poor quality of the experience and stops concentrating on the communicated message.

The optimum situation is one in which the bitrate is sufficiently high so as to provide no distractions to the viewer, but sufficiently low to ensure that the delivered video does not overload the network infrastructure. This optimum bitrate is sometimes called the "sweet spot."

Concurrent with the transition from analog to digital is the growth of bandwidth available for data transmission. Corporate networks are continually being expanded and developed. DSL coverage is increasing, and broadband access is becoming more widely available. Experience shows, however, that in the corporate communications sector there is constant demand for increased bandwidth.

A method of addressing this challenge is to use progressive downloading as a complementary approach to streaming live data. This method has the advantage of allowing higher-bitrate clips to be created and their transmission will not impact a network unduly. The disadvantage is that it is not suitable for live video events.

Another major influence on the success of a digital video communications project is consideration of the audience and the method by which they will view the video. By understanding the viewing environment, it is possible to determine the bitrate sweet spot, and in turn understand the network requirements prior to rollout of the service. It is vital for the survival of any new video service or channel that the audience rapidly becomes loyal and enthusiastic for the service; overestimating where that sweet spot lies will quickly discourage potential customers with stuttering video.