Video Clarity – RTM

Today’s multi-device delivery scenario - to TV, PC and handheld devices - puts high demands on broadcasters and multi-channel operators. Digital media transmission now requires most live or stored assets to be prepared in different formats and delivered through a diverse set of network paths to the consumer. Advertisers and program providers demand high quality. The technology required to deliver multiple formats and versions of the same asset is now highly complex which can lead to errors that affect quality. Therefore, a high priority should be placed on constantly testing at each step in the delivery chain so that the desired user experience is achieved. Testing digital assets and delivery methods for quality has also led to new challenges. While experienced analog engineers could detect and classify errors by predictable means, new digital technologies have created a dynamic environment. Minor imperfections generally have no noticeable effect on quality in a digital transmission until the degradation hits a threshold. This unpredictable “digital cliff” drops quality to unacceptable levels. At the processing layer, problems arise when downconverting HD to SD, changing formats and compressing the signal into the available bandwidth. Also the separate processing of audio, video and data can lead to synchronization problems. At the transmission layer, broadcasters encounter familiar RF problems with a new challenge - coverage and interference problems caused by more channels at lower powers. For multi-channel distribution, operators are relying on a multiplicity of distribution steps in the network and therefore latency, packet loss and synchronization add additional concerns. Errors in one layer can cause errors in the next. For example blockiness caused by compression looks similar to packet loss/bit errors hidden by the set-top box (receiver). For this reason, the quality must be assessed at multiple points across the network including a continuous test through an end point device (IRD or set top box) or end point IP stream sample.