You've heard of HANC -but have you met VANC? Making the most of ancillary data

摘要

The ability to manage metadata effectively throughout the transport stream is critical to ensuring a high-quality result for viewers - but it's become much more complex in today's environment of digital and file-based operations, loudness regulations, and sophisticated delivery mechanisms such as surround sound. The good news is that metadata can be a critical tool for ensuring that the proper downstream processing is applied to specific types of audio streams, in a manner that is cost-effective and efficient for operators. One example is the emerging SMPTE 2020 standard, which enables the use of Dolby-type metadata for non-Dolby audio. In this article, Martin Winsemius, sustaining engineering manager for Wohler Technologies Inc, will explore the latest developments in audio metadata for SDI broadcasting, and the role of metadata monitoring in today's most advanced signal processing environments. The simplest way to grasp the challenges of working with metadata is to think of it as 'the data about the data' - in other words, information about the actual audio signal that travels along with a multichannel audio bitstream. The audio metadata is intended to establish key audio parameters used to create the programme for downstream equipment to detect so that processing is done appropriately. Today's standards for digital audio include metadata that describes the content and properties of the digital files, including how they were created and (for digitised content) the original analogue object, metadata used to manage and preserve the digital files, and any other additional info such as unique material identifier (UMID) or programme ID data.