Canal Overseas Simplifies SD/HD with Wohler

Canal Overseas, part of Canal+, has deployed the HDCC-200A HD/SD-SDI closed-captioning bridge from Wohler for better handling and storage of World System Teletext (WST) subtitle data within its HD/SD playout infrastructure.

The new card avoids the need for a separate ingest and playout set up for subtitles since it carries out subtitle encoding within an HD ingest workflow and decodes subtitles back at the time of playout. It also supports dual SD/HS video storage at Canal Overseas' facility outside Paris.

Canal Overseas uses 11 HDCC-200A units to embed WST data in the HD-SDI signal (VANC) during the ingest stage. Six programmes are simultaneously recorded either from external HD feeds with SD and the VBI-related signal; from external SD feeds upconverted during the ingest process; or from HD tape programs with EBU subtitle files. These are then stored on an HD broadcast server.

For playout, Canal Overseas uses 16 HDCC-200A bridges to extract the HD-VANC data and re-encode it as conventional VBI teletext subtitling into a parallel SD-SDI signal downconverted from HD. The SD-VBI subtitles are then either displayed for local monitoring (preview channels); converted into DVB teletext subtitles on the downconverted SD transmitted channels; or converted into DVB subtitling on HD-transmitted channels.

"The teletext data solution provided by Wohler perfectly met our project's functional specifications and constraints," said Gino Ma-Paw Youn, technical manager at Canal Overseas. "We were searching for an innovative solution for managing WST subtitles with HD material, and the Wohler closed-captioning bridge helped us optimize this process within our new HD broadcast facilities."