Compatibility Issues Dog 3D Discussions
As increasing numbers of operators run 3D experiments, opinions within the DVB Project are divided over whether adopting the existing HDMI formats are enough, or whether other formats should be added to the DVB Phase 1 system.
A number of meetings have been arranged by the DVB Commercial Module on 3DTV to resolve the format issue, which has led to some heated email exchanges. Meanwhile, the separate HDMI group has been meeting to decide which formats should be classified as mandatory for displays to handle.
To date the majority of tests that have taken place have been led by the commercial sector. Broadcasts, such as the already launched Sky 3D service, and tests by operators that include Astra, Eutelsat, Canal+ and UPC, have used both HD receivers and displays already in the marketplace through a method known as Frame Compatible.
The EBU membership, which largely comprises broadcasters with public service obligations, would like to use a method known as Service Compatible that would enable them to broadcast occasional 3D events. The Service Compatible approach has been adopted by Blu-Ray and requires almost twice the bandwidth of current 3D signals.
Italian broadcaster RAI is suggesting a 1080p50 Frame Compatible format that is also Service Compatible. Significantly, a 1080p50 STB would still bring 2D 1080p50 in addition to 720p per eye 3D. This means a broadcaster could simply extend the bandwidth used for a 3D transmission while allowing viewers without a 3D set to enjoy the same programme without the need to send them to an alternate channel.
In submissions to the DVB seen by Broadband TV News, RAI suggests that the DVB considers all the available formats, arguing that the favoured side-by side-format is just as strange as a format where a 1080i frame can have 720i 2D viewing but also 720i per eye.
But the manufacturer Panasonic points out that while it is necessary Phase 1 to run on existing formats already in the marketplace, Phase 2 should concentrate on future systems without working through unnecessary compromises. “Discussions on “strange” formats like 720i in our understanding leads to nothing in the 3D discussion”.
By Julian Clover, Broadband TV News
