More Details on BDA’s Final 3D Specification
The Blu-ray 3D specification calls for encoding 3D video using the Multiview Video Coding (MVC) codec (ISO-MPEG-14496-10:2008, Amendment 1), an extension to the ITU-T H.264 Advanced Video Coding (AVC) codec currently supported by all Blu-ray Disc players. MPEG4-MVC compresses both left and right eye views, and can provide full 1080p-resolution backward-compatibility with current 2D Blu-ray Disc players.
MVC was developed by MPEG to support multiple simultaneous views of a subject. In general, an MVC encoder receives N temporally-synchronized video streams and generates one output bitstream. The decoder receives the bitstream, and decodes and outputs the N video signals. The video representation format is based on N views, and for stereoscopic 3D, N=2. MVC works by exploiting the similarities between multiple-camera video captures of a scene. By eliminating redundant information across camera views, MVC achieves a reduction in bit rate of approximately 20-25% on average, when compared to encoding views from each camera separately.
The new Multiview High Profile, as defined in the MPEG-MVC Amendment, uses the same coding tools as supported by the previous High Profile (HP) of the MPEG-4 AVC standard, which was already adopted into the Blu-ray Disc specification. Level constraints for this profile have also been specified so that fixed decoder resources of single-view AVC decoders, such as memory, could be repurposed for decoding stereo and multiview video bitstreams (MPEG-4 also defines a High Stereo Profile; it’s not immediately known which of these is specifically part of the BDA specification). Moreover, MVC is backwards compatible in the sense that one view (the so-called base-view) can be decoded from a part of the MVC stream by using a HP decoder, which could then be output on a conventional monoscopic display. An MVC decoder would generate multiple output views from the full stream and forward them to a stereoscopic or multiscopic display.
It often takes several years for an industry to develop and embrace a single standard, with "format wars" all too often the case. MPEG-MVC, while defined over a year ago, was rapidly adopted by the Blu-ray Disc Association nonetheless, and this haste shows how this emerging market is motivating manufacturers and content providers to get Blu-ray 3D products and content quickly out the door: expect the first products and titles sometime next year.
By Aldo Cugnini, Display Daily
