We met with Dolby Laboratories at NAB where we talked about Dolby Vision in addition to Dolby’s audio codec, AC-4. AC-4 is currently being voted on in the ATSC 3.0 group, but it is anticipated to be approved as the audio codec for use in the U.S. The alternative, MPEG-H, is expected to be approved for use in Korea and some European countries. ATSC has said that either can be used, but only one can be used on a regional basis.
At NAB, Dolby announced a collaboration with Samsung Electronics to adopt Dolby AC-4 in select television models that are scheduled to begin shipping in 2017. Don’t be surprised to see all the other TV makers adopting AC-4 as they have no choice – MPEG-H can’t be used in the US market. In Fact, LG was showing a prototype TV using AC-4 decoding at NAB.
AC-4 and MPEG-H are more than just a codec – they are an immersive audio solution with lots of options. As a codec, it is more efficient than its predecessor, AC-3, but it also allows for many personalization features. These include allowing the user to choose and language version, choose services for hearing-impaired and visually impaired audiences and make other choices about multiple audio tracks like dialog enhancement. Support for audio objects is also included.
While over the air ATSC broadcasts may take a few years to gain ground, Dolby expects the OTT part of the standard to roll out much faster. Using AC-4 enables better efficiency and these new personalization options.
In a demo at NAB, we watched some HDR content with AC-4 encoded Atmos audio on a Vizio HDR TV with a set top box from Sagecom and an Atmos-capable soundbar from Yamaha.
We also saw some content captured with the new Grass Valley broadcast 3-chip camera, the LDX 86, that has two sets of electronics. The camera has dual outputs that support an SDR and HDR workflow. This is handled in their baystation, the XCU Universe XF, that can output a HD/4K SDR stream and HD/4K HDR stream (in Quad SDI level A or B format or IP encapsulated using a 4:1 TICO compression). Apparently the PQ SMPTE 2084 EOTF is applied to the HDR output, but with no metadata attached. This conforms to the PQ10 workflow outlined in the UHD Forum’s Guideline document (see related article – UHD Forum Issues Important HDR Guidelines at NAB).
Dolby also advises us that the new Vizio M-series now support Dolby Vision, a mid-tier line of TVs from the company. In addition, Sony DADC has agreed to be the first to produce UltraHD Blu-ray discs with the optional Dolby Vision format. No titles or time frame for releases was announced, however. Dolby expects there to be about 150 HDR Dolby Vision movies available by the end of the year. Dolby’s dual stream HDR approach requires about 20% more bandwidth than a single stream, said Dolby. – CC