Original URL: http://www.theregister.co.uk/2004/06/14/dvd_forum_aac/
Forum approves Apple music format for DVD Audio
Steering Committee says 'yes'
The DVD Forum has approved the first version of its next-generation High Definition DVD (HD-DVD) specification.
The organisation, which controls the DVD format, has also approved the mandatory use of the Apple-favoured AAC for audio tracks stored in the DVD-ROM partition of future DVD Audio discs.
Approval of HD DVD 1.0 follows the approval last November of version 0.9 of the spec. The specification covers the physical construction of an HD-DVD, either as a 15GB single-layer disc or a 30GB dual-layer product. An early version of HD-DVD-RW was approved last February.
Approval of the spec. paves the way for disc makers and drive suppliers to build products around the technology. The Forum has already begun promoting the format to such companies. HD-DVD provides a higher capacity that DVD by the use of a blue laser. The optical systems shorter wavelength (405nm to DVD's 650nm) essentially means the laser can read smaller pits on the discs surface. Smaller pits mean a greater pits in a given area and thus a higher data capacity.
HD-DVD was developed by NEC and Toshiba and uses discs of the same thickness and size as today's DVD products. That should make it much easier for disc manufacturers to re-tool production lines to churn out the new discs.
That contrasts with Blu-ray, HD-DVD's biggest rival, which has different layer widths, and requires new production lines to be installed. Blu-ray products are already available from the likes of Sony, one of the format's main backers. The 23.3GB format is expected to be succeeded by a 50GB second-generation, consumer-oriented product later this year.
Meanwhile, the Forum also approved the use of Advanced Audio Codec (AAC) in DVD Audio discs. The DVD Audio specification already includes a much higher quality music storage format than AAC. However, the Forum wants to add a DVD-ROM 'zone' to the spec. to allow music companies to embedded lower resolution versions of the content for computer users. To meet the requirements of the DVD Forum's licensing Ts&Cs, such audio content will need to be encoded using AAC.
Specifically, the Forum calls for the use of High Efficiency (HE) AAC improves on vanilla AAC - part of the MPEG 4 standard - with better audio quality at higher compression rates. In practice, that means decent sound at 48kbps and 5.1 surround sound at 128kbps - the rate regular stereo AACs are usually encoded at. HE AAC also adds a 96kHz sampling rate.
It emerged last March that the Forum's ROM zone working group had selected AAC. However, at that time, the organisation would not confirm the approval since it had not yet been ratified by its Steering Committee. That ratification has now been given. ®
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