AfterDawn: Glossary

BDMV

Blu-ray allows two basic formats for titles. BD titles authored with menu support are in the BD-MV (Blu-ray Disc Movie) format. BD-MV discs contain audio, video, and other streams in Blu-ray's BD-AV (MPEG-2 TS) Container. In addition, BD-MV discs normally include interactive menus using BD-J (Blu-ray's Java implementation). BD-MV is the format intended to replace standard definition DVD.

Video and Audio Formats

BD-MV supports high definition video encoded according to MPEG-2, AVC (MPEG-4 Part 10), and VC-1 specifications. Supported audio formats are LPCM (uncompressed / mandatory), AC-3 (Dolby Digital / mandatory), DTS (mandatory), Dolby Digital Plus (optional), DTS-HD (optional), Dolby TrueHD (lossless / optional), and DTS-HD Master (lossless / optional). Audio formats listed as mandatory must be supported by every player. Due to the relatively small size of even uncompressed audio, compared to the total size of BD media, it's common to find uncompressed or losslessly compressed audio on many commercial discs.

Resolution

BD-MV supports both high definition (HD) and standard definition (SD) content. Typically main features are in high definition resolutions, while extras may all use SD or use a combination of HD and SD resolutions. Picture in Picture (PiP) video is all SD.

Supported resolutions for HD video are 720p (1280x720 Progressive), 1080i (1920x1080 Interlaced), and 1080p (1920x1080 Progressive).

Framerate

Standard analog video framerates of 25fps (PAL) and 29.97fps (NTSC) are supported for SD video. For HD video, supported framerates are 25fps and 30fps for interlaced HD video as well as 24fps progressive. Video encoded in 720p may be at 24fps, 50fps, or 60fps.

Profiles

BD-MV has three distinct profiles associated with it. Different profiles support different features and require different hardware. The reason for multiple profiles was the lack of a finished specification at the time the first players were designed. Since hardware requirements for more advanced BD-MV profiles build on the requirements for earlier profiles, some first and second generation players may be capable of being upgraded to support the final BD-MV profile.

The three BD-MV profiles are Profile 1.0, also known as Grace Period Profile or Initial Standard Profile, Profile 1.1, also known as Final Standard Profile or Bonus View, and Profile 2.0, also called BD-Live.

Profile 1.0

The original profile supported on Blu-ray players prior to November 1, 2007. No secondary video decoder is included for Picture in Picture (PiP) support, and there is also no internet connectivity.

Profile 1.1

Profile 1.1 adds PiP support via secondary video and audio decoders. This requires that a second program be present in the BD-AV video stream. 256MB of internal (persistent) storage is also mandated.

Profile 2.0

The highest profile in the Blu-ray specifications increases internal storage to no less than 1GB and adds an internet connection for downloading content in conjunction with BD-MV programming.

Encryption

BD-MV uses the same ACSS encryption as rival format HD DVD. Unlike HD DVD, Blu-ray isn't designed with consumer authoring of interactive titles in mind. Provisions in Blu-ray licensing require BD-MV discs to be ACSS encrypted to be played. Blu-ray players with older firmware may play BD-MV discs with no encryption, but newer firmware updates require ACSS for playback. BD-AV discs, which have no menu functionality, don't require encryption.

Upgradable DRM

One reason for Blu-ray's acceptance among Hollywood studios is a built in allowance for improving DRM by adding additional protections not envisioned in the original specification.

BD+

The first additional DRM measure added to the BD-MV specification as after programs for decrypting the discs appeared on the internet. BD+ is a virtual machine that adds another layer of security to bypass in order to access BD-MV content. Almost as soon as BD+ protection was introduced, SlySoft announced a version of AnyDVD able to bypass it to copy BD+ protected discs.

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