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what are BDMV files? How are they related with Blu-ray Disc, BDAV, M2TS and AVCHD?

BDMV (Blu-ray Disc Movie) files are Blu-ray Information files contain information about the contents of the Blu-ray disc, shown as Blu-ray Disc titles authored with menu.

Directory

Blu-ray Disc Movie

Filename extension: .m2ts
   
Internet media type: video/MP2T
   
Developed by: Blu-ray Disc Association
   
Type of format: Media container
   
Container for: Audio, video, data
Contained by: Blu-ray Disc, AVCHD
   
Contained by: MPEG-2 transport stream
   
Open format: No
   

7BDMV Player

software list that can play BDMV

8BDMV converter

8-1convert BDMV to other video formats
8-2convert other video files to bdmv

9DVD/Blu-ray disc burning and copy

10BDMV to digital video devices

11Basic BDMV Editing

2 Overview

BDMV Application Format is defined in Blu-ray Disc Association, System Description Blu-ray Disc Rewritable Format, part 3: Audio Visual Basic Format Specifications, version 3.0, which has a format for realtime recording and editing by using BDMV Application format.

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

3 BDMV file structure

There are at least 6 items that a BDMV folder contains, and all be present for it to be playable. They are: BACKUP, CLIPINF, PLAYLIST, STREAM, INDEX.BDMV, MOVIEOBJECT.BDMV (simetime it may be bdm.) This is one example.

You can find M2TS (titled as 10000.m2ts, 10001.m2ts, 100002.m2ts, ...) in Stream Folder. It is the actual video files forBlu-ray Disc movie.

Figure 3-1 Directory structure for BDMV Application

Figure 3-2 Application Format Structure and Conten Protection System for BDMV Application

3-1.Clip

Each pair of an AV stream file and its attribute is considered to be one object. A Clip is an object consisting of a Clip AV stream file and its corresponding Clip information file. A Clip AV stream file stores data, which is basically an MPEG-2 transport stream defined in a structure conforming to Blu-ray Disc Association, System Description Blu-ray Disc Rewritable Format, part 3: Audio Visual Basic Format Specifications, version 3.0. The Clip Information file stores the time stamps of the access point into the corresponding AV stream file. The Player reads the Clip Information to find out the position where it should begin to read the data from the AV stream file.

3-2.Playlist

A PlayList is a collection of playing intervals in the Clips. One such playing interval is called a PlayItem and consists of a pair of “IN-point and OUT-points”that point to positions on a time axis of the Clip. Therefore, a PlayList is a collection of PlayItems. Here the IN-point means a start point of a playing interval and the OUT-point means an end point of the playing interval.

3-3.Movie Objects

A Movie Object consists of an executable navigation command program. This enables dynamic scenario description. Movie Objects are a layer above PlayLists. A navigation command in a Movie Object can launch a PlayList playback or a Move Object can call another Movie Object so that a set of Movie Objects can manage playback of PlayLists in accordance with user’s interaction and preferences.

3-4. Index Table

The Index Table is top-level information of the application format. This table contains entry points for all Titles, First Playback, and Top Menu. The Player references this table whenever a Title, First Playback, or Menu executing operation needs to be performed.

3-5. First Playback

First Playback may be optionally defined in the Index Table and points to a Movie Object, which then plays automatically. When the disc is loaded, the player refers to the entry of “First Playback” and obtains the corresponding Movie Object. First Playback Movie Object is an optional function. A disc may or may not contain First Playback Movie Object.

3-6. Top Menu

Top Menu may be optionally defined in the Index Table and points to a Movie Object. Top Menu can be called by a user operation such as “MenuCall”. A Movie Object indexed by Top Menu executes a PlayList whose PlayItem links a Clip having Button Objects. Each Button Object branches off to another Movie Object as a child Menu. Top Menu Movie Object is an optional function. A disc may or may not contain Top Menu Movie Object.

3-7. Title

Title is a logical unit for the user to recognize one playback group. The group may be one linear playback block or it may be a non-linear playback block with branching points. Each Title has a title_number. Title_number values are defined in ascending order, starting from one. All the values of the title_number shall be defined at least once on a disc.

3-8. Content Protection System

A Content Protection System(CPS) Unit is assigned to each Clip, which is encrypted by using the CPS Unit Key (Kcu) associated to the CPS Unit. Two different Clips shall not belong to same CPS Unit. Each CPS Unit has its corresponding CPS Unit Usage file. Each CPS Unit has a CPS_Unit_number. CPS_Unit_number values shall be in the range of 1~200, and the Unit_Key_File_Header() in CPS Unit Key File defines the all CPS Unit number currently used for BDMV Application. CPS Unit Key File for BDMV Application is defined in 3.2.1 of this specification.

4 BDMV Media Parameters

4-1.Video and Audio

BDMV 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.

4-2. Video Resolution

BDMV 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).

4-3.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.

4-4.BDMV Profiles

BDMV 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 BDMV profiles build on the requirements for earlier profiles, some first and second generation players may be capable of being upgraded to support the final BDMV profile. The three BDMV 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 BDAV 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 BDMV programming.

4-5.Encryption

BDMV 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 BDMV discs with no encryption, but newer firmware updates require ACSS for playback. BDAV discs, which have no menu functionality, don't require encryption.

5 BDMV, BDAV, M2TS, MTS, AVCHD

BDAV is Blu-ray Disc Audio Video transport stream, or, more commonly *.m2ts. The *.m2ts is what's in the BDMV (Blu-ray Disc Movie) folder, Actually the Stream folder within the BDMV folder. It's a container format for multiplexing audio and video.

M2TS is a filename extension used for the Blu-ray Disc Audio-Video (BDAV) MPEG-2 Transport Stream (M2TS) container file format. It is used for multiplexing audio, video and other streams. It is based on the MPEG-2 transport stream container. This container format is commonly used for high definition video on Blu-ray Disc and AVCHD.

M2TS and MTS are usually encoded with AVCHD (Advanced Video Coding High Definition) which is a file-based format for the digital recording and playback of high-definition video.