The BDAV container format is a modification of MPEG-2 transport stream specification for random-access media, such as Blu-ray Disc, DVD, hard drives or solid-state memory cards. It is informally called M2TS. In order to optimize the storage size, the format uses variable rate Transport Streams instead of the typical constant rates found in MPEG-2 TS broadcast. To be able to reconstruct a T-STD compliant constant rate Transport Stream for playback the arrival timestamp of each packet needs to be recorded. The standard MPEG-2 TS 188-byte packet is prefixed with a 4-byte extra header to a total size of 192 bytes. The header consists of a 2-bit copy permission indicator and the 30-bit arrival timestamp with a resolution of 27 MHz. The BDAV container format is a standard used on Blu-ray Discs. Blu-ray Disc titles authored with menu support are in the BDMV format and contain audio, video, and other streams in BDAV container, which is based on the MPEG transport stream format. The BDAV container is also used in the BDAV disc format, the consumer-oriented alternative to the BDMV discs. BDAV disc format is used on BD-RE and BD-R discs for audio/video recording. The BDAV container with filename extension.MTS or.m2ts is also used in AVCHD format, which is a high definition digital video camera recorder format. AVCHD is a simpler form of the Blu-ray Disc standard with just one video encoding algorithm and two audio encodings. Compared to Blu-ray Disc format, AVCHD can use various storage media, such as DVD media, memory cards or hard disk drives. The BDAV container contains videos recorded using AVCHD camcorders, such as Sony's HDR-SR series models. Panasonic, Canon and other brands of AVCHD camcorders also store recorded video in BDAV container format. There are some problems with AVCHD compatibility between brands.
The names of M2TS files are in the form, where zzzzz is a 5-digit number corresponding to the audiovisual clip. This number is also used in the filename of an associated clip information file "". Each stream has its own file. Files in AVCHD format use legacy "8.3" file naming convention, while Blu-ray Discs use long filenames. This is why the filename extension of video files is ".MTS" instead of Blu-ray Disc's ".m2ts". Also, other files use different extensions: .CPI – .clpi, .MPL – .mpls, .BDM – .bdmv. The M2TS files on a Blu-ray Disc are placed in the subdirectory "" of the "" directory, which is at the root level. On some AVCHD equipment, the "" directory is located in the "" directory, which is placed at the root level.
Software support
Almost all commercially produced Blu-ray Disc titles use copy protection method called Advanced Access Content System, which encrypts content of the disc. Software that supports M2TS files usually works only with decrypted or unencrypted files. Blu-ray Disc software players can usually play back encrypted content from original disc. Video content created using AVCHD equipment is commonly unencrypted. Currently, M2TS files can be played using the Picture Motion Browser, which is an application video player provided with Sony AVCHD camcorders. Most M2TS files can be played with ALLPlayer, MPlayer, VLC, PotPlayer and other media players, depending on used compression formats in a M2TS file. Some players will need an appropriate codec, component or plugin installed. Current versions of Nero Vision, FormatFactory, MediaCoder, HandBrake and Picture Motion Browser are capable of converting M2TS files into MPEG-4 files, which can also be viewed using the aforementioned media players. In August 2012, VLC media player 2.0.1 could convert.m2ts files into MP4 as well. DVDFab can also convert.m2ts to various other formats, including.mkv or.mp4. Sony products Media Manager PRO for PSP, Media Manager PRO for Walkman, and Mobile Media Manager PRO are all capable of converting M2TS format to MP4 files. M2TS format from Sony is not necessarily the same as that of Panasonic or Canon camcorders. However, programs like Sony Vegas Pro and AVS Video Editor can open and edit both Sony M2TS files as well as Panasonic M2TS files. The only other piece of software known currently to handle both types is Pinnacle Studio 12 Ultimate and Cyberlink Power Director, starting with v8. M2TS files can also be played on Sony PlayStation 3s, Sony Bravia TVs, Western Digital WDTVs, Xtreamermedia player, Amkette FlashTV HD Media Player and Panasonic Viera TVs supporting playback of AVCHD. Apple's Final Cut Pro can read.MTS files by using the AVCHD plugin in the Log and Transfer window.
