.m2ts

Overview

The BDAV container format modifies the MPEG-2 transport stream specification for random-access media such as Blu-ray discs, DVDs, hard drives, or solid-state memory cards. It is informally called M2TS. To optimize storage, variable rate Transport Streams are used instead of the constant rates typical of broadcast MPEG-2 TS. For playback, each packet's arrival timestamp is recorded to reconstruct a T-STD compliant constant rate stream.

The standard 188-byte MPEG-2 TS packet is prefixed with a 4-byte extra header, making a total of 192 bytes; this header contains a 2-bit copy permission indicator and a 30-bit arrival timestamp at 27 MHz resolution. The BDAV container is used on Blu-ray discs in both the BDMV (Blu-ray disc Movie) format, which supports menu authoring, and the BDAV disc format, a consumer-oriented alternative for BD-RE and BD-R discs. It is also used in the AVCHD format, a simpler high-definition camcorder standard that can store video on DVD media, memory cards, or hard disk drives.

Formats

On Blu-ray discs, the BDAV container can hold one of three mandatory video compression formats: H.262/MPEG-2 Part 2, H.264/MPEG-4 AVC, or SMPTE VC-1. Audio may be Dolby Digital, DTS, or uncompressed Linear PCM, with optional support for Dolby Digital Plus, DTS-HD High Resolution Audio, DTS-HD Master Audio, and Dolby TrueHD. For AVCHD equipment, the container is restricted to H.264/MPEG-4 AVC video and either Dolby Digital (AC-3) or uncompressed LPCM audio.

File and directory structure

M2TS filenames use a five-digit number corresponding to the audiovisual clip, which also appears in the associated clip information file. On Blu-ray discs, these files reside in a subdirectory of the BDMV or BDAV directory at the root level. AVCHD format uses the legacy 8.3 filename convention, so the extension is .MTS instead of .m2ts, and other files use extensions such as .CPI, .MPL, and .BDM. On some AVCHD equipment, the directory is located within a root-level AVCHD directory.

Software support

Most commercially produced Blu-ray titles use Advanced Access Content System encryption, so software that handles M2TS files typically works only with decrypted or unencrypted content; Blu-ray disc players can play encrypted files from the original disc. AVCHD content is commonly unencrypted. Many media players, including ALLPlayer, MPlayer, VLC, and PotPlayer, can play M2TS files depending on the compression formats used, sometimes requiring additional codecs or plugins. Conversion tools such as Nero Vision, FormatFactory, MediaCoder, HandBrake, and Picture Motion Browser can convert M2TS to MPEG-4. Playback is also supported on devices like Sony PlayStation 3, Sony Bravia TVs, Western Digital WDTVs, Xtreamer, Amkette FlashTV HD Media Player, and Panasonic Viera TVs. Apple's Final Cut Pro can read .MTS files from Sony HDR camcorders via the AVCHD plugin.