.m2ts

Not to be confused with .m2t.

BDAV MPEG-2 Transport Stream

Filename extension	.m2t, .m2ts, .MTS
Internet media type	video/MP2T[1]
Developed by	Blu-ray Disc Association
Initial release	August 2004; 20 years ago (2004-08)
Latest release	5th edition January 2018; 6 years ago (2018-01)
Type of format	Container format
Container for	Audio, video, data
Contained by	Blu-ray Disc, AVCHD
Extended from	MPEG-2 transport stream (ISO/IEC 13818-1)
Open format?	Yes
Free format?	No

.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, such as subtitles. It is based on the MPEG-2 transport stream container.^[2][3][4][5] This container format is commonly used for high-definition video on Blu-ray Disc and AVCHD.^[6]

Overview

The BDAV container format is a modification of the MPEG-2 transport stream (ITU-T H.222.0 | ISO/IEC 13818-1) specification for random-access media, such as Blu-ray discs, DVDs, hard drives or solid-state memory cards. The format is informally called M2TS.

In order to optimize the storage size, the format uses variable rate Transport Streams instead of the 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.^[7]

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.^[8]

The BDAV container format (.m2ts) is a standard used on Blu-ray discs.^[9][10][11] Blu-ray disc titles authored with menu support are in the BDMV (Blu-ray disc Movie) format and contain audio, video, and other streams in a BDAV container (.m2ts), which is based on the MPEG transport stream format.^[4][5] The BDAV container is also used in the BDAV (Blu-ray disc Audio/Visual) disc format, the consumer-oriented alternative to the BDMV discs. The BDAV disc format is used on BD-RE and BD-R discs for audio/video recording.^[5][12]

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.^[13] AVCHD is a simpler form of the Blu-ray disc standard with just one video encoding algorithm and two audio encodings.^[13][14] 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(xx) series models. Panasonic, Canon and other brands of AVCHD camcorders also store recorded video in the BDAV container format.

Formats

The BDAV container format used on Blu-ray discs can contain one of the three mandatory supported video compression formats–H.262/MPEG-2 Part 2, H.264/MPEG-4 AVC or SMPTE VC-1^[15]–and audio compression formats, such as Dolby Digital, DTS or uncompressed Linear PCM. Optionally supported audio formats are Dolby Digital Plus, DTS-HD High Resolution Audio, DTS-HD Master Audio and Dolby TrueHD.^[11][16]

The BDAV container format used on AVCHD equipment is more restricted and can contain only H.264/MPEG-4 AVC video compression and Dolby Digital (AC-3) audio compression or uncompressed LPCM audio.^[14]

File and directory structure

See also: Blu-ray Disc § Directory and file structure, and AVCHD § Overview

The names of M2TS files are in the form zzzzz.m2ts, where zzzzz is a five-digit number corresponding to the audiovisual clip. This number is also used in the filename of an associated clip information file "zzzzz.clpi".^[11] (This number can be a date and time stamp of when the video clip was recorded.) Each stream has its own file.^[17]

Files in the AVCHD format use the legacy 8.3 filename convention, whereas 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.^[13][18][19]

The M2TS files on a Blu-ray disc are placed in the subdirectory "STREAM" of the "BDMV" (or "BDAV") directory, which is at the root level. (e.g. \BDMV\STREAM\00001.m2ts or \BDAV\STREAM\00001.m2ts)^[2][10] On some AVCHD equipment, the "BDMV" directory is located in the "AVCHD" directory, which is placed at the root level (e.g. \AVCHD\BDMV\STREAM\00001.MTS).^[13]

Software support

Almost all commercially produced Blu-ray disc titles use a copy protection method called the Advanced Access Content System, which encrypts the content of the disc, including M2TS files. 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 the original disc. Video content created using AVCHD equipment is commonly unencrypted.

Most M2TS files can be played with ALLPlayer, MPlayer, VLC, PotPlayer and other media players, depending on the compression formats used in the 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.

M2TS files can also be played on Sony PlayStation 3s, Sony Bravia TVs, Western Digital WDTVs, Xtreamer media player, Amkette FlashTV HD Media Player and Panasonic Viera TVs supporting playback of AVCHD.

Apple's Final Cut Pro can read .MTS files (as stored in Sony HDR camcorders) by using the AVCHD plugin in the Log and Transfer window.^[19]

See also

• Comparison of container formats
• Enhanced VOB (used on HD DVD)
• MOD and TOD (video format)
• VOB (used on DVD)

Notes

1. RFC 3555: "MIME subtype name: MP2T – MPEG-2 Transport Streams". Accessed 2009-09-01. Archived 2009-09-04.
2. Blu-ray Disc Association (March 2005) BD ROM – Audio Visual Application Format Specifications (PDF) Page 15, Retrieved on 2009-07-26. Archived 2009-07-29.
3. Blu-ray Disc Association (2010), Application Definition – Blu-ray Disc Format – BD-J Baseline Application and Logical Model Definition for BD-ROM – March 2005 (PDF), archived from the original (PDF) on 2011-07-08, retrieved 2010-06-10
4. AfterDawn.com Glossary – BD-MV (Blu-ray Disc Movie) and BDAV container, Retrieved on 2009-07-26. Archived 2009-07-29.
5. AfterDawn.com Glossary – BDAV container, Retrieved on 2009-07-26
6. "VideoHelp Glossary – M2T, m2ts, mts". Retrieved 2010-06-10.
7. Doom9.org forum (2006) New HD Format - AVCHD (By Sony and Panasonic)
8. Doom9.org forum (2011) Question about m2ts h264 files
9. Blu-ray Disc Association (August 2004) Blu-ray Disc Format, White paper Archived 2009-06-12 at the Wayback Machine (PDF) Pages 18 and 22, Retrieved on 2009-07-28
10. Blu-ray Disc Association (March 2008) BD RE – Audiovisual Application Format Specification for BD-RE 2.1 (PDF), Retrieved on 2009-07-28. Archived 2009-07-29.
11. Videohelp.com What is Blu-ray Disc and HD DVD?, Retrieved on 2009-07-26. Archived 2009-07-29.
12. Sony. "Upscale Blu-ray Disc (BDAV) content". Retrieved 2010-06-10.
13. Backing up AVCHD video onto DVDs and playing them on a Blu-ray Disc player^[usurped], Retrieved on 2009-07-27. Archived^[usurped] 2009-07-29.
14. AVCHD Information Website AVCHD format specification overview, Retrieved on 2009-07-27
15. "Blu-ray Disc To Support WHS, MPEG-4, VC-1 – PC World". Archived from the original on 2009-05-20. Retrieved 2009-07-01.
16. "1st HD DVD Players To Decode All Mandatory, Optional Audio Codecs". TWICE. Archived from the original on 2009-04-09. Retrieved 2009-01-29.
17. M2TS filename extension, Retrieved on 2009-07-27. Archived 2009-07-29.
18. Doom9.org forum (2008) Changing Blu-ray Disc structure to AVCHD, Retrieved on 2009-07-29
19. "MTS". iCoolsoft. Archived from the original on 2012-01-26. Retrieved 2012-03-07.