Apple Final Cut Pro 7 - Manual (Page 1913)

MPEG-1 supports three layers of audio compression, called MPEG-1 Layers 1, 2, and 3.
MPEG-1 Layer 2 audio is used in some formats such as HDV and DVD, but MPEG-1 Layer
3 (also known as MP3) is by far the most common. In fact, MP3 audio compression has
become so popular that it is usually used independently of video.
MPEG-1 elementary stream files often have extensions such as .m1v and .m1a, for video
and audio, respectively.
MPEG-2
The MPEG-2 standard made many improvements to the MPEG-1 standard, including:
• Support for interlaced video
• Higher data rates and larger frame sizes, including internationally accepted standard
definition and high definition profiles
• Two kinds of multiplexed system streams—Transport Streams (TS) for unreliable network
transmission such as broadcast digital television, and Program Streams (PS) for local,
reliable media access (such as DVD playback)
MPEG-2 categorizes video standards into MPEG-2 Profiles and MPEG-2 Levels. Profiles
define the type of MPEG encoding supported (I-, P-, and B-frames) and the color sampling
method used (4:2:0 or 4:2:2 Y
′
C
B
C
R
). For example, the MPEG-2 Simple Profile (SP) supports
only I and P progressive frames using 4:2:0 color sampling, whereas the High Profile (HP)
supports I, P, and B interlaced frames with 4:2:2 color sampling.
Levels define the resolution, frame rate, and bit rate of MPEG-2 video. For example, MPEG-2
Low Level (LL) is limited to MPEG-1 resolution, whereas High Level (HL) supports
1920 x 1080 HD video.
MPEG-2 formats are often described as a combination of Profiles and Levels. For example,
DVD video uses Main Profile at Main Level (MP @ ML), which defines SD NTSC and PAL
video at a maximum bit rate of 15 Mbps (though DVD limits this to 9.8 Mbps).
MPEG-2 supports the same audio layers as MPEG-1 but also includes support for
multichannel audio. MPEG-2 Part 7 also supports a more efficient audio compression
algorithm called Advanced Audio Coding, or AAC.
MPEG-2 elementary stream files often have extensions such as .m2v and .m2a, for video
and audio, respectively.
MPEG-4
MPEG-4 inherited many of the features in MPEG-1 and MPEG-2 and then added a rich set
of multimedia features such as discrete object encoding, scene description, rich metadata,
and digital rights management (DRM). Most applications support only a subset of all the
features available in MPEG-4.
1913 Appendix B Video Formats