Video Compression Knowledge Database


   Last updated: February 19, 2011






QuickTime Components




Apple QuickTime components


  • Sorenson Video Compressor

    It's also known as 'Sorenson Video 2' or 'SV2.' The Sorenson Video codec is licensed by Sorenson Media.  Sorenson Video 2 was first brought to QuickTime (QuickTime 3.0) in March, 1999.

  • Sorenson Video 3 Compressor

    It's known as 'Sorenson Video3 or 'SV3.'   It was first introduced to QuickTime (QuickTime 5.0.2) in July, 2001.   Sorenson Video 3 gives good compression.   Compared with SV2, Sorenson Video 3 is as much as twice faster in encoding video, maintaining the file size and the bitrate.

    The settings may be only changed through Sorenson Squeeze if you have it.

  • H.264

    It was developed by ITU-T (The ITU Telecommunication Standardization Sector) and MPEG.   It is also called MPEG-4 Part 10.  H.264 is a more familiar named to indicated that it was co-developed by ITU-T while MPEG refers it as AVC.

    H.264 is designed to offer a flexible, universal standard at substantially lower rates than other popular standards such as MPEG-2, H.263 and MPEG-4 Part 2.   H.264 is now considered as QuickTime's main video compressor.   But QuickTime adopted it only with the introduction of v. 7.0.   So you need to make sure that video viewers have QuickTime 7.0.3 (H.64 bugs fixed) or highter.

  • Cinepak

    Cinepak was developed by SuperMac, Inc. (now part of Apple Computer, Inc.) in 1990.   It is designed so that video can be played at low bit rates possibly from single-speed CD-ROM drives.   It is an old compressor and is hardly used.


    Read 'Converting VOBs into DV with MPEG Streamclip.'

  • DV - Pal

    A major difference between DV - NTSC and DV - Pal is

    DV - NTSC uses 4:1:1 color-sampling
    DV - Pal uses 4:2:0 color-sampling

  • H.263

    It is designed to offer video encoding solution for video-conferencing at low bit rates.   It's rarely used for video compression nowadays.  Its successor is H.264.

  • Motion JPEG A and Motion JPEG B

    It applies the ISO-JPEG specification field by field to compress digital video streams.   Motion JPEG A supports markers.   Motion JPEG B doesn't, and QuickTime instead inserts a header at the beginning of the bitstream.

  • MPEG4 Compressor

    It is called MPEG-4 Part 2 to distinguish it from H.264.   External DVD players that are labeled MPEG-4 compatible should play any video that is compressed in MPEG-4 Part 2.

  • Animation

    It is a lossless codec which is capable of playing back uncompressed RGB video.   Nowadays, it is hardly used.





MPEG-1, MPEG-2 and MPEG-4


Compared with MPEG-1, which is optimized at around 1.5 Mbps, MPEG-2 has a wider range of bit rates.   The DVD is based on MPEG-2 compression.   Many commercial DVD movies run at around 4,500 Mbps.   The DVD is considered to be able to deliver video in high quality mostly because of its high bit rates.  In this sense, if it's played at a low bitrate, say 3 Mbps or lower, MPEG-2 video can underperform MPEG-1 video.   And while MPEG-1 only supports progressive video, MPEG-2 supports both progressive and interlaced frames.   Therefore, MPEG-2 is suitable for both PC- and TV-viewing.

MPEG-4 is designed to preserve MPEG-1 and MPEG-2 technology and offer high-quality video transmission at low bit rates.   MPEG-4 is designed such that it is capable of projecting the same video quality at half the bitrate of MPEG-2.   But because of its relatively low bit rates in use, MPEG-4 video is more likely to suffer block-like artifacts.

A major improvement over video compression under MPEG-4 is use of meshes to support 3D rendering.   MPEG-4 samples the surface of an object by a number of points that creates a mesh.   While MPEG-2 handles a perspective object somewhat poorly over time, an object rendered in MPEG-4's 3D rendering shows dynamic flexibility in its shape.












Third-Party QuickTime components


  • DivX 3 and DivX 4

    Originally, it's a hacked version of Microsoft's MPEG-4 Version 3.   At the end of the 1990s, Microsoft required that multimedia data be put in the ASF container, limiting the choice of audio and video codecs.   This hacked version was circulated among those who wanted to preserve AVI as a multimedia format and the flexible choice of codecs.

    The original members created a company called DivXNetworks, Inc. in 2000.   They started an open project called 'Project Mayo' in January, 2001.   DivXNetworks abruptly shut down the project several months later.   And the company used it to release DivX 4.

    Although it's a hacked version and then considered illegal, there are many people who still compress video with DivX 3.  In fact, it is largely considered to outperform DivX 4.

  • DivX 6

    It offers good video quality and compression.   On the other hand, it has serious shortcomings.

    (1) The encoding time is fairly long.
    (2) Accessing it through QuickTime Pro and DivX Converter (a standalone application exclusively used to access DivX QuickTime Component) does not always allow users to embed audio.
    (3) The only audio compressor supported by DivX 6 is MP3.

  • XviD

    After Project Mayo crumbled, some of the original members and new participants developed a video codec that is originally based on the prior open project.   XviD is an open-source project started by these volunteer programmers that offers a free video codec in response to DivX, which has been capitalized.

    An XviD QuickTime component for Mac OS X is currently made possible by Nägeli, Christoph.  It can be downloaded here. Compared with DivX, it gives users many options for advanced simple profile (ASP) features such as B-frames, QPel and GMC.  And this free, one-source codec gives access to QuickTime's simple audio codecs such as AMR Narrowband, Apple Lossless, MPEG-4 (AAC) and IMA 4:1.

  • 3ivx

    It is somewhat popular MPEG-4-compliant codec.  The freeware version doesn't support advanced MPEG-4 features such as B-frames, QPel and GMC.  And the current version (D4 4.5) is only for Power PC Macs.


DivX 6 Mac

DivX 6


XviD QuickTime Component

XviD QuickTime Component