MPEG-4 absorbs many of the features of MPEG-1 and MPEG-2, adding new features such as (extended) VRML support for 3D rendering, object-oriented composite files (including audio, video and VRML (Virtual Reality Modeling Language) objects), support for Digital Rights Management and various types of interactivity.
Most of the features included in MPEG-4 are left to individual developers to implement. This means that there are very few complete implementations of the MPEG-4 standard. Anticipating this, the developers added the concept of "profiles", allowing various capabilities to be grouped together.
MPEG-4 consists of several standards—termed "layers"—as follows.
Layer 1 (ISO 14496-1) describes synchronization and multiplexing of video and audio.
Layer 2 (ISO 14496-2) is a compression codec for video signals.
Layer 3 (ISO 14496-3) is a compression codec for perceptual coding of audio signals.
Layer 4 (ISO 14496-4) describes procedures for testing compliance.
Layer 5 (ISO 14496-5) describes systems for software simulation.
Layer 6 (ISO 14496-6) describes Delivery Multimedia Integration Framework (DMIF).
Layer 10 (ISO 14496-10) is an advanced codec for video signals which is also called H.264 or AVC.
Layer 14 (ISO 14496-14) describes the designated container for MPEG-4 content MP4, which was also defined within MPEG-4.
Layer 17 (ISO 14496-17) describes the MPEG-4 Timed Text subtitle format
This is 4.1.00.3917 decompressor with hacks to enable playback capability of MPEG4 V3 and quality slider.
One problem (or mystery rather) still remaining with this decompressor is that it does not have the quality slider enabled for large resolutions.
Currently Windows 2000 CD is the only source for this decompressor since Microsoft has put the old version for auto-download where this version used to be.
I conducted a technology review comparing the coding efficiency of the MPEG2, MPEG4-2 and MPEG4-10 (MPEG4 part 10, h.264 or h.26l) codecs in order to pick an effective and efficient compression algorithm to be used in a new satellite DBS system.
The goal of these tests was to achieve the highest quality video at the lowest possible bit rate, thus allowing a large number of video channels to be placed into a single satellite transponder.
At the moment there are no real-time decoders available, so it is not possible to encode video using MPEG4 part 10 and then play it back in Windows Media Player (or any player, for that matter).
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