MPEG-4 (ISO 14496) is a broad Open Standard developed by the Moving Picture Experts Group (MPEG), a working group of the International Organization for Standardization (ISO) which also did the well known MPEG-1 (MP3, VCD) and MPEG-2 (DVD, SVCD) Standards, standardizing all sorts of audio/video compression formats and much more
By its nature the MPEG-4 Standard doesnt aim at standardizing one potential product (eg something comparable to DVD) but covers a broad range of Sub-Standards, which Product Providers can choose from to follow, according to what they need for their product
The MPEG-4 Standard, as mentioned, is divided into many different sub-standards, where for us users on Doom9 the following parts might be of major interest:
- ISO 14496-1 (Systems), Animation/Interactivity (like DVD Menus)
- ISO 14496-2 (Video), e.g. Advanced Simple Profile (ASP), as followed by XviD, DivX5, 3ivx...
- ISO 14496-3 (Audio), Advanced Audio Coding (AAC)
- ISO 14496-10 (Video), Advanced Video Coding (AVC), also known as H.264
- ISO 14496-14 (Container), MP4 container format (uses the .mp4 extension)
- ISO 14496-17 (Subtitles), MPEG-4 Timed Text subtitle format
This information thread now aims at providing some usefull infos on most of these parts, with a focus on MPEG-4 ASP and AVC/H.264
What are the possible advantages of an open standard, like MPEG-4, compared to closed formats, like Micro$oft's Windows Media?
The good thing about an open standard is that its open for everyone to follow when creating a product. therefore we already have a lot of different products which are compatible to the MPEG-4 Standard and are therefore also compatible to each other
Next to interoperability and big product range to choose from, an open standard leads to competition, which means for the consumer that products in the competitive market will most likely have a better increase in quality, lower prices and a better focus on the consumers needs
but not to forget and thats maybe the most important point for me:
an open standard allows open source development, like we all know from XviD for example
ISO 14496-1 (Systems) - MP4
As
already mentioned the MPEG-4 Standard defines its own Container Format:
MP4 (other container formats not covered by the Standard are for
example AVI, OGM, Matroska aso...), which allows not only the storage
of audio and video content but also of animated/interactive content
(also known as BIFS), as defined in MPEG-4 Systems, as needed for
DVD-like Menus for example (MP4 has now been moved from ISO 14496-1 to
its own ISO 14496-14)
Interactivity/Animation
without getting into technical details the MPEG-4 Systems Standard
defines a broad range of powerfull tools which allow all sorts of
animations (similar to what we know from flash) or interactivity (for
example as known from DVD Menus...)
These animations/interactivity can be done in both 2D and 3D
To check out some nice samples of what MPEG-4 Systems can provide have a look here
Note that to playback systems files you also of course need a systems
decoder/player, where the most popular ones for Systems 2D content are GPAC's Osmo4 (supports now 3D too) or EnvivioTV - for Systems 3D also have a look here
Interoperability
the MP4 container is a very important part of the MPEG-4 Standard, as
if you want to reach 100% interoperability between different MPEG-4 A/V
implemenatations there is no way around using a standardised container
too
on the contrary still the most popular container format is AVI, also
for MPEG-4 video content, and the AVI container is also the major
reason when it comes to incompatibilities between exisiting MPEG-4
stuff (ie on hardware players)
further documentation
If you want to read more about the MP4 container have a look at the MP4 FAQ in the New A/V Container forum
some documentation on MP4 is available from here and here
A FAQ especially about MPEG-4 Systems is available from the Motion Picture Experts Group (MPEG)
also if you are interested in the described interactive content also have a look at this document from the GPAC project
A draft of the MPEG-4 Systems Specs can be downloaded here
The Specs for the ISO base media file format (14496-12), on which MP4 is based on, can be found here
ISO 14496-2 (Video) - Advanced Simple Profile (ASP)
文章整理：西部数码--专业提供域名注册、虚拟主机服务
http://www.west263.com
以上信息与文章正文是不可分割的一部分,如果您要转载本文章,请保留以上信息，谢谢!
