about mpeg-4 source

[farjami]

Is mpeg-4 free(open source) that xvid and divx and 3ivx created from it? Is it a source code of an algorithm that every one (buys or don’t buy) it and enhances it for himself? Is this true about advanced audio coding(aac)?:thanks:

[GodofaGap]

Using MPEG4 for commercial purposes is not free. DivX and XviD are not based on an MPEG4 'source code', but on an specification.

Same thing for AAC.

[Sirber]

IIRC DivX and XviD were based from ProjectMayo, also called OpenDivx

http://www.projectmayo.com/

[farjami]

thanks my friend but i need more information
1- why 3ivx and xvid are called mpeg-4 codec?
2- if the divx and xvid are not based on an MPEG4 "source code"
so why both of them can be decoded by one of their decoder if we change its fourCC?
3- is mpeg-4 "open source"? and if yes how can i get it? like xvid source code

[The Link]

1. Every video codec that fulfills the mpeg4 specs can be called a mpeg4-codec (XviD, DivX, 3ivx, nero/atheme, ...)

2. Because the specs tell you how a mpeg4 stream should look like and if your encoder follows the specs every mpeg4 decoder will be able to decode the stream. How you implement it is up to you since there are no rules (perhaps just some coding standards) so the source code of every independently developed mpeg4 codec will be different (of course that's trivial if different programming languages were used).

3. Mpeg4 specs are open afaik and perhaps there's even some reference code you could compile but it doesn't make sense to use it for real life encoding since this code isn't much optimized and more for educational purposes. I don't know if there is such reference code but perhaps someone else or google will tell you.

IIRC DivX and XviD were based from ProjectMayo, also called OpenDivxAfaik the XviD source code has been rewritten from scratch in the past so there's no ProjectMayo code left.

[foxyshadis]

There is a "reference codec" for each mpeg spec, but it's usually slow as sin, bad quality, and not free. (AAC is the major exception to the first two.) If you remember the old Xing and Blade mp3 encoders, they sounded horrible because they were based on the reference code. You have to be a member of one of the industry associations that peddle the specs to get them (unless you found them online somewhere).

See http://www.m4if.org/ for more details.

[farjami]

thanks to all but two questions

Every video codec that fulfills the mpeg4 specs can be called a mpeg4-codec (XviD, DivX, 3ivx, nero/atheme, ...)
1-where can i find these specs?
2-where can i find mpeg-4 reference code?

[foxyshadis]

http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=39259 - ASP
http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=43058 - AVC
http://www.iso.org/iso/en/prods-services/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=36086&ICS1=35&ICS2=40&ICS3= - ASP Reference Code
http://www.iso.org/iso/en/prods-services/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=39593&ICS1=35&ICS2=40&ICS3= - AVC/AAC Reference Code (might be included in ASP's)

[farjami]

thanks to all for helping and bye:thanks:

[ac-chan123]

@foxyshadis: Tell not so much shit. The reference encoders are free and the most are also come with source. For the standards you must pay but not for the final drafts(with are identical but have not the ISO/IEC title cover).


Free standards(that can be documents, bitstreams and software) of the ISO can be found at http://standards.iso.org/ittf/PubliclyAvailableStandards/ .
Documents, like drafts, of the MPEG and JPEG group can be found at http://www.itscj.ipsj.or.jp/sc29/ . not all are free.

[foxyshadis]

Strange, I didn't find a link to that anywhere, and I looked all over their site! They must hide it pretty well. But it seems to mostly be there.

Isn't there a couple minor differences between the AVC final draft and standard?

[farjami]

special thanks to (ac-chan123) for a best answer that i need.:thanks:

[ac-chan123]

@foxyshadis: In the most time there are only the Cover changed. Some time there are corrigendum for spell mistakes, but the forum descript is the same. When a new standard is finished it will be released at the national standards organisation/institutes/eg. DIN in germany) some timeds you get them in the early time for free.

[Selur]

iirc the avc draft contained Yv24 support and the final doesn't

[farjami]

iirc the avc draft contained Yv24 support and the final doesn't
what is draft and what is final?

[ac-chan123]

a draft is a document in progress.
with final he means the final standard as you can buy them.

@selur: which darf have you caompared? fcd?

[akupenguin]

iirc the avc draft contained Yv24 support and the final doesn't
No.

(note: I won't use the term "yv24", because it could mean 4:4:4@8bit or 4:2:2@12bit (both of which are supported by h264 high profile) or 4:2:0@16bit (which is not, but is still a valid format).

The draft from 2002/8 ("JVT-G050") which was finalized in 2003/5 did not contain 4:4:4.
The ammendment in 2004/5 made no significant changes.
The draft from 2004/7 ("JVT-L049") which was finalized in 2005/3 ("High Profile") added 4:4:4 among other things.
The ammendment in 2005/9 made no significant changes.
The ammendment in 2006/6 removed 4:4:4.
A replacement 4:4:4 is planned, and you can read the drafts at ftp3.itu.int/av-arch/jvt-site/2006_04_Geneva/

[Selur]

@ac-chan: "JVT-L049" vs. ammendment in 2006/6, kind of missed ftp3.itu.int/av-arch/jvt-site/2006_04_Geneva/ (since I stopped reading mpeg4 specs stuff :))

[Hyper Shinchan]

There is a "reference codec" for each mpeg spec, but it's usually slow as sin, bad quality, and not free. (AAC is the major exception to the first two.)
The AAC reference software was an exception? You're kidding? It's slow as the hell also on the most modern machine, and it has ugly quality. The 3GPP refence AAC Plus encoder is very good (for a reference software) and it's avaible for free. The same for the AMR-WB +