Let me try to describe status quo on this market from my point of view. Corrections are welcome. 1. Important participants. As we all know, there's a big and rich company called Microsoft. This company has so much money that it can afford to spend some of it on research and development in the area of video codecs ( and in many other areas, but it's not important for us now ). We also know that there's a standard called ISO MPEG-4 Version 1. It is described in document ISO/IEC 14496-2 and covers several areas, but most interesting for us is the MPEG-4 Video specification, more specifically, its subset, MPEG-4 Video Simple Profile. The standard was finalized sometime around 1998 ( don't remember the exact date ). Microsoft did a lot of work on this standard, but now it claims that it's too restrictive and it's impossible to achieve best compression ratios while staying within the standard. There are also a few other companies that work ( or worked during last few years ) on compression technologies partially or completely outside MPEG-4. I can recall Sorenson, Real and Ligos, there may be more. 2. Formats. MPEG-4 clones: 1) ISO MPEG-4 Video Simple Profile ( open format ). Finished around 1998. 2) MS MPEG-4 v.3 aka DivX ;-) 3.11. Actually, format from (1) with some modifications that do not affect significantly compression ratio. About as old as (1). Recently was successfully reverse engineered and now there are several open-source programs that are able to decode/encode it. 3) Windows Media Video 7. Yet another Microsoft modification of (1). 4) Windows Media Video 8. Newest Microsoft compression format. First beta version of codec for this format was released this winter. Potential MPEG-4 clones ( I'm not sure that they are derived from MPEG-4 specifications ): 5) Sorenson Video 3. 6) RealVideo 8. 3. Codecs. Format (1) is easiest to support due to its openness. It is supported by: ProjectMayo OpenDivX codecs ( open-source, license - LGPL clone, available for Windows, x86 Linux, Mac, Pocket PC, Amiga ); DivX 4.0 codec ( free, closed-source, license - EULA, available for Windows and x86 Linux ); I heard about a few other companies releasing their MPEG-4 encoding/decoding software, but they are usually slower than DivX 4.0, don't release any sources, don't use AVI format and thus are not interesting for us. AVI codec for format (2) is originally created by Microsoft. Original version had disabled encoding and wasn't widely used until a guy with nickname Gej discovered how to unlock it and re-released the hacked codec as 'DivX ;-) 3.x'. This format is also supported ( decoding only ) by DivX 4.0. Both codecs are closed-source; DivX ;-) 3.11 is available for Windows, Mac, some x86 Unices ( e.g. Linux ) through Windows DLL loader, and maybe BeOS. DivX 4.0 is available so far only for Windows and x86 Linux. Windows Media Video codecs are somewhat better than (2) at lowest bitrates, but they are less popular because they are bound to ASF file format. They are supported on even fewer number of platforms. For example, you can't encode into WMV8 on anything except Windows or into anything except ASF file. Sorenson Video 3 is supported only in Quicktime files. It is closed-source, encoder costs $500, player is free and available for Windows and Mac. RealVideo 8 is supported only in RealMedia files, closed-source, full-featured encoder costs $200, player is free and available for Windows, Mac and select Unices. Both Sorenson and Real encoders claim to compress better than DivX ;-) 3.11. -----Original Message----- From: video4linux-list-admin@xxxxxxxxxx [mailto:video4linux-list-admin@xxxxxxxxxx]On Behalf Of Emmanuel Michon Sent: Monday, August 20, 2001 2:35 AM To: video4linux-list@xxxxxxxxxx Cc: Raphael Wegmann Subject: [more about divx :-) format mutations please!] Eugene Kuznetsov <divx@xxxxxxx> writes: > I haven't looked at the source, but only from these messages I can > conclude that the program you're talking about uses divx encoder to > encode into DivX 4.0 format ( fourcc DIVX ), but marks it as encoded > in DivX 3.11 ( fourcc DIV3 ). These formats are different, though divx > 4 is able to decode both of them. I would be glad if someone could make a clear point or show us to a web page stating the difference between the following video ``standards'': along with: supported OS (decoding/encoding), backward compatibilities, availability of source code, approximate license... Let's talk only about the video part. There may be some fun with the way it's muxed with audio and what kind of audio it is, but let's keep it simple 1- MPEG-4 video (ISO/IEC 14496-2 simple visual profile @L1-L3) 2- an elusive microsoft codec (as source code???) people talked about at the very beginning of all this (with file MPEG-4.asf?): a web pointer? 3- Project Mayo OpenDivX:-) 4- Project Mayo DivX4.0 alpha (= www.divx.com) 5- DivX:-) used in most Windows divx players, this one is certainly also the one avifile accesses thru binaries.zip (e.g. md5sum=99aeecb78c268bcf30f207f0223938e7 divxc32.dll? ) Is there a source code for this one somewhere? Who delivers updates then? 6- Intel Indeo 5.0 7- Microsoft Windows Media Technology 8- Sorensen quicktime codec 9- Other candidates? Very sincerely -- Emmanuel Michon _______________________________________________ Video4linux-list mailing list Video4linux-list@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/video4linux-list
