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Starting with DivX 4.0, it is a true MPEG4 codec. However, it has not been set as a standard.
MPEG4 is the algorithm used to compress the video, and DivX uses this algorithm as well as it's own to compress the video.
Well if it uses it's on algorithim then it can't be true MPEG4. Yes, it is heavily based on MPEG4, but it's not TRUE MPEG4. If it were, I'd be able to play Divx encoded files with QuickTime 6 without any additional codecs. Also, Divx compressed video files use Mp3 audio compression for audio, typically. MPEG4 audio (also known as AAC) does a considerably better job at compressing audio. Plus MPEG4 includes things like copy right material as well as piracy protection, if it's encoded as such.
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The algorithms that are used by DivX are the official MPEG4 standard with optimizations put in for certain architectures. You can actually playback DivX files without the DivX codec installed by installing other MPEG4 codecs (Xvid, WMV10 may also do it), or using an MPEG4 filter (FFDSHOW). Some filters do include the optimization information for DivX and will show cleaner video, but they aren't required to include more than the MPEG4 specs.
The only true MPEG4 compression codec comes with quicktime 6. As seen here, for example, these are the compatibility settings for MPEG4. http://homepage.mac.com/mestinkbad/.Pictures/web/allakhazam/mpeg4-quicktime.gif
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At least, this is how I understand it, as I can watch stuff encoded in DivX on a linux box that has never had DivX installed, but does have Xvid installed and uses the FourCC code for DivX as MPG4.
Xvid isn't true MPEG4 video.
Listen, think about it. Why would Divx, if it were true mpeg4, use the .avi extension? That should raise a flag right there that's its not true MPEG4.
Don't get me wrong, I like Divx. It's a very fast encoder. And it's multiplatform. But it has a hard time breaking into the Consume Electronics industry, which have far more impact on what becomes a standard and what doesn't. The iPod, for example, is able to play AAC encoded audio. A number of DVD players already support MPEG4. Yet, only one device I know of that might be considered a CE device, supports Divx. It's Plextors USB2 device for recording TV shows onto your PC. (Why USB2 and not FireWire? Cuz they're morons). Ironically, from what I've read, Recording with DiVX format yields the same compression ratios as MPEG2. Regardless, I suggest getting a TiVo instead. I have an ATI AIW, which I can also use in a simular fashion. But it does NOT COMPARE TO MY TIVO. Could you imagine playing FFXI when suddenly your show comes on? Disaster!
Edited, Thu Dec 23 01:58:04 2004 by MeStinkBAD Edited, Thu Dec 23 01:59:06 2004 by MeStinkBAD Edited, Thu Dec 23 02:05:10 2004 by MeStinkBAD