[-=(Lord Crosis)=-]

I wrote an article detailing MPEG 4 in regards to it's Mac history...

I invite any corrections or additions anyone can suggest... :^)
http://www.macopz.com

-=(Lord Crosis)=-

[T Allen]

Originally posted by -=(Lord Crosis)=-:
<STRONG>I wrote an article detailing MPEG 4 in regards to it's Mac history...

I invite any corrections or additions anyone can suggest... :^)
http://www.macopz.com

-=(Lord Crosis)=-</STRONG>

Yes, keep up the good work! I can't think of a topic that's more misunderstood
than MPEG-4/DivX.

Would adding a timeline help? I noticed a couple of grammer/usage errors and a "QuickTime" in all lower case.

FWIW, the articles listed below may provide additional background info for you:

Salon.com
- - - - - - - - - -

The MP3 of movies? May 31, 2000 http://www.salon.com/tech/feature/20...ivx/index.html


Double DivX trouble Sept. 28, 2000 http://www.salon.com/tech/log/2000/0...dux/index.html


Escaping the Napster trap By Damien Cave March 15, 2001 http://www.salon.com/tech/feature/20...rt1/index.html

This article has a little different 'take' on why he started to hack the codec.
Also "Gej" is Jerome Rota, a French graphic artist.

"He had originally used a piece of Microsoft software -- namely the Windows
Media "codec" (short for compressor/decompressor) that enables users to compress digital video -- to shrink the size of the ad he had created so it would fit
snugly onto a CD-ROM. But in September 1999, Microsoft released an upgrade of
Windows Media that failed to play what was essentially Rota's artistic portfolio
and résumé. Instead, the new program presented only a blank screen. Rather than
reencoding the work with Microsoft's new codec, Rota decided to rework the
codec's code."


Stop. Pay toll. Download. March 6, 2002 http://www.salon.com/tech/feature/20...peg/index.html


DV.com
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THE MANY FACES OF MPEG-4 By Ben Waggoner http://www.dv.com/magazine/2001/0501/waggoner0501.html

Lots of technical stuff here, but a really good read on what ISO MPEG-4 is all
about. Does his explaination of MS MPEG-4 v3 and MS WMP 7 differ from yours?

"After MS MPEG-4 v3, the next version of the codec was renamed Windows Media
Video v7 to avoid confusion with the real MPEG-4, and to bring the numbering
into sync with the rest of the Windows Media architecture.

Microsoft's Windows Media 7 architecture has what is labeled as an ISO-standard
MPEG-4 encoder and decoder, but it still uses the ASF file format. However, this
may enable the Windows Media server and player to create and play back ISO
MPEG-4 streams once Windows Media includes support for the MPEG-4 audio codecs."

Couple of corrections:

Gej hacked MS MPEG4-V3 because the codec only supported the ASF format (ms mpeg4-v1 and v2 both supported both ASF and AVI, but the AVI support was removed by Microsoft in v3). MS simply implemented the unfinished yet still official ISO MPEG-4 v1 and called is MS-MPEG4 V1. v2 and v3 had enhancements made to the codec. People could have continued to use MS-MPEG V2, but for some reason it never took off, even though it was more or less identical to Divx 3.11 and had all the same capabilities and features. Somehow the word 'divx' became popular quickly in the underground.

Divx5 is fully ISO MPEG-4 compliant (divx 3.11 and 4.0 were not). That means that any ISO MPEG-4 compliant decoder will decode Divx5 MP4 files without the need to have any kind of Divx5 codec installed. The same would be true of the Sorenson MPEG-4 codec which Apple hopes to use with Quicktime6, but isn't due to MPEG-LA licensing issues. Divx5, since it is now iso-compliant, has to abide by the same MPEG-LA licensing terms as Apple would, which is why they Pro version (which supports b-frames and other ISO features, is distributed via ad-ware or for $30). If all goes well, Apple's Quicktime6 should be able to play back Divx5 MP4 files without any additional quicktime codecs being installed on the system.

The Cisco ISO-compliant MP4 decoder already decodes Divx5 MP4's perfectly, so it is indeed compliant. Divx5 is the first codec that actually supports the official MPEG-4 file format (MP4). This file format is based on the Quicktime MOV file format, with added streaming enhancements. The MP4 format also handles VBR MP3 and VBR AAC audio codecs without any problems, whereas non-standard methods have to be used to get the same to work with AVI.

Hopefully there will soon be a Divx5 encoder for the Mac as well. In that case, there would really be no need for the Sorenson MPEG-4 codec, since the Divx5 MPEG-4 codec would produce ISO-compliant MP4 content as well.

[-=(Lord Crosis)=-]

Thank you both for the info and links... I shall review them, and post version 1.1 when I have some time.

I will attempt a timeline, though it will definately take a bit of research to say the least... The entire thing was written off the top of my head, and I can tell that as I expand it I will be doing *ALOT* more reading... :^)

-=(Lord Crosis)=-

[-=(Lord Crosis)=-]

Originally posted by T Allen:
<STRONG>
"After MS MPEG-4 v3, the next version of the codec was renamed Windows Media
Video v7 to avoid confusion with the real MPEG-4, and to bring the numbering
into sync with the rest of the Windows Media architecture.

Microsoft's Windows Media 7 architecture has what is labeled as an ISO-standard
MPEG-4 encoder and decoder, but it still uses the ASF file format. However, this
may enable the Windows Media server and player to create and play back ISO
MPEG-4 streams once Windows Media includes support for the MPEG-4 audio codecs."</STRONG>

Interesting... I rather think you can see where I got my confusion if you go to http://www.microsoft.com/windows/win...ult.asp#codecs

It doesn't really make it sound like Windows Media Video v7 is even related to MS-MPEG4, but does both list MS-MPEG4 as a supported CODEC and WMV as a seperate supported CODEC... I guess what they are trying to convey here is that it's backwards compatible with the stuff you've already encoded, and can continue to encode in that same format if you prefer?

And last time I had visited that site they didn't say *ANYTHING* about supporting ISO MPEG 4. So they support ISO MPEG 4 compression, but not ISO MPEG 4 file format... Interesting...

Has anyone done any testing into what "ISO MPEG 4" CODECS truly are compatable? (If I understand correctly encoding in DivX 5 should allow you to play back with say Apple's QT MPEG-4 CODEC if they both adhere to standards, no?)

I've also been interested in the different forms of MPEG 4... MPEG-4 Simple Profile and MPEG-4 Advanced Simple Profile and whatever other profiles there are...

Also, (And maybe this is a question I ought to ask in the DivX forum, but I'll throw it out here first) the DivX 5.0 new features page says "DivX 5.0 can encode and decode the brand new DivX™ file format, based upon the MPEG-4 file format. DivX can now create fully MPEG-4 compatible video files including the file format. The new file format allows you to take advantage of all the new advanced video tools and algorithms (some of which aren't available in the AVI file format), improves audio/video synchronization, and breaks the old 2 GB file size barrier of AVI files." Does this mean that if I get my hands on a DivX 5.0 file I shouldn't have the same issues playing it on the Mac without doctoring since it isn't using Quicktime's .avi handler? I suppose if I really want to know I can find a DivX 5 file and try it out...

Finally, what is (are?) the officially supported MPEG 4 sound CODEC(s)? It being based on the QT file format, it ought be able to use a myriad of sound CODECs, but is there an actual MPEG 4 one, and if so, what is it based on? AAC?

-=(Lord Crosis)=-

Has anyone done any testing into what "ISO MPEG 4" CODECS truly are compatable? (If I understand correctly encoding in DivX 5 should allow you to play back with say Apple's QT MPEG-4 CODEC if they both adhere to standards, no?)

Yes, any ISO MPEG-4 decoder should be able to decode both the Apple (Sorenson) and Divx5 MP4 files. However, that does not mean that they both have to use the same method of encoding the file. The codec itself can use any number of different algorithms and methods to achieve the best quality per bitrate. It's the same situation with MP3 audio codecs, for example. There are a number of MP3 encoders (Xing, Fraunhofer, Lame, Blade, etc). They don't all sound the same, and today Lame probably has the best quality per bitrate overall, however, any ISO MP3 decoder will play MP3 files produced by any of these encoders.

Also, (And maybe this is a question I ought to ask in the DivX forum, but I'll throw it out here first) the DivX 5.0 new features page says "DivX 5.0 can encode and decode the brand new DivX™ file format, based upon the MPEG-4 file format. DivX can now create fully MPEG-4 compatible video files including the file format. The new file format allows you to take advantage of all the new advanced video tools and algorithms (some of which aren't available in the AVI file format), improves audio/video synchronization, and breaks the old 2 GB file size barrier of AVI files." Does this mean that if I get my hands on a DivX 5.0 file I shouldn't have the same issues playing it on the Mac without doctoring since it isn't using Quicktime's .avi handler? I suppose if I really want to know I can find a DivX 5 file and try it out...

Divx5 can use both the AVI and the new MP4 file formats. AVI has a number of limitations which MP4 doesn't have. The most important of MP4's capabilities is the ability to stream the file without the need to download the entire thing first. It also means broken downloads can still be played. But most importantly, any ISO MPEG-4 decoder will play the MP4 file, while the same is not true with AVI.

Finally, what is (are?) the officially supported MPEG 4 sound CODEC(s)? It being based on the QT file format, it ought be able to use a myriad of sound CODECs, but is there an actual MPEG 4 one, and if so, what is it based on? AAC?

AAC is the official MPEG-4 audio codec. At present, when trying to make a fully 'standard' MP4 file using Divx5, the video would need to be encoded, then the audio would need to be encoded with one of the ISO-compliant AAC codecs, and then a utility would need to be used to combine and video and audio. The final output would be playable on any ISO MPEG-4 decoder.

[T Allen]

&lt;bobbinson&gt;, if the following is true,

"It's the same situation with MP3 audio codecs, for example. There are a
number of MP3 encoders (Xing, Fraunhofer, Lame, Blade, etc). They don't all
sound the same, and today Lame probably has the best quality per bitrate
overall, however, any ISO MP3 decoder will play MP3 files produced by any of
these encoders."

then wouldn't the same apply to MPEG-4 encoders as well? How do you know that Sorenson's MPEG-4 codec won't do a better job than DivX? Have you made an assumption here?

"Hopefully there will soon be a Divx5 encoder for the Mac as well. In
that case, there would really be no need for the Sorenson MPEG-4 codec, since
the Divx5 MPEG-4 codec would produce ISO-compliant MP4 content as well."