[M4IF Technotes] About DivX ( Was Re: reference code advise)
Darrius "Junto" Thompson
dnthompson divxnetworks.com
Fri Dec 6 10:24:37 EST 2002
Ben,
> > Specifically, most DivX files use MPEG-4 (simple or
> > advanced simple) video and MP3 audio in the AVI file format.
> > These are obviously not MPEG-4 compliant.
The DivX Codec is just that, a video codec that compresses the video
bitstream and uses a standard interface to interact with just about
any PC video editing or encoding application using the Video for Windows
or DirectShow interface. This means it is a plugin for compression of
the video stream and in itself is not a tool for muxing the audio and video.
The actual file wrapper is generally implemented as part of an editing or
encoding application. Look at Quicktime Pro, Adobe Premiere, etc.. and you'll
see that you can pick any video codec that you have available and pick a different
file format to encapsulate the actual audio, video, or other multimedia components
within the stream. The codec is the video compression plugin for
applications and the application usually includes several choices for file
wrapping or muxing. This also allows anyone video professional to use
their file format of choice. The file wrapper is a seperate component from the
video codec.
If we forced everyone to use a different file format which is then not supported
in their application of choice the video codec would not be able to be used or
supported within their application. Even within the technote threads everyone
keeps asking for tools that can support the MP4 file format so there is an obvious
lack of tools available not only to general consumers but to the video market as a whole.
However, they will exist and we (DivX) will be pushing foward in creating these tools.
We provide the codec in a way that can be used today while we're also very rapidly
building MP4 tools such as MP4 Interoperable file wrapper plugins with some interesting
features that can be used within atoms. (coming soon) These will be available off of
our site in the coming weeks and months. While we'll also be pushing the plugins into
many partner consumer products.
> > Specifically, most DivX files use MPEG-4 (simple or
> > advanced simple) video and MP3 audio
In regards to MP3 audio. We have the same approach here, and isn't MP3 audio compliant within
MP4? We provide a video codec plugin and we allow the end user to pick their audio format of choice. The consumer
should be given the choice. The other piece that must be taken into consideration
is consumer electronics. With DivX Certified devices are already hitting the market this year and many
more next year, these devices and hardware generally all support MP3 audio today and to support
other audio format obviously adds to the cost of materials in building these devices.
The choice of audio formats for support in these devices is also the Consumer Electronic
manufacturers choice for what they will provide their customers. MP4 AAC will gain adoption and
users, as they do today, will have the choice of using any audio format within their applications along
with DivX video :)
> > .AVI doesn't have any technical advantages over MPEG-4,
> > and many many disadvantages
Yes that's somewhat true. And again, the choice of file wrapper is provided by the end users application. As mentioned
an MP4 Interoperable file format plugin and application is in the works. And remember AVI has one
advantage: It is supported in consumer level and professional video applications. The MP4 file format
is not yet supported, but as mentioned, we will work with partners to provide the support. For simple
video editing where there is only a concern video and audio, AVI works fine, but when you want to have more
"interesting" features the MP4 file format is the way to go. It is these interesting features that we
provide consumers within the MP4 file format. If a consumer wants to encode and edit video with just
audio and video and are not concerned with anything else there needs to be a more compelling reason to use
the MP4 file format. We will provide features that add value to consumers but still gives our users
the choice of tools and technology. Whatever tools are best (easy to use, feature rich) within their
category will win for end consumers. So the full system of MP4 must be compelling before all the pieces (file format,
audio, etc..) are used by general consumers creating and editing content. As a whole we can all create
the tools necessary that will give consumers a reason for using the full suite of MP4 tools since they
will make the choice of tools.
Darrius Thompson
Director DivX
858-909-5307
http://www.divx.com
> I'm sure someone is listening :-)
P.S. Thanks Rob :)
> -----Original Message-----
> From: Rob Koenen [mailto:rob.koenen m4if.org]
> Sent: Thursday, December 05, 2023 9:39 PM
> To: 'Ben Waggoner'; technotes lists.m4if.org
> Subject: RE: [M4IF Technotes] About DivX ( Was Re: reference code
> advise)
>
>
> I'm sure someone is listening :-)
>
> Rob
>
> > -----Original Message-----
> > From: Ben Waggoner [mailto:ben interframemedia.com]
> > Sent: Thursday, December 05, 2023 9:00 PM
> > To: technotes lists.m4if.org
> > Subject: [M4IF Technotes] About DivX ( Was Re: reference
> code advise)
> >
> >
> > Rob,
> >
> > Specifically, most DivX files use MPEG-4 (simple or
> > advanced simple) video and MP3 audio in the AVI file format.
> > These are obviously not MPEG-4 compliant. They sometimes use
> > VBR MP3 audio, which isn't really AVI compliant either, which
> > is why tools like QuickTime often have sync issues playing
> > back .divx files.
> >
> > DivX 4 was Simple only, and DivX 5 is Simple or Advanced
> > Simple. DivX 3 was a hacked version of the early MS MPEG-4
> > codecs that weren't compliant with the final MPEG-4 spec.
> > Lots of these are still around, alas.
> >
> > .AVI doesn't have any technical advantages over MPEG-4,
> > and many many disadvantages, so it'd be great if DivXNetworks
> > would adopt .mp4 with AAC audio as their standard file
> > format. Their tools can do .mp4 export right now, but
> > without audio. They weren't included in the NerdTV shootout
> > for that reason. Their video codec is quite good, though.
> > 2-pass support and some novel quality optimization techniques.
> >
> > Ben Waggoner <http://www.benwaggoner.com>
> > Compressed Video Consulting, Training, and Encoding
> >
> > My Book: http://www.benwaggoner.com/books.htm
> > Compression Books: http://www.benwaggoner.com/bookshelf.htm
> >
> >
> >
> > on 12/5/02 19:57, Rob Koenen at rob.koenen m4if.org wrote:
> >
> > > DivX video coding is supposed to be compliant, the file format is
> > > different as I understand it. As you can see from the M4IF
> > home page,
> > > DivXNetworks recently joined the M4IF interop program.
> >
> >
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> >
>
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