Divx + AAC: mini-howto

[tanksimpson]

I came across a working solution for muxing Divx and AAC (in sync) at http://mpeg4ip.sourceforge.net but it requires that you have linux installed with the necessary developer tools to complile software. Prepare a video-only AVI encoded with Divx, I'll call it example.avi. Then convert the audio wav to AAC with Psytel's encoder (which can be found at http://www.inf.ufpr.br/~rja00 ), I call it example.aac. Now download the mpeg4ip package to your linux box, unzip and compile it according to the readme. Move the .avi and .aac files over to the linux machine (I used samba to access the shared folder on my Windows box). Mux the audio and video files into an .mp4 with the following commands:

mp4creator example.aac -p=2250 example.mp4

mp4creator example.avi -p=2250 example.mp4

Now you can play the .mp4 on linux with:

gmp4player example.mp4

The downside so far is that the two .mp4 players I have for Windows, Philips Webcine Player and Envivio plug-in for Quicktime can not read this file properly. Everybody and their mother claims to be "ISO compliant" with MPEG-4, but it does not seem to be true yet. I do not know yet whether the problem lies with mpeg4ip's implmentation or with Philips' and Envivio's. Also, I could have muffed it up myself :) But the fact remains that the .mp4 plays just fine on linux with gmp4player with AAC synced nicely. Advice from any .mp4 gurus out there would be appreciated!

[ProfDrMorph]

I read something about a bug concerning MPEG4 ISO compliancee that was fixed in XviD ( I read it on the forum of www.videocoding.de ). Since XviD is based on the OpenDivX4 encore2 ( DivX4 is also based on it ) I think that this bug may still be in DivX4 and the other implementations are correct. I also know that MPEG4IP uses OpenDivX code and maybe this is the reason why this file plays fine on your Linux.

[tanksimpson]

It seems to me that while gmp4player is able to use libdivxdecore on linux rather than the reference(?) iso mpeg-4 decoder, the Windows mp4 players like WebCine are not able to use the Windows equivalent divx 4 .dll or whatever. This could be by design and therefore divx-wrapped-in-mp4 playback on Windows could be hopeless for the time being. My understanding of these issues is hazy I'm afraid. I checked out the videocoding.de website and there is a lot of interesting stuff there.

[Nic]

With Avery Lee's excellent description of how Nandub mux's VBR MP3 on his news page, im going to retry modifying Nandub to Mux AAC correctly this weekend....

-Nic

[ChristianHJW]

... wow Nic, sounds great !! I could finally use my AAC sound streams i made from Gladiator these days ...

I read Avery's comments about what Nando did and what the potential problems are, but i was too stupid to understand this could help you for your own AAC muxing project ....

[BlackSun]

mp4 will be used very soon, expect some tools for the next month... :D

[Nic]

MP4 will be the future, (Christian did you ever read my final post in the --r3mix thread here? :)

Anywayz the way im going to try and get it to work, is to scan the AAC file first and find the biggest block (in AAC this varies a hell of a lot) & set the blockalign to that in a copy of the VBR Mux code in Nandub & start from there... :)

-Nic

[BlackSun]

Btw Does anyone sucessfully compiled the mp4creator under a Win32 system, mp4 player work fine, but not the mp4creator...

[ChristianHJW]

.. this is starting to be a very intersting thread !!

@BlackSun : why doesnt your very first PowerDivX 4 supporter have any idea about your plans to include mp4 support in your next player ;) ??

@Nic : Really looking forward to what you're trying to do. I will gladly start double blind listening tests between AAC and Ogg Vorbis once last is available in RC3 .... i hope i have my 2nd speaker fixed 'til then, Stereo would be helpful for listening tests i guess :D

[BlackSun]

I am waiting for someone who will release DirectShow Filter

[Nic]

What directshow filter do you mean BlackSun? My AAC one???

-Nic

[LigH]

@Nic: Oops - now you've promised! ;)

[Nic]

He can have my AAC DShow filter & source now if he wants....

...But perhaps his talking about a MP4 Splitter or DivX Decoder filter that connects to pure MP4 type stream (im just guessing of course)

-Nic

[BlackSun]

Originally posted by Nic
He can have my AAC DShow filter & source now if he wants....

...But perhaps his talking about a MP4 Splitter or DivX Decoder filter that connects to pure MP4 type stream (im just guessing of course)

-Nic

I am interested in both filter, your filter can have his place in PowerDivX 4 (see my new forum), but as I know, DivXNetworks is about to release a DirectShow filter for MP4, I dunno if they will need a splitter, I hope they will need one because MP4 should be able to handle MP3...