Talk:MPEG-4 Part 3

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What does "Bifrication" mean? It's in the heading "Bifrication in the AAC technical standard" Tompagenet 5 July 2005 12:17 (UTC)

Google returns only 111(!) results for "Bifrication". I guess 'Bifrication' is surely wrong to use here. --GrAndrew 15:01, 14 February 2006 (UTC)
It should perhaps be "bifurcation" instead?
Perhaps use "fork"? 00:02, 26 November 2006 (UTC)

CBR with AAC vs VBR AAC?[edit]

Also, can someone please explain the use of CBR with AAC vs VBR AAC and present what programs (Nero is the only one I think) do VBR?--Bennmann 20:41, 7 August 2005 (UTC)

Hard to understand[edit]

Article is very hard to understand. Eagle (talk) (desk) 16:58, 3 December 2005 (UTC)

Can you please point out exact paragraphs to work on? I find this article rather exhaustive. Except for 'Bifrication' clause. --GrAndrew 15:01, 14 February 2006 (UTC)

iTunes support for aacPlus[edit]

As far as I can tell, iTunes does support aacPlus, at least in the latest Mac OS X version. I downloaded the samples that made up the listening test at [[1]], and after muxing the raw .aac files (which were the aacPlus encodes, v1 and v2 I believe) into .mp4, iTunes played all the aacPlus samples fine. In fact, the only AAC samples from that test it couldn't play were the Nero HE-AAC v2 samples. Or does this section mean that iTunes doesn't actually do SBR, and decodes them as LC? That's something I have no idea about - the samples sound the same to me in VLC. Dicey 20:59 24 April 2006 (UTC)

You will only hear the LC-AAC part. HE-AAC and HE-AACv2 are backwards compatible. Seems iTunes is buggy if it fails to play the Nero files.

eAAC+ not mentioned[edit]

Enhaced AAC+ is not mentioned. At least in the GSM world the name eAAC+ is used often. It means AAC+ v2, that is AAC+SBR+PS (in contrast to AAC+ v1, which is only AAC+SBR). Also this looks like a useful link :


eAAC+ is becoming a popular choice for mobile music downloads. More and more devices are supporting it. Coding Technologies should also be mentioned as the inventors of SBR and PS. I would like to see more on this format too.


-- 08:01, 1 September 2006 (UTC)

3gpp and free software[edit]

The only restriction in 3gpp code is that your product should stay 3gpp compliant. That's not a huge restriction, in my opinion. So what do you really expect by "free software"? You know that "Free Software" is not fully possible regarding AAC, don't you? (same situation as mp3) --Gabriel Bouvigne 08:05, 27 September 2006 (UTC)

That's not the only restriction (even if it was that would be in conflict with the definition of free software per the FSF[2]). If you go to the 3GPP site to obtain the encoder source (, clicking the download link results in the following notice (emphasis mine):

This publication is copyright protected. ETSI continues to assert its rights on ETSI documents published in any form. For additional copyright information about this publication please refer to the copyright statement contained in the document. The document that you are downloading is provided to you on the condition that it may not be modified, redistributed, sold or repackaged in any form without the prior consent of ETSI and where appropriate other copyright holders. It is strictly for your private use. If you do not agree with these conditions please go back now, else if you agree with these conditions, you can start downloading the document.

This is not complaint with the free software definition or even the open source definition per the OSI. --Bk0 (Talk) 11:36, 27 September 2006 (UTC)

This text is only relevant to the ETSI version of the material. The 3gpp version is directly downloadable. As you can see, on the mentionned page there is a direct link to the zipped source code.
I am quite sure that the only restriction is that the derived product must still be 3gpp compliant. This condition is the same as the one that was related to the mpeg-1 dist10 audio source code, on which BladeEnc is heavily based.
To me, you will not have much better things regarding mpeg audio code.
Anyway, mpeg natural audio encoders can not fit into Free Software (with capitals) because of the patents covering them. Do you think that keeping 3gpp compatibility is a too strong restriction? I don't think so.--Gabriel Bouvigne 13:01, 27 September 2006 (UTC)
My opinion is irrelevant; the objective reality is that 3GPP licensing does not appear to be compatible with free software. Patents are also irrelevant as they do not involve copyright or licensing and are jurisdiction-dependent while the majority of the world does not live under governments that recognize software patents. The only point I'm making in the article is that no free software HE-AAC encoder yet exists, which as this discussion demonstrates is true. --Bk0 (Talk) 23:34, 27 September 2006 (UTC)
Patents are relevant are they are in direct contradiction with some GPL and LGPL clauses. What I am wondering is why pointing that there is no Free Software (I am assuming that you mean Free Software with capitals and not just free software) available, while not pointing the same for mp3. Either you think that the case is similar with mp3, and it should be mentionned on both articles or none, or you think that the situation is different from mp3, and then you probably need to explain it, as I don't get it.--Gabriel Bouvigne 10:40, 28 September 2006 (UTC)
It is a very concrete reality that users of free operating systems have no HE-AAC encoder available to them. I understand the various minutia of licensing and patent law can be debated yet I don't know why you object so much to mentioning this simple fact in the article. I will edit it in once more. --Bk0 (Talk) 22:45, 29 September 2006 (UTC)
Ok, I now understand what you mean. If you mean availability of encoder for *nixes, then the 3gpp code can be used. I thought that you meant an encoder with a Free Software compliant license, which is not possible until all relevant patents have expired (same situation as mp3). Btw, I agree with your new wording of things in the article. --Gabriel Bouvigne 08:31, 30 September 2006 (UTC)

Explain to me aacPlus[edit]

I know I'm being dumb here, but what is aacPlus? The article doesn't state it very well. -Daniel Blanchette 21:20, 8 November 2006 (UTC)

I agree; it redirects from "AAC+", but it doesn't actually appear anywhere but in the external links! Is it just another name for a documented AAC variation? In that case, it should probably be added as a small "also known as AAC+" part where appropriate. -- Northgrove 22:24, 8 December 2006 (UTC)
Ahh, sorry, missed the "aacPlus" part. Since it's often referenced as that, I think I'll add something for "AAC+" here too for ease of searching. -- Northgrove 22:27, 8 December 2006 (UTC)

VS Advanced Audio Coding[edit]

To me it seems like the AAC portions of this article should be merged with the Advanced Audio Coding article. As of now there is a lot of duplication with it. --XanderJ 03:02, 29 January 2007 (UTC)

Missing container formats (LATM/LOAS)[edit]

Advanced Audio Coding states (in 'Container formats') "Two more formats are defined in MPEG-4 part 3: Low-overhead MPEG-4 Audio Transport Multiplex (LATM), which provides a way to combine separate audio payloads, and Low Overhead Audio Stream (LOAS), a self-synchronizing streaming format."

Neither LATM nor LOAS is mentioned here. (And these only now exist as redirects because I've just created them!)

Someone to add these here, please?

Hymek (talk) 10:38, 19 August 2009 (UTC)