AC3 in MP4! [Archive] - Doom9's Forum

Doom9

14th April 2002, 01:34

the mp4 muxer on my site supports mp3, aac and ac3 input.. I cannot guarantee that standalones will eventually support that.. very much is still in the designing phase.. if I remember correctly the specs only contain aac.. but maybe due to the fact that there will be devices also capable of playing AC3 it may be possible to use that audio format. But at this point.. nobody really knows.. and those who are working on creating devices usually cannot share what they know until there's an official press release

DeXT

15th April 2002, 00:14

This thread contains useful info about this topic. Basically AC3 can be muxed, but not supported by the ISO spec. Anyways, AAC is far superior to AC3, and at lower bitrates, so there should be no good reason to do that.

http://forum.doom9.org/showthread.php?s=&threadid=19497

Deptmaster

18th April 2002, 07:58

In some cases its not really worth it to me to re-compress the AC3 which is already fairly compressed in some cases (2channel@192kB/s) to save a little space and loose alot of quality. This is usually on the case with anime series and movies i cherish. But i do agree that 5channel AC3 on most filmed movies is necessary to downmix and re-compress so AAC is ideal in those cases.

Gawen

18th April 2002, 09:47

For my best knowledge the ISO supported Codecs for MP4 are: AAC LC, AAC Main, AAC LTP, AAC SSR, AAC LD, ER AAC (LD), CELP, TwinVQ and PCM raw.

Nobody knows yet what future hardware players will support. The only leads i found were from Ivan Dimkovic (Psytel):

Originally posted by Ivan Dimkovic

Audio object types supported are MPEG-4 audio object types:

AAC (Main, LC, SSR, Error Resilient, Low Delay, Scalable...), TwinVQ (VQF), CELP (Speech Codec), Synthetic Audio (similar to midi/wavetable) and even PCM data - you can put as many audio objet tracks as you want...
Ivan Dimkovic seems to recommend AAC-LC for now:

Originally posted by JohnV
Yes, Ivan also said to me that he recommends the use of LC-profile with MP4 streams, because it's the only profile supported by hardware devices (at least at the moment).

Of course multi-channel audio is also possible.

(Quotes from the developer forum on hydrogenaudio.org)

ChristianHJW

19th April 2002, 22:23

Thanks guys, very useful information ... reminds me i wnated to invite ivan to come here by time ...

Neo Neko

21st April 2002, 00:24

Originally posted by Deptmaster
In some cases its not really worth it to me to re-compress the AC3 which is already fairly compressed in some cases (2channel@192kB/s) to save a little space and loose alot of quality. This is usually on the case with anime series and movies i cherish. But i do agree that 5channel AC3 on most filmed movies is necessary to downmix and re-compress so AAC is ideal in those cases.

I understand that AC3 whether it is 2 channel 5.1 or 7 it a 5:1 compression ratio. MP3 at average bit rates is usually about 10:1. And AAC can beat MP3 at lower bitrates than MP3. So by keeping the AC3 yes you would save time. But AC3 at 5:1 has relatively few errors or loss. And recompressing at a propper bit rate should incur very little loss. So recompressing to somethin like AAC would take a bit more time, but would leave me a ton more room to max out the bitrate on the video(Anime needs all the video bit reate it can get!). That way I could have the best visual quality as well as audio quality for my cherrished anime. A little extra time means nothing to me to get something done right. Did I get anything wrong?

canadian_fbi

21st April 2002, 04:23

if you kept the original ac3 along with a video stream like xvid, all you would have to do to get an mpeg-4 compliant file in the future when standalone players are available and such files become needed would simply be to transcode the audio to aac or something and then mux the new audio and old video streams together, right? and then you get to take advantage of the latest in aac encoding technology and whatnot, while not losing any of the original ac3 quality. so from this standpoint, regardless of whether or not mp4 supports ac3, it's the most flexible solution for the future.

LiFe

30th September 2006, 06:54

Is there now any official way of muxing AC3 into MP4?

I'm encoding my library with x264 @ Q24, which looks fantastic, but when I encode my 5.1 AC3 with nero cmd encoder at @0.30, which appears to be a good balance between size and quality, I end up with a 5.1 audio file within 100MBs of the AC3, so I may as well keep the origional.

Turns out AC3 seems to use about 64kb/s per channel? Which appears to be reasonably efficient?

TIA

bond

30th September 2006, 09:51

JohnV

25th January 2007, 08:15

Added a "Coming updates" -section for some hints what can be expected in the near future.

sjchmura

1st February 2007, 17:45

JohnV...

Anything more you can "share" or hint?

JohnV

5th February 2007, 17:31

NeroDigital Cinema-AVC and HDTV-AVC -profiles will have multichannel AC3 support, so Nero Digital will support AC3 in MP4.
It's gonna take some months, but should be here before the summer 2007.

JohnV

5th February 2007, 17:44

JohnV...

Anything more you can "share" or hint?
I'll do regular updates to the new section.
One remarkable thing is that Cinema-AVC and HDTV-AVC NeroDigital profiles will be officially supporting multichannel AC3 audio. I think this will be a special interest for many who want to archive HDTV tv-streams, or re-encode (unencrypted) blu-ray/hd-dvd into smaller size stream. Skipping the re-encoding of the audio to AAC will also speed up the overall encoding process.
The AC3 support for NeroDigital MP4 will come before the summer.

JarrettH

5th February 2007, 17:51

Those changes we all forgot about last month...

Version number 2.4.5.0

Release Date: 01-18-2007
Changes/Bugfixes

* Under Windows, the Data Files tab was not correctly drawn in Aero mode

Version number 7.7.5.1

Release Date: 01-18-2007
Changes/Bugfixes

* Under Windows Vista, Windows Movie Maker crashed if Nero was running in a few cases
* Burning a compilation to the image recorder was not possible in some cases
* Improved AC3 encoding
* Preview of AC3 files was not possible in some cases
* Nero Burning ROM could not always read the previous session of a multisession disc
* The size bar was not updated when using "continue multisession disc" feature
* Audio books could not be burned on CDs in some cases
* A misleading error message was displayed when trying to use a folder that did not exist

Is Nero embarrassed about these updates? Why are changes posted 3 weeks later? :devil:

Drachir

5th February 2007, 18:30

NeroDigital Cinema-AVC and HDTV-AVC -profiles will have multichannel AC3 support, so Nero Digital will support AC3 in MP4.
It's gonna take some months, but should be here before the summer 2007.

Just of interest, are there any plans by Nero to register this at http://www.mp4ra.org/ or to bring this up at a MPEG meeting?
This might be not an bad idea for Vobsub too.

SeeMoreDigital

5th February 2007, 19:06

NeroDigital Cinema-AVC and HDTV-AVC -profiles will have multichannel AC3 support, so Nero Digital will support AC3 in MP4.
It's gonna take some months, but should be here before the summer 2007.That sounds promising...

Shame the implementation wont be extended to some of the MPEG-4 Part-2 profiles as well. Or can they?

the mp4 muxer on my site supports mp3, aac and ac3 input.. I cannot guarantee that standalones will eventually support that.. very much is still in the designing phase.. Are you no longer intending to carry on using MP4Box for muxing Doom9?

SeeMoreDigital

5th February 2007, 19:08

Just of interest, are there any plans by Nero to register this at http://www.mp4ra.org/ or to bring this up at a MPEG meeting?
This might be not an bad idea for Vobsub too.How about their chapter implementation?

Cheers

mediator

5th February 2007, 20:07

Shame the implementation wont be extended to some of the MPEG-4 Part-2 profiles as well. Or can they?

ASP is covered already. So what do you mean exactly?

SeeMoreDigital

5th February 2007, 20:21

ASP is covered already. So what do you mean exactly?JohnV was referring to providing multichannel AC3 support within .MP4 for use with their CinemaAVC and HDTVAVC profiles. And sadly not for use with their CinemaASP, or "Main Profiles" as they like to call them.

Cheers

bond

6th February 2007, 00:04

will nerodigital devices now not need to support aac anymore? what about multichannel aac?

why does nero not simply use .mov? because the extension .mp4 is more funkier? and why dont you use .mpg with avc and ac3 like hddvd does?

bond

6th February 2007, 00:06

Skipping the re-encoding of the audio to AAC will also speed up the overall encoding process.
The AC3 support for NeroDigital MP4 will come before the summer.yeah, saving 7 minutes is a good thing for skipping interoperability :p

edit: JohnV, you shouldnt forward every nonsense request you hear on boards to your developers and bosses

JohnV

6th February 2007, 09:09

will nerodigital devices now not need to support aac anymore? what about multichannel aac?Sure they need. Multichannel AC3 is just added for flexibility for the 2 highest AVC profiles.
why does nero not simply use .mov? because the extension .mp4 is more funkier? and why dont you use .mpg with avc and ac3 like hddvd does.Nero Digital uses .mp4, it has been set long ago. But it's possible that our encoding software will include larger scale encoding support for different purposes in the future.. ;)

JohnV

6th February 2007, 09:13

yeah, saving 7 minutes is a good thing for skipping interoperability :p

edit: JohnV, you shouldnt forward every nonsense request you hear on boards to your developers and bosses Any speed up is a good thing, especially if you want to include multiple audio streams, though our next AAC encoder version should be 20-25% faster. :)

Sorry bond but you are wrong, this was not my idea nor my forwarding, but it is a very good idea, since many people want to preserve the original AC3 track of HDTV tv-streams and use AVC (very clear trend out there), don't have to use mkv, and future hardware supporting these specific 2 high profile ND-AVC profiles will play it.. ;) You can always keep interoperability by using AAC if you want, this is just added flexibility and choise for users. And notice that this AC3 option will be available only for the 2 highest Nero Digital AVC-profiles, not for Nero Digital ASP or "lower" AVC-profiles.

Hopefully also Haali, MPC's and VLC's etc. splitters will add support for this new addition when it comes out. :)

sillKotscha

6th February 2007, 11:47

[...] it is a very good idea, since many people want to preserve the original AC3 track of HDTV tv-streams and use AVC (very clear trend out there) [...] You can always keep interoperability by using AAC if you want, this is just added flexibility and choise for users. [...]

and this is why I always wondered about the whole discussion why AC3 shouldn't be added to mp4... it is a question of private choice - from a technical point of view this might_be nonsense... but it seems to be a way to go for a huge company like Ahead... if SAP's will support it and (future) sales figures entitle to do so... hm, why not :)

SeeMoreDigital

6th February 2007, 13:16

Like Bond, I was not keen about the idea of incorporationd AC3 into MP4.

However, since owning a few MP4 capable hardware devices (two with NeroDigital support), it's become clear to me that the majority of end-users are totally baffeled as to why their surround sound amplifiers can't accuratlely decode the (6Ch AAC) audio element of Recode2 generated streams.

When you try to explain to them that surround sound amplifiers don't actually include AAC decoder chip-sets, only DolbyDigital/AC3 and DTS decoder chip-sets. And that in order to hear 6Ch AAC audio streams correctly, they'll have to use their players/amplifiers 6Ch analouge connections instead (if indeed they have them, most devices don't), most end-users response is: "no thanks, I'll stick with using .AVI" or "I think I'll wait for MKV to be supported in stand-alones".... Which is not good :(

More-over, now neither of the new high-def disc formats include AAC audio within their specifications, there's no urgency for surround sound amplifier manufacturers to include support for AAC decoding in their chip-sets.... Which is a great shame!

Personally I love using AAC audio. All my audio CD's are backed up to this format.... But amplifier manufacturers don't seem very enthusiastic about it. Hopefully their minds will be changed as and when the specifications for DAB 2 (radio) (http://en.wikipedia.org/wiki/Digital_radio#DAB_version_2) are sorted.

Cheers

Sharktooth

6th February 2007, 19:38

ah... i smell EVOs...

bond

6th February 2007, 19:41

if i would have an avc and ac3 stream i would place them in .mpg/.evo, cause it will have a bigger change to be handled on hardware players than a strange .mp4 with ac3 audio...

JohnV

7th February 2007, 01:35

if i would have an avc and ac3 stream i would place them in .mpg/.evo, cause it will have a bigger change to be handled on hardware players than a strange .mp4 with ac3 audio...The point here is Nero Digital uses .mp4 and was set long ago, not what you would do. But if you need something else, I think remuxing shouldn't be impossible..

ChronoCross

7th February 2007, 02:00

I think the problem is AC3 in mp4 is not part of the spec for mp4. So now special workarounds in every demuxer has to be made.

sillKotscha

7th February 2007, 03:16

specs are nice for the vast majority of hardware producers ... but ahead/ nero build their own units thus are able to play their own content... if the user/ buyer is satisfied with the result - TRUE 5.1 digital sound without analogue loop ways - the user is the last one who cares about specs ;)

Sharktooth

7th February 2007, 03:18

well, i wouldnt call them "workarounds" but support for AC3 private streams.
Private streams are also in the specs, so it's not completely out of specs...
It's just a "private" solution but since there are tons of ac3 decoders it would suffice to implement private streams parsing in the splitter and "connect" the ac3 decoder when necessary.

SeeMoreDigital

7th February 2007, 11:41

Yep... that's right..

Unlike with situation with the .AVI container, it's not like "private streams" in .MP4 are an out-and-out hack ;)

The placing of VOBsubs subtitles within MP4 as a "private stream" has, by all accounts, proved to be a very useful implementation. As it makes use of the original subtitle decoder engine, installed within all MPEG-4/DVD players.

Placing AC3 within MP4 as a private stream and have it use the original AC3 (or even DTS) decoder engine, installed within all MPEG-4/DVD players seems a very logical step forward.... And far more understandable for end-users.

SeeMoreDigital

7th February 2007, 11:44

I guess these last few posts would be better placed in this thread: -

http://forum.doom9.org/showthread.php?t=23084

Mtz

7th February 2007, 11:53

Ok, if this posts will be moved I'll post also my opinion: Nero was "forced" by some manufacturers of standalone player chipsets to support AC3 in their MP4. I think they made a good decision.

enjoy,
Mtz

foxyshadis

7th February 2007, 13:31

Perhaps, instead of flouting the standards, what's really happening is a forced evolution of the format, hopefully on a sponsored standards track. Although my first instinct is to agree with bond, it almost seems that AC3, Vobsub, and MPEG-2 were deliberately kept out of the mp4 format to keep it from competing with DVD/HD. If others follow nero's private standards, it isn't so bad, provided they tell us how to mux compliantly.

SeeMoreDigital

7th February 2007, 14:28

... it almost seems that AC3, Vobsub, and MPEG-2 were deliberately kept out of the mp4 format to keep it from competing with DVD/HD. As far as I know, MPEG-2 and MPEG-1 video along with MP2 and MP3 audio is in the ISO 14496 specification.

easy2Bcheesy

7th February 2007, 21:46

Nero Digital Information Thread
updated 5th February 2007

Coming updates from Nero:
-HD-DVD, Blu Ray BDMV and AVCHD authoring support in NeroVision

This is pretty earth-shattering stuff. Any idea of any kind of timescale on this? Will we be able to encode our own content into AVC for these formats?

bond

7th February 2007, 23:37

what we need are official specs for placing ac3 in mp4, everything else is just private stuff having no chance to get "big" somewhen

JohnV

8th February 2007, 05:54

what we need are official specs for placing ac3 in mp4, everything else is just private stuff having no chance to get "big" somewhenSure it would be nice if it became official in MPEG4. But if that won't happen, this is better than no support. At least we'll now see support in both hardware and software for AC3 in MP4.

foxyshadis

8th February 2007, 06:48

Sure it would be nice if it became official in MPEG4. But if that won't happen, this is better than no support. At least we'll now see support in both hardware and software for AC3 in MP4.

He may have meant, from you. :p Private stream identification, indexing, interleaving, header storage method, frame header stripping if any, per-frame structure if necessary, any potential gotchas. With that, anyone can support your format.

Hyper Shinchan

9th February 2007, 17:18

Just of interest, are there any plans by Nero to register this at http://www.mp4ra.org/ or to bring this up at a MPEG meeting?
This might be not an bad idea for Vobsub too.

Yep, it will be really great. But I think that Nero isn't interested in mp4ra registration.... their profiles aren't registered (I mean the brand aren't registred, otherwise they aren't really the brand of a new specification) and the Vobsubs sample entry that they use for the subtitles isn't registered either. To don't mention the chapters stored in the udta box, of course XD
the mp4 muxer on my site supports mp3, aac and ac3 input..
Where can I find it? I've searched in the download page, but I haven't find it. Anyway at the moment Haali media splitter offers a directshow filter able to mux ac3 in mp4.

why does nero not simply use .mov? because the extension .mp4 is more funkier? and why dont you use .mpg with avc and ac3 like hddvd does?
Maybe coz Apple owns MOV and they can't change it as they like without occuring in "Steve's Wrath"? MP4 is based on MOV and Apple own the licenses but for example asking registration for an ISO media code or a QT code is different, the mp4ra says:
"Please note that Apple Computer owns and defines the QuickTime file format, and Apple Computer makes no promise or undertaking to accept applications, and the definition and use of codes in the QuickTime file format are at Apple's sole discretion. If your suggested code-point is already in use, or Apple considers that the suggested value is unsuitable, may be misleading, or is otherwise inappropriate, the authority may suggest an alternative value or refuse the registration, at its sole discretion.".

bond

9th February 2007, 19:27

placing ac3 in mov is nothing apple would want or could prevent and i assume ac3 streams in mov can already be created. actually placing ac3 in mov wouldnt also harm as mov is meant as a general purpose container and therefore a mess already. mp4 is (till now) not a mess

about the registration on mp4ra. nero is not interested to make their private stuff public. they want to create a (semi-)private format out of an open format. they did it with the chapters and vobsubs, they did it with the nero video profiles and they will do it with ac3 too. in the end they want to earn from selling "nero-format" devices. they dont earn anything by spreading 100% spec compliant files playable on the ipod or psp or other non-nero but mpeg-4 devices

in the end mp4 was designed to be an open standard, being playable on every mp4 player...

Hyper Shinchan

13th February 2007, 16:50

placing ac3 in mov is nothing apple would want or could prevent and i assume ac3 streams in mov can already be created. actually placing ac3 in mov wouldnt also harm as mov is meant as a general purpose container and therefore a mess already. mp4 is (till now) not a mess

I don't agree. Apple own the licenses of the MOV file format, and then if you want to use it (and adding a new codec) you've to ask permission (and pay licenses probably) to Apple. For example VirtualDub doesn't support any longer ASF because M$ owns the licenses and prevents them from "infringe" their licenses. But maybe I'm wrong, i'm not expert of these problems
Otherwise Nero is interested in promoving their software player (Nero Showtime) but for the large public MOV=QuickTime player.

About the mp4ra registration, well, you're probably right, they don't want to create true standards (well, Apple's shits too aren't really standard though they're registered at the authority that they run XD. For example ITunes metadata isn't specified anywhere).

in the end mp4 was designed to be an open standard, being playable on every mp4 player...
For this reason I was hoping in a MP4RA registration....

SeeMoreDigital

13th February 2007, 17:21

It it not a requirement of the MPEG-4 ISO specification, for any "private stream" implementation to be registered with the ISO/IEC.... Or are "private streams" by definition, totally "private"?

Cheers

JohnV

13th February 2007, 18:05

nero is not interested to make their private stuff public. they want to create a (semi-)private format out of an open format. they did it with the chapters and vobsubs, they did it with the nero video profiles and they will do it with ac3 too. in the end they want to earn from selling "nero-format" devices. they dont earn anything by spreading 100% spec compliant files playable on the ipod or psp or other non-nero but mpeg-4 devices.
Maybe you are right (though I can't say for sure). But even if you are right, why you always blame Nero? I mean it's a commercial company and the purpose is to make money for the owners and employees, and provide commercial as well as free solutions to people. You say yourself that Nero wouldn't make money otherwise, so what is so hard to understand?

Although I don't agree with you completely. You can make 100% spec compliant MP4 files with Nero Digital playable with iPod and others. Maybe not with the extra features, but still. If this wasn't possible, I think Nero Digital value would be considerably less..

Drachir

13th February 2007, 19:04

...You can make 100% spec compliant MP4 files with Nero Digital playable with iPod and others. ...
Well, I would say only 95% spec compliant.

There are some problems with the scene width and height inside the IOD with anamorphic streams. For more info look here: http://sourceforge.net/tracker/index.php?func=detail&aid=1585831&group_id=84101&atid=571741

Also the width and height inside the TrackHeaderBox[tkhd] get set wrong with anamorphic video streams . For more info look here:
http://sourceforge.net/forum/forum.php?thread_id=1597636&forum_id=327349

In files with 2 audio tracks you can't change to second track with an MPEG 4 Systems Player( with a real MP4 Player ;) ).

Subtittle don't get mentioned at all inside the Scene and OD track.

I am not sure if it is right to set the Main File Brand to avc1, and still to use the the .mp4 extension. Maybe some one should investigate that.

All I want to say is that it may help Nero if some of there engineer would go from time to time to a MPEG Meeting and talk with the people who write the pecs. It is one thing to read the spec and an other to talk to some one who knows what it should mean.

If Nero want to use only something based of the ISO based media format, it should write a Nero Brand into the Main File Brand and use a different extension.

This is just my opinion.