AC3 in MP4! [Archive] - Page 2

Kurtnoise

20th February 2007, 21:06

I'd like remember that Nero uses that stupid metadata format used by Foobar that it's 100% out of standard.
So what ?

imo this is the *right* place to store these kind of things (by storing, I mean easier to read/write such datas) and this is entirely defined in the specs...

Well, I'm not a lawyer, but I think that it's strange if you can use a file format (not regulated by ISO or open source licenses) without asking permission to the developpers....
why having permission ? reverse-engineering is more interesting in this case. Regarding Apple : the firm supply a lot of things for developpers. Much more for Mac OS users for sure but huh this is more than nothing after all. Unfortunately, note also that Windows users don't have the same rights as Mac users (just one example : Qt aac encoder can be used w/o restrictions for them but for win users paying fees & royalties is *of course* mandarory...)

SeeMoreDigital

20th February 2007, 21:14

While we are talking about the .MOV container.....

Out of interest, has anybody seen examples of .AC3 audio within the .MOV container? I know I have not!

Cheers

sjchmura

1st March 2007, 21:26

Any ETA ..... I would love ot test the splitter for MP4 (AC3/aac).

mediator

2nd March 2007, 08:20

The MP4-splitter with AC3 support will come with this months (march) Nero 7 web-update. But there is not much to test since AC3-direct-stream-copy-support will come with Nero 8, so probably not much material to test with.

sjchmura

2nd March 2007, 16:25

So you are saying that Recode (march) will not "create" a MP4 with intact ac3? For example

ATSC TS -> AVC 720p profile+Direct Stream copy Ac3?

Ronin-7

4th March 2007, 12:28

The Nero MP4 Splitter works with any DirectShow application that uses automatic graphbuilding. Hence, there should also be no problem in WMP11 or MCE2005/Vista.

Actually got the opportunity to test this out on a notebook with Vista Home Premium and Nero 7.7.5.1, it works as the MP4 decoder in WMP11 just fine but in media centre things don't work so well. Thumbnails don't work properly though you can play the video it takes a little while for it to start (20-30 seconds) & after you stop the video you can actually see what would be the thumbnail in the just played section in the bottom left hand corner (weird).

Also for whatever reason some of the files I've done in AutoMKV with MP4 containers wont generate a thumbnail in explorer which does seem to work for some MP4 files but not for others.

Not too bothered about thumbnails in explorer but hopefully Nero can sort out the kinks in media centre which would be nice.

mediator

6th March 2007, 09:35

So you are saying that Recode (march) will not "create" a MP4 with intact ac3?

creation of AC-3 Nero Digital files (using Direct Stream Copy) is scheduled to be introduced with Nero 8.

Hyper Shinchan

6th March 2007, 16:35

So what ?

imo this is the *right* place to store these kind of things (by storing, I mean easier to read/write such datas) and this is entirely defined in the specs...

Yes, but you must create something that fit to the Atom/Box World. Foobar/Nero creates simply crap; please read this thread:
https://sourceforge.net/forum/forum.php?thread_id=1465020&forum_id=514419

why having permission ? reverse-engineering is more interesting in this case. Regarding Apple : the firm supply a lot of things for developpers. Much more for Mac OS users for sure but huh this is more than nothing after all. Unfortunately, note also that Windows users don't have the same rights as Mac users (just one example : Qt aac encoder can be used w/o restrictions for them but for win users paying fees & royalties is *of course* mandarory...)

I don't think that it's a problem of reverse-engineering, Apple offers the specs of its file format but I'm not sure that they'll allow to an external company to use it without permissions.

While we are talking about the .MOV container.....

Out of interest, has anybody seen examples of .AC3 audio within the .MOV container? I know I have not!

But why in MOV? We could use MP4 considering it as the ISO Media Base file format, and thus use it as base for another file format compatible with the ISO specs.
MPEG-4 Part 12 can also be used to store not MPEG-4 contents (3GPP and Apple docet). Of course this could be a little confusing for some people, but I think that placing AC-3 in MOV is confusing too (Apple doesn't provide a standardized way to place AC-3 in their file format).

Kurtnoise

6th March 2007, 20:37

Yes, but you must create something that fit to the Atom/Box World. Foobar/Nero creates simply crap; please read this thread:
https://sourceforge.net/forum/forum.php?thread_id=1465020&forum_id=514419

First, don't mix up fb2k and Nero stuff please. Second, believe me or not, using this atom is probably the most easiest way to store these infos.

I don't think that it's a problem of reverse-engineering, Apple offers the specs of its file format but I'm not sure that they'll allow to an external company to use it without permissions.
Ask to FFmpeg crew whether or not they have recieved a permission from Apple to implement the mov muxer/demuxer...:rolleyes:

acidsex

6th March 2007, 21:57

when can we expect this nero 8?

mediator

7th March 2007, 15:54

Foobar/Nero creates simply crap

please read http://www.hydrogenaudio.org/forums/index.php?showtopic=44283&st=25

thanks!

Hyper Shinchan

10th March 2007, 10:13

First, don't mix up fb2k and Nero stuff please. Second, believe me or not, using this atom is probably the most easiest way to store these infos.

Ask to FFmpeg crew whether or not they have recieved a permission from Apple to implement the mov muxer/demuxer...:rolleyes:
1. Foobar 2000 and Nero tags looks to me identical.... though I think that Foobar stopped to use that format (not sure, anyway in newer version there was an option to re-write the metadata on m4a files that removed the old Foobar 0.9 metadata and rewrite just the ITunes metadata).
2. FFmpeg implements asf and some windows crappy codec too, but I don't think that it's very "legal" (from a M$ viewopoint).

please read http://www.hydrogenaudio.org/forums/...ic=44283&st=25

thanks!
And so what? For Nero guys is okay to write 'meta' boxes in a place that isn't allowed just because it's under a 'tags' box that they have "created"? And I still doesn't understand how they explain the hell that it's placed in this 'meta' box.
They also know that exists UUID boxes to place everything you want in a ISO Media File but they prefer to create their own crap.
Don't mention that if you want to embed pictures they'll be embede twice, in the standard ITunes metadata and in the moov.udta.tags.meta box (just like everthing else, of course). So the overhead will increase twice.
If they want to have a more flexible metadata than ITunes' one the mp4ra website created a standardized way to store ID3 2.x in 'meta' boxes. AtomicParsley partially support this metadata (at the moment, and probably for a long time in future, it doesn't support external referenced frames).
http://www.mp4ra.org/specs.html#id3v2

mediator

10th March 2007, 13:04

And so what? For Nero guys is okay to write 'meta' boxes in a place that isn't allowed just because it's under a 'tags' box that they have "created"? And I still doesn't understand how they explain the hell that it's placed in this 'meta' box.
They also know that exists UUID boxes to place everything you want in a ISO Media File but they prefer to create their own crap.

MP4-Parsers are required to skip any unknown atom. So if they cannot handle 'tags' then they should completely ignore it (and everything what is inside). And so there is / will be no problem...

jagaskywalker

20th November 2007, 17:26

SeeMoreDigital

20th November 2007, 18:20

What is currently the best way of muxing ac3 within mp4 ? (7 months after the last post in this thread)Hmmm... Asking "what's best" is a violation of rule 12.

You might find the easiest tool to use is Haali's "gdsmux.exe" which comes as part of his "Matroska Splitter".

Cheers

bond

20th November 2007, 21:04

Hmmm... Asking "what's best" is a violation of rule 12.

You might find the easiest tool to use is Haali's "gdsmux.exe" which comes as part of his "Matroska Splitter".

Cheersthe ps3 will not support this non standard stuff

B4tm4n

20th November 2007, 22:59

has anybody tried mp4 with ac3 in the PS3 ? Now with multi-channel support since fw 2.0 it might be an option..

What is currently the best way of muxing ac3 within mp4 ? (7 months after the last post in this thread)

THX

I tried it muxing using mp4box. It muxed OK but the PS3 just played the video without audio.

SeeMoreDigital

20th November 2007, 23:37

I tried it muxing using mp4box. It muxed OK but the PS3 just played the video without audio.As far as I'm aware, MP4box is not able to mux .AC3 elementary streams.

B4tm4n

21st November 2007, 00:48

As far as I'm aware, MP4box is not able to mux .AC3 elementary streams.
I used imkvextract to get .h264 .ac3 files.
Then used mp4box and it worked. But as I say it only plays the video.

MacBook:~ B4tm4n$ mp4box -fps 23.976 -add /Users/B4tm4n/Desktop/\[mkvextract\]csi.miami.s06e09.720p.hdtv.x264-ctu/video2.h264 -add /Users/B4tm4n/Desktop/\[mkvextract\]csi.miami.s06e09.720p.hdtv.x264-ctu/audio1.ac3 test.mp4
AVC-H264 import - frame size 1280 x 720 at 23.976 FPS
Import results: 61510 samples - Slices: 773 I 29161 P 31576 B - 1 SEI - 757 IDR
Stream uses B-slice references - max frame delay 2
Unknown input file type
Unknown input file type
Saving to test.mp4: 0.500 secs Interleaving

Just tried it with quicktime on my mac and its recognised as an mp4 file with no audio present.

Kurtnoise

21st November 2007, 11:00

MP4Box is able to parse AC-3 streams but unknown file types are discarded to the mux...

foxyshadis

23rd November 2007, 04:25

This was with a scene release

Then we don't want to hear about it. Struck.

Drachir

24th February 2008, 10:39

It seems Apple is using ac3 in iTunes files(*.m4v), now too.

http://forum.handbrake.fr/viewtopic.php?f=4&t=4726&st=0&sk=t&sd=a
http://sourceforge.net/forum/forum.php?thread_id=1948597&forum_id=59136

SeeMoreDigital

24th February 2008, 13:00

Anybody have any test samples?

cacepi

25th February 2008, 04:00

Anybody have any test samples?
Here you go (http://www.filesend.net/download.php?f=9f928933b76e41e6874c87ad3216b2a8), courtesy of the latest HandBrake.

Don't know if you'll get any sound, however, as there is no third-party AC3 decoder component for Windows QuickTime yet and neither MPlayer nor VLC will play the audio for these files even on the Mac. Media Player Classic and the latest Haali Splitter won't play back the audio either.

SeeMoreDigital

25th February 2008, 16:42

Many thanks for the sample...

Jeez... muxing any audio stream format along with video and referring to it as an ".M4V" file is just plain wrong :eek:

cacepi

26th February 2008, 07:31

Jeez... muxing any audio stream format along with video and referring to it as an ".M4V" file is just plain wrong :eek:
To say the least. The hacks that Apple have added to their code to make ac3 in MP4 work will take some time to implement in other players, if ever at all. It's still so new that there isn't a way mux raw streams even with mp4creator: the changes have only been to the mp42 library, none of the mpeg4ip command line binaries.

I guess Windows users will have to stick with Matroska or transport/program streams for the time being.

AKarpo

26th February 2008, 07:35

If you could, please check this thread out. Trying to get around this whole Apple issue.

http://forum.doom9.org/showthread.php?p=1105296#post1105296

SeeMoreDigital

15th March 2008, 17:06

Yep that's right....

I've just got my hands on a Ziova CS615 test sample unit (based around Sigma's SMP8634 chip-set) and have been able to play files containing MPEG-4 ASP video with 6Ch AC3 audio in MP4 and MPEG-4 AVC video with 6Ch AC3 audio in MP4 without any issues. The AC3 bit-stream was passed perfectly to my amplifier.

Cheers

fico99

10th April 2008, 09:47

has anybody tried mp4 with ac3 in the PS3 ? Now with multi-channel support since fw 2.0 it might be an option..

What is currently the best way of muxing ac3 within mp4 ? (7 months after the last post in this thread)

THX

You have to remux your MP4 with AC3 to the M2TS file format.

The PS3 can playback M2TS files containing H.264 video and AC3 5.1 audio up to 640kbps :)

refulgentis

9th May 2008, 13:46

It seems like both mp4creator won't be updated anymore, and mp4box won't add AC3. Is there *anyone* who could patch mp4creator to do it? It seems like it wouldn't take more than a week of hacking to do.

9th May 2008, 14:13

Why would you want to put AC3 in MP4? Is there a hardware player that supports it? Otherwise I don't see the point since Matroska and MPEG TS cover the rest of the usage areas.

blaz

9th May 2008, 21:30

And avi works with ac3 on the ps3

(gawd I love abbreviations)

SeeMoreDigital

9th May 2008, 22:24

refulgentis

10th May 2008, 10:32

Why would you want to put AC3 in MP4? Is there a hardware player that supports it? Otherwise I don't see the point since Matroska and MPEG TS cover the rest of the usage areas.
Apple TV :/

refulgentis

10th May 2008, 10:35

Just to let you know... Nero Recode 3 has added the placing of AC3 audio streams within the MP4 container.

Not only that, I'm currently testing a hardware device that can play these streams.... And it works very well too ;)
Yeah, I saw (I think your?) earlier post about that, but its my understanding it doesn't run on Linux/Mac OS X, so its useless to me unless I start dualbooting.

SeeMoreDigital

10th May 2008, 10:44

The Ziova CS615 is a "network capable" media player.... So it's able to pull in files from any network connected computer or NAS.

You can even install an HDD within the CS615 and drag-and drop files over your network.

Cheers

Drachir

10th May 2008, 11:29

Me would interest, if Apple and/or Nero planning to register the new audio sample entry box for the ISO base media format here: http://www.mp4ra.org/codecs.html

As far as I know, do they use different box names. If I remember correct, Nero is using "sac3" (this would fit into the naming schema of 3GPP) and Apple TV is using "ac-3" (according to handbrake).

In the past Apple registered a new file brand ( http://www.mp4ra.org/filetype.html ) for the file format used by iTunes & co.
We will see, if we will get then an ObjectTypeIndication for ac3 in the MP4 file format too?

Nero could also really register a new file brand(file format), they added enough things and leave other things away, in there ISO media based format.

SeeMoreDigital

10th May 2008, 12:31

As far as I know, do they use different box names. If I remember correct, Nero is using "sac3" (this would fit into the naming schema of 3GPP) and Apple TV is using "ac-3" (according to handbrake).Yes that's correct.

refulgentis

10th May 2008, 12:42

Elias

12th May 2008, 19:43

SeeMoreDigital

12th May 2008, 19:56

Ac3 in mp4 is a bad idea. Please don't screw with standards. Keep mp4 as a standards only container.Adding .AC3 audio to the .MP4 container is not screwing with the standards.... They can all be added as a "private stream" implementation.

The only problem with mp4 is that it lacks chapters. If you want a universal container then use Matroska, don't screw up mp4 with ac3.That's not correct.... Chapter navigation can be added to .MP4 very easily. What's more many software and hardware players recognise them ;)

Elias

12th May 2008, 20:06

Adding .AC3 audio to the .MP4 container is not screwing with the standards.... They can all be added as a "private stream" implementation.I know, but that's still not a standard because it has not been accepted by MPEG or ISO. Hence, it shouldn't be added.

Let's keep mp4 clean. Or else we might as well just use Matroska. When I open an mp4 file, I want it to contain MPEG-4 codecs or H.264, nothing else. I don't want to look for codec filters; mp4 is MPEG-4, not Dolby.That's not correct.... Chapter navigation can be added to .MP4 very easily. What's more many software and hardware players recognise them ;)There are no MPEG chapter standard for mp4 as far as I know.

Drachir

13th May 2008, 12:29

Ac3 in mp4 is a bad idea. Please don't screw with standards. Keep mp4 as a standards only container. The only problem with mp4 is that it lacks chapters. If you want a universal container then use Matroska, don't screw up mp4 with ac3.

About what standard are you talking? The MP4 file format(ISO/IEC 14496-14)? The MP4 file format has a lot features and is quite universal.
But if you are strict, then nobody is using the MP4 file format nowadays.

If you take a look around, you will only find file formats in use, which are based at the ISO base media file format (ISO/IEC 14496-12).

There are for example, the 3GPP file format(.3gp) and Apple file format used for iTunes&co (.m4v). This file formats are not MP4 files, they don't depend/use the Object Descriptor Framework.
Most opensource tools are also unable to handle the Object Descriptor Framework. So if your are strict, the so called MP4 files, created by most opensource tools are only free-format files, they don't apply the MP4 file format.

To make it clear "ISO/IEC 14496-12" is not equal "ISO/IEC 14496-14"

So what do you want keep clean(don't screw up)?

In ISO base media file formats, the main file brand tells you which rules(standard) have to taken into account for propper presentation.
If you have a .M4V file with main file brand set to "m4v ", you don't have to look for MPEG-4 Systems(MP4 file format) information. But you will find additional information like iTunes tags.

You can already use other audio/video formats beside AAC or MPEG-4 video in file formats based at "ISO/IEC 14496-12".
Take a look here: http://www.mp4ra.org/codecs.html
There is for example "vc-1", if you want to use it in the MP4 file format(MPEG-4 Systems context) use the ObjectTypeIndication "0xA3". If you want to use it in an other "ISO/IEC 14496-12" based file format use the video sample entry box "vc-1".

I don't have a problem with ac3, as long as people/companies could decide which file format they want to use. I am not a fan of files, which look like someone took all "ISO/IEC 14496-12" based formats and threw them into a meat chopper.

I think it would be a good idea to register new audio/video formats here: http://www.mp4ra.org/codecs.html

Elias

13th May 2008, 13:54

About what standard are you talking? The MP4 file format(ISO/IEC 14496-14)? The MP4 file format has a lot features and is quite universal.
But if you are strict, then nobody is using the MP4 file format nowadays.

If you take a look around, you will only find file formats in use, which are based at the ISO base media file format (ISO/IEC 14496-12).

There are for example, the 3GPP file format(.3gp) and Apple file format used for iTunes&co (.m4v). This file formats are not MP4 files, they don't depend/use the Object Descriptor Framework.
Most opensource tools are also unable to handle the Object Descriptor Framework. So if your are strict, the so called MP4 files, created by most opensource tools are only free-format files, they don't apply the MP4 file format.

To make it clear "ISO/IEC 14496-12" is not equal "ISO/IEC 14496-14"

So what do you want keep clean(don't screw up)?

In ISO base media file formats, the main file brand tells you which rules(standard) have to taken into account for propper presentation.
If you have a .M4V file with main file brand set to "m4v ", you don't have to look for MPEG-4 Systems(MP4 file format) information. But you will find additional information like iTunes tags.

You can already use other audio/video formats beside AAC or MPEG-4 video in file formats based at "ISO/IEC 14496-12".
Take a look here: http://www.mp4ra.org/codecs.html
There is for example "vc-1", if you want to use it in the MP4 file format(MPEG-4 Systems context) use the ObjectTypeIndication "0xA3". If you want to use it in an other "ISO/IEC 14496-12" based file format use the video sample entry box "vc-1".

I don't have a problem with ac3, as long as people/companies could decide which file format they want to use. I am not a fan of files, which look like someone took all "ISO/IEC 14496-12" based formats and threw them into a meat chopper.

I think it would be a good idea to register new audio/video formats here: http://www.mp4ra.org/codecs.htmlLook, as far as I'm concerned, mp4 is for MPEG-4 only. I know that mp4 is capable of handling non-MPEG4 codecs, but that is not what it was made for. mp4 as a container along with MPEG-4 codecs, is a world standard. Let's keep it like that and not clutter mp4 with all kinds of codecs. You want to feel 1337? Do it with other containers like Matroska. Matroska is a container made for this kind of codec mixing and codec experimenting, mp4 wasn't.

Please, for the sake of the future of codecs, let's keep mp4 clean and free from codecs that aren't officially recognised for use in the container. It's easier and better that way for all of us. Let's not resort to cheap hacks.

Drachir

13th May 2008, 18:52

...I know that mp4 is capable of handling non-MPEG4 codecs, but that is not what it was made for...
Why do you think so? The propose of MP4 file format is to store natural or synthetic “media objects”.

...let's keep mp4 clean and free from codecs that aren't officially recognised for use in the container.
For this reason there is the officially Registration Authority http://www.mp4ra.org/ for file formats based at ISO/IEC 14496-12.

C.5 Storage of new media types
There are two choices in the definition of how a new media type should be stored.

First, if MPEG-4 systems constructs are desired or acceptable, then:
a) a new ObjectTypeIndication should be requested and used;
b) the decoderspecificinformation for this codec should be defined as an MPEG-4 descriptor;
c) the access unit format should be defined for this media.

The media then uses the MPEG-4 code-points in the file format; for example, a new video codec would use a
sampleentry of type ‘mp4v’.

If the MPEG-4 systems layer is not suitable or otherwise not desired, then:
a) a new sampleentry four-character code should be requested and used;
b) any additional information needed by the decoder should be defined as boxes to be stored within
the sampleentry;
c) the file-format sample format should be defined for this media.

Note that in the second case, the registration authority will also allocate an objecttypeindication for use in
MPEG-4 systems.

refulgentis

22nd May 2008, 10:04

Look, as far as I'm concerned, mp4 is for MPEG-4 only. I know that mp4 is capable of handling non-MPEG4 codecs, but that is not what it was made for. mp4 as a container along with MPEG-4 codecs, is a world standard. Let's keep it like that and not clutter mp4 with all kinds of codecs. You want to feel 1337? Do it with other containers like Matroska. Matroska is a container made for this kind of codec mixing and codec experimenting, mp4 wasn't.

Please, for the sake of the future of codecs, let's keep mp4 clean and free from codecs that aren't officially recognised for use in the container. It's easier and better that way for all of us. Let's not resort to cheap hacks.
I understand the underlying feelings behind your point, but its moot. A media extender from a popular consumer electronics company does it, and its hardly a threat to the integrity of the MP4 format if I'm able to listen to surround sound on an already non-standards compliant device. I'd use AAC, but unfortunately it looks as though there's no consumer-level receivers that will decode it any time soon.

I just want to be able to put AC3 in an MP4, and so do many others. I'm assuming its hardly difficult, just there's a lack of interest in writing up a patch.

Elias

22nd May 2008, 13:32

I understand the underlying feelings behind your point, but its moot. A media extender from a popular consumer electronics company does it, and its hardly a threat to the integrity of the MP4 format if I'm able to listen to surround sound on an already non-standards compliant device. I'd use AAC, but unfortunately it looks as though there's no consumer-level receivers that will decode it any time soon.

I just want to be able to put AC3 in an MP4, and so do many others. I'm assuming its hardly difficult, just there's a lack of interest in writing up a patch.Why does it have to be in mp4? Aren't there hardware devices capable of playing XviD+AC3 in avi already?

The reason why I don't want to see anyone write such a patch, is because it'll get widespread usage if anyone does, and that means teh Internet will eventually be filled with mp4 files containing AC3 codec, and that would piss me off because it's breaking standards. It's bad enough as it is that Apple introduced a non-standard way of tagging mp4 files instead of using the mp4 container's native metadata, now we're going to have to put up with AC3 in mp4 too?

I just don't see the point. What you and others should do, instead, is start using Matroska all the time; mp4 is already more or less a success right now, because of industry support. So now we should all support Matroska, and eventually, it will be inevitable for hardware manufacturers to add support for Matroska as well because it will be as popular as avi/mp4.

And really, Matroska is a lot more suited for codec mixing than mp4 ever will be.

SeeMoreDigital

22nd May 2008, 14:34

The reason why I don't want to see anyone write such a patch, is because it'll get widespread usage if anyone does, and that means teh Internet will eventually be filled with mp4 files containing AC3 codec, and that would piss me off because it's breaking standards. It's not breaking standards at all.....

As I've mentioned before the ISO/IEC 14496 MPEG-4 specification makes allowances for the inclusion of "Private Streams" to be placed within the .MP4 container.

Admittedly, what we don't want is a whole bunch of differing/competing implementations :eek:

refulgentis

22nd May 2008, 18:48

Why does it have to be in mp4? Aren't there hardware devices capable of playing XviD+AC3 in avi already?

The reason why I don't want to see anyone write such a patch, is because it'll get widespread usage if anyone does, and that means teh Internet will eventually be filled with mp4 files containing AC3 codec, and that would piss me off because it's breaking standards. It's bad enough as it is that Apple introduced a non-standard way of tagging mp4 files instead of using the mp4 container's native metadata, now we're going to have to put up with AC3 in mp4 too?

I just don't see the point. What you and others should do, instead, is start using Matroska all the time; mp4 is already more or less a success right now, because of industry support. So now we should all support Matroska, and eventually, it will be inevitable for hardware manufacturers to add support for Matroska as well because it will be as popular as avi/mp4.

And really, Matroska is a lot more suited for codec mixing than mp4 ever will be.It's all a large catch 22 of tradeoffs for people who use the iTunes ecosystem (read Apple TV) right now. The MP4 format allows the most metatagging right now, because that's what Apple uses to tag their MP4s so its quite easy to duplicate. MOV doesn't support quite enough for the most anal taggers. So MOV is out for AC3, and the Apple TV only supports MP4 or MOV out of the box.

Is the Apple TV an open platform worth supporting? No. And yes, it can be hacked to do MKVs, with a considerable amount of effort, including voiding your warranty. I doubt MKV will ever be supported officially, since it introduces a lot of variables with content that Apple just won't want to deal with.

Until an AC3 muxer or consumer-level AAC decoding receiver is released, there's no hope of getting surround sound on an Apple TV. I already send 'feedback' to Apple regarding this, and its a widely known issue, but they have no incentive to fix anything because it just drives rentals of their movies rather than piracy.