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maurj
Mar 25, 2007, 04:28 PM
Interesting article about 5.1 support (or otherwise) on the Apple TV...

http://www.thismuchiknow.co.uk/?p=34

- maurj



localoid
Mar 25, 2007, 09:42 PM
Interesting article about 5.1 support (or otherwise) on the Apple TV...

http://www.thismuchiknow.co.uk/?p=34

- maurj

Great info. Thanks for post the link. I'd found the ThisMuchIKnow site earlier in the week and read the "earlier article" the author refers to; finding it to be one of the better sources of information on this topic.

apfhex
Mar 25, 2007, 10:32 PM
So what exactly CAN get true surround out of Apple's 6-channel AAC movie trailers? Only a product like the Firewave and speakers that have 6-channel input? Never made much sense to me. :confused:

Anyway, the lack of real 5.1 and the limited codecs the AppleTV can play means I definitely won't be getting one anytime soon. Heck, even my cheapo DVD player can play some Divx/Xvid files and get 5.1 (AC-3) sound from them.

princealfie
Mar 25, 2007, 10:38 PM
I don't know. I kinda think that 5.1 is overrated to begin with.

localoid
Mar 25, 2007, 11:10 PM
So what exactly CAN get true surround out of Apple's 6-channel AAC movie trailers? Only a product like the Firewave and speakers that have 6-channel input? Never made much sense to me. :confused:

Correct. I have a Firewire sound device, w/6 channels out, and Apple Quicktime 5.1 surround sound will playback in iTunes or QT Pro on discrete channels if "speakers" are configured accordingly in Audio Midi Devices (in Utilities).

In "theory" at least, there are other methods that should allow some-degree of surround sound playback; those topics and theories are addressed in the article mentioned at the beginning of this thread @ ThisMuchIKnow (http://www.thismuchiknow.co.uk/?p=34), from which the following quote is taken:

If Apple are saying “we support 5.1″ to mean “we support Dolby Pro Logic II”, what they really mean is:

“If you have an existing QuickTime-friendly movie with a stereo soundtrack, which happens to have Dolby Pro Logic II 5.1 information matrix-encoded into it, then we’ll happily play that stereo soundtrack to your amplifier. If your amplifier then happens to detect and decode the Dolby Pro Logic II encoding, then you’ll get 5.1 sound out of your speakers.”

But at this point in time we have no real proof that Apple actually said :apple: tv does support 5.1, and actual "controlled experiments" with Apple TV in regards to surround sound have been few and far between. So, at this point in time, what we don't know (for certain) about :apple: tv amounts to more than we actually do know (for certain)...

Someone should take a known QT 5.1 sound file, play it via :apple: tv that's correctly connected to a receiver w/Dolby Pro Logic and report what they're able to get (sound wise) out of this experiment.

Until then... confusion will reign in regards to this topic.

maurj
Mar 26, 2007, 04:30 AM
Someone should take a known QT 5.1 sound file, play it via :apple: tv that's correctly connected to a receiver w/Dolby Pro Logic and report what they're able to get (sound wise) out of this experiment.

Localoid,

Do you mean a known 6-channel AAC file? I think that's what the guy at ThisMuchIKnow did, so that seems a pretty good test of how it treats 6-channel (5.1) AAC tracks.

Or do you mean a known Dolby Pro Logic II track? I've not seen a 'test' DPL II file, to be sure of what's coming out of each speaker. But since the DPL II is encoded into a stereo signal, there's no reason why this shouldn't play via QuickTime / Apple TV to a DPL II amp...

mkaake
Mar 26, 2007, 05:24 AM
I don't know. I kinda think that 5.1 is overrated to begin with.

I thought so too until I got a 5.1 system.

Now, watching movies w/o is... disappointing. I find it more important to have 5.1 than I do to have HD...

Just MHO, but that's the main point of contention between me and the macTV...

localoid
Mar 26, 2007, 06:10 AM
Localoid,

Do you mean a known 6-channel AAC file? I think that's what the guy at ThisMuchIKnow did, so that seems a pretty good test of how it treats 6-channel (5.1) AAC tracks.

Or do you mean a known Dolby Pro Logic II track? I've not seen a 'test' DPL II file, to be sure of what's coming out of each speaker. But since the DPL II is encoded into a stereo signal, there's no reason why this shouldn't play via QuickTime / Apple TV to a DPL II amp...

I'm advocating rounding up some test files of various types and test them.

.. Someone find a trailer on iTunes that's known to be surround sound.

.. Has anyone tried making a QT reference movie to a AC-3 file?

.. There's QuickTime movie with AAC encoded 5.1 channel audio (http://web.synkaudiostudios.com/blog/2005/11/10/musicbed-dv-surround-sound-demo.html) available for d/l'ing near the bottom of that page. Someone try it on their atv...

To (accurately) determine what does or doesn't work, on the atv end, you'd first need some test files (known to work in iTunes), etc. Does this logic make sense? :)

patrick0brien
Mar 26, 2007, 05:17 PM
-All

Apple couldn't get HDMI cert without the hardware being capable of 5.1.

That means it's likely locked off for now, and we all know that the content isn't there yet...

Diatribe
Mar 26, 2007, 05:20 PM
I don't know. I kinda think that 5.1 is overrated to begin with.

Speak for yourself :p

This is actually one of the basics of a good movie experience.

patrick0brien
Mar 26, 2007, 05:36 PM
Speak for yourself :p

This is actually one of the basics of a good movie experience.

-Diatribe

Fancy seeing you here.

You though 5.1 was nifty, 7.1 is creamy goodness too ;)

Yes, you're right. Must... have... multi... channel... well... balanced... speakers... good... acoustics......popcorn.

Diatribe
Mar 26, 2007, 05:41 PM
-Diatribe

Fancy seeing you here.

You though 5.1 was nifty, 7.1 is creamy goodness too ;)

Yes, you're right. Must... have... multi... channel... well... balanced... speakers... good... acoustics......popcorn.

Hehe, same to you :)

Yeah I could see myself with a nifty 7.1 setup with some front presence speakers as well, but I guess that'll have to wait until I have a dedicated movie room :D

Anyway, I am with you, sound, image and food are the most important prequisites of a good movie evening besides the movie itself of course. :)

musicpenguy
Mar 26, 2007, 10:26 PM
Wouldn't it play 5.1 if all the necessary codecs are added to the ?TV? Say from an AC-3 audio from an AVI Container as it does on the mac???

patrick0brien
Mar 27, 2007, 01:05 AM
Wouldn't it play 5.1 if all the necessary codecs are added to the ?TV? Say from an AC-3 audio from an AVI Container as it does on the mac???

-musicpenguy

Sure, but the :apple:TV needs a codec update - I'm sure it's coming.

localoid
Mar 27, 2007, 06:34 AM
-musicpenguy

Sure, but the :apple:TV needs a codec update - I'm sure it's coming.

A few enterprising people, not content to wait, already have xvid and divx files playing via their :apple: tvs. :rolleyes:

Any of those people checked "teh 5.1"...? :p

sycho
Mar 27, 2007, 08:45 AM
-All

Apple couldn't get HDMI cert without the hardware being capable of 5.1.

That means it's likely locked off for now, and we all know that the content isn't there yet...


very true, maybe someone can try the HDMI output???
http://forums.macrumors.com/showthread.php?t=290656

Diode
Mar 27, 2007, 08:50 AM
I'm fairly certain someone said the chipset used was capable of 5.1

sycho
Mar 27, 2007, 09:14 AM
I'm fairly certain someone said the chipset used was capable of 5.1
So? The chipset in the Intel Mac's is 5.1 compatible, but still only outputs 2 channels. What we'd like to know is if the HDMI output will spit out 5.1 or even 7.1 audio

patrick0brien
Mar 27, 2007, 11:11 AM
I use HDMI

I'll try to rip a movie to 5.1 again, but I don't think it'll work until Apple updates the device.

TBi
Mar 27, 2007, 11:18 AM
Shouldn't the Apple TV just pass through the AC3 information to a decoder if you have one?

sycho
Mar 27, 2007, 11:44 AM
I use HDMI

I'll try to rip a movie to 5.1 again, but I don't think it'll work until Apple updates the device.

Sweet :) What receiver are you using?

pilotError
Mar 27, 2007, 11:50 AM
arstechnica.com did an in-depth review and was unable to get it to do 5.1 surround.

http://arstechnica.com/reviews/hardware/appletv.ars

Athough it is capable of doing 5.1, I think we are going to need a software update.


Although Apple makes no claims regarding Apple TV's ability to play "full" surround sound, it is emerging as a major sticking point among audiophiles. To be sure about the Apple TV's audio capabilities, we enlisted the help of a friend of ours, one of our readers, and fellow forum member John Averitt. What we found confirmed most people's fears: Apple TV is limited to playing files that are present in iTunes, which limits the number of 5.1 file types. A 5.1 AAC QuickTime movie gave only 2-channel sound through the Apple TV, or (at best) Dolby Digital Pro Logic II when played through the optical connection. This is different than Front Row behavior on a Mac mini—Front Row uses QuickTime and all of its associated plugins. With Front Row, Dolby Digital (AC3) encoded audio can be output through the optical cable, giving "true" surround sound. Since there is no way (that we know of) to play Dolby Digital or DTS encoded audio in iTunes, that leaves AAC 5.1 for the Apple TV, which the device treats the same way as a default 10.4 QuickTime install does—by putting all five channels into two. So, there is no 5.1 surround sound, just the older Pro Logic II, two-channel Dolby format.

The inclusion of the optical port like all the other HD settings suggests that Apple is going to start selling or at least thinking about selling HD 5.1 content. If that wasn't the case, Apple could have made a much cheaper media extender for the iTunes Store than the Apple TV to handle their current content.

princealfie
Mar 27, 2007, 11:52 AM
Speak for yourself :p

This is actually one of the basics of a good movie experience.

True but for me, a good movie makes it more important than fidelity to the original theatrical experience.

Of course, I heard that Frauenhofer was updating the mp3 codec to include built in 5.1 encoding a few years ago. What happened to that project?

patrick0brien
Mar 27, 2007, 11:57 AM
Sweet :) What receiver are you using?

-sycho

Oh boy. Umm, let's just say I'm running pretty near an 'ideal' system.

All HDMI (except the DVD player, it's Component)

DVR, :apple:TV, and that DVD player go to a Denon AVR-4306, which, in turn HDMI to the Sharp Aquos.

The Receiver is technically 7.1, but I particularly like it's intelligence. I could be watching plain'ol SD stereo TV and it'll accurately interpolate the 2 channels into 5.1 for me. Needs a LOT of ventilation though.

sycho
Mar 27, 2007, 11:58 AM
ok, since people just seem to post in here about stuff we've known for a while now, i'll do this:

SPDIF output is currently only stereo PCM, no Dolby Digital or dts
Don't think that the AppleTV can be updated to output Dolby Digital for any surround content. The SPDIF output works like any other Macintosh: Outputs PCM for system and regular sounds, and will out PASS Dolby Digital and dts, not encode it.<edit> apple hasn't yet enabled Dolby Digital or dts passthough</edit>

The HDMI output should be able to output 5.1, or even 7.1 output, but this does not seem to have been tested yet.
If this way works, it will only work with a Multi-Channel receiver, not a TV with HDMI and SPDIF out.


I'm glad we have got this out of the way.

patrick0brien
Mar 27, 2007, 11:59 AM
True but for me, a good movie makes it more important than fidelity to the original theatrical experience.

Of course, I heard that Frauenhofer was updating the mp3 codec to include built in 5.1 encoding a few years ago. What happened to that project?

-princealfie

I believe that was stopped because they were successful in doing it to the MPEG2 codec.

sycho
Mar 27, 2007, 12:00 PM
-sycho

Oh boy. Umm, let's just say I'm running pretty near an 'ideal' system.

All HDMI (except the DVD player, it's Component)

DVR, :apple:TV, and that DVD player go to a Denon AVR-4306, which, in turn HDMI to the Sharp Aquos.


Ok, give a HD trailer with a 5.1 AAC track a try on that.
The Receiver is technically 7.1, but I particularly like it's intelligence. I could be watching plain'ol SD stereo TV and it'll accurately interpolate the 2 channels into 5.1 for me.

That is called Pro Logic II :P

patrick0brien
Mar 27, 2007, 12:19 PM
Ok, give a HD trailer with a 5.1 AAC track a try on that.

-sycho

I like that idea better. Got one in mind?

sycho
Mar 27, 2007, 12:36 PM
-sycho

I like that idea better. Got one in mind?

300 should work :)

patrick0brien
Mar 27, 2007, 12:41 PM
300 should work :)

-sycho

I'm sorry if I haven't explored much in that menu, but when I did pay 300, it sure didn't look HD to me. How can I tell what it's supposed to be HD 5.1 and not?

RustyM
Mar 27, 2007, 12:49 PM
How about the newly released "28 Weeks Later" trailer:
http://www.apple.com/trailers/fox_atomic/28weekslater/

Just watched the 720p version and checked the encoding settings:
"AAC, 5.1 (C L R Ls Rs LFE), 48.000 kHz"

sycho
Mar 27, 2007, 12:52 PM
-sycho

I'm sorry if I haven't explored much in that menu, but when I did pay 300, it sure didn't look HD to me. How can I tell what it's supposed to be HD 5.1 and not?

You have to download the HD 720P trailer and add it to your iTunes, then play it on the AppleTV

patrick0brien
Mar 27, 2007, 01:10 PM
You have to download the HD 720P trailer and add it to your iTunes, then play it on the AppleTV

-sycho

Ah-HA!

Got a link offhand?

crees!
Mar 27, 2007, 01:42 PM
Ten Myths of the Apple TV: 5.1 Audio (http://roughlydrafted.com/RD/RDM.Tech.Q1.07/147048D8-D8B7-45E7-9A97-3CD5B4C2B75A.html)

sycho
Mar 27, 2007, 02:23 PM
Ten Myths of the Apple TV: 5.1 Audio (http://roughlydrafted.com/RD/RDM.Tech.Q1.07/147048D8-D8B7-45E7-9A97-3CD5B4C2B75A.html)

to quote the author:

Yikes, that’s wrong on nearly every count. Where to begin?

If he doesn't know the difference between a matrixed (Dolby Surround) and discrete (5.1 dolby digital or dts) then he should not be writing about it.

and, now, i will point you to this post:

ok, since people just seem to post in here about stuff we've known for a while now, i'll do this:

SPDIF output is currently only stereo PCM, no Dolby Digital or dts
Don't think that the AppleTV can be updated to output Dolby Digital for any surround content. The SPDIF output works like any other Macintosh: Outputs PCM for system and regular sounds, and will out PASS Dolby Digital and dts, not encode it.<edit> apple hasn't yet enabled Dolby Digital or dts passthough</edit>

The HDMI output should be able to output 5.1, or even 7.1 output, but this does not seem to have been tested yet.
If this way works, it will only work with a Multi-Channel receiver, not a TV with HDMI and SPDIF out.


I'm glad we have got this out of the way.

Got a link offhand?

http://images.apple.com/movies/wb/300/300-tlr2_h720p.mov
http://images.apple.com/movies/wb/300/300-tlr1_h720p.mov

musicpenguy
Mar 27, 2007, 06:55 PM
My original post was saying if you hack the ?TV and add all of the necessary codecs to the quicktime folder as you do now in your mac won't it play AC-3 audio, I don't have one yet to check but if you find all of the codecs for quicktime that let your mac do it then the ?TV should right or am I missing something???

omnirune
Mar 28, 2007, 11:38 AM
You have to download the HD 720P trailer and add it to your iTunes, then play it on the AppleTV

Tested this last night with analog cable and optical cable (And added the 720P trailer through itunes). The receiver picks up the sound as PCM. As previously confirmed, the Apple TV does NOT output surround through either audio connection. Unfortunately.

Avatar74
Mar 28, 2007, 11:49 AM
Tested this last night with analog cable and optical cable (And added the 720P trailer through itunes). The receiver picks up the sound as PCM. As previously confirmed, the Apple TV does NOT output surround through either audio connection. Unfortunately.

That could mean TWO things, though...

1. The trailer has no pass-through AC-3.

2. The so-called pass-through AC-3 is actually in an MPEG-4 container as multichannel AAC and needs to be transcoded to AC-3.

The thing you need to realize is that AC-3 is a proprietary codec of Dolby Laboratories. In order for Apple to give it functionality they need to use a licensed decoder or make a decoder that Dolby Labs will license.

This is actually GOOD because you don't want a decoder that cannot guarantee the fidelity standards set for AC-3 by Dolby Labs. There are plenty of licensed AC-3 encoders and decoders, and it's not out of reach for Apple to implement something like Dolby Digital Live to transcode multichannel AAC to AC-3.

But of course it depends on the source actually possessing multichannel AAC.

For the record, I have not seen a single blog entry, review, or other statement anywhere from a user who can verify that AC-3 pass through has actually ever worked with any Dolby Digital decoder.

omnirune
Mar 28, 2007, 11:52 AM
The trailer definitely uses 5.1 AAC audio, and does not utilize AC3. I did notice this post:

fyi. I grabbed a DTS encoded wav, synced it onto a "testing" playlist on my appleTV and played it...

static for about 1/2 second, and then the glorious blue led stripe on my Sony receiver lit up and pushed through sound in DTS. Looks like it's doing the same thing my creative xFi is doing in my PC when it gets a DTS encoded signal: passing along a bitstream and letting the receiver do the work.

any reason that if i rip and encode into a multichannel sound format that itunes would support (is that the real issue?) that it wouldn't play me a 5.1 audio track along with a movie?

Avatar74
Mar 28, 2007, 12:26 PM
The trailer definitely uses 5.1 AAC audio, and does not utilize AC3. I did notice this post:

Then if it doesn't hit the receiver as AC-3, either AppleTV has no transcoder or has a transcoder (e.g. Dolby Digital Live) which is not enabled yet.

As for the comments about DTS WAV. DTS is a different coding schema from Dolby Digital. In its theatrical implementation, DTS is fundamentally an ADPCM bitstream. DTS in DVD's however is a perceptual coding system based on ADPCM. In this sense, a DTS stream in WAV, which is basically a container for PCM, is probably detectable by a DTS decoder but I'm curious about any metadata that might be lost when converting DTS to DTS WAV.

Dolby Digital is a different matter because it relies on a number of metadata parameters which extend its dynamic range while minimizing bitrate requirements to produce equivalent or greater fidelity than DTS (despite what the audiophiles seem to think).

QuarterSwede
Mar 28, 2007, 03:46 PM
I'd personally be content if it just passed the AC-3 stream, or any stream for that matter, through to my receiver. I really don't think it's Apple TV's job to decode Dolby Digital. My receiver would do it much better anyway.

If Apple doesn't implement true multi-channel audio in some form, this one's out for me. Although, I'd bet Apple is working on adding it.

patrick0brien
Mar 28, 2007, 03:56 PM
I really don't think it's Apple TV's job to decode Dolby Digital.

-QuarterSwede

Agreed. If it were it would likely be able to drive the speakers directly, but then, that's not the intent of the device. Oh, and that'd add a $$load of $$.

If Apple doesn't implement true multi-channel audio in some form, this one's out for me. Although, I'd bet Apple is working on adding it.

-QuarterSwede

The chip is in there, the ports are certified to standards, I think its just a matter of time. I think the holdup is that there isn't any legal content available to the :apple:TV that'd use it...

... right? Can't think of any besides the hi-def trailers (which look GREAT off the :apple:TV BTW)

sycho
Mar 28, 2007, 04:46 PM
So patrick0brien, any progress on multichannel output via HDMI?

patrick0brien
Mar 28, 2007, 05:31 PM
-sycho

Nope! Not passing the signal. Tried optical too.

sycho
Mar 28, 2007, 05:52 PM
-sycho

Nope! Not passing the signal. Tried optical too.

OK, so the AppleTV is (for now) limited to 2.0 PCM via HDMI, and will always be limited to 2.0 PCM over the optical. Again, like I have said in several threads, although it would be possible to have an Dolby Digital or dts output for the AppleTV, it would only work for pre-encoded content, non of which is avalible on iTunes.

mightymike
Apr 8, 2007, 10:00 PM
OK, so the AppleTV is (for now) limited to 2.0 PCM via HDMI, and will always be limited to 2.0 PCM over the optical. Again, like I have said in several threads, although it would be possible to have an Dolby Digital or dts output for the AppleTV, it would only work for pre-encoded content, non of which is avalible on iTunes.

I've successfully gotten AppleTV to pass DTS and Dolby Digital 5.1 via optical to my receiver with WAV files from http://www.diatonis.com/downloads_dts_ac3.html. Just load them or stream with iTunes.

Note that my ATV is off the shelf... unhacked.

Now that we know it's possible...

imacdaddy
Apr 8, 2007, 11:36 PM
I've successfully gotten AppleTV to pass DTS and Dolby Digital 5.1 via optical to my receiver with WAV files from http://www.diatonis.com/downloads_dts_ac3.html. Just load them or stream with iTunes.

Note that my ATV is off the shelf... unhacked.

Now that we know it's possible...

Wonder if I can rip my dvds and then encode them using VirtualDub (Winblows only http://www.free-codecs.com/download/VirtualDub.htm) to get 5.1. Need to find a Windows machine to test. :rolleyes:

Numbers9-1
Apr 14, 2007, 12:56 AM
First off, this will allow you to play on a DD receiver ONLY. If you try to play on your laptop, you get static... so that said.

1) Demux with MPEG Streamclip to M2V and AC3.
2) Copy AC3 to windows machine to use BeSweet to convert to DD-Wav. (if there is an OS X alternative, please let me know.
3) Copy DD-Wav back onto Mac.
4) Open m2v in Quicktime Pro.
5) Open dd-wav in quicktime pro, then add to the m2v movie.
6) Export to Quicktime. h.264 (i used one pass to save time @2400kbps) w/ Apple Lossless 44.1 stereo w/o streaming box clicked.
7) Add to iTunes Library
Play on AppleTV with glorious 5.1 DD!

That's it.

Here's the THX intro from Monster's Inc.
http://www.crackedpolystyrene.com/thx.mov

appleguy
Apr 14, 2007, 01:24 AM
you can only get the 5.1 if you use the optical port?

I am getting a new 5.1 Sound System in the next week that has 2 optical inputs I will test a DVD in my DVD player and then rip the DVD (using handbrake) with 5.1 encoding then report my results

Numbers9-1
Apr 14, 2007, 01:39 AM
They are working on handbrake getting 5.1. It's not there yet. Try my tutorial and/or file above. And yes, you need optical. If you d/l my file and it sounds like static, that's cause it's a dolby signal. When you play it on your AppleTV through the optical to a receiver that understands DD, then it will play correctly with 5.1.

iDeal
Apr 14, 2007, 06:01 AM
These are neat hacks, from what I have found it seems like Quicktime is the weak point as it cannot transcode to Dolby Digtal or DTS so the only way to playback multichannel Quicktime files is with a USB/Firewire to multichannel anologue decoder. But if we can work on a system that can easily create a Quicktime file with a DTS encoded soundtrack that could be genius. Afterall that thx.mov file works great.