Rip DVDs w/ Dolby Digital 5.1 sound & Play over Apple TV?

[pickerin]

AppleTV plays DTS 5.1 without Modifications

According to an article at Anandtech, the audio chip inside the Apple TV is a Realtek ALC885.

Realtek's description of this chip is as follows: "The ALC885 is a high-performance 7.1+2 Channel High Definition Audio Codec with advanced lossless content protection technology that protects pre-recorded content while still allowing full-rate audio enjoyment from DVD audio, Blu-ray DVD, or HD DVD discs."

Apple? So whats the deal with not being able to play 5.1 on my Apple TV with an audio chip with this kind of horsepower?

Well, this is my first post to MacRumors and I figured I'd make a "rumor squasher".

The AppleTV most definitely plays Dolby DTS 5.1 audio, without any modifications or additional software.

This is a great article on support for 5.1 on Apple hardware, and I'm very surprised I haven't seen it more:

http://www.roughlydrafted.com/RD/RDM.Tech.Q1.07/147048D8-D8B7-45E7-9A97-3CD5B4C2B75A.html

If you'd like to hear glorious 5.1 audio (yep, front, center, and rear speakers, all playing different tunes). Download this DTS 5.1 surround sound reference file:

http://www.diatonis.com/downloads/diatonis_dts_wav_io_afos.zip

Unpack it, load it into your iTunes library and play it. It'll sound like static. That's because iTunes itself cannot decode it properly, so it is trying to downsample it.

The above file is available on this site, along with a different one, as well as other audio reference files:

http://www.diatonis.com/downloads_dts_ac3.html

After you have the reference file loaded into iTunes, the magic starts.

Just tell your AppleTV to sync the file. iTunes will copy it across.

Have your AppleTV play the file, and your DTS receiver will click over to DTS 5.1 surround and play the file on all 6 channels.

Over on the Handbrake forums, they're talking about how the latest build of Handbrake should be able to properly encode a DTS 5.1 audio track into a DVD rip. In theory, that'll mean those files will then play in 5.1 on an AppleTV.

Try this out yourself. Then spread the word. I think the AppleTV is getting a bad rap regarding audio when in fact it's just bad encoding.

-Rob

p.s. Here's the link to the Handbrake forums about it:
http://handbrake.m0k.org/forum/viewtopic.php?p=2649&sid=cf8ff6898c56826914fdbdefcdf58a84

 

[pickerin]

AppleTV plays DTS 5.1 without Modifications

According to an article at Anandtech, the audio chip inside the Apple TV is a Realtek ALC885.

Realtek's description of this chip is as follows: "The ALC885 is a high-performance 7.1+2 Channel High Definition Audio Codec with advanced lossless content protection technology that protects pre-recorded content while still allowing full-rate audio enjoyment from DVD audio, Blu-ray DVD, or HD DVD discs."

Apple? So whats the deal with not being able to play 5.1 on my Apple TV with an audio chip with this kind of horsepower?

Well, this is my first post to MacRumors and I figured I'd make a "rumor squasher".

The AppleTV most definitely plays Dolby DTS 5.1 audio, without any modifications or additional software.

This is a great article on support for 5.1 on Apple hardware, and I'm very surprised I haven't seen it more:

http://www.roughlydrafted.com/RD/RDM.Tech.Q1.07/147048D8-D8B7-45E7-9A97-3CD5B4C2B75A.html

If you'd like to hear glorious 5.1 audio (yep, front, center, and rear speakers, all playing different tunes). Download this DTS 5.1 surround sound reference file:

http://www.diatonis.com/downloads/diatonis_dts_wav_io_afos.zip

Unpack it, load it into your iTunes library and play it. It'll sound like static. That's because iTunes itself cannot decode it properly, so it is trying to downsample it.

The above file is available on this site, along with a different one, as well as other audio reference files:

http://www.diatonis.com/downloads_dts_ac3.html

After you have the reference file loaded into iTunes, the magic starts.

Just tell your AppleTV to sync the file. iTunes will copy it across.

Have your AppleTV play the file, and your DTS receiver will click over to DTS 5.1 surround and play the file on all 6 channels.

Over on the Handbrake forums, they're talking about how the latest build of Handbrake should be able to properly encode a DTS 5.1 audio track into a DVD rip. In theory, that'll mean those files will then play in 5.1 on an AppleTV.

Try this out yourself. Then spread the word. I think the AppleTV is getting a bad rap regarding audio when in fact it's just bad encoding.

-Rob

p.s. Here's the link to the Handbrake forums about it:
http://handbrake.m0k.org/forum/viewtopic.php?p=2649&sid=cf8ff6898c56826914fdbdefcdf58a84

p.s.s. If you try it out and it works, or if you just believe me, please Digg this article and help get the word out (I didn't post it):
http://digg.com/apple/Ten_Myths_of_the_Apple_TV_5_1_Audio

 

[iJon]

I believe you can play 5.1 (AC-3) off the Apple TV if you perform a certain hack. This hack involves pulling out the hard drive, mounting it, copying a few files to the OS and then putting it back together. I use this file on my MacBook Pro to play HD movies with Dolby Digital EX and DTS with my audio reciever.

http://trac.cod3r.com/a52codec/

jon

also: I have never been able to get my MacBook Pro to output AC-3 to my reciever without the help of that codec. I see the article above states it isn't necessary but who knows. I'm a bit skeptical.

 

[Yuvi]

Unpack it, load it into your iTunes library and play it. It'll sound like static. That's because iTunes itself cannot decode it properly, so it is trying to downsample it.

iTunes isn't trying to downsample it; it's playing the file exactly as what it claims to be - 2 channel 16 bit linear PCM audio. It's crafted in such a way that when the data is played unmodified over a digital output, it almost matches the official spec on how to send DTS audio over S/PDIF connections (at least one bit is still set incorrectly, but most receivers ignore it.)

The Intel HD Audio chipsets do seem to be specifically geared toward implementation of Dolby Digital Live which is the key technology licensed out by Dolby for exactly this kind of application... transcoding multichannel bitstreams into AC-3. In this case, specifically transscoding AAC into AC-3.

Interesting, is there actually a codec-level technique that allows more efficient transcoding from AAC to AC-3 than simply decoding to PCM and re-encoding to AC-3, like there is for E-AC-3 to AC-3? My understanding of the two codecs was that they weren't similar enough for this.

 

[Avatar74]

Well, this is my first post to MacRumors and I figured I'd make a "rumor squasher".

The AppleTV most definitely plays Dolby DTS 5.1 audio, without any modifications or additional software.

This is a great article on support for 5.1 on Apple hardware, and I'm very surprised I haven't seen it more:

http://www.roughlydrafted.com/RD/RDM.Tech.Q1.07/147048D8-D8B7-45E7-9A97-3CD5B4C2B75A.html

If you'd like to hear glorious 5.1 audio (yep, front, center, and rear speakers, all playing different tunes). Download this DTS 5.1 surround sound reference file:

http://www.diatonis.com/downloads/diatonis_dts_wav_io_afos.zip

Unpack it, load it into your iTunes library and play it. It'll sound like static. That's because iTunes itself cannot decode it properly, so it is trying to downsample it.

The above file is available on this site, along with a different one, as well as other audio reference files:

http://www.diatonis.com/downloads_dts_ac3.html

After you have the reference file loaded into iTunes, the magic starts.

Just tell your AppleTV to sync the file. iTunes will copy it across.

Have your AppleTV play the file, and your DTS receiver will click over to DTS 5.1 surround and play the file on all 6 channels.

Over on the Handbrake forums, they're talking about how the latest build of Handbrake should be able to properly encode a DTS 5.1 audio track into a DVD rip. In theory, that'll mean those files will then play in 5.1 on an AppleTV.

Try this out yourself. Then spread the word. I think the AppleTV is getting a bad rap regarding audio when in fact it's just bad encoding.

-Rob

p.s. Here's the link to the Handbrake forums about it:
http://handbrake.m0k.org/forum/viewtopic.php?p=2649&sid=cf8ff6898c56826914fdbdefcdf58a84

You're getting things mixed up here... First, Dolby Digital and DTS are two different encoding systems. Second, there is currently no support for AC-3 in the AppleTV. Regardless of the fact that Handbrake/Mediafork has the ability to mux 5.1 AAC into the audio portion of an MPEG-4 AVC file, there's currently no means of transcoding 5.1 AAC to AC-3 in the AppleTV and your receiver will NOT recognize the 5.1 AAC bitstream.

The audio chipset in the AppleTV allegedly does support Dolby Digital Live which can transcode AAC to AC-3, but assuming it is the Intel HD Audio chipset, the Dolby Digital Live feature has not yet been enabled and there are no hacks out that have a demonstrated, verified ability to transcode and transmit AC-3 from the AppleTV.

Also, as much as I enjoy reading the philosophical rants at roughlydrafted, the guy doesn't know what the hell he's talking about when it comes to Dolby Digital vs. Dolby Surround. These are two entirely different formats.

Dolby Surround audio does indeed reside in most iTunes movies and DVD movies in the two front channels (L-R), but it is NOT a discrete 5.1 channel surround format. Dolby Surround is an analog stereo matrixed surround format whereby the information for the back surround channel(s) is phase shifted by 90 degrees and added to the main L-R audio. Because of the 90 degree phase shift, the surround information is not audible if played back through a conventional 2-channel system. But a Dolby ProLogic or Dolby Digital decoder will extract the phase-shifted analog signal from the main audio in a manner similar to a Fourier transform, and send the extracted analog matrix to the surround channel(s).

Dolby Digital has an improved dynamic range, various metadata parameters including dialogue normalization and Dynamic Range Control, which Dolby Surround does not possess. Additionally, as a discrete digital multichannel surround format, Dolby Digital does not experience the phase incoherence of Dolby Surround in which stereo and front-back separation range from less distinct to simply unintelligible.

 

[Avatar74]

Interesting, is there actually a codec-level technique that allows more efficient transcoding from AAC to AC-3 than simply decoding to PCM and re-encoding to AC-3, like there is for E-AC-3 to AC-3? My understanding of the two codecs was that they weren't similar enough for this.

Well, as I understand it, Dolby Digital Live is actually a hardware transcoder in the Intel HD Audio chipsets. There isn't much public documentation on the exact method of transcoding from AAC to AC-3 in Dolby Digital Live. However, my guess is that it doesn't involve decoding the signal to Linear PCM as AAC is fundamentally built upon many of the perceptual coding techniques in AC-3. Dolby was one of the major partners, along with Fraunhofer-IIS, that developed the AAC codec.

 

[Forced Perfect]

It seems from the description of the chip in aTV, 5.1 sound is certainly supported on the hardware side of things, but doesn't have any software support (yet.)

Furthermore, although aTV supports 720p videos, there are currently no such movies or shows available to purchase through the iTunes Store.

These are the two biggest gaps in the aTV. The hardware is there. The demand and interest is there. But the content isn't.

Exactly. There's hardware support for 5.1 on the sound controller, however, it is not enabled in software. So until Apple decides to activate it we're stuck with 2 channel.

It probably won't be enabled until Apple starts selling movies with 5.1 on the Apple Store.

(If you're reading, please enable it before then, Apple!)

 

[stompy]

Also, as much as I enjoy reading the philosophical rants at roughlydrafted, the guy doesn't know what the hell he's talking about when it comes to Dolby Digital vs. Dolby Surround. These are two entirely different formats.

You should send him your corrections, he's usually happy to make updates on such things. (I've seen several links over to his blog, would be nice if all those readers got the straight story.)

 

[iJon]

Exactly. There's hardware support for 5.1 on the sound controller, however, it is not enabled in software. So until Apple decides to activate it we're stuck with 2 channel.

It probably won't be enabled until Apple starts selling movies with 5.1 on the Apple Store.

(If you're reading, please enable it before then, Apple!)

Once again, I'm going to have to bash this into the heads of people in this thread.

Hack your AppleTV either buy booting OS X or taking the hard drive out, drop this codec in the right folder and you have true 5.1, simple as that.
http://trac.cod3r.com/a52codec/

jon

 

[GregA]

To me, there is absolutely ZERO point in owning something that doesn't have 5.1 sound. I can't even fathom how it got out of the development stage without being able to play 5.1 sound. It seems like right after they determined how to make it play HD they should figure out how to make it 5.1.

Apple has done something strange here. A system that is hardware capable of 5.1 surround but doesn't enable it, and a system which can play 720p but Apple doesn't sell anything HD.

I suspect we'll see an anouncement of support of both. Perhaps they'll charge $25 for 5.1 surround and bundle a couple of movies... just to get people buying. I wonder when it'll happen... at NAB? or WWDC?

I can do something like archive a DVD using 5.1 AAC, and the Apple TV will still play it, even if the audio is 320Kbps... (The 160kbps limit is a bit of a lie by Apple, as is the 5Mbps limit, it is closer to 6Mbps).

It may not be a lie - Apple may know that the AAC->AC3 transcoding can only handle up to 160kbps. Or it may just be the quality Apple will sell at on the iTunes store.

 

[weldon]

Exactly. There's hardware support for 5.1 on the sound controller, however, it is not enabled in software. So until Apple decides to activate it we're stuck with 2 channel.

I'm not sure that this is the proper understanding of what the hardware support for 5.1 on the sound controller would do. The purpose of 5.1 support is to decode the digital stream into analog. 5.1 support in hardware is useless without 6 analog audio outputs. In fact, what you really want is for the hardware decoder to NOT TOUCH the audio stream at all and just pass it to the optical out so an external DAC (most likely in your A/V Receiver) can decode it.

Just to be clear, I don't think we need the AppleTV to decode the audio to get surround sound. If it does decode the audio to convert it from digital to analog, we would need separate analog outputs on the box. What we do need is for the hardware to NOT decode the audio stream and just bypass this to send the raw stream (DD or DTS) to an external receiver which would then decode into 5.1 sound.

If you don't have access to a surround sound receiver, then you still need the AppleTV to downmix the audio to 2-channel stereo because that is the only thing that your receiver would understand (over optical and/or analog). This is where the hardware support for 5.1 audio would actually come into play - to decode the signal into analog (and downmix to the two available channels).

The other possible use for hardware support would be to do real-time transcoding from one multi-channel audio format to another, but I think this is unusual and fraught with problems and out of scope for our current discussion.

 

[weldon]

The other possible use for hardware support would be to do real-time transcoding from one multi-channel audio format to another, but I think this is unusual and fraught with problems and out of scope for our current discussion.

Of course, as soon as I post I realize that I've ignored the very important and real possibility of transcoding 5.1 AAC in quicktime to DD.

I'll admit to ignorance here, are there any other multi-channel audio formats that are possible in AppleTV compatible files that would require transcoding to send to a reasonably current A/V receiver? AAC to AC3 is one - are there more?

 

[cingularpat]

Take 2?

So does any of this change with the release of the Take 2 update for Apple TV? I've been toying with mine all day trying to get something 5.1 out of it, but haven't gotten very far. HOWEVER! I can confirm that when it starts up and plays the opening video, I get Dolby Digital 3/2.1 on my Sony receiver, so it IS passing over something useful! Let's figure it out everyone!!!!

 

[trainguy77]

Well rip a DVD in 5.1 and give it a shot. I have a 50mb DTS wave file that someone could try too.

 

[cingularpat]

Tried some stuff that I already had ripped/converted into H.264 with 6-channel discrete. No luck. But I'm telling you, that opening video was in Dolby Digital somehow!!!

 

[trainguy77]

Tried some stuff that I already had ripped/converted into H.264 with 6-channel discrete. No luck. But I'm telling you, that opening video was in Dolby Digital somehow!!!

The odd part about that. If its encoded that means that the apple TV is converting it to 2 channel as otherwise it would just play as static.

 

[cingularpat]

The stuff I have is encoded with multi-channel AAC. The ATV appears to convert that to Dolby Pro Logic. My theory though is that something in there may be capable of converting AAC to Dolby Digital because of that startup video. When connected to a DD receiver, it plays in DD. But I'm sure if I had it hooked up through standard stereo RCA jacks, I would hear it in 2-channel glory. I've only had my ATV for a few days, so I don't know much about booting OSX on it or anything like that - otherwise I'd try to figure this out myself. I would imagine someone would have to boot OSX on it, find the video file that plays when it boots, and use movie inspector to find out what's going on. Any ideas??

 

[knockturnal]

The stuff I have is encoded with multi-channel AAC. The ATV appears to convert that to Dolby Pro Logic. My theory though is that something in there may be capable of converting AAC to Dolby Digital because of that startup video. When connected to a DD receiver, it plays in DD. But I'm sure if I had it hooked up through standard stereo RCA jacks, I would hear it in 2-channel glory./QUOTE]

you stereo cannot decode multi channel AAC, thats why now matter what you try discreet, 5.1 aac or others you wont get Dolby Digital. look on your reciever and see what logos are on there. most likely all you can support is Dolby Digital, or DTS or some form of it. maybe if its newer you can get mp3 wma or other audio formats. i dont belive there is a home stereo with 5.1 aac though. maybe sony will have one soon since the ps3 supports it, i belive!?

anyways...the file has to be encoded with DD to get DD. hd is only available from the apple tv so its tricky to view the properties.

 

[cingularpat]

Yeah I know all that.

I guess with time it'll get figured out. I just figured since that opening video plays no matter what kind of TV/receiver you have it hooked to, that maybe there was something going on behind the scenes. ::sighs:: it's still a fun little device though.

 

[QuarterSwede]

As far as I understand, the new software refresh (Take 2) updates the AppleTV to play 5.1 DD. Because, seriously, Dolby Pro Logic is terrible compared to 5.1 DD or DTS. I remember thinking "it's about time Apple gets it" while watching the MWSF 2008 keynote.

 

[knockturnal]

Yeah I know all that.

I guess with time it'll get figured out. I just figured since that opening video plays no matter what kind of TV/receiver you have it hooked to, that maybe there was something going on behind the scenes. ::sighs:: it's still a fun little device though.

the video that starts up is probably 5.1 DD. the thing we need to know is what container the movies are supported in first of all. the fact that you cant downlaod them to your computer gets me. makes me think that something else is going on behind behind, way behind the scenes. "iTunes Store purchased video" from apple tech specs for ATV makes me think they're using a different container and dont want people to know, something that supports ac3. i used nero to make a .mp4 file with ac3 audio, wont play on ATV or PS3 but does on pc, so???

 

[JasonKerner]

Surround Sound and Apple TV

Surround sound on the Apple TV has these following methods on the take 2 software...

The Apple rented movies have two soundtracks. They are in .MP4 format. They have an H264 video track, followed by a 'stereo' track and a 'surround' track. The stereo track is AAC 5.1. The Apple TV will output this as a muxed Dolby ProLogic signal - but heres the key thing - most amplifiers won't 'detect' a Dolby ProLogic signal, you'll just have to put your amp on that mode and see if it sounds better. Switching your amplifier to Dolby ProLogic is the thing to do here and have a listen. You could put any feed into a Dolby ProLogic amp and it would send some of the sounds to the rear speakers, so its not the same as a Dolby Digital signal.

The surround track in the Apple TV files is an AC3 digital stream, encoded in the Private stream of the MP4 file, making it a legal MP4. Private streams can contain pretty much what you want, but the public streams have strict rules to make it a legal file.

Why are the two sound tracks and how does the Apple TV know what to use, you ask? Well, AC3 can only be decoded by a Dolby Digital surround amplifier - so if this signal is sent to TV speakers or a stereo amp, you wouldn't hear anything - so thats why theres an AAC track too. For those people out there that don't have Dolby Digital decoders. In Take 2's menu, there is an option to turn Dolby Digital output on, when this is turned on, it looks for an AC3 track on the file playing, if it has one, it plays that.

So what options do we have for putting our on movies on there and play in Dolby Digital?

Visualhub 1.31 has an Apple TV 5.1 preset - using this, you could take a file and it would pass through the AC3 soundtrack and put it into a .mov container. Why .mov??? Because to get it into an mp4 as a private stream, along with a legal stereo AAC soundtrack is a bit more tricky presently. If you have a file that has an AC3 source, this works. If you have something that isn't, eg, a DTS file or AAC 5.1, it won't convert it to AC3 - it'll just make it stereo.

The guys over at Handbrake have got a SVN version that gets AC3 into the private stream of an MP4 file, its not a public release yet, but they're working on it.

If you try to play any of these files on your Mac, you'll need Perian 1.1 installed to take the AC3 and convert it to stereo so you can actually hear it on your speakers as not all of us have Dolby decoders plugged to our Mac and Quicktime doesn't output an AC3 via the optical connection anyway - only DVD Player does.

Does it work, you ask? Yes, I've converted a bunch of VOBs and MKVs with AC3 soundtracks and put my amplifier (Denon 1802) on Direct mode and it detects the AC3 feed and the display says Dolby Digital.

What about DTS? The Apple TV could play DTS as is by using it as a passthrough track and again, letting the amp decode it, but so far no one has made a conversion app to do this automatically, you'd have to rip it as a loseless AAC and then paste it in to your file manually to make this work - haven't tried it myself yet, but heard others do it.

Think thats pretty much it.

Jason

 

[smilinmonki666]

Cheers for that JasonKerner. So by my understanding, its not the best time to convert files as of yet until the guys at HB make a public version available to enble the .VOB to .MP4 conversion include the 5.1 private stream.

I've been clever & allowed my self time to just rip my DVD's to my PC as i'm waiting on my funds for a mac. I'm currently using DVD Decrypter. So I'm hoping when the time comes to be able to convert files to :a:TV file type with 5.1DD I will be able to que them up & leave my pc to do the work.

Why couldn't they just allow the :a:TV to playback .vob file types? When I was playing with Ubuntu a while back on my laptop, if i dragged the .vob file over to my HDD, I could watch a film straigh off? I know streaming via wireless, it wouldn't be feasable, not yet anyway, but surely via a gigabit wired network, it could work? That way, people would only have to worry about converting to iPod/iPhone products? A DVD bitrate isn't that high as a standard .vob file?

 

[JasonKerner]

DVD/VOB and conversions

Technically a DVD bitrate and a VOB file are the same thing. A film DVD disc as a VIDEO_TS folder and inside that will be a bunch of VOB files. DVD video is generally between 6-8Mbps (although it can go upto 10Mb as per the DVD spec).

The Apple TV has a 4Gb file size limit, so you'd have to pick a bitrate that generates a file less than 4Gb - this is pretty easy as the H264 codec is pretty efficient. Most of my DVD rips come out between 1.5-1.7Gb, HD rips are 3.74Gb.

If you've got a load of VOB files, you can use VisualHub to put everything in and throw out compatible Apple TV 5.1 files - this would produce .movs with an AC3 soundtrack - which work fine in the Apple TV. The only advantage of waiting for Handbrake with AC3 Mp4 support would be 1) tagging the files with metadata in MetaX for example rather than iTunes 2) if the Handbrake guys can get stereo AAC in there too, then you'd be able to play the same file on iPod/iPhone, etc... (as long as the resolution was supported by all). But if you've got a Mac with the Perian plugin and an Apple TV with a Dolby Amp wired to it - then I'd just use VisualHub as it does a few more formats than Handbrake.

Jason

 

[smilinmonki666]

Ok. So I use HB as i'm on PC Format, I use:

H.264
AAC with 6 Channel Descrete
and a bit rate of say 3000 for video

This would give me a video file with 5.1DD?