"Turning your AppleTV into a high-quality music server, without breaking the bank"

[orgel]

Deleted.

[orgel]

When you say to select Airplay instead of the DAC, I assume that you mean via the usual triangle-within-rectangle at the lower-right in iTunes. Is that right?

 

I think maybe the way is to select AirPlay in the A+ prefs: Audio System > Preferred Audio Device. I think this will only work with 10.8.x (because I don't remember AirPlay showing up as a general audio output option prior to 10.8), but it should work with any AirPlay-capable device, not just ATV2.

 

--David

[Superdad]

David:

Yes, it must be a new capability with A+ under 10.8 since earlier this evening I tried it out under 10.6 and did not see my ATV2 listed (except in its usual spot in iTunes).

 

If someone with A+ under 10.8 and an Airplay device (AE or ATV) would please check this out more definitively I would appreciate it. It seems to me that it would mark a big change for Apple to allow applications access to Airplay devices outside the triangle/rectangle of iTunes. Not that the user interface aspect of that is the big deal; more that it would seem to mean that the software>hardware access to Airplay devices has been opened up in Mountain Lion. Such could be a big deal for the hifi developer community.

 

If this is the case, and if A+ is able to perform its audio algorithms while more directly connecting to an Airplay device, then perhaps they or someone else will soon overcome the other Airplay limitations. Could have huge implications!

 

--Alex

[Bloodwound]

I don't think there is any reason to get past the 48khz resampling, jailbroken or not. Part of the reason that it resamples is to avoid buffer over/underruns.

Example: when using Airplay (or actually the old Airtunes audio only) protocol from the computer to an Airport Express is that the Airport slaves to the incoming stream. You "push" the audio from your computer to the AExpress and it tries to sync to the incoming stream. The ATV on the other hand use it's own timegenerator/clock/PLL (whatever you want to call it) and there it cannot sync to the incoming stream without getting buffer over/underruns, and therefore has to resample everything.

 

This can be verified by using Shairport (google it), after a while when the audioframes and/or buffer is too much out of sync, the music stops/skips/pops for a couple of seconds. Apparently RogueAmoeba has getting past this with their Airfoil Speaker but. They probably has som built-in login to skip/duplicate audio frames.

[dave_kiwi]

Good to know! When you say to select Airplay instead of the DAC, I assume that you mean via the usual triangle-within-rectangle at the lower-right in iTunes. Is that right? I guess Audirvana gets its hooks into iTunes/CoreAudio in a very different way than Pure Music and others.

That really makes me wonder: Since Apple's Airplay OS routines take over to convert and send the stream out to devices (ATV, AE, or 3rd-party Airplay receivers/speakers), how/when does Audirvana do its magic (memory-play, hog-mode, integer mode, upsampling etc.) when sending audio to Airplay devices? And is that only when Audirvana is in "iTunes integration mode"? I guess you can tell I have never used Audirvana (downloading trial now...).

 

While I am asking questions about it (which don't seem to be addressed on their sparse web site): Is Audirvana's Airplay compatibility only for OS X 10.8 and only with ATV2 (is 10.6 and AE left out?)?

 

Sorry if I am asking questions that you might not know the answers to. Airplay is very locked down with encryption and Apple is a bit hardnosed about it (licensing AP is not cheap). But I would find it exciting if Audirvana has somehow cracked Airplay! It might mean that someone (maybe Audirvana) could work around the downsampling and ALC conversion that has limited the appeal of Airplay devices for audiophiles.

 

You need to select "Airplay" within Audirvana Plus prefs --- NOT iTunes. Airplay only came into play with 10.8 as far as I am aware, for MacBooks, (not IOS devices) and yes, need ATV2 / ATV3.

 

I did - from memory - get direct mode to work once -- but after that had to disable, and integer mode is no go ... though it great to be able to play DSD files through the ATV:-)

[Superdad]

I don't think there is any reason to get past the 48khz resampling, jailbroken or not. Part of the reason that it resamples is to avoid buffer over/underruns.

Example: when using Airplay (or actually the old Airtunes audio only) protocol from the computer to an Airport Express is that the Airport slaves to the incoming stream. You "push" the audio from your computer to the AExpress and it tries to sync to the incoming stream. The ATV on the other hand use it's own timegenerator/clock/PLL (whatever you want to call it) and there it cannot sync to the incoming stream without getting buffer over/underruns, and therefore has to resample everything.

 

This can be verified by using Shairport (google it), after a while when the audioframes and/or buffer is too much out of sync, the music stops/skips/pops for a couple of seconds. Apparently RogueAmoeba has getting past this with their Airfoil Speaker but. They probably has som built-in login to skip/duplicate audio frames.

 

While I am not a s/w engineer, I think it is likely that what you are stating is not correct. The AE and ATV are Ethernet attached devices and they receive audio through the layers of the 802.x protocol stack. The packets don't always come in in order, and both devices have to buffer and assemble them for their internal DAC or Toslink/HDMI output. There is plenty of ram in an ATV for buffering of a high-bit-rate stream (the thing streams and processes HD video with no problem).

 

While I am not advocating for 24/192 AIFF over wifi (though 24/96 could work fine), wired CAT5 and Airplay devices are certainly capable. I think Apple could easily enable at least the s/w portion of Airplay to allow for high-res audio.

 

By the way, I own licenses to both Airfoil and AirServer. Both sound terrible to my ears.

I got excited about news that Audirvana Plus is directly supporting Airplay because if they are doing so with their own audio processing routines then that means developers are being allowed to pry deeper into Airplay components.

[Superdad]

You need to select "Airplay" within Audirvana Plus prefs --- NOT iTunes. Airplay only came into play with 10.8 as far as I am aware, for MacBooks, (not IOS devices) and yes, need ATV2 / ATV3.

 

I did - from memory - get direct mode to work once -- but after that had to disable, and integer mode is no go ... though it great to be able to play DSD files through the ATV:-)

 

Thanks Dave. Good to know. I only use my ATV2 for pulling music and movies (from various iTunes libraries around the house) and its not part of a critical system. So Audirvana's support of Airplay is intriguing to me mainly in that it indicates Apple has possibly opened some audio doors with Mountain Lion. I have been lamenting for years the (arbitrary, I believe) limitations of Airplay. Given that Airplay is so ubiquitous (in iTunes, iOS, and in a growing number of 3rd-party components--see: AirPlay Speakers | Everything AirPlay), it has frustrated me that it was mostly off-limits to high-end audio.

[Bloodwound]

While I am not a s/w engineer, I think it is likely that what you are stating is not correct. The AE and ATV are Ethernet attached devices and they receive audio through the layers of the 802.x protocol stack. The packets don't always come in in order, and both devices have to buffer and assemble them for their internal DAC or Toslink/HDMI output. There is plenty of ram in an ATV for buffering of a high-bit-rate stream (the thing streams and processes HD video with no problem).

RAM was never the problem. Of course the ATV streams and process HD fine, it pulls these streams and clocks them out via it's built-in clock sync.

Airtunes is *pushed*, and there is also sync issue which means that if you play from itunes and choose both computer and airtunes device they will play in sync. You cannot just allocate an insane amount of ram and let it drift forever. (And for cases of underruns you can't let it drift forever if you wanted to, because the buffer would run out )

 

Apart from this there is a approx 2 second buffer to let the packets arrive safely. This is not rocket science.

Sometimes Airtunes will give pops, so it's not like it is immune to bad packets or anything. Airtunes is UDP based so the airtunes device won't sit around and wait for missings packets. Mostly this thing works great as network packets in a normal LAN-environment arrives either 1) in order 2) if not in order, they still arrive timely within the buffertime. It doesn't matter if they are a little as the packets are time stamped.

[Superdad]

Bloodwound:

I promise I am not trying to be combative, but if your point is to say that the Airplay protocol is incapable (as opposed to just currently locked) of pushing out audio streams greater than 16/48, I'm still going to be stubborn and wait for better evidence than you have provided.

 

a) One can PUSH hi-def video (with audio) via Airplay to ATV2/3 (either from within iTunes on a computer or from an iPad) and it works perfectly. (I frequently push hi-def movies, stored on a shared network drive, from my iPad1 to my ATV2, using AirVideoServer to avoid having to transcode from MKV to MP4.).

 

b) Various other devices are capable of receiving "pushed" hi-res audio over Ethernet (e.g. Squeezebox, any DLNA Renderer).

 

c) Several standards exist (both open and proprietary) for multi-channel/multi-device audio/video over Ethernet. Cobranet, Ethersound, AVB, Dante--all these allow transmission of simultaneous, very low-latency media streams to >64 devices. (Greatest adoption of this stuff is in the pro-sound/pro-video markets. Woefully few consumer devices have licensed/embraced them.)

 

Airplay is nothing more than Apple's closed server/rendered/controller system. Bridgco (now SMSC/Microchip) did the original chipsets and encryption scheme for them. And Apple makes money allowing companies to license Airplay for the rendering devices. (I am certain you know all this.)

 

It is possible (though it would be odd given the ample processing power of the devices and the network) that both the Airport Express and ATV boxes are crippled in the audio department. Maybe Apple designed them around 16/44-48. I would accept that being the case.

I am just looking for proof that there are no inherent limitations (other than Apple being slow to catch up with--or uninterested in--audiophiles) preventing Airplay from someday pushing upwards of 24/192 over CAT5 or 24/96 over wifi. If/when it opens up, then we might see some audiophile Ethernet-connected devices from 3rd parties.

 

As I said a couple of posts up: If Audirvana is (under OS X 10.8) accessing an ATV2/3, sending memory-play and/or re-sampled streams, and getting around Apple's usual Airplay routines, then I will take that as a major clue that I and others may someday get their wish. Maybe it is time that I give Audirvana a call...

[dave_kiwi]

Just a idea, but me thinks the ATV 16 / 48 kHz limitation on ATV is tied to the nominal "rate" of most Movie DVD soundtracks etc.

 

If you look at Handbreak for "converting" DVD files to ATV friendly files you will notice that max sample rate is 48 kHz, and there is never a mention of bit rate.

 

Airplay is different from iTunes "home sharing" which has been demonstrated that 24 / 96 playback (and possible higher) with an iPad and CCK is possible.

 

After all ATV stands for Apple television :-), not an exotic high Rez audio playback device :-).

[dave_kiwi]

As I said a couple of posts up: If Audirvana is (under OS X 10.8) accessing an ATV2/3, sending memory-play and/or re-sampled streams, and getting around Apple's usual Airplay routines, then I will take that as a major clue that I and others may someday get their wish. Maybe it is time that I give Audirvana a call...

 

Certainly Audirvana + is working its re-sampling magic - in a downwards direction :-), for anything non Redbook when doing "AirPlay" -- guess the advantage is that Audirvana + uses a "superior" re-sampling algorithm as opposed to iTunes.

[Bloodwound]

Bloodwound:

I promise I am not trying to be combative, but if your point is to say that the Airplay protocol is incapable (as opposed to just currently locked) of pushing out audio streams greater than 16/48, I'm still going to be stubborn and wait for better evidence than you have provided.

That is all not I'm saying. Of course 32/384khz is technically possible if Apple wanted to.

 

a) One can PUSH hi-def video (with audio) via Airplay to ATV2/3 (either from within iTunes on a computer or from an iPad) and it works perfectly. (I frequently push hi-def movies, stored on a shared network drive, from my iPad1 to my ATV2, using AirVideoServer to avoid having to transcode from MKV to MP4.).

When you are pushing video via Airplay to the ATV2/3, you really aren't pushing. The iPad tells the url of the stream and tells the ATV2/3 to fetch it. One exception might be Airplay mirroring. I guess if you use an iPad app that plays mkv files and stream to the ATV, mirroring will be used since the ATV does not support mkv. The client exports its master clock which is used for A/V synchronising and clock recovery.

 

b) Various other devices are capable of receiving "pushed" hi-res audio over Ethernet (e.g. Squeezebox, any DLNA Renderer).

They are fetched, not pushed.

 

I don't mean to get all too technical, my idea was that Apple hardcoded the ATV2/3 to resample the audio instead of using some clever clock recovery or whatnot. Not that it is impossive in the general scheme. And since they did it this way, I don't think you can disable the resampling whether the ATV is jailbroken or not. I am not trying to *convince* you or anybody, or saying its a definite fact, lets just call it my own personal opinion/guessing.

[Superdad]

Thanks all for your cogent and friendly replies. (Lately some of the threads here at CA have gotten combative on even simple subjects. Tiresome.)

 

Bloodwound: My iPAd 1 is not capable of official Airplay mirroring, so it is not clear to me how it works when I sling MKV files to my ATV2 using AirVideo.

 

Again all: My interest is mostly about what might (someday?) be possible within the Airplay software protocol/drivers/etc. I recognize that Apple designed the AE and ATV units in a specific and tight way. But they also license Airplay to a small raft of third-parties for wireless speakers, receivers, network players, etc. And AFIK, even units (like the Pioneer N-50) which can do 24/192 as a DLNA renderer, are, when receiving/fetching AirPlay streams, limited to 16/48 (and forced to do live conversion of everything back from ALAC).

Other than Apple being stubborn or uninterested, I really can see no good reason for this. But maybe we will see a change, and I am taking Audirvana's compatibility with AirPlay under Mountain Lion as an early sign...

 

Cheers,

ALEX

[Bloodwound]

 

Bloodwound: My iPAd 1 is not capable of official Airplay mirroring, so it is not clear to me how it works when I sling MKV files to my ATV2 using AirVideo.

 

 

 

Cheers,

ALEX

Aha, you use Airvideo. Actually your iPad tells your ATV the url to the Airvideo stream. So in other words, the ATV connects directly to the Airvideo server, which does real time transcodes/remuxes from MKV into MP4 or HLS.