Airplay & downsampling

Why would it be necessary to have a new AE? Isnt the job of the AE just to pass along what it gets from the wireless stream? Or is it a limitation in the "thing" that turns the stream into the optical signal? surely its possible to send hirez via toslink with a good cable ?

Hi all,

I'm convinced it has to to with the AirPlay protocol as such.

I have a Denon avr4311 which is AirPlay enabled. The receiver can accept dlna stream of 24 bit / 96 kHz. When I use AirPlay from iTunes (pc) I can see on my TV screen i only get 44.1 kHz from a 24 bit / 96 kHz ALAC source.

This has been confirmed by a Denon Engineer (see my previous post).

I read that Apple TV goes to 48 kHz but what is the input signal? Is there no upsampling taking place?

I believe Apple has the key in their hands...

There's nothing in the AirPlay protocol that prevents it from working at higher sample rates or bit depths, but the current generation of AirPlay devices seems to be limited to streaming at 44/16 resolution. This is true even of Apple TV which, despite having a 48/16 optical output, also streams at 44/16 when used with iTunes, iPod, etc. This means that any 48/16 or higher content you may have will first be downsampled to 44/16 by iTunes, etc. for streaming before being upsampled again to 48/16 by ATV, losing quality in the process. (AirPort Express simply output the 44/16 without any further conversion.)

Having experimented with the Audio MIDI Setup app, I can confirm that this makes no difference to AirPlay streaming via AE or ATV, so I guess we're stuck with 44/16 for the time being. What would happen if some third-party software tried to stream at a higher sample rate or bit depth is anybody's guess – for example, the device might simply reject the stream – but given that AirPlay is a proprietary protocol, I can't see this happening any time soon.

What's slightly frustrating thing about all this is that a lot of these restrictions could probably be lifted via software updates to iTunes and AE/ATV as the hardware appears capable of supporting higher bit rates (e.g. multi-channel surround sound via Apple TV). However, since high resolution audio is not a priority for Apple, they appear to have restricted AirPlay devices to work with CD/iTunes formats only, which use a 44/16 audio resolution.

If people would like to improvements in this area, a good place to start would be reporting the issue to Apple via the following forms:

http://www.apple.com/feedback/appletv.html

http://www.apple.com/feedback/airportexpress.html

The more people that do this, the more chance there is of this happening! Personally, I'd love to be able to stream high definition and/or multi-channel audio to my amplifier via AirPlay, and this would certainly buy Apple a good following in the audiophile market… Apple TV 3, anyone? 😉

Personally. I'm wondering whether you can stream 24/96. Apple TV and AE seem to have limited DACS but other companys enable Airplay in slightly higher end audio gear, can you stream 24/96 to those?

I understand Airplay streams Apple Lossless, ALAC. You can have 24/96 ALAC files. Is it the protocol that limits it? I don't know enough and its quite tricky finding out.

I just bought a Philips Fidelio product, sounds very good, seems to upsample MP3s (although you can put the lost info back in) but is limited to 16/44.1, I presume that's the DAC. Once more, 16/44.1 is a great sound.

Another point is that Apple staff and Philips staff have very little idea what their products do...

The DAC is only required for analogue output, not digital, so it's not a bottleneck for streaming as such.

There's no reason why a device that supports higher audio resolution, e.g. 24/96, shouldn't be able to accept ALAC streams at this rate, it's just that none of the current devices appear to do so, possibly because the AirPlay support in iTunes etc. is limited to 16/44 (this restriction may even be mandated by Apple to ensure maximum compatibility).

Even a device with a 16/44 DAC could theoretically downsample higher resolution streams for analogue output, but offer a digital pass-through at the original resolution. Indeed, the existing AE/ATV hardware may well be capable of doing just that, it's just not supported by the current firmware or iTunes application.

I don't think the current Airplay implementation allows higher resolutions.

I tried the Airplay plug-in with Foobar. The only 'downside' of it is it can only stream the resolution you are playing (so no down- or upsampling).

I selected my Denon AVR-4311 (which I know can handle 24/96) as playback device.

When playing 16/44.1 it works great, when going to 24/96 sources nothing happens.

In both cased I used ALAC format. I didn't try (yet) flac, mp3 or other... since I connected to my iTunes library.

So in theory Airplay might be capable of streaming 24/96, the implementation at the receiver side does not accept it.

Anyhow, I really like the Airplay funtionality, DLNA does not allow gapless streaming which is a real downside of it.

Airplay together with the remote function (iphone/ipod/ipad) it makes live not only easy but would be very welcomed by audiophiles when adding the high resolution capabilities.

The best would be that devices are autosensing their capabilities and the Airplay stream is adapting to that one.

Audioengine released a wireless 24 bit 96khz streaming option, the D2 for $600. It creates it's own wi-fi network and can support 3 DACs receiving the wireless signal. The sending/broadcasting device plugs into USB on your mac. The DAC receives the 24bit 96khz music wirelessly. You could plug an external DAC into the receiving unit if you want and bypass the internal DAC.

The logitech squeezebox touch also streams 24 bit 96khz music on your existing wi-fi network.

Has anyone tried the new AE (dual band) audio quality yet? I am especially interested in the analog sound quality, but I am also curious whether the digital passthrough over Airplay has been improved or is it still stuck at 16/44.1

This seems to answer the question very well at least: http://www.computeraudiophile.com/content/465-new-apple-airport-express-bit-perf ect-still-limited/comments2.html

Thank you! This is exactly what i was looking for!

Good 🙂

16/44 limitation is by current Airplay limitation. I have tested using a Pioneer VSX-1121. Airplay from iTunes comes over as 16/44. I've even send files that are 24/96 within iTunes, but they get knocked down to 16/44. When I use the Pioneer to play the same files, but in .flac from my NAS, they come to the Pioneer as 24/96.

I know that this thread is a bit old, but I've been wondering whether or not Apple TV (3rd gen) reduces the quality of streaming music the same way AirPlay does. My impression is no: I have my apple TV plugged directly into my amp via an optical cable for the sound (and via an HDMI, for the image). If I stream music from my Apple TV directly, instead of from my phone *to* the Apple TV, the music is definitely louder and, it seems to me, less compressed. Anyone else have the same impression or know how to verify the above?

PS My amp (a Denon) does have a "restorer" feature for digitally recorded music that does improve the sound, but I still perceive a difference when it comes directly from the Apple Tv.

Good question. Although I cannot 100% verify your impression I do have the same impression. I used the ATV2 for a while to listen to music through Airplay and iTunes Match directly on the ATV2. They were both connected optically to a cambridge audio DACmagic, in your case the build in DAC of the Denon AVR, which is the biggest determinant of audio quality (together with the speakers of course 😉 ). My experience was that streaming directly from iTunes match on the ATV2 (preferably using a UTP cable instead of wireless, although the difference is really small "they" say it makes a difference) sounded a lot more dynamic than streaming over Airplay from iTunes/iPhone/iPad. I also wondered why this makes such a big difference since you'd say it's just 1s and 0s.. there are probably more than a dozen factors playing a role here but when I asked a guy in a HIFI store his answer was: "When you stream audio instead of data over the air, you know you're in trouble!"

I think the difference is that when you use AirPlay, you actually push music over the air (using iTunes or iOS as music player/converter from data to audio) whereas with iTunes Match you pull data (not audio) from Apple's servers. This way the ATV is the source of audio and from there it only has to go through an optical cable to reach your DAC, no AirPlay involved.

Makes sense? I don't know, at least this is my impression 🙂

Vanerp wrote me a interesting reply that I cannot seem to find on this forum. First of all, thanks, Vanerp--and I think you and your audiophile friend are right about streaming over air vs. pulling from the cloud directly. If you think of it, pulling it to your phone/device and then sending it back to Apple TV certainly would take up more bandwidth than a direct, ethernet provided stream to the Apple TV. (I, too, connect my Apple TV via ethernet cable; I also separate sound from image, as described above.) I, too, am not sure, becasue the music from the Apple TV is always louder than that streamed over another device to it, but it does seem more dynamic, too. It's nice to know someone else has the same impression, even if we can't verify why.

Now if Apple would just come up wiht a slightly more convenient remote app --one that would allow for manipulation of the volume, in particular --but then, I suppose I'm really wanting to control the amplifier, not the Apple TV, which doesn't seem to have any sort of volume/signal control.

Thanks again, Vanerp!