Can HD audio downloads work with iPads?

[Dave2002]

I'm just experimenting tonight. I've never fully "got on" with the Apple TV we've had for a few years, but tonight I plugged the optical cable from my DAC in, and am now listening to some baroque music by Franz Xaver Richter (Naxos CD) courtesy of Amazon. However, this is an Auto Rip mp3 of a CD, and the quality is only just about bearable for background listening.

Is there any way of getting HD audio (or even just decent CD quality downloads) on to new iPads, and then listening to them via (say) Airplay - or does the technology (with the wireless link, and possibly software constraints) just compromise this approach too much?

I like the idea of the kind of convenience these devices offer (which work quite well with TV and iPlayer), but not so much if the sound quality is only so-so passable.

[richardfinegold]

It's an interesting question that I don't know the answer to. I have only very belatedly--as in the last month--embraced doing High Resolution downloads. I do note that when I once attempted to purchase a High res download from Presto while using the iPad the sale would not go through. I then reconsidered and decided it wasn't a good idea so I switched to my laptop. The download proceeded uneventfully.
It defeats the purpose to play a High Res download through a lossy playback system such as bluetooth or AirPlay, although I have to admit they sound better than I thought they would
btw, the new ATV come with a bit of Hard drive, in theory enough to handle some High Res downloads

[Dave2002]

It's an interesting question that I don't know the answer to. I have only very belatedly--as in the last month--embraced doing High Resolution downloads. I do note that when I once attempted to purchase a High res download from Presto while using the iPad the sale would not go through. I then reconsidered and decided it wasn't a good idea so I switched to my laptop. The download proceeded uneventfully.
It defeats the purpose to play a High Res download through a lossy playback system such as bluetooth or AirPlay, although I have to admit they sound better than I thought they would
btw, the new ATV come with a bit of Hard drive, in theory enough to handle some High Res downloads

I"m not sure that AirPlay is necessarily lossy - but I don't know the details sufficiently well. I think Bluetooth can't do it, as the data rates are too low. Basic Bluetooth (1 and 2) doesn't have the capacity, but Bluetooth 3+HS - which also relies on an 802.11 link might be able to do it.
Bluetooth 4 might also be able to do that, as it is similar to Bluetooth 3, but has features for low energy usage. The claimed max data rate for the enhanced Bluetooth variants ia around 25 Mbps.

https://en.wikipedia.org/wiki/Bluetooth#Bluetooth_v2.1_.2B_EDR

Some Bluetooth audio devices use the aptX codecs - https://en.wikipedia.org/wiki/AptX - some of which are lossy, but there is a lossless variant - aptX Lossless. Whether any consumer devices actually use that yet I don't know.

CD quality reproduction using iPads over Airplay could work, I think a simple check on feasibilty is on data rates. CD audio is approx 1.4 Mbps so a communications channel with a rate exceeding that would be needed to make that work. Using FLAC or ALAC lossless encoding, could probably reduce that by 50%, so essentially a communications channel running at over 1 Mbps might work OK, though would require a decoder at the receiver end. A few years ago broadband systems were not delivering this, and neither were most domestic LANS, either wired or wireless, but now it is quite posible to have quite high data rates on a domestic LAN, even a wireless one - though such are often temperamental, depending on environmental conditions, and other loads on the network.

So CD quality audio from iPads ought really to be possible, but that still leaves a question mark over Hi Res audio formats. What I don't know there is what the actual data rate is for a typical Hi Res audio stream, though I'm guessing that 10 Mbps would be good enough for many 2 channel recordings. This shoiuld now be within the range of feasibility for some domestic LAN networks and devices, but whether iPads could deliver I'm still not sure. What could work is to use a tablet, such as an iPad, in conjunction with a file server on the same network, which is, after all, what Logitech were doing with their streaming systems years ago before they bailed out - and I think Sonos are doing with theirs even today. In that mode the tablet (or phone e.g Android phone) simply sets up the connection between the file server and the playback device on the LAN, which may be wired to give satisfactory throughput.

PS: Re the data rates of Hi Res audio, compare with CD. 24 bits cf 16 bits per sample - factor 1.5. 96 kHz re 44.1 factor 2.18. 192 kHz vs 44.1 factor 4.36. 384 kHz vs 44.1 factor 8.72 - so "sane" Hi Res rates should be no more than 6-10 times higher than CD rates and of course FLAC or similar lossless encoding can be used.

[johnb]

What could work is to use a tablet, such as an iPad, in conjunction with a file server on the same network, which is, after all, what Logitech were doing with their streaming systems years ago before they bailed out - and I think Sonos are doing with theirs even today. In that mode the tablet (or phone e.g Android phone) simply sets up the connection between the file server and the playback device on the LAN, which may be wired to give satisfactory throughput.

After Logitech discontinued the Squeezebox product range there were various people in the "Squeezebox community" (i.e. people who contributed to the SlimDevices forum) who successfully tested using their iPads in this manner. They substituted the iPad plus a Squeezebox Player App for the Squeezebox Touch and connecting the iPad to a USB DAC using an iPad Camera Connection Kit. I seem to remember that the maximum sample rate was limited to 48 kHz.

[Cockney Sparrow]

So - speaking from inexperience and lack of knowledge** and if I understand correctly - a recording was downloaded (and purchased at a premium) and stored in a file in a sample rate of 96khz and then it was replayed at 48khz (as opposed to CD at 44khz).

(** Because I can't hear the difference above FLAC at CD quality. So I don't buy Hi-Res)

[johnb]

.....They substituted the iPad plus a Squeezebox Player App for the Squeezebox Touch and connecting the iPad to a USB DAC using an iPad Camera Connection Kit. I seem to remember that the maximum sample rate was limited to 48 kHz.

It seems that the early iPads did have a 48kHz limit but this was removed on later models.

Also, not all USB DACs were compatible with the iPad Camera Connection Kit output.


[Later Edit] I see that the iPad "Lightning to USB Camera Adapter" performs the same function as the earlier iPad Camera Connection Kit.

Also, I read that iOS 7 or later is required.

Additionally it seems that most USB DACs can be configured to work with the more recent versions of iOS.

[johnb]

I"m not sure that AirPlay is necessarily lossy

I seem to remember reading somewhere that when using AirPlay with iTunes, iTunes converts to music into a lossless format before streaming. Incidentally, doesn't AirPlay have a maximum sample rate of 44.1kHz?

[Dave2002]

After Logitech discontinued the Squeezebox product range there were various people in the "Squeezebox community" (i.e. people who contributed to the SlimDevices forum) who successfully tested using their iPads in this manner. They substituted the iPad plus a Squeezebox Player App for the Squeezebox Touch and connecting the iPad to a USB DAC using an iPad Camera Connection Kit. I seem to remember that the maximum sample rate was limited to 48 kHz.

That's interesting, but would require the iPad to be wired up, which loses some of the benefits of a mobile device. However, for anyone who only has an iPad, or happens to have a spare one or two lying around, that could be useful.

btw, the new ATV come with a bit of Hard drive, in theory enough to handle some High Res downloads

I assume that's SSD type of memory.
How big a "bit" is that? It might be useful for some video applications, such as catchup TV - where I think the ATV 3 did not have any such memory. I do recall that the very first ATVs did have extra storage for the content.

[Stunsworth]

How big a "bit" is that? It might be useful for some video applications, such as catchup TV - where I think the ATV 3 did not have any such memory. I do recall that the very first ATVs did have extra storage for the content.

There are two models of ATV 4, one with 32 gig of memory, the other with 64. I have the latter.

[Dave2002]

There are two models of ATV 4, one with 32 gig of memory, the other with 64. I have the latter.

What does the memory do for you?

[Stunsworth]

What does the memory do for you?

It gives you storage space for apps and their data.

[Dave2002]

It gives you storage space for apps and their data.

Ah - is it like a Roku or othe gadget which can download/install "apps" for many different channels?

I suppose the ATV 3 has partial similarity, though as I noted before, anything I might want to watch - such as medici.tv - apart from the basics - is not available, and renders it of limtied use for UK users.

[Stunsworth]

Ah - is it like a Roku or othe gadget which can download/install "apps" for many different channels?

Yes, so there are the usual Netflix, YouTube and iPlayer apps, also the Berlin Phil's digital concert hall. All of which load a lot more quickly, and are more responsive, that the equivalent on my TV or Blu-Ray player.

[Dave2002]

Trying to get HD audio out of an iPad may be tricky. There is a player App, called PlayerXtreme which may play back Hi Res files including .flac files, but the problem then is getting the files onto the iPad in the first place. This particular tool does have its own somewhat clunky data transfer tools built in, so if a user has downloaded files onto another "regular" computer, then they can be pulled across the local LAN. Possibly this is going to be too much hassle for many people, so they won't bother, and end up listening to poor mp3 quality streams or downloads instead.

I have always disliked the way iOS tries to pretend that files don't exist, because apparently a significant part of the user base don't understand hierarchical file systems (or any file system), so Apple "deliberately" didn't provide a file system, so that "files" are somehow stored with each application.
Then some applications may be able to talk to each other - e.g Drop Box - but the whole thing is a mess really. This means that similar applications may end up storing copies of the same data, and the whole data transfer business can be a nightmare.

From a software engineering point of view, having different bits of software doing essentially the same thing is generally considered to be really bad practice, but I don't suppose that thought bothered the Apple people at all. Well, certainly not the marketeers anyway, who very frequently don't have a clue about technology stuff.

OK - Apple claims that using iCloud will overcome most of the issues, but I am holding out against being forced to use iCloud.