AppleTV Dac really 16bit@44.1khz sampling rate?

For audio, PCM output seems to be limited to 48kHz 16bit it seems.
This is more than adequate when playing back CD rips eitehr lossless or lossy as the original audio never exceeded this.

For movie audio it's not qute as clear - AppleTV will not in theory be doing any conversion, merely passing the dolby digital bitstream to the audio processor/receiver for offboard decoding either via HDMI or optical. You'd only get stereo or at best DPL from analogue out anyway so I don't think the quality of the internal DAC is an issue (and it will only be used for the analogue out).

The question is what quality audio is stored in Apple movies - I suspect it's bog standard dolby digital at best, as all the new-fangled 'HD' audio variants would require significantly higher room to incorporate in the file this could only be done to the detriment of picture quality given the stipulation of h264 files having a bitrate of <5 Mbps - some have achieve higher but this is a key factor.

AC

Message was edited by: Alley_Cat

The question remains - why doesn't AppleTV output 96/24 digitally? From what I have read, the hardware is capable of that output rate, but is intentionally limited to 48/16 by Apple.

DVD audio weighs in at bitrates of up to 9.6 Mbps, so the tv hardware is not capable of playing it.

Your comment "AppleTV is not a high-end product" doesn't hold water. My cheap DVD player can output a 96/24 audio stream on the optical output. That's not high-end, it is mainstream now.

Your cheap DVD player cannot output 96/24 unless you are playing a DVD audio disc and even then video requires a dual zone disc which means you cannot output video and 96/24 together

I have a lot of 96/24 music that the AppleTV downsamples to 48/16. Why?

Because as already pointed out to you very few people use 96/24 and the additional cost of creating a device for you and a handful of other audiophiles would have to be borne by the vast majority of other users who have no interest in listening to audio at these specifications.

The bitrate for 96/24 is 4mbps.

96 x 24 x 6 is 13.8 Mbps, so you are either heavily compressing your audio or limiting yourself to 2 channels which are not always available. Uncompressed you will struggle to deliver. Compressing something too much is worse than lightly compressing a lower resolution and limiting what type of 96/24 you could play would be farcical.

Oh and let's not forget there is no audio available in these formats.

The Beatles DVD........

You cannot legally copy this content, so apart from almost non existent unprotected sources, *there is no content available in these formats*. Do you really think Apple would get a license to support the playback of content that is almost certainly illegally obtained.

just like I rip CDs

No not like that at all, you rip CD's legally.

AppleTV currently provides 1080p video......

It outputs 1080p it can only handle 720p and even then not at 30 fps, as has been said before it isn't a high end device. In fact if we had your audio at 4 Mbps we really wouldn't get much video at all.

That would be 192/24. I've been talking about 96/24 which the AppleTV's hardware is capable of playing, but it is software-restricted.

9.6 Mbps is maximum datarate a DVD audio disc could handle, 192/24 exceeds this and has to be compressed unless we are limiting ourselves to 2 channels again.

It is difficult to use 96/24 when it is not there.

It might not be there on the tv, I was talking in general, it's only a handful of people who buy DVD-A and SACD's, the majority aren't interested.

Additionally, the AppleTV hardware currently can support 96/24. So there would not be any additional cost.

Firstly there would be the cost of licensing (which they wouldn't likely get anyway, more likely the cost of a court case). Secondly 96/24 might work in limited formats, but (ignoring the legality for a moment) 96/24 doesn't come in these limited formats and to avoid half a solution the tv would need to be much more powerful than it is now.

AppleTV supports 1080p video even though the "vast majority" of users have little or no source material at that level of quality.

As I said before, no it doesn't. It supports 720p at 24 fps and this format is readily available from itms as movies, tv shows and podcasts as well as over air through broadcast tv. But more importantly people notice the difference between SD video and 720p and appreciate it, the majority of people don't notice or don't have the facility to notice the difference between CD an 96/24.

camper wrote:

speakerfritz wrote:

Finally some sanity here. Thank you.

I was beginning to be concerned with the steady stream of comments that Apple should strive for mediocrity with the AppleTV.

Camper

With respect, it's not a question of sanity, more a question of reality.

The reality is the device doesn't do what you want it to do. Neither I or other posters begrudge you the desire for it to offer better quality output, and it indeed seems likely that this is crippled in software, and not necessarily by the hardware, though it would be wrong to assume this is intentional. It's more likely an oversight.

Apple's business model for this device has firmly shifted to playing back audio and video from the iTunes store, and though better than CD audio can be obtained legally in many ways, I think they've overlooked this on the basis that ripping audio from DVD-Audio and SACD would be almost universally be seen as illegal as it would circumvent copy protection.

The only proactive thing to do is send feedback to:

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

You have already done that I believe - do not feel dissapointed by the lack of response - that is standard, it does not mean they haven't read the comments. I got frustrated with lack of any response about music video playlists, then it just happened in 2.2 update.

AC

speakerfritz wrote:
The answer, after much research, is that the cirrus chip used in the DAC circuit is capable of up to 24bit@192khz. The limitation to 16bit@44.1khz is simply the software.

For CD sourced media, 16bit@44.1khz is fine. But for video content with accompanying high quality audio, down converting to 16bit@44.1khz is not a consumer expectation. Since the hardware can support industry standard bit and sampling rates, I'm optimistic, that at some point, the software, will catch up to the hard ware that is already in place.

Finally some sanity here. Thank you.

I was beginning to be concerned with the steady stream of comments that Apple should strive for mediocrity with the AppleTV.

The AppleTV is not a high end product...Similarly with audio the quality is very reasonable but you shouldn't be expecting to compare it to true HD audio or even SACD, ...

The question remains - why doesn't AppleTV output 96/24 digitally? From what I have read, the hardware is capable of that output rate, but is intentionally limited to 48/16 by Apple.

Your comment "AppleTV is not a high-end product" doesn't hold water. My cheap DVD player can output a 96/24 audio stream on the optical output. That's not high-end, it is mainstream now.

I have a lot of 96/24 music that the AppleTV downsamples to 48/16. Why?

camper wrote:

Your comment "AppleTV is not a high-end product" doesn't hold water.

Sorry I disagree. It is not a high-end audio product.
It provides the equivalent of CD audio which is still the prevailing audio standard for the vast majority of consumers.

DVD-Audio and SACD are niche products that never took off, though undoubtedly sound better than CD.

My cheap DVD player can output a 96/24 audio stream on the optical output. That's not high-end, it is mainstream now.

It may not be high-end and may have more audio features than AppleTV but they are entirely different products and just because that cheap DVD player can, doesn't mean AppleTV must provide the same features.

Yes, the hardware may be up to better output and I too would love the feature, but currently it doesn't have it.

I have a lot of 96/24 music that the AppleTV downsamples to 48/16. Why?

Because it's primary audio function is to play back CDs ripped with iTunes or songs from the iTunes store which are not 96/24.

You are in a minority having a lot of 96/24 music.
You are not typical for AppleTV's target consumer group.

Sorry, but that's just the way it is.

I too wish it was different.

speakerfritz wrote:
For CD sourced media, 16bit@44.1khz is fine. But for video content with accompanying high quality audio, down converting to 16bit@44.1khz is not a consumer expectation.

It doesn't do that for multichannel audio - it simply passes the audio bitstream (across optical anyhow). That's not to say Apple may not be giving you lower quality multichannel audio when encoding to keep overall bitrates within spec for the device.

mwheelerk wrote:
I just made a post with a similar interest. I am considering the Apple TV but because I suspect you are right about the sampling rate I am considering adding an external DAC to up-sample audio.

AppleTv provides excellent sound output but it's hardly designed or touted as an audiophile audio product - many feel that sound quality via optical is extremely good, I certainly do.

AC

These formats produce massive bitrates, they are what are known as optional formats so would need another audio track sat alongside them, then there's licensing and the problem of delivering such large files to the AppleTV

The bitrate for 96/24 is 4mbps. Not really massive. I routinely "deliver" 96/24 files from my Macmini to the AppleTV without any problem whatsover. I have no idea of what you speak when you say "the problem of delivering such large files to the AppleTV". In fact there are over 20 such files sitting on my AppleTV as I type this, and that number increases nearly daily.

Oh and let's not forget there is no audio available in these formats.

The Beatles DVD "Love" allows my DVD player to output the music at 96/24. I captured that data stream to a disk file and now that data file resides on my AppleTV, just like I rip CDs.

Chesky download site adds 96/24 music: http://mobile.twice.com/index.asp?layout=article&articleid=CA6603951

Nine Inch Nails album The Slip available free of charge in 96/24 format: http://dl.nin.com/theslip/signup btw, this 96/24 set of files copied over to my AppleTV without any problem. 🙂

DVD audio weighs in at bitrates of up to 9.6 Mbps, so the AppleTV hardware is not capable of playing it.

That would be 192/24. I've been talking about 96/24 which the AppleTV's hardware is capable of playing, but it is software-restricted.

Because as already pointed out to you very few people use 96/24 and the additional cost of creating a device for you and a handful of other audiophiles would have to be borne by the vast majority of other users who have no interest in listening to audio at these specifications.

It is difficult to use 96/24 when it is not there.

Additionally, the AppleTV hardware currently can support 96/24. So there would not be any additional cost.

AppleTV supports 1080p video even though the "vast majority" of users have little or no source material at that level of quality.

The tv is not a high end product, video at SD is comparable to DVD but HD is not comparable with Blu-ray and the user shouldn't expect it to be, although personally I don't think the difference is worth jumping up and down about.

Similarly with audio the quality is very reasonable but you shouldn't be expecting to compare it to true HD audio or even SACD, again it's a personal opinion but for me the difference isn't that big of a deal.

If these differences between the tv and high end equipment matter to you then perhaps you are looking at the wrong product.

up-sampling dont add the infomation lost when the sound was sampled
the only real reason you would ever want to up-sample is if you mean
to do modifications to the audio stream afterwards where the higher resolution
would yeal a better result

think if it like if you dec the size of your photo to mail it
then the reciver cant just inc the size and zoom into all the info
lost when you dec the size

speakerfritz wrote:
The answer, after much research, is that the cirrus chip used in the DAC circuit is capable of up to 24bit@192khz.

I wouldn't know what chip was used inside the tv, but it doesn't really matter, you are missing the larger picture.

These formats produce massive bitrates, they are what are known as optional formats so would need another audio track sat alongside them, then there's licensing and the problem of delivering such large files to the tv.

Oh and let's not forget there is no audio available in these formats.