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bigdaddycool1
Feb 23, 2008, 08:42 AM
I am considering using the Apple TV as a way to store a meaningful portion of my CD collection so I can play them on my home stereo without the hassle of CDs and with the benefit of the iTunes UI. My problem is that the bitrate on my Mac's iTunes collection is typically 192 or 256, and through burning music at that resolution onto a CD and playing on my home stereo, I know this is discernably worse than CD quality. I could store all my music in lossless format on my Mac, but my problem there is that I would be able to store a lot less music on my iPod. With a 160GB Apple TV, this wouldn't seem to be an issue. My question then is two-fold. Does anyone have suggestions on how I could store higher-bitrate music on Apple TV than what I'd like to be syncing to my iPod, and what is the most efficient way to get that music onto the Apple TV in the first place? Thanks in advance for any suggestions.



richpjr
Feb 23, 2008, 08:49 AM
I am considering using the Apple TV as a way to store a meaningful portion of my CD collection so I can play them on my home stereo without the hassle of CDs and with the benefit of the iTunes UI. My problem is that the bitrate on my Mac's iTunes collection is typically 192 or 256, and through burning music at that resolution onto a CD and playing on my home stereo, I know this is discernably worse than CD quality. I could store all my music in lossless format on my Mac, but my problem there is that I would be able to store a lot less music on my iPod. With a 160GB Apple TV, this wouldn't seem to be an issue. My question then is two-fold. Does anyone have suggestions on how I could store higher-bitrate music on Apple TV than what I'd like to be syncing to my iPod, and what is the most efficient way to get that music onto the Apple TV in the first place? Thanks in advance for any suggestions.

Virtually all the music I purchase is on CD just to address this problem. I burn two copies of each CD: one in VBR ACC format for the iPod and one copy in Apple Lossless format. I created a smart playlist for each type and use them to synch (the ACC files to the iPod and the lossless for listen on my home stereo system). Works great, but obviously takes more time and space.

MikieMikie
Feb 23, 2008, 09:08 AM
Rich has some good approaches that I hadn't thought of, especially using smart folders in iTunes.

I find that with my 160 GB :apple:TV, I can handle syncing some, and streaming others. I have also taken to changing the bitrate based on the type of music I am ripping. Some CDs merit lossless quality, others do not.

I originally purchased the :apple:TV for film, all of which I stream, but now find that I am thrilled at the ease of access it provides for my music, most of which is synced.

richpjr
Feb 23, 2008, 05:29 PM
Rich has some good approaches that I hadn't thought of, especially using smart folders in iTunes.

I find that with my 160 GB :apple:TV, I can handle syncing some, and streaming others. I have also taken to changing the bitrate based on the type of music I am ripping. Some CDs merit lossless quality, others do not.

I originally purchased the :apple:TV for film, all of which I stream, but now find that I am thrilled at the ease of access it provides for my music, most of which is synced.

I am experiencing the same thing. I mainly bought the ATV to rip my DVD collection and have all movies available without hunting for discs, but streaming my lossless movies into the room where my home theatre system is has gotten a lot of use as well.

bigdaddycool1
Feb 23, 2008, 09:14 PM
I understand what you're proposing regarding playlists, but doesn't having two formats of each CD give the appearance that you have doubles of everything when you look at your collection through something like coverflow? With the HD DVD format wars over, I'm almost wondering if I shouldn't wait to see if Apple releases a version of :apple:TV with a Blu-ray disc player, and then I could dispense with all of the hassle of loading the huge lossless files onto my Mac. I would then presumably be able to rip straight onto the device.

richpjr
Feb 23, 2008, 09:49 PM
I understand what you're proposing regarding playlists, but doesn't having two formats of each CD give the appearance that you have doubles of everything when you look at your collection through something like coverflow? With the HD DVD format wars over, I'm almost wondering if I shouldn't wait to see if Apple releases a version of :apple:TV with a Blu-ray disc player, and then I could dispense with all of the hassle of loading the huge lossless files onto my Mac. I would then presumably be able to rip straight onto the device.

You see two copies of each song if you are looking in the music folder under library. If you look under either of the smart playlists (I call them ACC Music and Lossless Music) only the copy of the song in that playlist appears.

Avatar74
Feb 23, 2008, 10:49 PM
I am considering using the Apple TV as a way to store a meaningful portion of my CD collection so I can play them on my home stereo without the hassle of CDs and with the benefit of the iTunes UI. My problem is that the bitrate on my Mac's iTunes collection is typically 192 or 256, and through burning music at that resolution onto a CD and playing on my home stereo, I know this is discernably worse than CD quality. I could store all my music in lossless format on my Mac, but my problem there is that I would be able to store a lot less music on my iPod. With a 160GB Apple TV, this wouldn't seem to be an issue. My question then is two-fold. Does anyone have suggestions on how I could store higher-bitrate music on Apple TV than what I'd like to be syncing to my iPod, and what is the most efficient way to get that music onto the Apple TV in the first place? Thanks in advance for any suggestions.

I want to preface this by saying that I'm speaking as someone who has professionally recorded, mixed and mastered CD audio as well as Dolby Digital soundtracks that meet the fidelity criteria of Dolby Laboratories in order to qualify for usage of their logos and trademarks.

Ok, aside from the fact that 128 Kbps is acoustically transparent to 16-bit LPCM according to SMPTE and AES... and the fact that 16-bit LPCM is itself far from pristine quality...

I ran some SNMP monitoring on AirPort Extreme and found that the bitstream sent when using AppleTV as remote speakers in AirTunes mode doesn't differ much from 128 Kbps AAC to 24-bit Linear PCM.

However, when using AppleTV, the bitrates vary in a manner correlated with the bitstream of the source. For example, a 256 Kbps AAC file generates throughput of around 288 Kbps. A 16-bit LPCM bitstream generates throughput of around 1712 Kbps (16-bit LPCM @ 44.1kHz is 1411 Kbps), and a 24-bit LPCM bitstream (2308 Kbps) generates a throughput in AirPort Extreme of around 2560 Kbps.

However, no matter what the source, when it reaches AppleTV, it is reconstructed as 16-bit, 44.1 Kbps LPCM, regardless, before making its way to a receiver.

What this tells me is two things:

1. Any bitrate file is going to be reconstructed as 16-bit LPCM, and considering the fact that AES and SMPTE engineers have in actual scientific studies found 128 Kbps AAC transparent to the source (regardless of purely anecdotal "evidence" layperson "audiophiles" repeatedly fool themselves into believing), there is no additional discernible benefit gained by encoding in Apple Lossless (AAC VBR). It's all going to be reconstructed as 16-bit LPCM. If we were comparing MP3 that would be a different story, but unlike MP3, AAC is a perceptual encoding schema that mitigates a great deal of unnecessary data using techniques similar to ATPX-100, ADPCM and AC-3.

2. The only method for actually achieving adequate bitstreams in real time from the source is to sync or stream from AppleTV, and not to put AppleTV in Remote speaker mode. This limits your options for organization because you will have to store the music on a drive linked to a PC/Mac running iTunes.

You could either use large internal storage on the machine you're streaming from, or use network-based storage if it's linkable to iTunes in the preferences pane... but you can't get around the fact that either you'll have to sync the same files to your iPod or encode secondary files at lower bitrates to iPod. However, if I'm not mistaken isn't there an option to instruct iTunes to convert high-bitrate files to lower-bitrate files on the iPod by on-the-fly transcoding during sync? Or is that only an option for the iPod Shuffle?

Frankly, if you do not possess a library consisting of 24-bit Linear PCM audio, it's not worth the extra storage to encode anything as lossless or uncompressed 16-bit LPCM. CD audio is dithered and limited to 65,536 amplitude values per quantization interval and at 128 Kbps, AAC is more than capable of delivering the same amplitude resolution, dynamic range and frequency response (when the sample rate is left at or above 2x the Nyquist rate). I have a lot of 24-bit LPCM and I leave that uncompressed, everything else I encode between 128 to 256 Kbps AAC.

John.B
Feb 24, 2008, 12:22 AM
You can also create unique iTunes libraries; one for lossless, one for VBR AAC (or MP3).

MikieMikie
Feb 24, 2008, 09:40 AM
Avatar,

Thank you for your comprehensive answer as it helped me better understand the realities of physical limits being imposed. I would like to sum up what you said in a simplistic way, to see if I understood its implications.

Encoding in anything more than 128 Kbps is not going to render a better sound because of the physical limits of the devices involved. Lossless will not generate a better listening experience since streaming down-converts.

Is that correct?

Avatar74
Feb 24, 2008, 11:32 AM
Avatar,

Thank you for your comprehensive answer as it helped me better understand the realities of physical limits being imposed. I would like to sum up what you said in a simplistic way, to see if I understood its implications.

Encoding in anything more than 128 Kbps is not going to render a better sound because of the physical limits of the devices involved. Lossless will not generate a better listening experience since streaming down-converts.

Is that correct?

Not quite.

AppleTV upconverts 128 and 256 Kbps AAC to 16-bit (1411 Kbps), 44.1kHz, Linear PCM. AppleTV also downconverts 24-bit, 48kHz, Linear PCM (2308 Kbps) to 16-bit PCM.

Given this, there's no point in storing anything as 16-bit Linear PCM since the system will decompress AAC back to that format anyway. AAC is an excellent perceptual coding scheme, and at 128 Kbps AAC the bitstream is sufficient to reproduce the dynamics of CD audio.

You have to recognize that the difference between AAC and, say, Mp3, is that MP3 is largely a strict compression format that discards information that is not restored upon reconstruction of the analog signal during playback. AAC isn't deemed lossless because it doesn't reconstruct the 16-bit LPCM signal bit for bit, but it doesn't have to.

What's at issue here is, more than just the hardware, the limitation of the CD audio format itself. CD Audio is pretty limited in terms of its dynamic range (96.7dB) and its amplitude resolution (the degree of detail with which changes in amplitude can be represented). Nothing more than 128 Kbps AAC is really required to faithfully reconstruct the analog waveform with artifaction so minimal your ears can't detect it.

There's a lot of reasons for that, but basically since you can't actually achieve reconstruction of higher than CD audio bitrates, the resolution of iTunes AAC is not insufficient. If you were using a lot of 24-bit Linear PCM audio, then you might want to preserve the originals as well as use a different transmission system than AppleTV.

So to summarize... Even though iTunes will transmit 128 and 256 Kbps AAC, and 16- and 24-bit LPCM, in their native resolutions, over the network, when they reach AppleTV they all get upconverted or downconverted to 16-bit CD audio. Since CD audio isn't that great to begin with, and since your storage concerns are warranted having an iPod, you really could just store everything as 128 Kbps AAC.

alFR
Feb 24, 2008, 11:48 AM
Does Apple Lossless = LPCM then? If so, is it 16-bit or 24-bit?

Avatar74
Feb 24, 2008, 12:04 PM
Does Apple Lossless = LPCM then? If so, is it 16-bit or 24-bit?

No. Apple Lossless is a proprietary format that uses linear prediction to reduce the data requirements relative to Linear PCM. The bitstream of Apple Lossless is typically 40-60% the size of an equivalent 16-bit Linear PCM stream, whereas AAC is about 1/10th the bandwidth.

alFR
Feb 25, 2008, 02:09 AM
OK. Now (excuse me for wearing the audio dunce's hat here in the corner), is LPCM basically what we get off a CD then?

dunawaydk
Feb 25, 2008, 02:36 AM
You can also create unique iTunes libraries; one for lossless, one for VBR AAC (or MP3).

I rip all of my CDs in Apple Lossless Encoder and then copy at a lower bitrate "automagically" when transferring those songs to my iPod(s) (this is an option within iTunes). Is this same capability not available for music transferred to the AppleTV?

alFR
Feb 25, 2008, 05:06 AM
I can't find the option to do this automatic copying of lower bitrates in iTunes for my iPod 5G or my iPhone: can you tell me where it is?

Avatar74
Feb 25, 2008, 07:32 AM
OK. Now (excuse me for wearing the audio dunce's hat here in the corner), is LPCM basically what we get off a CD then?

Yes. CD Digital Audio (Red Book) is dithered 16-bit, 44.1kHz, stereo LPCM.

dunawaydk
Feb 25, 2008, 02:56 PM
I can't find the option to do this automatic copying of lower bitrates in iTunes for my iPod 5G or my iPhone: can you tell me where it is?

Hmmm..my bad...I get the option "Convert higher bit rate songs to 128 kbps AAC" on my 1G and 2G Shuffles, but not on my 3G 40GB iPod or my 3G 8GB Nano. You would think that option would be available across all iPods, so those using the Lossless encoder can decide if they want to limit the space used on any iPod device.

roland.g
Feb 25, 2008, 03:16 PM
I rip everything at AAC 160. I always figured that one step up was a little better. But too many concerts and loud stereos have left me hard for hearing, so I really can't discern the discernable, let alone the undiscernable.

Volante
Jul 25, 2008, 07:40 AM
Avatar74, so appleTV up/downconverts, but what about, mac mini and the rest of the mac lineup? I plan to get a mac media center, but I don't know which will provide best audio. I'm also interested what happens in with DTS passthrough?

smilinmonki666
Jul 26, 2008, 05:48 AM
I don't want to throw a spanner in the works, but, kinda within the same sandbox, but I've been ripping all my CD's to .AIFF 16-bit / 48kHz. I'm then streaming to an AppleTV but via ethernet. I'm I playing the stupid fool by using .AIFF as many people are telling me there is no difference between .AIFF & Apple Lossless??

telecomm
Jul 26, 2008, 07:59 AM
I'm I playing the stupid fool by using .AIFF as many people are telling me there is no difference between .AIFF & Apple Lossless??

Both are lossless and so you don't lose any audio info in either format.

AIFF has the advantage of being compatible with everything, whereas Apple lossless won't play on anything but Apple stuff. If that's not a concern, Apple lossless results in a smaller file size.

bilbo--baggins
Jul 26, 2008, 04:32 PM
I'm I playing the stupid fool by using .AIFF as many people are telling me there is no difference between .AIFF & Apple Lossless??

Apparently you can convert AIFF to Lossless and back to AIFF and the resulting files will be identical to the original AIFF files. You can convert your AIFF files to Lossless to save space, and should be able to convert them back to AIFF if you ever need to.