Well, the downside of having iTunes convert to AAC when syncing to the iPod is when you mess up it takes a long time to redo it. I was trying to replace my best CDs with the Apple Lossless files and didn't set things right. Now I have about a 24 hour delay allow it to sync everything in AAC again. I think I've got it figured out for next time. |
Why compress. Use AIFF. It takes twice the space as ALAC, but who cares? Disk is cheap.
Steve N.
Empirical Audio |
I'd say bitrate is not arbitrary on ALAC files. Rather a measure of 'complexity'. If what you mean by arbitrary is that you have no control over it, that's also true. But not in the sense that somebody just picked a number. ALAC would seem to end up about 30% to 35% reduced from the original.
Very complex, rapidly changing or 'dense' music will get a higher bitrate than sine waves. Maybe I'll test this, later today. I think you may be on to something with file size/length math. I'll look over some of the large number of songs I've got in ALAC and look for a pattern.
The idea behind lossy files...and this applies to photography, too, is to only discard the least significant data. That which couldn't be heard (seen?) anyway.
Of course, this doesn't work well, at least at higher compressions. In Photoshop, I have a choice of 10 or more 'levels' of compression. Using extreme enlarements of small parts of a picture, you can clearly see what changes. The changes are most readily apparent in more.....complex parts of an image. Big enlargements are hurt worse than small prints. Images for monitor use are nearly immune!
Yes, processer overhead makes sense. Again, using photoshop as an example, when I make a big change to a photo, It can take several seconds to process.
I just decided early on, after experimenting with FLAC, to change over to ALAC. It was more.....painless, for me. And I Tunes makes it easy to 'downconvert' to a much smaller but still listenable MP3-160 bitrate. Album art is more easily manged, at least for me. That, and the fact I can stream music wirelessly to my stereo is the icing on the cake. I only wish the Airport Express were better clocked. |
Way I understand ALAC is that it is 100% lossless, but runs a compression algorithm to reduce file size. Think a self executing zip file that automatically unzips itself in RAM every time you play it, while the disk copy remains compressed. FLAC, I think, is similar, but with a variable, user-selectable compression ratio (from 0 to more), whereas ALAC is the Apple version, which invariably means two things: compression ratio is fixed because Apple picks it for you and FLAC not supported on Apple. (And by "fixed" I mean not user-adjustable, I think the compression ratio on ALAC is very variable, just adjusted in secret by the Apple tech boffins and their sneaky algorithms depending on the nature of the track. Again, think zip files – depending on the nature of the file and density, it will be more or less compressable).
The only theoretically possible source of sonic difference between ALAC and an uncompressed lossless format (AIFF / WAV) is the processor burden of uncompressing the ALAC files every time you access them. Once upon a time, that may have mattered more, but with current processors I expect it really doesn't. (Although folks do still argue about it.)
Finally, the explanation for different bitrates on lossless files that has made the most sense to me is that all the bitrate represents is filesize divided by length of the track (kbps, kb/s, to be precise). So, if you compress a track, making the file size smaller, it will read as having a lower bitrate as against the same track uncompressed. But lossless / bit perfect is just that, compression or no, so the bitrate stat for a lossless track is really pretty much meaningless. Put differently, track density or complexity may well have an impact on the compression efficiency and ratio, so there's your source of variability, but all bitrate represents is that result (compressed file size) divided by length. Nothing to lose sleep over.
Flip side, when you pick a bit rate as the controlling factor for track compression – rather than anything to do with the track itself -- it’s kinda like the tail wagging the dog. You’ve imposed an arbitrary variable, mashed the track through it, and then discarded everything else so that your pre-determined kb/s = X equation comes out to equal X. What’s left is only what wasn’t lost, ie deleted, in order to make this arbitrary number (and hence the opposite of lossless). This, in turn, is I expect why “variable bit rate” makes sense, cause it gives the algorithms “discretion” (flexibility?) to take the nature and complexity of the track into account, from second to second adjusting bit rate in accordance with what is actually going on, instead of just hacking and slashing to make an arbitrary number – but in such a way to come out with an average “X” result to meet the predetermined outcome. (OK, that last one was pure guesswork.) So, for ALAC, bitrate is an arbitrary number, but a meaningless arbitrary number. While, for a loss-y format, bit rate is still an arbitrary number, but a fantastically meaningful one because it is what was chosen to determine how much of the original lossless file survived. |
Real,
My personal theory is that the bitrate is indeed variable but based on music complexity. This is pretty obvious by the bitrate speeds listed...if you enable that function in I-Tunes.
I just copied 'The Man With The Horn', a Miles Davis album. Indeed, the copy speed varied from 6x to over 10x. When I looked at the files, the copy speed pretty much agreed with the bitrate.
More complex music would demand a higher bitrate. As a test, I'd record a few simple test tones. If the bitrate is very low, that'd nail it.
My analogy would be my photography. JPG is a compressed format with many different levels available to users of Photoshop and other programs. Camera Raw, is basically a digital negative and is 4x or 5x larger than even a large JPeg. So, Camera Raw is an uncompressed format, while JPG is equal to an MP-3 / 320.
There's more to it than that, like screen resolution and bit depth, but you get the general idea. |
Mysterious stuff, no? No accounting for (or predicting) synergies, daffy combos, or personal taste -- far as I'm concerned. I've got a pair of Grado RS-80s that I use on the AAC stuff through the iPad/pod, mostly to and from work on the subway. Like'em just fine for that, in fact, think they sound surprisingly great. But when I tried the Grados on the home rig (all AIFF, Ayre QB-9, dedicated Headroom Home amp for the cans), it was downright unlistenable. Strident, harsh, painful, even. Plain couldn't do it. Actually, I was entirely floored by how genuinely unpleasant it was. Go figure? (But, then, my baseline for cans is Senn HD-600s with Cardas wires, which have got to be near as dark and syrupy as it comes....).
Anyway, not totally surprised to hear that, at least in some cases, there appear to be significant variances in iPod DACs / hardware. I can attest that the itunes software has been noticeably improving on the sonic end also, for what thats worth. Maybe something driver end? Could also be that the hardware at issue was in fact designed to optimize, balance or otherwise sound best with lower bitrate material? Gosh, I'm really reaching here.... Generally, I always assumed that the differences in sound through an iPod would be dominated by factors other than file format to the point where differences in software format wouldn't be particularly determinative. My basis form this assumption? Well, nothing whatsoever, actually. Just a guess that I've been happy enough to just go with. Anyway, very interesting "hard" results. And even more interesting when it's not what you expected going in. Keep us posted. Cheers. |
Magfan I am cornfused - if ALAC is lossless, why do I get different readings on different ALAC files for bitrate, when querying them in iTunes or in Windows Explorer? For example AIFF always shows 1411 kbps. But ALAC files are all over the place. Is this because the ALAC compression is variable, and I am getting an average reading, like I hypothesize above? Incidentally I did some research and yeah its lossless. The bitrates are winding me up. |
My coworker listens to headphones at work often and isn't an iPod owner. I set him up to listen to the same song that came from the same CD and iTunes computer. I didn't tell him anything beyond giving them both a listen and report if he heard any difference.
The funny thing was that he wanted to know what was different in the two iPods that could make them sound so different (this is my reading between the lines paraphrase). It was clear that he heard a difference and said the 128 AAC sounded fuller.
A test doesn't get any more blind than this, but this isn't a perfect test. Maybe I'll revese the files and let him try it again and see if the iPod rules or if the format rules. |
ALAC is indeed 'lossless' in the sense that you can re-create a bit-accurate copy of the original file.....from the ALAC file.
The very definition of lossless: |
All iPod's are not created equal. They use different DACs in different ones. The 5G, 30GB iPod video uses a Wofson DAC. The current models use a proprietary DAC that Apple developed themselves, I think. Its not Wolfson, I know that. There are also differences in power and cicuit design.
I have not done a test like this, but let me ask a few ?s:
Was your vinyl guy listening to the same song on both iPods?
Does this person have an iPod himself, is he used to having earbuds in?
The difference I hear between lossless and compressed iPod files is in the extreme frequencies - there is more detail in the low/high end with lossless files. Its something I had to listen for, and its more noticeable on some tracks than others. For example, the re-mix that Jimmy Page did on the entire Led Zepplin back catalog did not reveal more dynamic range in the recordings; this is not music I would recommend for a test like this. Tool is good. Electronica or IDM is good. Classical would work.
I have never A/B'd lossless vs. compressed in a blind test, then tried to ID the lossless rip. I will try to do this soon. I might surprise myself, and re-rip my entire library into 128 .mp3.
Eh...Probably not!
Also consider that Apple Lossless is not really lossless - it is a variable compression at a very high average bitrate, using a very efficient codec (MPEG4 I think). AIFF, WAV and FLAC are true lossless formats. Not sure if this would have made a difference in your test, but that was great to read about. |
Here's an interesting happening. I have my 30GB iPod at work loaded with the down converted 128 AAC format and last night I loaded my old 8 GB iPod with the Apple Lossless that is actually on my computer. I brought both iPods to work today and handed them to a coworker that's in to music (about the only guy I know that's into vinyl) and asked him what he thought. Ironically, he strongly preferred the sound of the iPod with 128 AAC and described the sound a being more full. I had to laugh. I can't say that I can really tell a difference.
Are all iPods created equal? I believe they are of similar vintage, but one is a standard one and the other is a nano (I believe). The standard iPod was the preferred sound.
I put the iPod with Apple Lossless on my Onkyo dock last night and it was the first time that an iPod was an acceptable source for at least background listening. It wasn't nearly as good as the CD or SACD players, but but improved over the MP3s on my wife's iPod. |
Doesn't ALAC cut file size by about 30%->35%? Cutting by half while 'suffering' the loss of quality of even the best bet in MP3 using VBR and 320KbS base rate?
I'm not sure the marginal saving of disk space is worthwhile....at least not for me.
I'm well served by double copies, and ALAC for the house and MP3-160 for the car / pod.
Storage these days is CHEAP. Having a PAIR of backups may not be a bad idea and a terrabyte is a massive amount of music. I don't know current state-of-art, but RAID systems....RAID5, for example, are reasonably safe and redundant though at a COST! $$$$ I would only backup ALAC or other bit accurate copies, NOT any MP-3 which can be easily redone.
The OTHER advantage of MP3-160 is that most (all since say.....'06 or so) car CD players handle this format just fine, thank you, so you can leave the 'pod in out of the loop when driving. |
Once advantage to ripping in Apple Lossless and using the auto downsampling to 128 AAC is that if iTunes is updated in the future to allow other downsampling options I'll be set and ready to go at the click of a button and a few hours of waiting. |
I just ripped my whole collection at 320kbps VBR. Sound quality is very close to lossless, and file size is a little under half of what lossless typically works out to.
Maybe I should have done lossless but I am using a 64GB iPod touch for a source and it would not have been able to hold everything.
The downsampling option with syncing is useful but it would have been so much better if it didn't limit you to 128 kbps. I imagine if they ever come out with a new version of Itunes that allows this then I may wind up ripping my CDs one last time.
I do use the downsampling when syncing my iPhone. 128K is good enough for lower end earbuds and noisy environments, IMHO. Keep in mind that the downsampling sync takes FOREVER. It is definitely an overnight type of thing. |
Realremo - If I were planning to use my iPod for anything beyond listening at work on occasion I would probably be more concerned about the quality. I have an iPod dock at home that uses the iPods DAC and it sounds like junk no matter what format is used so on my good system it'll always be CDs for listening. I have all of the files in Apple Lossless so I'll be ready in case I ever get an external DAC and setup a music server.
Once I finish putting all of my CDs on my iPod I'll reevaluate how much space I have remaining and may manually load the Apple Lossless files for my best/favorite CDs if there is room. I think I'm about half way through the stack and have only used 5 GB in the AAC format so I should be able to load quite a bit in lossless.
I want to toy around with creating parallel MP3 versions, but with a new baby in the house it'll be a long process finding the time to do it. |
To each his own Mceljo, happy listening...! |
I just did a one song comparison of Apple Lossless, 128 AAC, and 192 MP3 and can't say that with my headphones that there is a significant enough difference to not just go with the AAC format that iTunes will do automatically. There is a small difference, but it's difficult to even describe so for non-critical listening on my iPod I don't think it matters. |
Mezmo, great tip about converting formats, I didn't know iTunes did that. I am just about to purchase an Apple TV so I can stream Netflix, and this will probably lead to upgrading my entire library to AIFF so I can push it into my Denon 3310's Burr-Brown DACs. I doubt I will create double copies tho...I'll probably just run AIFF on my iPod and have fewer songs, at least at first... :-) All this ripping and re-ripping and converting is freakin' time consuming! |
The iPod spent the night updating. Just under 26 GB to just over 4 GB. I'll check the sound quality and see how it compares and play around with creating parallel mp3 files as well. |
I managed to still have iTunes version 7 so now it's updated and I have identified the button. Thanks! |
It appears that the option to down convert isn't on my version of iTunes that was downloaded just a few days ago. |
Right, three things.
First and foremost: yes, once you rip things lossless, you never have to touch the CDs again. Far as I'm concerned, that's the whole point.
Second, on my version of itunes, when you plug an ipod in, and you then select it from the menu on the left, you get the screen with various tab-like choices on the top to manage what's on the thing ("Summary, Apps, Movies, TV.".. etc.) On the "Summary" tab, there are three areas ("ipod" "version" "options") and the third "option" is "convert higher bit rate songs to 128 kbps AAC." If you select that, it's precisely what it'll do for you when you sync. No fuss, no muss, and a full ipod.
Third, our genuine Remo is of course correct, if you want full auto, 128 kbps AAC is your only option. Typical Apple: you want it easy, it's our way or not at all. But, you can also get itunes to manually make you a copy of any track you want in any other format that itunes supports (AAC, mp3, AIFF, Apple Lossless, WAV -- basically anything but FLAC). How to do this, however, aint obvious.
The itunes "help" file explains it thusly:
To convert a songÂ’s file format:
Choose iTunes > Preferences, click General, and click Import Settings.
In the Import Using pop-up menu, choose the format you want to convert songs to, and click OK to save the settings.
Select one or more songs in your library and choose Advanced > Create [Format] Version.
In the off chance that this made no sense at all, it kinda goes like this. Both in your "Advanced" pull-down menu and in the right click menue for any given track, you will be presented with the option to "Create [blank] Version", where [blank] is the default import setting. In other words, if your default setting is to import AIFF, and you have just ripped your entire library AIFF, this option will very helpfully (and apparently without a touch or irony) give you the opportunity to make another AIFF copy. Lovely.
BUT, and I suspect you may see where this is going, if you change your import preferences (say to whatever bit rate mp3 floats your boat), then this same right click / "advanced" option will then the present you with the ability to make a copy in whatever your new default is. You can then select your entire library (or as many or few tracks as you like) and make a copy of all of it in whatever format you want (just remember to switch your default back before ripping any more CDs, or that's what you'll get from them as well).
To sum up, the Apple way is either their way or the hard way -- but you can usually get the job done.... Personally, I like the easy way (think it's spelled l.a.z.y.), but also because I am fanatical about best possible quality on the full rig, but neither care about nor appreciate any difference once it goes on the ipod. But, if your ears and/or the gear you run the ipad through appreciate the benefit of higher bit rate lossy-ness (and I won't pretend that's a particularly difficult task) then you're stuck doing it the hard way and juggling multiple copies of each track in different formats. Enjoy, and as long as you do, you're of course doing it just right. |
I'm still looking for the iPods properties, but I'll keep looking.
Also, is it possible to convert from Apple Lossless to MP3 using the existing files and not having to mess with the CDs again? |
auto-converting to AAC when synching the iPod is a checkbox you can click in the iPod's properties when you connect to the computer. This produces 128 kbps files. IMHO this bit rate is too low and you will hear a decrease in quality compared to 320 kbps .mp3 or 320 kbps AAC. I don't recommend this low bit rate, 320 kbps files are not that much bigger in size. I rip the music I love to Apple Lossless, stuff I get from friends is .mp3 and I still have a ton of music in .mp3 format that I haven't re-ripped and probably won't. No, I cannot fit my entire collection on my iPod, but I have 30GB and that is plenty to keep me happy for weeks without deleting and re-loading. I recommend .mp3 over AAC because it is compatible with everything. For example, I cannot network my Denon 3310 AVR to play AAC files, only .mp3...
The shortcut for getting to import settings is pressing CNTRL and , at the same time on a PC. Then click the Import Settings button next to "Import CD" on the General tab. |
I'll double check when I get home, but if I am remembering correctly, when you plug in a device to sync, go to the “General Preferences” (or rough equivalent) tab for that specific device and there should be a radial button to check, towards the bottom third of the page, that says something along the lines of “convert higher resolution formats to AAC when syncing.” Check that, and it will automatically do all of the converting work for you while it syncs. In other words, it's a device-specific setting and is not at all related to your import settings. Hope that helps.
Having two libraries, with a primary lossless and then a smaller copy is also a perfectly sensible way to go. For my usage, however, I've found the auto-converting feature while syncing to be both tidier and easier than maintaining separate libraries (which I've tried and gave up on once I discovered the button to ask the computer to do it for you). |
Unless you use the IPod as a hi-end source, MP3-320 is probably the highest you need to go......
In I-tunes, go to 'preferences', 'General', 'Import Settings' and set to your preference.
I, for example, use ALAC then have 2 playlists. One is the lossless files I send to stereo and a COPY of that in MP3-160 goes on the 'pod...for auto duties.
You can COPY any lossless files in your music folder as another, lower resolution format. Set the import settings back to whatever for lower res....It'll leave the ALAC stuff alone, but you'll have 2 copies in your music folder...1 of each. |
"I always set the synching preferences to automatically convert to AAC (the compression/trimming ratio from AIFF to AAC is about 10:1)." - Mezmo
How do I do this? I can't seem to figure out where or how to adjust the settings. I'm ripping everying thing in Apple Lossless and already have more than my iPod can handle. |
With an ALAC file...(Apple Lossless), you can reconstruct a bit-accurate copy of the original file.
Than the conversation turns to the speed / accuracy of the reconstructing computer.
The quoted bitrate (above) would seem pretty spot on. Very complex music will run 1000+ while music of low complexity dips below 600, but rarely.
Check out a copy of a CD in ITunes to get the idea. Part of the listing for a sony recorded in ALAC is its bitrate. |
Apple AAC and apple lossless both use mpeg4 compression, apple lossless is simply compressed at a MUCH higher bit rate, and its variable compression. If you get into the specs, apple lossless has a bit rate of anywhere from 600kbps to 1100kbps, + or -, depending upon the track. AAC only goes up to 320kbps. AIFF is ripped at 1411kbps, which tells me that its a more true lossless format than apple lossless. I don't have any WAV files.
Your optical drive and the ripping software you use matters more than which file format you pick (AIFF, WAV, FLAC, etc.) when talking about bit-perfect rips.
I have Audio Tecnica earbuds, which are OK, not great, and I can hear the difference between a 320kbps rip into .mp3/AAC, and a 1411kbps rip into AIFF. More frequency extension and detail. I only rip AIFF and apple lossless, I avoid the lossy formats. Can I hear the difference between AIFF and apple lossless? Not really, not with the earbuds. If I went from my laptop through a DAC into my system, maybe. I recommend apple lossless, its a great middle ground. I don't want to listen to my favorite music at work knowing that I am missing something in the sound because the file format is clipping the waveform. |
Rip without any compression and then create separate libraries for iPod compressed files. It will save you the time and effort of ever having to re-rip as your library evolves. I believe this is along the lines Mezmo suggested. |
Yea, I've ripped 500-plus CDs twice, and don't recommend it one little bit. Unless you're either starting from scratch or really biting the bullet for a total conversion to a computer-based source, no reason at all to redo everything. Sounds like you've got the perfect plan. Cheers and enjoy. |
Mezmo,
If I were planning to rip everything again from scratch I'd probably take your advice. I don't do anything, at this point, on my main system outside of my CD player so having the lossless files isn't an issue right now. I'm just planning to rip my new CDs in Apple lossless and will go back to "upgrade" only a select few of the ones that are already ripped.
I didn't realize that I could down covert to the iPod, that's a great feature. Thanks!
I'm planning to rip a couple of songs in multiple formats and do some comparison listening on my headphones. We'll see how strong the placebo forces are soon enough. |
My two cents, rip everything lossless. Full stop. Eventually, you will come to regret it if you do not do it right the first time. Whether that is AIFF, WAV or Apple Lossless really dosn't matter -- they are all bit perfect and cross-convertible. Storage is super cheap, get them ripped and archived, and know you have them. As beteen lossless formats, don't know any real sonic difference personally, but AIFF or WAV is thought by some to be better, as both are bit perfect and uncompressed. Apple Lossless is in fact lossless, but compressed to about (I thought) 1/2 the size. I use AIFF, but not sure it's important.
Now, all that said, when you put them on a portable unit (ipad/pod/phone, etc), I always set the synching preferences to automatically convert to AAC (the compression/trimming ratio from AIFF to AAC is about 10:1). This way, you have the benefits of everything archived lossless, while your portable versions -- where the format just ain't going to get you that much of a differnce and putting a premium on quantity over quality makes sense at least to me -- convert automatically. Just to re-tweak the math, let's guess that 500 CDs would run you roughly 300gigs AIFF (think I actually have > 700 just north of 350gigs, but anyway). If you set it to automatically convert to AAC when synching, you can easily fit all 500 CDs on a 32gig ipod. Just saying....
Finally, you could rip things twice and essentially have two archived libriaries on disk someplace -- but it's a lot easier to rip lossless and then have a program do the converting for you. As you can go lossless to more compressed, but not the other way -- just make sure to start with lossless and you only need to rip once. Wether you ultimately keep sets of each or just convert on synching is up to you. (The only practical difference that I am aware of is that synching takes significantly longer if you are also simultaneously down-converting to AAC. 300 gigs could run you over 10 hours, so a good overnight task.) Just my two cents. |
I think what I'm going to do is rip all of my audiophile CDs in Apple Lossless and the in the same MP3 format that I've previously ripped the rest of my CDs. I may need to upgrade the quality of a few CDs. |
I was just doing a little more research on the Apple Lossless format since I didn't realize that it reduced the file size so much compared to WAV.
Is this calculation correct?
30 GB = 30,000 MB / 652 MB (max per CD) = 45 CD (approx.)
If I assume that Apple Lossless is about 2/3 then the total goes up to 45 x 3/2 = 67 and the majority of CDs do not contain a full 652 MB so I should expect greater than 70 CDs to fit? |
Apple Lossless takes about two/thirds of the original file. |
Yes, I'm talking about a lossy format not WAV or Apple Lossless. I would assume that they both take up nearly the same amount of space?
Is there a lossy file type that is an Apple format? I'm assuming that the reason that the Apple Lossless is better than WAV is because the iPod DAC is better at the D/A on it. |
In my experience, the sweet spot for compressed on an iPod would be AAC format 196Kps or MP3 format 256kps VBR (variable bit rate) for maximum music given your listening situation, (ear buds.)
Anything more would reduce the amount of music without much gain in fidelity that you could hear on ear buds. |
If by compressed you mean a Lossy format, than 320kps MP3 sound very good. If you mean a Lossless format than Apple lossless is the choice. |
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