saving space with 80 kbps AAC with high-efficiency

HeavenlyYeti

macrumors member
Original poster
Feb 8, 2008
54
0
U.S.A.
I don't know what this new "high-efficiency" option does in conversion, but I've found that an 80 kbps AAC with the high-efficiency turned on sounds MAGNIFICENT. Plus, I think I've lowered my music space at least 5 times over.
I listened to various Radiohead, U2, and Brian Eno tracks with my Dr. Dre headphones, and honestly could only spot very very miniscule differences between the 320kbps and the 80kbps.

AAC is awesome. If you're looking to free up a ton of space, this is a sweet idea. :apple:
 

HeavenlyYeti

macrumors member
Original poster
Feb 8, 2008
54
0
U.S.A.
Is this something built within iTunes? Or another program?
it's in itunes. Go to EDIT > PREFERENCES > GENERAL > IMPORT SETTINGS > click CUSTOM > choose 80 kbps and check the box that says "high efficiency".

go back to your music and press CTRL+A so all your stuff is highlighted. Go up to ADVANCED > CREATE AAC VERSION.

then you leave the computer to go workout or watch avatar or something, come back a day (or more, depending on how many songs you got) later and you should be set. I converted 6 GBs of music down to 2 GBs. And like I said, there's really no difference in quality that you can hear.

Best part? you can delete all those MP3s taking up all your hard drive space. More room for new music and movies!

Take that, Thom Yorke! :)
 

BlizzardBomb

macrumors 68030
Jun 15, 2005
2,537
0
England
HE-AAC at 80 kbps is roughly equivalent to MP3 at 160kbps, so to most of the population, any distortion/ quality loss is inaudible. Any songs you have at 128kbps are definitely worth converting to HE-AAC if you're tight on space.
 

cubeeggs

macrumors member
Dec 1, 2009
68
0
If you’re trying to hear the difference between HE-AAC and AAC or MP3, HE-AAC parametrizes (destroys and reconstitutes) high frequencies, and low-bitrate HE-AAC also parametrizes stereo separation.
 

Yvan256

macrumors 603
Jul 5, 2004
5,032
886
Canada
I'm not a big fan of re-encoding lossy audio. This is not a good way to evaluate a new CODEC since you're starting out with already compressed, lossy audio.

I'll have to try it with a CD, however. But do all iPods support HE-AAC? How about my old 3rd generation iPod touch and my 2nd generation iPod shuffle? :confused:
 

lostless

macrumors 6502
Oct 22, 2005
347
6
I'm not a big fan of re-encoding lossy audio. This is not a good way to evaluate a new CODEC since you're starting out with already compressed, lossy audio.

I'll have to try it with a CD, however. But do all iPods support HE-AAC? How about my old 3rd generation iPod touch and my 2nd generation iPod shuffle? :confused:
Ive found that the older ipods will play the AAC HE, but do not play the extra high frequency track. So it comes out sounding like a 80kb/s AAC.
 

kalafalas

macrumors regular
Aug 26, 2008
173
387
California
Ive found that the older ipods will play the AAC HE, but do not play the extra high frequency track. So it comes out sounding like a 80kb/s AAC.
iPod classic 6.5 generation (120GB, or the thin 160) will play it perfectly, Any iOS Device running 3.1 or higher, and iPod Nano 4th generation and up will play HE-AAC perfectly, any older model will treat it as a regular AAC song, and only see the 80 kbps part, not the HE reconstruction
 

JulianL

macrumors 65816
Feb 2, 2010
1,120
107
London, UK
Yes, AAC-HE is great. My main archive on my file server is stored in FLAC (that's a lossless format, i.e. a perfect copy of the source CD, equivelent to Apple Lossless Encoder) so I have the option to convert my music to whatever format I want without lossy-to-lossy conversion artefacts.

I did some experiments a couple of years back when I wanted to put as much of the music on my 30GB iPod onto my smartphone which at the time only had about 6GB of free space so I had to look at aggressive compression. I experimented with all the formats I could find at 64kbs (MP3, MP3 Pro, AAC, Ogg Vobis and AAC-HE). To my ears they were all unlistenable-to at 64kbs with the exception of AAC-HE that really did sound pretty much as good as 128kbs MP3.

Edit: I also tried WMA in my old tests and it was also unlistenable-to at 64kbs.

- Julian
 

DealerQueen

macrumors newbie
Aug 2, 2010
4
0
I did some experiments a couple of years back when I wanted to put as much of the music on my 30GB iPod onto my smartphone which at the time only had about 6GB of free space so I had to look at aggressive compression. I experimented with all the formats I could find at 64kbs (MP3, MP3 Pro, AAC, Ogg Vobis and AAC-HE). To my ears they were all unlistenable-to at 64kbs with the exception of AAC-HE that really did sound pretty much as good as 128kbs MP3
128 is surely better than 64, but is it listenable anyway? I can hardly imagine myself listening to stuff like Godspeed You! Black Emperor or King Crimson in 128:confused:
 

JulianL

macrumors 65816
Feb 2, 2010
1,120
107
London, UK
128 is surely better than 64, but is it listenable anyway? I can hardly imagine myself listening to stuff like Godspeed You! Black Emperor or King Crimson in 128:confused:
It's best to think of them as very, very different formats with different design goals. "normal" AAC and "normal" MP3 are designed to offer a satisfactory experience at 128kbs and an increasingly more faithful reprodruction of the original as the bit rate increases (192kbs, 256kbs, maybe all the way up to 320kbs).

AAC-HE is not just AAC at lower bit rates, it uses different algorithms that are optimised for lower bit rates. If you want to see the difference then try istening to the same song encoded at 64kbs AAC vs one encoded at 64kbs AAC-HE; the difference is staggering, at least to my ears.

General wisdom seems to be that 64kbs AAC-HE is not quite at the quality level of 128kbs MP3 but it is very, very close and my own listening tests seem to tally with this "general wisdom". Because of this I am pretty confident that, when I come to start trying out 80kbs AAC-HE for the new format on my iPhone 4, I personally will have no issues with the quality level and expect it to have no problem equalling 128kbs MP3 and maybe even beat it slightly.

- Julian
 

supercooled

macrumors 6502a
Sep 6, 2007
737
1
Do you folks keep two separate libraries for your mobile devices and your home system? I haven't have to think about space conservation since storage became affordable a few years back so I'm basically content with 192kbps or above which seems to be the norm in terms of the stuff that are shall we say, procured through downloads.

I just converted a Keane song from 320kbps mp3 @ 7.9MB to 2.1MB and the differences are negligible at best. I've looped it a few times and I lost track which bitrate I was listening to. If you just sample it briefly, say a few seconds your bias will more than likely prefer the higher bitrate due to the placebo tendencies. Of course that is not the most scientific method of testing but there are people that do that and will dismiss it outright.
 

rWally

macrumors regular
Sep 17, 2006
165
0
Denver, CO
I'm not a big fan of re-encoding lossy audio. This is not a good way to evaluate a new CODEC since you're starting out with already compressed, lossy audio.

I'll have to try it with a CD, however. But do all iPods support HE-AAC? How about my old 3rd generation iPod touch and my 2nd generation iPod shuffle? :confused:
What he said. Are you guys re-encoding your MP3/AAC files or are you re-ripping from a CD? I cringe at the thought of re-encoding a lossy file.
 

JulianL

macrumors 65816
Feb 2, 2010
1,120
107
London, UK
What he said. Are you guys re-encoding your MP3/AAC files or are you re-ripping from a CD? I cringe at the thought of re-encoding a lossy file.
Mine is essentially from CD (CD -> FLAC -> AAC-HE).

I chose FLAC years ago but now that I have an iPhone (the iPhone 4 is my first) it's become an issue that iTunes won't work with FLAC so I plan to do a one-off conversion of all my music from FLAC -> ALAC for my raw source material. (FLAC and ALAC are both lossless compression algorithms.)

Re supercooled's other recent question. At the moment I keep separate libraries, my master source material as discussed above and then a separate directory structure with the compressed versions for my portable devices. I currently manage both folder structures manually and my compressed library is a mess with a mixture of some stuff in MP3, some in AAC-HE 64kbs, various tagging errors, artwork at a resolution appropriate to 5 year old screen resolutions and not today's iPhone with retina display, and some CDs (FLAC files) not converted into compressed format at all. I plan to delete my current compressed library completely and re-generate it from scratch, all in AAC-HE 80kbs with consistent tagging and coverart.

For my re-build of my compressed library I'm considering using the automatic encode-on-copy-to-device feature in the newer iTunes to do the conversion to AAC-HE and then take a backup of the music on the device so that I don't need to spend days re-encoding when I move to a new device.

I don't know enough about iTunes to know how to backup the music on my device though (I really am new to the Apple world), where the backup is stored on my PC, what sort of folder structure will be created for it, and if I will be able to easily identify what's stored in the backup. I need to start doing some reading and experimenting; it's on my to-do list for this month.

- Julian
 

Sol

macrumors 68000
Jan 14, 2003
1,564
6
Australia
For those of you thinking about having two libraries, one made of high quality and one made of low-bitrate music, you should be aware that such a function exists in the latest iTunes. When your iPod, iPhone or iPad is connected to your computer and recognised by iTunes, select the device from the left side of iTunes and put a check-mark on 'Convert higher bitrate songs to 128 kbs.' It would be ideal if we could select what format and bitrate to down-convert to but for most casual listeners 128 kbs should be fine.

Now that we can buy cheap 2 TB drives it makes sense to rip CDs in Apple Lossless format. You can always down-convert using the above mentioned method in order to fit all your music on a current iPod and in a few years you will have portable devices with the capacity to hold lossless libraries.
 

JulianL

macrumors 65816
Feb 2, 2010
1,120
107
London, UK
For those of you thinking about having two libraries, one made of high quality and one made of low-bitrate music, you should be aware that such a function exists in the latest iTunes. When your iPod, iPhone or iPad is connected to your computer and recognised by iTunes, select the device from the left side of iTunes and put a check-mark on 'Convert higher bitrate songs to 128 kbs.' It would be ideal if we could select what format and bitrate to down-convert to but for most casual listeners 128 kbs should be fine.

Now that we can buy cheap 2 TB drives it makes sense to rip CDs in Apple Lossless format. You can always down-convert using the above mentioned method in order to fit all your music on a current iPod and in a few years you will have portable devices with the capacity to hold lossless libraries.
Thanks, that's really helpful information. I was aware of the ability to do this automatic conversion in the latest iTunes but I hadn't been able to find such a nice simple explanation as to how to set it up.

One thing though. If I have my iTunes ALAC library then I know where to find all my ALAC tracks, I can just browse my iTunes music library directories and all the trachs are in a fairly sane directory structure, or even in my own directory structure if I've ticked the option to manage my own folders.

If I've chosen the down-convert option though, where do I find my AAC files? I see three possibilities:

1) They only exist on my device so, if my phone is stolen, my next device sync will be measured in days because everything is re-converted from the source ALAC files.

2) They are part of the iPhone backup but mixed in with lots of other stuff in the general very cryptic backup file structure where it is pretty much impossible to tell what's what.

3) As well as down-converting and pushing to the device, iTunes also saves the files in a well structured music library on my PC, possibly just saving them in the same folder structures alongside my original ALAC files.

Which one of the three does iTunes do?

I must say though, I now have a dilema. I'd been assuming that the same options were available as the "Import from CD" options so I was really banking on being able to use the iTunes down-convert feature for 80kbs AAC-HE. It's profoundly disappointing to discover that this isn't the case. I guess that iTunes is upgraded quite frequently and the next iPod Touch launch would be a sensible time to make major enhancements in the music management area so I might just hold off a bit before deciding what to do. In the meantime, pending an answer to my question above, at least I seem to be really close to fully understanding one of my options.

- Julian
 

Sol

macrumors 68000
Jan 14, 2003
1,564
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Australia
If I've chosen the down-convert option though, where do I find my AAC files? I see three possibilities:

1) They only exist on my device so, if my phone is stolen, my next device sync will be measured in days because everything is re-converted from the source ALAC files.
That is how it works. Today it takes days, tomorrow hours.

AAC-HE looks like a format made for streaming. It may save space but I do not think it is meant to be used for that purpose. The space it saves is negligible considering how cheap hard drives have become.
 

JulianL

macrumors 65816
Feb 2, 2010
1,120
107
London, UK
Sol said:
That is how it works. Today it takes days, tomorrow hours.

AAC-HE looks like a format made for streaming. It may save space but I do not think it is meant to be used for that purpose. The space it saves is negligible considering how cheap hard drives have become.
Yeah, but iPhones don't have hard drives! I wouldn't have been so bothered if Apple had done its usual doubling of storage capacity with the iPhone 4, it's one of the reasons I held off buying the 3GS, but I'm finding 32GB restrictive so the space saving for me of 80kbs (AAC-HE) vs 128kbs (AAC) is well worth having.

Thanks for the clarification on how the down-converted files are managed.

- Julian
 

ortuno2k

macrumors 6502a
Nov 4, 2005
647
0
Hollywood, FL
Try listening with good headphones. The ones that come with the Apple products don't let you experience the music at its full.

Try some AKG K701s, Grados, and for under $100, you can get these, which REALLY made a difference from the $20.00 Sennheiser I was using before.

Apple Lossless or AIFF all the way... down-convert to 128 kbps automatically in iTunes while synchronizing to my iPhone. Can't take all my music, but it's okay. :rolleyes:

And - don't get rid of the higher-quality files... you'll regret it later. ;)
:D
 

JulianL

macrumors 65816
Feb 2, 2010
1,120
107
London, UK
ortuno2k said:
Try listening with good headphones. The ones that come with the Apple products don't let you experience the music at its full.

Try some AKG K701s, Grados, and for under $100, you can get these, which REALLY made a difference from the $20.00 Sennheiser I was using before.

Apple Lossless or AIFF all the way... down-convert to 128 kbps automatically in iTunes while synchronizing to my iPhone. Can't take all my music, but it's okay. :rolleyes:

And - don't get rid of the higher-quality files... you'll regret it later. ;)
:D
I sort of agree, within reason. I absolutely agree about keeping lossless source files for home use (ALAC, FLAC, WAV or whatever) and as the source for subsequent lossy conversions. I also agree about the basic Apple headphones being poor and it's certainly worth upgrading them but how far it's worth going is heavily affected by one's use of the mobile device (iPhone, iPod or whatever).

I used to use Etymotic ER4S headphones for a long time and I still have them but a lot of my use is on aeroplanes and that's such a noisy environment that aspiring to anything more than the quality of a decent car stereo is, to my mind, pretty pointless. I now use V-Moda Vibes because that rumble that pervades the inside of an aircraft really sucks the bass out of the music so I find that a bass-heavy headphone works best for me.

So ultimately, even if one can hear a difference between two different formats when listening at home in a quiet environment, for me the issue is more as to whether I can really hear any appreciable difference on an aeroplane, out jogging or walking through town.

Honestly though, I still haven't made up my mind. I think I'm going to download dbPoweramp, convert all my source material from FLAC to ALAC (I'm in the Apple world now so I might as well do that) and then convert some tracks to 128kbs AAC and 80kbs AAC-HE and see if How much of a difference I can detect. I could even break out my Etymotics as part of the testing; that's not a bad idea actually.

- Julian
 

blairbeckwith

macrumors regular
May 14, 2008
121
1
Ottawa, Canada
I love listening to music casually. I'm more then your average Top 40 Listener, and I'd say I know significantly more about music then a lot of people, but I am by no means an audiophile.

I converted a few songs to 80 kbps AAC-HE, and I have to admit... I can not for the life of me tell the difference between this and 256 kbps iTunes+ tracks, 320 kbps MP3 tracks, or Apple Lossless tracks (versions of the same tracks, rather).

I've converted a selection of 650 tracks which weighed in at 5.10 GB to 80 kbps, and I've ended with a total of 1.48 GB. If I can listen to these without noticing any difference, I'm gonna convert the rest of my library.

Very exciting stuff.
 

JulianL

macrumors 65816
Feb 2, 2010
1,120
107
London, UK
...

Very exciting stuff.
Very rare stuff. AAC-HE is one of those hard to find technologies, one that really does live up to the hype (not that there's been that much hype around AAC-HE, but it deserves it).

I don't like the idea of having to reconvert all my music every time I upgrade my phone, and I might as well get the space saving of 80kbs AAC-HE so that my current 32GB phone can last a year longer (otherwise it'll probably be full and need a 64GB upgrade be next year) so I've decided not to go with the iTunes on-the-fly down-convert to 128kbs. I'm going to use dbPoweramp Music Converter (http://www.dbpoweramp.com/dmc.htm) to create a shadow tree of AAC-HE encoded files alongside my FLAC originals and then import the AAC-HE folder tree into iTunes to sync with my device.

- Julian