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iPod saving space with 80 kbps AAC with high-efficiency
- Thread starter HeavenlyYeti
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The 650 songs were a pretty much even split of 256 kbps AAC songs purchased from the iTMS, and 320 kbps MP3's ripped from CD's. I converted to AAC HE in iTunes.
ouch! 80kbps HE-AAC really hurt my ears 
i wanted to try it after your description, but i can't agree that this is how music was meant to be heard. maybe for people with these rip-off white apple earphones. okay. I'm on iPod Classic 8G with Ultimate Ears SuperFi 5 and i'm missing so much of the sound! 15 Hz Bass makes your brain shake, you won't go with less than 192 kbit AAC!
Regards,
Baguette
i wanted to try it after your description, but i can't agree that this is how music was meant to be heard. maybe for people with these rip-off white apple earphones. okay. I'm on iPod Classic 8G with Ultimate Ears SuperFi 5 and i'm missing so much of the sound! 15 Hz Bass makes your brain shake, you won't go with less than 192 kbit AAC!Regards,
Baguette
ouch! 80kbps HE-AAC really hurt my ears
Regards,
Baguette
I agree; that is not how music was meant to be heard but at 80 kbps and below you may not have a better option. When you are trying to fit your whole music library on an iPod Nano the trade-off in sound quality is worth considering for some people; commuters in public transport for one.
As for down-converting purchased AAC, no-one should do that. The original sound quality is something that you pay for and once it is reduced it cannot be recovered unless you re-download the file from iTunes, if that is possible. Imagine buying a CD, recording to a cheap cassette and throwing the disc away; that is essentially what you would be doing.
You've got it exactly right. I finally got round to doing some test conversions today, with the source being lossless FLAC files derived from ripping CDs and the encoding done using dbPoweramp which uses the Nero encoder for AAC. The results surprised me. Today I am much less happy with AAC-HE than I was when I did my original tests about 3 years ago and I think that Sol has hit on the reason why.
Three years ago I had all my mobile music in 128kbs MP3 (originals always FLAC) and it used just under 24GB of space. I'd decided that I wanted to streamline my gadgets and use my Windows Mobile phone for as much of my music as possible but the biggest memory card at the time was 8GB so I only had about 7GB of space to play with after other apps and data and stuff. I was desperate to cram as much as I could onto the phone and chosing just 25% of my collection to put on the phone was just too small a subset so the fact that 64kbs AAC-HE was at least listenable-to in a noisy environment won the day.
I remember now that the real differentiator with AAC-HE was that, once one got to the sub 128kbs range, all the other formats (Ogg, WMA, MP3, AAC-nonHE) had very audible encoding artefacts that really did hurt my ears, some even so bad that they had a "warble" all the way through the tracks; AAC-HE didn't. Doing my tests again today though, although AAC-HE 64kbs and 96kbs don't have the huge encoding artefacts, I definitely notice a loss of details and attack vs even 128kbs regular AAC.
I now have a 32GB iPhone 4 that, once I've allowed for apps and other data, probably has about 25GB available for music. I estimate that at 128kbs my total music collection now needs about 27GB today so in theory 128kbs isn't enough compression but I don't need to trim my library too ruthlessly to fit it in and I hope that in a year's time the next iPhones will be 64GB at which point the problem goes away completely so my new plan is to go with regular 128kbs AAC for my iPhone format.
- Julian
I tried this the other day and while it doesn't sound too bad, I can still hear the "low quality" in it. I have good ears for that and I'm picky about the bit rate of my music. It doesn't sound a bit like its has that "radio compression" on it.
on a fairly related note...
so clearly transcoding from one lossy format to another (mp3 -> AAC) is very bad. but what about going from a higher bit rate to a lower bit rate within the same lossy codec?
a lot of my music in iTunes is at 192 kbps, but after some intensive listening tests i've concluded that 92 kbps is perfectly sufficient given my playback equipment and ears. if i do the proposed transcode, will the result be the same as if i went from WAV (or FLAC) to 92 kbps AAC? or am i essentially getting a severely shrunk version of the 192 kbps file?
so clearly transcoding from one lossy format to another (mp3 -> AAC) is very bad. but what about going from a higher bit rate to a lower bit rate within the same lossy codec?
a lot of my music in iTunes is at 192 kbps, but after some intensive listening tests i've concluded that 92 kbps is perfectly sufficient given my playback equipment and ears. if i do the proposed transcode, will the result be the same as if i went from WAV (or FLAC) to 92 kbps AAC? or am i essentially getting a severely shrunk version of the 192 kbps file?
It's never going to be the same; the codecs aren't just 'lossy', they replace patterns with approximations and more compressible fillers. If it just snipped bits out, I'd have said yes...
Best case; the patterns get replaced with more compressed versions. But that's not always (often) going to happen, and you'll likely get different approximations of approximations; the software could even attempt to preserve and enhance what previously was just an artifact of the original compression.
Best case; the patterns get replaced with more compressed versions. But that's not always (often) going to happen, and you'll likely get different approximations of approximations; the software could even attempt to preserve and enhance what previously was just an artifact of the original compression.
Anybody else think that to simplify such a decision for us, that '128kbps' reencode option should have been made configurable?
well, ok - forget I used the word "same"...would taking the 192 file and creating a 92 file from it be closer to creating a 92 out of a WAV (about 1/15 the size of the WAV), or closer to ending up with a file that's 1/15 the size of the 192 file? meaning a horribly compressed 92 version that's a much different animal than creating a 92 file from a WAV?
sorry, a bit of a layman here...just want to make sure it's worth taking the time to re-rip my CDs to 92 instead of just "creating an AAC version" from the existing AAC version via iTunes.
EDIT: actually, after rereading I think I absorbed your reply better....basically you're saying it might be OK going from 192 AAC to 92 AAC but it's a gamble and it could very well end up with crappy results. So probably worth the time to do a fresh WAV/FLAC > AAC 92 conversion. Thanks!
I'm looking to do this as I've ditched my touch and classic and only have my iphone now do desperately need the space. If I convert is the file replaced or a copy made so I could have a mobile library and normal for outputting through speakers/dock?
Converting by means of selecting the items in your library and using 'convert to aac' will make a copy, preserving the original. Problem is; you end up with two entries in your library for each track. You're going to have to sort these from the originals.
Using the 128k checkbox has the advantage of creating the compressed file on-the-fly for upload to the device, without affecting the library itself. Disadvantage; a little more processing to sync each track, and currently no modifiable settings.
You could easily make a smart playlist that is your entire library excluding the low bitrate duplicates.
The only reason I'd downgrade to low bitrate would be to save space on my iPhone, which I use for my running/biking playlist. The problem there is that I have a lot of hip hop on that list, which I think sounds strange at low bitrate. Maybe I'll give it a shot anyway.
Checking the 128 box only brings my library down to 24gb so is only a temporary solution (I like to have all my tracks and shuffle all as I still haven't listened to everything) plus when I try to do it it keeps finding unknown error (-50) and stops converting, from looking at the posts on 80 AAC HE I'm guessing my library will come down to around 15gb?
I should have been a bit clearer with my question my music folder is all manually managed by album for easy drag and dropping (Itunesmusic/Music/then albums), so if I convert will the AAC HE version go within that folder (for eg will each album folder have the original rip + the converted version) or does it/can it go to a new folder
Would probably be easier if you could output your conversion to somewhere else then drag in the fully converted folder and run a smart playlist from that
On my iPhone I keep everything @ 128kbps AAC, which brings everything down to ~10GB, but on my MBP I have everything as Lossless. I may do this 80kbps HE AAC when I get the 120gb SSD though.
I just don't find that there's enough space on mobile devices to fit all the music that I want to carry around with me. I can barely fit everything onto my phone at 128kbs. At 320kbs I'd be having to choose to not load up almost 2 out of every 3 albums that I have.
At the point when an iPhone has 128GB of storage then I'd definitely go to 256kbs on the "I can so I will" basis but until that happens then I need the lower bit rates. Even with a 128GB device I'm not sure that I'd be comfortable with the the amount of free space I had left over if I went to 320kbs.
For my home listening I use lossless compression and I really wish that the iTunes store would offer downloads as lossless files so that I had perfect duplicates of the source CDs as the starting point for my iPhone conversions. I don't buy music off iTunes because of this.
- Julian
Yes, lossless would be ideal but why settle for CD quality? I hope one day the iTunes offers 24 bit 192 kHz and better but that could take decades. Whatever the next bit-rate and codec are, Apple should handle the transition better than the transition from 128 kbs protected AAC to 256 kbs AAC. Asking us to pay for better quality versions of the files we already purchased was ridiculous. Just doubling the bit-rate is not worth the price they ask for it.