RyanBellaCine
Well-known member
I stumbled upon a relatively new technology relating to digital "consumer" audio formats. It's called HE- AAC or High Efficiency AAC. What's most impressive about this format is the insanely low bitrate and file size in relation to the quality of sound. HE-AAC seems to only be limited to 80kbps. Which seems quite insane. Even if you wanted to encode at anything higher, you literally are unable to do it. It simply won't go any higher. This format has been added to iTunes 9, and you can now encode your audio using this format.
I've encoded just one album in HE-AAC so far and encoded the same album in 320kbps AAC, though I didn't use iTunes. I didn't realize iTunes could do it until later. The program I used to encode both versions is a small open source app called "XLD" made from some Japanese programmer. It's an OSX only app which transcodes audio to and from a few different formats. Originally I grabbed it to transcode FLAC audio into AAC files for iTunes. I stumbled upon the HE-AAC checkbox and wondered what that was… so i tried it out and opened the door to a new "whoa! That's cool" moment.
One track example compares as 80kbps @ 1.7MB in HE-AAC & as 320kpbs @ 6.7MB in standard AAC. Certainly, there would be less of a difference with 128kpbs AAC, but I wanted to see if I could notice any difference at all between the best of AAC and the best of HE-AAC.
That difference in file size is huge! yet I've played both versions over and over on 2 different audio systems, one of them containing a pair of Mackie HR624 Studio Monitor speakers fed by a Mac Pro & a 1402 Mackie audio mixer. I have not been able to tell the two formats apart at all.
There is some criticism out there that the format cuts out too much top end information on the audio spectrum and the format is not considered a Hi-Fi format. But again, I've tested this on one album so far, even dropped out all other frequencies below 4khz and focused on the top end.. I heard zero difference between HE-AAC or AAC in iTunes 9 playback. Not to say that a more complicated album, or busier sounding album might find some artifacts or differences. The only album I have tested with so far is the relatively acoustic sounding album "Blacklisted" by Neko Case. Metallica might encode a bit differently and maybe prone to more compression artifacts?? :~)
So far, from what I've found about the format is that the 3.1 iPhone/iPod Touch OS does support playback of HE-AAC, and possibly the newest Nano & Shuffle models. There is apparently a noticeable reduction in battery life as HE-AAC currently takes more processing power then standard AAC.
I don't have Satellite Radio, but it seems Sirius XM uses this format as the core of its audio streams & Dolby is has a new format called "Pulse" for surround sound that is also based on HE-AAC at it's core. And I think I saw info about FM HD stations using this, but I couldn't re-find that to verify.
Anyway I just wanted to share this out to the general public. I love discovering this kind of info on what new technologies are just coming over the horizon. I'm certain to play around with this some more, my 8GB iPhone 3G is full, and converting a few albums to HE-ACC would be a huge space saver!
I've encoded just one album in HE-AAC so far and encoded the same album in 320kbps AAC, though I didn't use iTunes. I didn't realize iTunes could do it until later. The program I used to encode both versions is a small open source app called "XLD" made from some Japanese programmer. It's an OSX only app which transcodes audio to and from a few different formats. Originally I grabbed it to transcode FLAC audio into AAC files for iTunes. I stumbled upon the HE-AAC checkbox and wondered what that was… so i tried it out and opened the door to a new "whoa! That's cool" moment.
One track example compares as 80kbps @ 1.7MB in HE-AAC & as 320kpbs @ 6.7MB in standard AAC. Certainly, there would be less of a difference with 128kpbs AAC, but I wanted to see if I could notice any difference at all between the best of AAC and the best of HE-AAC.
That difference in file size is huge! yet I've played both versions over and over on 2 different audio systems, one of them containing a pair of Mackie HR624 Studio Monitor speakers fed by a Mac Pro & a 1402 Mackie audio mixer. I have not been able to tell the two formats apart at all.
There is some criticism out there that the format cuts out too much top end information on the audio spectrum and the format is not considered a Hi-Fi format. But again, I've tested this on one album so far, even dropped out all other frequencies below 4khz and focused on the top end.. I heard zero difference between HE-AAC or AAC in iTunes 9 playback. Not to say that a more complicated album, or busier sounding album might find some artifacts or differences. The only album I have tested with so far is the relatively acoustic sounding album "Blacklisted" by Neko Case. Metallica might encode a bit differently and maybe prone to more compression artifacts?? :~)
So far, from what I've found about the format is that the 3.1 iPhone/iPod Touch OS does support playback of HE-AAC, and possibly the newest Nano & Shuffle models. There is apparently a noticeable reduction in battery life as HE-AAC currently takes more processing power then standard AAC.
I don't have Satellite Radio, but it seems Sirius XM uses this format as the core of its audio streams & Dolby is has a new format called "Pulse" for surround sound that is also based on HE-AAC at it's core. And I think I saw info about FM HD stations using this, but I couldn't re-find that to verify.
Anyway I just wanted to share this out to the general public. I love discovering this kind of info on what new technologies are just coming over the horizon. I'm certain to play around with this some more, my 8GB iPhone 3G is full, and converting a few albums to HE-ACC would be a huge space saver!