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HE AAC Audio Quality & Tuning
GreenSeer
post May 23 2012, 15:39
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I am new to the lossy coding world. I recently became a DROID owner and, in an effort to get down to carrying one device, I ripped all of my music to my DROID at 64 kbps. In the environments I often listen in (Airports, Planes, Rental Cars, Taxi's, etc.) this is good enough for me and has the great benefit of using minimal storage space. The efficiency of a codec that provides satisfactory audio quality while using lower bitrates appeals to me.

My question is whether this codec is still being developed and "tuned"? I guess I am curious as to whether HE-AAC is now about as good as it will ever get. For example, is the crossover point from real sound to where the SBR begins as finely tuned as possible? Will we ever get to the point where a 48 kbps rip is perceived qualitatively by a general audience like a 128 kbps AAC file is today? Thanks!
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IgorC
post May 28 2012, 16:22
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Chris,

The Average scores are:

Apple HE-AAC - 2.85
FhG HE-AAC - 3.01

One would think that the difference is pretty small. Yes, but I've performed the test on these codecs before and the results were the same. Let me see if I can find those results on my hard disk later.
Also the scores are pretty low because I didn't include the low anchor. The quality is actually pretty good and if it was a public test the average scores would be in range of 3.9-4.0.


CODE

Apple HEAAC FhG HEAAC
3 3,7
4,1 4
1,8 4,3
3,2 3,2
3,1 2,8
1,5 1
2 2,4
3 3
2 3,1
1 1,7
3 3,1
1 1
2,7 3,5
3,2 3,6
3,8 3,8
1 1
3,8 3,8
2,5 2,5
4 3,6
3,4 3,1
2 2,5
3,3 3,5
3,4 3,4
3,5 4
3,4 2,9
3,3 3,3
3,3 3,6
3,4 3,2
4 3,8
2,8 1,8

I won't post here particular ABC/HR logs as this test wasn't meant to be published. Nothing special, just private stuff.

Those are 30 samples from public test 64 kbps (2011). There were some pathological cases where both encoders don't perform well. Those are classical transient samples like castanets, fatboy and eig.
FhG did a good job comparing to Apple on all samples except the last one. Sample30. It was also a difficult sample for FhG LC-AAC encoder in last public AAC test.
It will be great to see an updates of your encoder.
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C.R.Helmrich
post May 29 2012, 20:47
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Awesome, thanks a lot, Igor!

QUOTE (IgorC @ May 28 2012, 17:22) *
FhG did a good job comparing to Apple on all samples except the last one. Sample30. It was also a difficult sample for FhG LC-AAC encoder in last public AAC test.

Yeah, that Sample30 (or 20 in the 96-kbps test) is a pain. I recently added a minimally invasive patch which gives a bit more (hopefully enough) bit-rate to that item without affecting others much. Once that encoder version becomes publicly available, I'll let you know.

Chris


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Posts in this topic
- GreenSeer   HE AAC Audio Quality & Tuning   May 23 2012, 15:39
- - Garf   Which codec? HE-AAC is a standard. There are seve...   May 23 2012, 15:54
|- - GreenSeer   QUOTE (Garf @ May 23 2012, 09:54) Which c...   May 23 2012, 18:59
- - IgorC   QUOTE (GreenSeer @ May 23 2012, 11:39) My...   May 23 2012, 17:31
|- - C.R.Helmrich   QUOTE (IgorC @ May 23 2012, 18:31) For HE...   May 27 2012, 11:03
- - IgorC   Chris, The Average scores are: Apple HE-AAC - 2....   May 28 2012, 16:22
|- - C.R.Helmrich   Awesome, thanks a lot, Igor! QUOTE (IgorC ...   May 29 2012, 20:47
|- - C.R.Helmrich   QUOTE (C.R.Helmrich @ May 29 2012, 21:47)...   Jun 22 2012, 16:00
|- - sluggy   QUOTE (C.R.Helmrich @ Jun 22 2012, 15:00)...   Jun 22 2012, 21:43
|- - benski   QUOTE (sluggy @ Jun 22 2012, 16:43) Hi i ...   Jun 22 2012, 21:56
|- - sluggy   QUOTE (benski @ Jun 22 2012, 20:56) QUOTE...   Jun 22 2012, 22:08
- - IgorC   Good news. Eagerly waiting to get home and try it....   Jun 22 2012, 19:45
- - GreenSeer   Is there a reference or an explanation somewhere f...   Jun 26 2012, 03:39
|- - saratoga   QUOTE (GreenSeer @ Jun 25 2012, 22:39) Is...   Jun 26 2012, 04:07
|- - C.R.Helmrich   QUOTE (GreenSeer @ Jun 26 2012, 04:39) Is...   Jun 26 2012, 17:20
|- - saratoga   QUOTE (C.R.Helmrich @ Jun 26 2012, 12:20)...   Jun 26 2012, 19:03
|- - C.R.Helmrich   QUOTE (saratoga @ Jun 26 2012, 20:03) I d...   Jun 26 2012, 19:32
- - benski   Side note: This is also the rationale behind the s...   Jun 26 2012, 20:11
- - GreenSeer   In my recent experience, there is a surprisingly l...   Jun 26 2012, 21:00
|- - IgorC   QUOTE (GreenSeer @ Jun 26 2012, 17:00) An...   Jun 27 2012, 01:17
|- - GreenSeer   I may try to do this if I can spare the time - are...   Jun 27 2012, 01:50
||- - db1989   QUOTE (GreenSeer @ Jun 27 2012, 01:50) ar...   Jun 27 2012, 06:34
|- - GreenSeer   Some time ago I've performed a personal blind...   Jun 30 2012, 01:03
- - lvqcl   The crossover frequency for Apple HE-AAC (CVBR 64 ...   Jun 27 2012, 00:26


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