5.1 HE-AAC in Nero 6.6.0.0 and small biterate

[JnZ]

Hi everybody!

I always encode 5.1ch AC3 -> 5.1ch HE-AAC using Nero AAC encoding plugin via Foobar 2000.

I encoded HE-AAC by this way manytimes using profile "Streaming Medium" (maximum alowed biterate for HE-AAC). Output AAC had always biterate between 200-300 kbps.

But now I have one small problem. I've just updated my Nero Burning Rom to latest version v6.6.0.0. And now output biterate is only about 135 kbps. I tested a few different AC3s, but the biterate is only betwen 120-180 kbps.

In this time, I must listen results, to compare quality, but I'm afraid, that 135 kbps 5.1ch AAC isn't good quality.

Can me somebody explain, what the .... is goin' on?
:thanks:

[hans-jürgen]

Obviously the new Nero AAC codec has been adapted to fulfill the estimated output bitrates for the VBR presets now. This is actually a good thing, because now you can rely on the information given in the GUI (50-70 kbps/stereo, as far as I remember). And yes, you have to listen to your files once in a while to tell how they sound... ;)

By the way, 200-300 kbps/6ch can easily be done with the AAC LC profile (e.g. with FAAC) which will lead to less problems on different platforms (hardware and software).

[JnZ]

Originally posted by hans-jürgen
And yes, you have to listen to your files once in a while to tell how they sound...
By the way, 200-300 kbps/6ch can easily be done with the AAC LC profile (e.g. with FAAC) which will lead to less problems on different platforms (hardware and software).
Yestereday, i done some listen tests, and my opinion is, that HE-AACs with this low biterates sounds very good. Yes, the VBR biterate now changes from 80-300 kbps based on how much channels plays,or dynamics changes,..., eg when plays music from all channels, biterate is high, and when only stereo plays, biterate is low.

I tryied make some LC-AACs with low biterates, but it sounds no good as HE-AACs with same biterate (size). I listen it on Koss Porta Pro headphones. High frequencies is cut too much and distorted. I use AVIs for only my need, and HE-AAC works for me fine.

BTW: Diferences between HE-AAC and AC3 is also audibly, high frequencies is lightly cut, but globally all sounds good. Dynamics is totaly the same. This is my opinion.

Thx for post, Hans.

[hans-jürgen]

Originally posted by JnZ
I tryied make some LC-AACs with low biterates, but it sounds no good as HE-AACs with same biterate (size). I listen it on Koss Porta Pro headphones. High frequencies is cut too much and distorted. I use AVIs for only my need, and HE-AAC works for me fine. That's interesting, which codec and which settings did you use for AAC LC, and what are the exact overall bitrates for a certain sample or whole movie? By the way, is your headphone capable of multichannel playback, i.e. generating a surround image?

[JnZ]

Originally posted by hans-jürgen
That's interesting, which codec and which settings did you use for AAC LC, and what are the exact overall bitrates for a certain sample or whole movie? By the way, is your headphone capable of multichannel playback, i.e. generating a surround image?

I used latest Nero encoder plugin via Foobar 2000.
We are talking about "low" biterates (about 20-40kbps/channel). So LC-AAC in this biterate isn't capable to keep acceptable quality. Solution is HE-AAC. But! , if we are talking about higher biterates (40kbps and above), of course, that LC-AAC may be better.

My headphones are stereo, of course. I'm testing only quality via headphones. If I test 5.1 channels effect and dynamics, I use my 5.1ch amplifier with speakers.

P.S.: Thx for your post Hans, I've got just new idea, i must test FAAC vs Nero plugin, but I'm afraid, that FAAC have no chnce against Nero. (my goal is convert 5.1ch AC3 to smaller file with nearly quality)

[hans-jürgen]

Originally posted by JnZ
I used latest Nero encoder plugin via Foobar 2000.
We are talking about "low" biterates (about 20-40kbps/channel). So LC-AAC in this biterate isn't capable to keep acceptable quality. Solution is HE-AAC. But! , if we are talking about higher biterates (40kbps and above), of course, that LC-AAC may be better. The multiplier to estimate an overall bitrate for 5.1 channels from a stereo bitrate is ~2.7, so do not simply take the bitrate for one channel and multiply it with 6 if you want to compare settings and expected resulting bitrates.

My headphones are stereo, of course. I'm testing only quality via headphones. If I test 5.1 channels effect and dynamics, I use my 5.1ch amplifier with speakers. So you should also judge the difference between AC-3, HE AAC and AAC LC multichannel encodings with your speakers and not primarily with your headphones.

P.S.: Thx for your post Hans, I've got just new idea, i must test FAAC vs Nero plugin, but I'm afraid, that FAAC have no chnce against Nero. (my goal is convert 5.1ch AC3 to smaller file with nearly quality) And I'm afraid I will ask you to post the samples that you tested then... ;) By the way, in case you didn't see it yet, here (http://forum.doom9.org/showthread.php?s=&threadid=74708) is a small test of AAC LC encodings done with FAAC, so if you want to do a fair comparison, use a Nero AAC LC setting that results in the same overall bitrates as FAAC.

[rjamorim]

Originally posted by JnZ
i must test FAAC vs Nero plugin, but I'm afraid, that FAAC have no chnce against Nero. (my goal is convert 5.1ch AC3 to smaller file with nearly quality)

If you want to have an idea of how they compare:

http://www.rjamorim.com/test/aac128v2/results.html

[JnZ]

Originally posted by hans-jürgen
So you should also judge the difference between AC-3, HE AAC and AAC LC multichannel encodings with your speakers and not primarily with your headphones.
I'm using my headphones only for testing cut-off frequency and high freq. replication, if accetable, because via speakers isn't so noticable.

Sorry, I started this thrad, to find, why my 6ch HE-AACs have too smal biterate with new Nero encoder. Not to compare LC-AAC and HE-AAC and start flamewar. As I sad, I use HE-AAC, because it sounds better with lower biterates (exactly I want to achieve smallest file).

Example: I test a short AC3/6ch,En,448 kbps track from Kill Bill 2 movie. Exactly I test first 7:32 minutes. I test Nero HE-AAC and FAAC 1.24.
Sizes and biterates:
Original AC3: 25 350 144 b
HE-AAC : 9 035 251 b
LC-AAC : 13 580 627 b

He-AAC settings: VBR profile Streaming Medium. (average biterate 160kbps).
LC-AAC settings: Q75,240kbps,LC,Automatic bandwith,mid/side coding on,TNS on.

My conclusion is, that HE sounds far better than LC. LC with this horrible quality isn't accetable for me. High freq. is too cut. But on other side HE at 160kbps isn't good for me too.

I want HE with 240kbps. In old nero it works, but now not. I don't know why.

[hans-jürgen]

I want HE with 240kbps. In old nero it works, but now not. I don't know why. I think this has already been answered. By the way, you could also use a higher cutoff than 13 kHz if that's the only concern you have with AAC LC encodings, i.e. don't use "Automatic bandwidth" in foo_faac, but rather 15 or 16 kHz. This will also increase the overall bitrate a bit, so it will not stay at 240 kbps/6ch. Nevertheless that decision should be made after listening over your 5.1 speakers, not on your headphone in my opinion. Anyhow, thanks for testing.

[JnZ]

Originally posted by hans-jürgen
I think this has already been answered.
So now I must only test old AAC encoder, which give 200-300kbps HE and new encoder, which give 130-170kbps, if sounds same.

Anyway thanks for Your posts Hans. Now, I know,that exist FAAC encoding plugin for Foobar 2000. (I read Your discussion with KpeX). ;)