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Topic: Nero: HE-AAC 5.1 Problem (Read 10014 times) previous topic - next topic
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Nero: HE-AAC 5.1 Problem

Hello there, this is my first post, so I'll do my best not to sound like a moron  .

I've been encoding with Xvid for the last 2 years but recently decided to switch to Nero Digital (MPEG4). I like the increased quality and the option for 5.1 audio. The video is great, but I've had problems with the audio.

First, I encoded a file in the AVC-Standard profile with 5.1 and left the audio settings on automatic (HE-AAC is auto for 5.1). This worked for 2 channel audio previously, so I gave it a shot. Bad Idea!

The result was audio that was full of artifacts. Anytime all 5 audio channels (LFE channel is not a factor) were involved in a scene their was significant (for somebody that cares) audio distortion at the higher frequencies. I was annoyed.

I did a test file and found that the default setting (automatic) is 128Kb HE-AAC. I re-encoded at 192Kb after some research into the "CD-quality" bitrate-per-channel capabilities of HE-AAC. Again, dissapointment  . So now I'm wondering, is the default that Nero gives really that far off? It seems that the only way to get quality 5.1 with HE-AAC is at 225Kb or greater.

My question is, does anyone know of a proper bitrate to ensure quality HE-AAC 5.1 reproduction? If it is very high, is it worth it to use HE-AAC instead of LC-AAC? What would the bitrate difference be for comparable quality?

Software Info:
Nero 6.6.0.18
Nero Recode 2
-Every plug-in ever made-

Thanks alot for any help you can provide!
Just an average nerd!

Nero: HE-AAC 5.1 Problem

Reply #1 –
HE is not to be used for transparent encoding, use LC instead. For 5.1 I personally use LC around 320 kbps.
For stereo signal LC works good down to 96 or 80 kbps, below that HE should sound better (but still not transparent)... For 5.1 use the same logic.

For interesting discussion on similar subject click h e r e.

Daniel

Nero: HE-AAC 5.1 Problem

Reply #2 –
Thanks for the info and the link.

One question I would state is that --- equivalently, what would be, in your opinion, the equal to a 192Kb CBR MP3 (2 channel)? In HE-AAC? In LC-AAC? I ask because I would still prefer to use the HE version only because it takes up less space within the audio/video stream. Thanks again!

With my rudementary knowledge, I'm coming up with 98Kb for HE-AAC and about 120-140 for LC-AAC.

What do you think of those numbers?
Just an average nerd!

Nero: HE-AAC 5.1 Problem

Reply #3 –
Please consider upgrading to Nero 7 and try what you originally tried again, first.

The HE-AAC encoder has had massive improvements.

If that is not an option, try (for 5.1 channels) 192, 256 or 320kbps LC-AAC.

Nero: HE-AAC 5.1 Problem

Reply #4 –
SpacemanSpiff0x0, if you try nero7 please report here about your findings, as i'm interested to hear about audio performance in new nero.

Nero: HE-AAC 5.1 Problem

Reply #5 –
Quote
SpacemanSpiff0x0, if you try nero7 please report here about your findings, as i'm interested to hear about audio performance in new nero.
[a href="index.php?act=findpost&pid=342234"][{POST_SNAPBACK}][/a]


BTW. There's a free 30 day trial, so it's easy to check yourself.

Nero: HE-AAC 5.1 Problem

Reply #6 –
Quote
Thanks for the info and the link.

One question I would state is that --- equivalently, what would be, in your opinion, the equal to a 192Kb CBR MP3 (2 channel)? In HE-AAC? In LC-AAC? I ask because I would still prefer to use the HE version only because it takes up less space within the audio/video stream. Thanks again!

With my rudementary knowledge, I'm coming up with 98Kb for HE-AAC and about 120-140 for LC-AAC.

What do you think of those numbers?
[a href="index.php?act=findpost&pid=342163"][{POST_SNAPBACK}][/a]


AAC is about 30% more efficient than mp3 - you do the math...

Bitrates for stereo AAC:

LC ...192-160-128-96
HE  80-64-48-40
PS  32-24-20-16...


Garf's recommendation for 192 kbps for 5.1 surround seems a little too little... :-)

Daniel

Nero: HE-AAC 5.1 Problem

Reply #7 –
>BTW. There's a free 30 day trial, so it's easy to check yourself.

too big dload.
your audio encoder (of nero recode) dissapointed me once. it won't do it again (if it's a part of such a big dload).
now i need to be sure it's good prior to dloading it.
offcourse, you can provide me with the standalone audio encoder(small dload) for me to test prior to dloading the whole shebang.
<wink>

Nero: HE-AAC 5.1 Problem

Reply #8 –
Quote
Garf's recommendation for 192 kbps for 5.1 surround seems a little too little... :-)

Daniel
[a href="index.php?act=findpost&pid=342245"][{POST_SNAPBACK}][/a]


It corresponds to about 80kbps for stereo. But the encoder can distribute bits a bit better, so it should end up relatively better.

Nero: HE-AAC 5.1 Problem

Reply #9 –
Quote
Quote
Garf's recommendation for 192 kbps for 5.1 surround seems a little too little... :-)

Daniel
[a href="index.php?act=findpost&pid=342245"][{POST_SNAPBACK}][/a]

It corresponds to about 80kbps for stereo. But the encoder can distribute bits a bit better, so it should end up relatively better.
[a href="index.php?act=findpost&pid=342286"][{POST_SNAPBACK}][/a]

If we normaly use at least 128 kbps for stereo I don't see the reason why would one use 80 kbps just because it's stereo inside 5.1... Didn't understand what you mean by "distribute bits a bit better".

Nero: HE-AAC 5.1 Problem

Reply #10 –
To clear a few things up.


1. I did encode using Nero 7
2. The codecs and features are the same between the two versions if you have the plugins. (which i do)
  - If you are thinking that it is worth it to get Nero 7....don't. The encoder is no different, in any respect. Nero 7 is really not worth the upgrade from Nero 6 and a few good plugins.
3. 192Kb HE-AAC 5.1 audio is not good. It gets messy when all the channels are asking for BW.
  - A good example is an explosion scene, it sounds gross.


So i was just asking for the proper bitrate. Research on the web shows that HE-AAC at 98Kb is CD-quality, and i have verified this with a simple rip of a CD  song. It looks like you need at least 225Kb to make it happen.


One last question. Does leaving the sample rate at 48000khz cause the codec more difficulty or use up more processor? I only ask because that is default for DVD-Audio but I am doubting that it will make much of a noticeable difference if I encode at 44.1.

What is the difference between sampling rates in regards to- sound-quality, file-size, and processor work?

Thanks again!
Just an average nerd!

Nero: HE-AAC 5.1 Problem

Reply #11 –
Quote
The codecs and features are the same between the two versions if you have the plugins. If you are thinking that it is worth it to get Nero 7....don't. The encoder is no different, in any respect. Nero 7 is really not worth the upgrade from Nero 6 and a few good plugins.

If the features are the same that does not mean that encoder is the same. People from Nero have put some serious effort in this new version (so they say), so I think you are rushing with the conclusion. You need to do some serious tests to see what's the difference between the two versions.
Quote
192Kb HE-AAC 5.1 audio is not good. It gets messy when all the channels are asking for BW. A good example is an explosion scene, it sounds gross.

If you need transparency use LC, not HE. However, even HE shouldn't sound too bad. Maybe you should post sample here so it gets examined.
Quote
So i was just asking for the proper bitrate. Research on the web shows that HE-AAC at 98Kb is CD-quality, and i have verified this with a simple rip of a CD  song.

HE at 98 kbps is too much. LC is better at this bitrate. As I already told you, use HE for bitrates 40 - 80 kbps, no more no less.
Quote
It looks like you need at least 225Kb to make it happen.

225 for 5.1 or stereo? LC or HE?
Quote
What is the difference between sampling rates in regards to- sound-quality, file-size, and processor work?

Sampling rate is directly proportional to file size - the higher sampling the more data you need to compress. 44.1 would save you around 8% (48/44.1) off the bitrate compared to 48 kHz. 
Quote
Thanks again!

You're welcome!

Nero: HE-AAC 5.1 Problem

Reply #12 –
Quote
Sampling rate is directly proportional to file size - the higher sampling the more data you need to compress. 44.1 would save you around 8% (48/44.1) off the bitrate compared to 48 kHz.


Would I be correct then, in assuming that using the same bitrates and a smaller sampling value (44.1) the result should be a higher quality file, considering that the smaller sample size leaves more bit-rate for other data?

Quote
225 for 5.1 or stereo? LC or HE?


For 5.1 HE-AAC. My rudementar calc's say that this would equate to about 42~46Kb per channel of audio.

Quote
If you need transparency use LC, not HE. However, even HE shouldn't sound too bad. Maybe you should post sample here so it gets examined.


Great Idea! I'm going to rip into a variety of bitrates a section of difficult 5.1 audio and I'll upload them onto my site. I'll post when they're ready  .
Just an average nerd!

Nero: HE-AAC 5.1 Problem

Reply #13 –
Quote
Would I be correct then, in assuming that using the same bitrates and a smaller sampling value (44.1) the result should be a higher quality file, considering that the smaller sample size leaves more bit-rate for other data?

It's not smaller sample size, but smaller number of samples. 44100 Hz means that you take 44100 samples of analog signal per second to represent it digitaly. If you take 48000 samples that's better, but takes more space... You need to do some reading on this before you will be able to understand it.

Yes, for same bitrate 44.1 will be better quality than 48 kHz.
Quote
For 5.1 HE-AAC. My rudementar calc's say that this would equate to about 42~46Kb per channel of audio.

It's not that simple since channel pairs (front and back) are encoded diferently than center channel. LFE is completely different story, it takes less than 10 kbps to encode it. So the math is not that simple. However, 225 should be enough.

Quote
Great Idea! I'm going to rip into a variety of bitrates a section of difficult 5.1 audio and I'll upload them onto my site. I'll post when they're ready

I hope Nero people will take it from here...

Nero: HE-AAC 5.1 Problem

Reply #14 –
I really do appreciate all of your help!

I'm ripping 20 second pieces of file right now and when I upload them I would appreciate any insight you have.

Also, to those that were talking about testing Nero's codecs, Your opinion would be great on the test files, they will be upped shortly.
Just an average nerd!

Nero: HE-AAC 5.1 Problem

Reply #15 –
Quote
The codecs and features are the same between the two versions if you have the plugins. If you are thinking that it is worth it to get Nero 7....don't. The encoder is no different, in any respect. Nero 7 is really not worth the upgrade from Nero 6 and a few good plugins.

Maybe it is not Nero v7.0.1.2 which has the improved AAC encoder but first nero 7 release (don't know the exact version)?

Nero: HE-AAC 5.1 Problem

Reply #16 –
I have ripped and upped the files.

I started a new thread since now this topic is moving into more of a listening test (albeit un-scientific).

Please check it out and give your opinions.

New Thread
Just an average nerd!

Nero: HE-AAC 5.1 Problem

Reply #17 –
Quote
Quote
Quote
Garf's recommendation for 192 kbps for 5.1 surround seems a little too little... :-)

Daniel
[a href="index.php?act=findpost&pid=342245"][{POST_SNAPBACK}][/a]

It corresponds to about 80kbps for stereo. But the encoder can distribute bits a bit better, so it should end up relatively better.
[a href="index.php?act=findpost&pid=342286"][{POST_SNAPBACK}][/a]

If we normaly use at least 128 kbps for stereo I don't see the reason why would one use 80 kbps just because it's stereo inside 5.1...


You don't need to use 128kbps to get acceptable quality. Specifically not so for a movie track - something lower should still be very usable.

Quote
Didn't understand what you mean by "distribute bits a bit better".
[a href="index.php?act=findpost&pid=342289"][{POST_SNAPBACK}][/a]


Bit reservoir and multiple channels allow the encoder to distribute it's bit spending more.

Nero: HE-AAC 5.1 Problem

Reply #18 –
Quote
To clear a few things up.


1. I did encode using Nero 7
2. The codecs and features are the same between the two versions if you have the plugins. (which i do)
  - If you are thinking that it is worth it to get Nero 7....don't. The encoder is no different, in any respect. Nero 7 is really not worth the upgrade from Nero 6 and a few good plugins.


As I already said, the encoder in Nero 7 is totally new and has significantly better quality.

Quote
So i was just asking for the proper bitrate. Research on the web shows that HE-AAC at 98Kb is CD-quality, and i have verified this with a simple rip of a CD  song. It looks like you need at least 225Kb to make it happen.


You do not want to use HE-AAC at such a high bitrate. Use it up to 80kbps (for stereo).

Quote
One last question. Does leaving the sample rate at 48000khz cause the codec more difficulty or use up more processor? I only ask because that is default for DVD-Audio but I am doubting that it will make much of a noticeable difference if I encode at 44.1.


It won't make much difference. I'd recommend leaving it at the source sampling rate.

Nero: HE-AAC 5.1 Problem

Reply #19 –
Quote
Yes, for same bitrate 44.1 will be better quality than 48 kHz.
[a href="index.php?act=findpost&pid=342384"][{POST_SNAPBACK}][/a]


This really depends on what the problem is he is percieving.

Nero: HE-AAC 5.1 Problem

Reply #20 –
Quote
Quote
The codecs and features are the same between the two versions if you have the plugins. If you are thinking that it is worth it to get Nero 7....don't. The encoder is no different, in any respect. Nero 7 is really not worth the upgrade from Nero 6 and a few good plugins.

Maybe it is not Nero v7.0.1.2 which has the improved AAC encoder but first nero 7 release (don't know the exact version)?
[a href="index.php?act=findpost&pid=342413"][{POST_SNAPBACK}][/a]


Nero 7.0.1.2 has the new encoder. The very first Nero 7 releases did not.

Nero: HE-AAC 5.1 Problem

Reply #21 –
I know:). My question was rather directed to SpacemanSpiff0x0.

Nero: HE-AAC 5.1 Problem

Reply #22 –
I thought the encoder was part of the Recode 2 Update for Nero 6.

If it is a whole new encoder and it's better, does that mean that I have to upgrade to Nero 7 to get the new encoder?

I'd rather not, unless there are some other new features available that I am missing. I don't really have much use for the HomeMedia apps.
Just an average nerd!