questions about ac3 to aac

[Hobojobo]

I am doing some testing in transcoding ac3 5.1 (384-448 kbit/s) to aac 5.1 in order to use the mp4 container for my movie backups (video avc, sound aac).
I find 192 kbit/s (Nero Audio Encoder LC) is not sufficient for 5.1 sound. The outcoming is clearly inferior to the original.
Using nearly the same biterate for the aac file as the ac3 is sort of nonsense, don't you think?
:confused:

Conclusion: I have to take another container, mkv, and stay with the original ac3.

What are your opions about it?

[Skelsgard]

What about a 256-320 range for AAC?
MKV is my choice for container but if you want to use MP4, then you should tried the above bitrates.

Cheers.

[shon3i]

I find 192 kbit/s (Nero Audio Encoder LC) is not sufficient for 5.1 sound.192 isn't good for LC profile, but is good for HE, aslo LC is only good around 320.

If you want quality better keep original ac3, but if you want mp4 container in final video, you should use 192kbps HE-AAC or 256kbps LC-AAC.

[Hobojobo]

Thank you for sharing your thoughts.

I like the idea of using mp4 as container.
But transcoding audio to another format with (nearly) the same bitrate to minimize quality loss is not an opion.
You hardly save space and whenever you transcode, the quality does not increase, does it?

I give aac HE a shot.

[Skelsgard]

You hardly save space and whenever you transcode, the quality does not increase, does it?
About the quality, no, never. About the space, if you backup to MP4 or MKV in DVD, to worry about a few extra 100 Mb is just pointless. If you backup to CD, that´s another story.

Cheers.

[SeeMoreDigital]

Hobojobo,

Do you mean you want to generate 6Ch AAC encodes from 6Ch AC3 sources?

If so, I recommend the latest BeLight daily build, with CT's AAC encoder. As it offers the ability to generate to either AAC-HE or AAC-LC :)


Cheers

[Hobojobo]

So far I used meGui to transcode ac3 5.1 to Nero aac.
I can choose between HE-AAC+PS, HE-AAC,AAC-LC.

Has the ct-encoder got an advantage over the Nero Encoder?

[SeeMoreDigital]

Has the ct-encoder got an advantage over the Nero Encoder?In my opinion it sounds slightly better than any of Nero's AAC encoders.... To my ears anyway :)


Cheers

[Favorito]

Take the encoder/quality you like when it's stereo and multiply it using 2.5 to get the approximate bitrate needed for 5.1 encode.

[Hobojobo]

For stero encodes aac-HE 96 kbit/s provides a decent quality for my taste.
As I said before, 192 kbit/s for 5.1 is crap.
I do some more transcoding with 256-320 kbit/s.

[shon3i]

As I said before, 192 kbit/s for 5.1 is crap.
Why you not just try HE-AAC @ 192kbps

[Romulus76]

Hello,
I need some help.... I want to make some testing with AAC 5.1 but I can't found the correct encoding software / guide.

Can someone give me some way to start with this new audio codec?

Thanks a lot.

[shon3i]

BeHappy or MeGUI is right app for you.

[Romulus76]

BeHappy or MeGUI is right app for you.

Many thanks, I just try them but without any result... I need a little step-guide on "How to convert" and "Basic program setup"....

What's the right links to the programs? And what's the right codec? :confused:

[Hobojobo]

@Romulus76 :

Use meGui:
Use the D2V Creator to demux the audio trax from the vob set.
Then select the audio track you want to transcode in the lower part of the input tab. Use an audio profile or configure one on your own. Press "Enqueue" and start it under the queue tab. Provided you have set up MeGui properly you end up with a transcoded aac file.

@all:
What audio profile/bitrate for 5.1 DD to 5.1 aac transcoding do you use to maintain decent quality?

[shon3i]

@all:
What audio profile/bitrate for 5.1 DD to 5.1 aac transcoding do you use to maintain decent quality?You should use LC-AAC over 250kbps

[Romulus76]

Thanks, but... I have internet connection only at work and I'm behind a proxy firewall, so I can't update anything of MeGUI data and profiles.

I need to download manually audio plugins / profile files and then put in the MeGui folder... can you give me these files please? (for LC-AAC encoding)

Or can you share your installed MeGui forder with me? Thanks....

[SeeMoreDigital]

Coding Technologies (CT) AAC-HE encoder set to 192Kbps sounds pretty good to me ;)

[Favorito]

For stero encodes aac-HE 96 kbit/s provides a decent quality for my taste.
As I said before, 192 kbit/s for 5.1 is crap.

As I said: you take bitrate AND codec when it's stereo and multiply it from 2.5 to get the aprox. bitrate for 5.1 to reach similar q. There is big difference between HE and LC.
192kbps for LC is not enough.
If you like how HE sounds, I suggest listening to 48-64kbps stereo(128-160 for 5.1) to. Do ABX to eliminate placebo, which will probably be strong here.
I would say for low bitrates or for 1CD backup use HE at about 160kbps. For larger bitrates(2-3CD)use LC at 256-320.
For max q keep original AC3.

[bananacreamandpeca]

I also have a quick question.
When I encode AC3 to multi-ch. AAC (Megui, keep all channels)
Muxed with video, I get 4 audio tracks I can choose from in in VLC.
The 1st track sounds OK.
As soon as I choose track 2, 3, or 4 The left channel starts to distort on "kick drums"

Why is this? --> Bad downmix by software of VLC internally?
Or is my AAC 5.1 sound just encoded wrong?