AAC Encoding

[JarrettH]

When I try to use megui to make aac files (Nero) they almost always come out larger than the AC3. I'll start the Q setting at 0.65 or 0.55 wait about 25% and see how large the file is. Even when I made a 2ch file smaller it was only by 9mb.

If I use BeLight the file is compressed enough to make it seem worth while. I know the Q settings aren't the same...

megui:
5.1
Q 0.65
Profile: Automatic

belight:
5.1
VBR Mode: Audiophile
Profile: none
Quality: High (um...now we use high right?)

megui would have made me a file 600mb+ and belight will be about 280mb...so what the hell is going on lol? I almost find using megui to do this stuff a waste of time. Are they using different versions? Someone explain this please :cool:

[JarrettH]

Why does Belight resample this stuff too? It should be 48kHz, I open it up in mediainfo and VLC and they say different. Is there nothing on earth to do this properly? :eek:

[emmel]

Try q=0.3 and mode=normal/extreme nstead. Or, if the original is 384k, try adaptive bitrate 192k. If the result sounds bad, or is too big for your needs, you might consider keeping the original.

[JarrettH]

I'd like to keep the AC3, but MKV is problematic for a lot of people (no video only audio)

[JarrettH]

This is so annoying. Is there no proper way to make a 5.1 aac?

Any 5.1 wav is too large to convert to aac, belight messes with the sample rate, megui makes larger files, can't put ac3 audio in mp4 container, arghhhhhhhhhh :mad:

Just tried the muxxer (6 mono wav) in BeLight. I hit Start and it spits out a tiny file a few seconds later =/

[Skelsgard]

Open your AC3 file in BeLight. Export it as "16 Bits (Six) Mono Waves". If u export as 6ch Wav, the file gets clipped at 4GBs. This is an issue with non WAVE_FORMAT_EXTENSIBLE output, unless u can set the file to be outputed to WAV_EXT.
Anyway.
Then, load the mono wavs into Wavewizard and export then as a 6-ch WAV (in Preferences, set "Stream Manipulation" to Merge Files, and "Output Format" as Wav EXT. If u choose to set output to WAV PCM, u´ll need to check the "Ignore file size header" to "Always").
In wavewizard, the order from top to bottom determines the order from channel 1 to channel n in the exported WAV.
Use L-R-C-LFE-SL-SR (WAV channel order), SNG will remap to the correct order for AAC.
When u have the 6-ch WAV set, then compress it with NeroAacEnc, or SNG (I love GUIs).
That´s it.
No hassle.
Cheers.

[JarrettH]

I'm pretty sure I got a 4.1gb file when I used BeLight. Does WaveWiz do anything different? I'm doing what you said anyway :)

[Skelsgard]

If Belight is using WAV_EXT, then it sounds right. It´s about 4GBs, I don´t remember the exact file size (haven´t use a >4GBs generating method in a long time).
The basic function of Wavewizard in here is to get to set the proper output formats and channel mapping if necessary. If u are already getting a >4GBs 6-ch WAV file without size clipping, then u can skip Ww´s part.
For me, to be able to handle exactly the channel mapping allows me both to assure a proper ouput and to have control or knowledge of the possible point of failure if something goes wrong.
Cheers.

[JarrettH]

Unfortunately I get the same result in Belight, SNG, and Megui. I'll hit encode and a second later it generates this small MP4 file...completely skips encoding.

[Skelsgard]

If the problem persists in all the frontends, u might have a problem with neroaacenc. Replace it, try again.
Post your Belight log file too.
Else, you can try to use WAV PCM output (with Ignore file size header --> Always) in Wavewizard.

[check]

When I try to use megui to make aac files (Nero) they almost always come out larger than the AC3. I'll start the Q setting at 0.65 or 0.55 wait about 25% and see how large the file is. Even when I made a 2ch file smaller it was only by 9mb.

If I use BeLight the file is compressed enough to make it seem worth while. I know the Q settings aren't the same...

megui:
5.1
Q 0.65
Profile: Automatic

belight:
5.1
VBR Mode: Audiophile
Profile: none
Quality: High (um...now we use high right?)

megui would have made me a file 600mb+ and belight will be about 280mb...so what the hell is going on lol? I almost find using megui to do this stuff a waste of time. Are they using different versions? Someone explain this please :cool:
As you have yourself stated - you are using different settings. When you encode with the same encoder (BeLight may use an older version although they will be functionally almost identical) it doesn't matter what frontend you use, if your settings are the same the output will be the same.
In this case you are obviously using settings in megui which result in higher quality files, and obviously q0.65 is a higher quality than 'audiophile' is. Either use adaptive bitrate with the bitrate output set to what you want or use a lower q setting.

[JarrettH]

I forgot where I read this...do I need to add the delay value when I'm going to wav too?

[SeeMoreDigital]

This is so annoying. Is there no proper way to make a 5.1 aac?

Any 5.1 wav is too large to convert to aac, belight messes with the sample rate, megui makes larger files, can't put ac3 audio in mp4 container, arghhhhhhhhhh :mad:

Just tried the muxxer (6 mono wav) in BeLight. I hit Start and it spits out a tiny file a few seconds later =/I can't say I have any such issues generating 6Ch AAC-LC or HE streams using BeLight!

All I do is feed BeLight with 6Ch AC3 source, select the WinAmp (CT) encoder and enter the bit-rate I require. Which is usually 128Kbps for a 6Ch AAC-HE encode!

Perfect results every time ;)

[Skelsgard]

I forgot where I read this...do I need to add the delay value when I'm going to wav too?
If u plan to specify delay on the container, then u don´t need to. But if have no way to set delay on container, then u need to set it for the WAV, since the encoded AAC will have to be ready to mux.

[Teegedeck]

MeGUI AAC encoding works splendidly, also with the Nero AAC encoder. Q 0.20 - Q 0.30 would seem a very sane quality range to use. Bitrates should be about 50% - 70% lower than those of the original AC3.

Q 0.65 is waaay to high. I would use that for encoding classical music if I had perfect hearing... (In fact Q 0.45 is good enough for me any time.) It should result in something ~248 kbps for a stereo encoding and would be way better quality (for people with perfect hearing) than AC3... See also this page (http://www.hydrogenaudio.org/forums/index.php?showtopic=44310) for a table of equivalent bitrates for the Q-settings for stereo encodings.

[JarrettH]

Thanks Teegedeck:D
I saw that table and could only really make a comparison with what ogg or lame would give me so I chose 0.55-0.65
So is the equivalent bitrate of an mp3 might be 25% higher?

I did it at 0.45 in megui and it came out about 10mb larger than the AC3 file. sigh :(
Is there something I'm completely missing when dealing with 5.1? Why does belight always give me 24khz sampled files when I try to do ac3--->aac

thanks for everyone's help ;)

[SeeMoreDigital]

Is there something I'm completely missing when dealing with 5.1? Why does belight always give me 24khz sampled files when I try to do ac3--->aacThat's because your AAC stream has been generated using the "HE" (High Efficiency) profile.

AAC-HE streams are encoded using a technique known as "Spectral Band Replication" (http://en.wikipedia.org/wiki/Spectral_Band_Replication) (SBR), which effectively halves the frequency of the source during the encoding process (base frequency) before doubling the frequency upon playback.

Some file readers are unable to take the SBR element into consideration when displaying the streams frequency and only display the "base" frequency.

[JarrettH]

Well I didn't specify any profile in Belight, but that is interesting to know :cool: I'm trying out AAC-LC for it now

[SeeMoreDigital]

Try BeLight 0.2.2.0 Beta 9 (2006-06-26), ie: the latest daily build. Once installed correctly you should see the following options for "stereo" 2Ch AAC encoding: -

http://img92.imageshack.us/img92/2450/belight2chaacencbw7.png


....and "5.1 Surround" 6Ch AAC encoding: -

http://img92.imageshack.us/img92/2117/belight6chaacencmw7.png


I run both BeLight versions in different folders....


Cheers

[Jeffster]

Maybe you might want to try this approach with foobar2000 instead...
Copy neroAacEnc.exe to the foobar2000 folder.

First convert your ac3 in BeLight to 16 Bits 5.1 Wav.

Open the wav file in foobar2000.

Go to File > Preferences (Ctrl+P) and select the Converter options.

Beside the Encoding Presets box press the Add New button.
In the Encoder drop down box choose Custom
Encoder: browse to neroAacEnc.exe
Extension: M4A (or MP4)
Parameters: -ignorelength -q 0.5 -if - -of %d
Put something meaningfull in the Display Info boxes and click OK and Close.

Now right click on your wav and choose Convert > Convert to...
In the Converter Setup window choose the encoding preset you configured earlier from the drop down box and click OK.


I've just tested this on a short sample, the original 5.1 ac3 file was 384Kbps and 25.5 MB.
The encoded file using the parameters above (q 0.5) is 214Kbps, 12.3 MB, 48000 Hz, 6 channel, AAC(LC).

Hope this helps. :)

(I'm not sure what the actual threshold is when it decides to switch from LC to SBR profile, but q 0.5 is fine.)

[JarrettH]

Oh my gosh that worked SeeMoreDigital <3

I used AAC-LC and it didn't mess with the sample rate. Is there some bug in belight maybe? I definitely didn't choose HE the first time and it always came out as 24khz. I thought it would use Main if i didn't select one :scared:

Thanks for that too Jeffster if I ever need another method :sly:

Some bits of this thread should go into the AAC FAQ :D

[Teegedeck]

I did it at 0.45 in megui and it came out about 10mb larger than the AC3 file. sigh :(No surprise there. :)

I wrote:Q 0.20 - Q 0.30 would seem a very sane quality range to use.Which translates "Q 0.45 is an insane value for transcoding AC3 to AAC.

Try 0.25, that would seem a good point to start. Test if you can hear a difference.