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Old 23rd November 2010, 15:20   #1  |  Link
buzzby
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Issues with AC3 to AAC conversion for AppleTV what tool to use

Hi,

A bit of background on what I am doing. I have bought one of the new AppleTV's and its great, but of course requires all video content to be in itunes and therefore MP4 files H.264 video and AAC audio. As i already have a large collection of film and television on my system I have been writing a command line tool to convert MKV or AVI's to MP4's. All I am really doing is wrapping up a bunch of command line tools into an automated process (extract, encode (if needed), create mp4, tag files from TVrage, move to correct file location on HDD and add file to itunes). AVI's are easy as I pass them through the handbrake CLI with a preset i'm happy with (the appleTV one).

MKV files are causing me more of a problem as i don't need to re-encode the video (yay) but i have to do something with the AC3 audio.

Having looked on here and googled i have had a couple of solution/ I managed to find a build of FFMEG that would do the AAC audio but the files sizes were MUCH smaller that the AC3 so i imagine i'm losing a lot of quality. I have tried Besweet but cannot get it to encode ac3 to aac, i found eac3to and thought this answered all my questions but every so often it fails, if i try the encode again it works without issue. It seems to be that if my machine is doing anything else while the audio is being encoded then it will fail.
I have downloaded the NeroAacEnc.exe for eac3to to use but everytime i run it it still starts with "The Nero decoder doesn't seem to work, will use libav instead."
I have got a copy of Nero 7.10 professional but cannot find the required DLL's anywere in the install directory.

I found a lot of posts talking about aac.dll from Nero, but cannot find it in the install


So to the root of my problem.
I am looking for a command line tool that will convert any given AC3 file (2.0 or 5.1) into an AAC equivalent with as little quality loss as possible. I have been going round and round reading posts and getting no where.

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Old 23rd November 2010, 17:07   #2  |  Link
tebasuna51
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Quote:
Originally Posted by buzzby View Post
...
I have downloaded the NeroAacEnc.exe for eac3to to use but everytime i run it it still starts with "The Nero decoder doesn't seem to work, will use libav instead."
And, what is the problem to use libav?, is the decoder, the encoder is always NeroAacEnc.
Is the same decoder than use BeSweet-Azid.
BTW, you can use BeSweet-Azid-NeroAacEnc with BeLight.
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Old 24th November 2010, 18:49   #3  |  Link
buzzby
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Thanks for the response.

I have no issue with using the libav, just wanted to be clear on what my process was. I converted my AC3 track to WAV so i could use NeroAacEnc directly and it would appear that this alone is what "sometimes" fails.

How can I use NeroAacEnc with Belight? I have the NeroAacEnc.exe in the same directoy but when I try to encode to AAC it immediately fails.

I take it all BeLight is doing is using BeSweet to convert to wav and then running the nero cmd line? I don't mind doing this within my program as I would like to pregain the audio.

Is there a way of detecting if the AC3 file is 2.0 or 5.1? Then I could automate BeSweet creating the WAV? Any recommended AC3 to WAV command line settings.

Thanks again

Buzz
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Old 24th November 2010, 20:44   #4  |  Link
ramicio
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I would stick with eac3to as it will tell you the AC3 or DTS file info without even needing to encode. I would also figure out what is causing the crash. It has happened to me before, too, and retries were successful. If you have the space it would be easiest, but slower, and crashproof, to extract the audio from MKV, then go to WAV, then encode to AAC.
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Old 24th November 2010, 22:06   #5  |  Link
buzzby
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Thanks, i'll stick with eac3to for the moment. I am already extracting the AC3 via mkvextract then pushing the AC3 into eac3to.exe. I've added a loop into my convertion program to try the ac3 to aac convertion up to 3 times. Seems to solve the issue of the 1 off failure.

I might add in a besweet step to convert to WAV.

Thanks
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Old 25th November 2010, 01:06   #6  |  Link
mariner
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Quote:
Originally Posted by buzzby View Post
...

How can I use NeroAacEnc with Belight? I have the NeroAacEnc.exe in the same directoy but when I try to encode to AAC it immediately fails.
...
Buzz
You need these courtesy of kurtnoise:

BeLight-0.22_RC1
bsn.dll
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