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New AAC ACM Codec, Decode AAC in VirtualDub

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fccHandler

Posted: Mar 20 2011, 04:17 AM

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Sheesh, I can't believe I missed that in the .inf files. I do consider it urgent, but I refuse to bump the version number over this! So sue me.

http://fcchandler.home.comcast.net/AC3ACM

Regarding 207469.avi, I have no control over the sample rate in an AVI file. If the AVI audio header declares that the sample rate is 22050 Hz (as this one does), then that is indeed what you will hear.

Interestingly, MPlayer gets stuck in an endless loop when playing this file.

To date I have never found any AAC audio which truly plays at 22050 Hz. I think if SBR is not stated explicitly, we must assume that anything <= 24000 Hz is meant to be played back at double rate. I see this logic also in the faad2 source code.

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ale5000

Posted: Mar 20 2011, 04:57 AM

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Edit: Post removed

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JaliM

Posted: Mar 20 2011, 07:52 AM

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QUOTE (fccHandler @ Mar 19 2011, 04:08 AM)

QUOTE (JaliM @ Mar 7 2011, 10:50 AM)

@fccHandler: I've been testing AAC ACM Codec 1.4 and Matroska plugin. and I've found some anomalities.... Firstly, 32 KHz, 44,1 KHz & 32 KHz MKV-LC-AAC files are supported in stereo mode only. If LC-AAC files are MONO then VirtualDub plays it at HALF-SPEED. If LC-AAC files are 5.1 then VirtualDub does not detect them (no audio info).
Note that all tests have been achieved with Matroska files with one AVC videostream and LC-ACC content, without ADTS headers. Not tested with AVIs or FLVs or with ATDS AAC streams.

I am not able to reproduce. Can you provide me a link to some examples which exhibit these issues?

I don't necessarily need the whole file; a one megabyte chunk of the beginning of the file should be sufficient.

Please, test this file. It's 44100 Hz mono and is played at half speed in VDub. VLC, Mplayer & MPHC play right.

http://www.mediafire.com/?ae105dbai0appb0

ale5000

Posted: Mar 20 2011, 09:30 AM

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fccHandler

Posted: Mar 20 2011, 05:55 PM

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I don't think it is actually misdetecting it, rather libfaad2 seems to always return stereo data due to an assumption of implicit PS in the decoder. I have added some code to downsample this when the client indicates that the AAC is actually mono.

http://fcchandler.home.comcast.net/AACACM

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ale5000

Posted: Mar 20 2011, 07:20 PM

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malky

Posted: Mar 29 2011, 11:21 PM

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Cannot get it to install on Windows 7 64.

ale5000

Posted: Mar 30 2011, 12:10 AM

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ale5000

Posted: Mar 30 2011, 06:59 PM

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ale5000

Posted: Apr 1 2011, 01:05 PM

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QUOTE (fccHandler @ Mar 19 2011, 05:09 AM)

QUOTE (ale5000 @ Mar 11 2011, 10:23 AM)

Does the codec support the 0x706D=FAAD AAC tag in addition to 0x00FF=AAC?

No. It knows about it, but does not expose it to ACM. I have not yet found any examples using this tag.

Test file with 706D audio: (link no longer working)

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ale5000

Posted: Apr 11 2011, 06:50 PM

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Test file (avi with AAC audio): (link no longer working)

VirtualDub say:

CODE

The audio codec reported an error while decompressing audio data.

Error code: 1 (MMSYSERR_ERROR)

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ale5000

Posted: Apr 21 2011, 12:14 PM

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Note: You must use the x86 folder for using with 32-bit VirtualDub instead the x64 folder for using with 64-bit VirtualDub (the bit of Windows doesn't matter).

Changes:
- Added a workaround to the "lost current dir", so now right click and "Run as administrator" on the .bat files works fine
- Added clear messages in .bat files when a problem happens
- Corrected the ReadMe.txt
- Removed the codec from ActiveMovie cache on uninstall
- Exposed the codec to some Microsoft applications

Edit: The updated .inf/.bat files of AACACM and AC3ACM are now included in the official version.

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fccHandler

Posted: Jul 2 2011, 05:50 AM

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I finally updated the codecs with the fixes of ale5000:

http://fcchandler.home.comcast.net/AC3ACM
http://fcchandler.home.comcast.net/AACACM

BTW, I did look into supporting tag 0x706D, but the file you posted is missing an AudioSpecificConfig structure after the WAVEFORMATEX header. Without that information I have to play yet another guessing game, and I am really tired of playing that game. For now I have decided not to support tag 0x706D.

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ale5000

Posted: Jul 2 2011, 01:58 PM

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Are you sure it must be guessed?
I don't really know but the change in mkvtoolnix to support this file look so simple.

Look at this change (Fixed handling AVIs with AAC audio format tag 0x706d and bogus private data size): https://github.com/mbunkus/mkvtoolnix/commi...045ad13890084dd

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fccHandler

Posted: Jul 2 2011, 06:55 PM

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The difference is that mkvtoolnix has full access to the AAC stream in the file. The AACACM codec does not. At the time of audio format negotiation, all he knows about the stream is what is contained in the WAVEFORMATEX structure; that's it.

If the base values there (channels, sample rate) are correct then it's all good. But that's not a safe assumption, since I have seen lots of examples (mostly from you) in which the WAVEFORMAT fields do not match the real AAC properties in AudioSpecificConfig.

So yes, it is a guessing game and I refuse to play. It is too easy to be fooled and guess wrong in this case.

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