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What is CELT? What is a .CELT file? How to convert it!
EarBender
post May 8 2012, 07:24
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I've read around on the internet in so many different places about CELT being a very quick and efficient audio format ( 1.3 ms to 24 ms anywhere from 32-96 kHz) and I have recently run into some .CELT files that I need to somehow convert into regular .wav files ( and vice versa ).

I've already attempted multiple ways of doing this - with most ending in failure. I managed to obtain about 5 different WIN32 versions of CELT and none of them are able to convert my .celt file into a .wav file.

I tried the decoder function (while in the command prompt, of course): celtdec input_file.celt output_file.wav

but it never seems to work. I even tried making the input file a .oga file ( I read somewhere this would work) yet still the same old error message: "This doesn't look like a CELT file." appears every time I try this in any of the versions.


I know I look like an idiot new-comer to the forums, but I really need some serious help! ohmy.gif
If anyone has experience with CELT/ the CELT decoder/encoder your help would be greatly appreciated.

This post has been edited by EarBender: May 8 2012, 07:27
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2012
post May 8 2012, 12:29
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Where did you get those .celt files?

CELT is a part of Opus now. It went through many bitstream changes until around mid 2011 or a little bit before. celt-tools (and later opus-tools) encode and decode with a OGG container (with .oga file suffix**).

So to sum up:

* We don't know if those .celt files you have are real.
* If they are real, we don't know when they were created (what bitstream version is used) and how they are contained.
* CELT is a part of Opus now. Look for Opus's latest code in http://git.xiph.org .


** One of the developers seems to like the .opus extention. But that's very new:
http://git.xiph.org/?p=users/giles/opus-to...0737d5952e35d2f

This post has been edited by 2012: May 8 2012, 12:30
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polemon
post May 8 2012, 14:25
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QUOTE (2012 @ May 8 2012, 13:29) *
** One of the developers seems to like the .opus extention. But that's very new:
http://git.xiph.org/?p=users/giles/opus-to...0737d5952e35d2f

An .opus extension makes only sense, if the file has no OGG container and is the plain codec stream (as it is with .aac) or it has a minimal container like .flac or .mp3 that makes the file easy to handle.

Other than that, it makes much more sense to use Ogg/Opus before anything.


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EarBender
post May 8 2012, 21:30
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Thank you for all the information you provided. I was completely unaware that celt was called opus now.

I obtained the other tools you provided in the previous link, but I was wondering how to compile them properly.

I know the language is C and I already have several compilers, such as MSVC.


Also, I should have made this link available in my previous post. It is the link to some of the .celt files I mentioned from before. You could download and take a look at them if you want. Maybe even be able to get them into a .wav file.

http://www.mediafire.com/download.php?l4joqrbx4jw3c0a

Thanks again,

EB
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saratoga
post May 9 2012, 00:07
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Like 2012 said, you should probably go back to the source of the files and investigate how they were encoded.
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Kein
post Oct 18 2013, 14:19
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No info on this front?
I'm interested in it as well now. I have raw CELT file without headers and such and I would love to convert them into PCM WAV.
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kode54
post Oct 18 2013, 16:38
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libcelt was a predecessor to Opus, before SILK was integrated and the two were combined into a hybrid codec. It also had its own Ogg bitstream format. Those .celt files are likely to be Ogg files containing libcelt streams in the last known specification. A good sign is the first packet containing a magic signature starting with "CELT". These files are in no way compatible with either Ogg Opus or the Opus codec.

You can try your luck with FFMPEG, but you'll need a version with libcelt support compiled in.
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