Hydrogenaudio Forums > Figuring out ADPCMs

Hydrogenaudio Forums > Lossy Audio Compression > Other Lossy Codecs

Tom Hicks

Mar 13 2007, 02:13

Hi, this is my first post on this forum. Everyone here seems to know a good deal about audio formats so, figers crossed, hopefully someone will be able to help me with a problem I've had for a while now.

I work on modding video games and the latest one I've begun working on is Codemasters' Brian Lara International Cricket 2007. There is a folder called Audio in which there is a .dic file and several .wia files. I have figured out the .dic file format, and it basically lists each sample in the .wia files, giving a name, which byte it starts at, and the sample rate.

I have successfully extracted each of the sound files from the .wia archives and have begun trying to figure out the audio format used. I know the audio is sampled at 32KHz. Unfortunately that is about all I know. I have tried playing the files as raw audio, and the nearest I have come to figuring out the file format is to play the file as a 32KHz Dialogic ADPCM - I can hear the intended sound through a lot of noise.

The files are seemingly headerless, except that they all start with either FF FF FF FF or 00 00 00 00. Does anybody know of any way of finding out exactly what compression is used on a headerless, unknown audio file?

If anyone can help I would be most greatful. I have file samples which I can share if anyone wants to have a look.

Cheers,

Tom

spoon

Mar 13 2007, 03:35

There are a variety of different ADPCM implementations, have you tried the Microsoft one?

Tom Hicks

Mar 13 2007, 04:00

QUOTE(spoon @ Mar 13 2007, 09:35)

There are a variety of different ADPCM implementations, have you tried the Microsoft one?

Well to be honest I can't really figure out how to open a headerless file AS something, if that makes sense. I have Soundforge, and can only open *.* files as things like 8-bit unsigned/signed, A-law, mu-law, etc. The only thing I've found to open unknown files as any sort of ADPCM is a program called Switch.

Do you have any suggestions on how to open the file as other types of ADPCM? I assumed that most types of ADPCM have file headers, which I'm currently lacking.

spoon

Mar 13 2007, 14:39

You might be able to take a header from aother file and transplant it.

Tom Hicks

Mar 14 2007, 02:00

QUOTE(spoon @ Mar 13 2007, 20:39)

You might be able to take a header from aother file and transplant it.

Thing is though, I don't know enough about ADPCM headers. Are they RIFF headers or is that just for PCM?

eevan

Apr 13 2007, 09:27

QUOTE(Tom Hicks @ Mar 14 2007, 10:00)

Thing is though, I don't know enough about ADPCM headers. Are they RIFF headers or is that just for PCM?

Yes, they are wav files whose Compression Code field of the "fmt" chunk has something of the following:

CODE

        Code        Description
     0 (0x0000)     Unknown
     1 (0x0001)     PCM/uncompressed
     2 (0x0002)     Microsoft ADPCM
     6 (0x0006)     ITU G.711 a-law
     7 (0x0007)     ITU G.711 µ-law
    17 (0x0011)     IMA ADPCM
    20 (0x0016)     ITU G.723 ADPCM (Yamaha)
    49 (0x0031)     GSM 6.10
    64 (0x0040)     ITU G.721 ADPCM
    80 (0x0050)     MPEG
65,536 (0xFFFF)     Experimental

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