sample usc_speech_codec decoding problem

[sweepang]

Hi, I just downloaded Intel IPP library for mac os. There are some ipp sample codes. I built the sample application, usc_speech_codec application and ran it. I'm interested in the decoding. I tried to decode GSM 6.10 wave format to PCM. I have a GSM 6.10 wave file(8kgsm.wav) that i downloaded from the web elsewhere. when I tried to run the decoding process:

./usc_speech_codec [options]

it complainted that the input file format unknow, "FAIL:Unknown decode format."

However, if I ran the encoder first(using the same usc_speech_codec app), PCM -> GSM 6.10(examplegsm.wav), then decoder GSM 6.10 -> PCM, the decoder will run successful. Why?

When I took the further look, the formatTag embedded inside the header between 8kgsm.wav & examplegsm.wav is different.

formatTag(compression code) value for 8kgsm.wav is 0x0031

formatTag value for examplegsm.wav is 0x7298

Aren't the compression code value standard?

The following is a list of the common compression codes used today(from http://www.sonicspot.com/guide/wavefiles.html#fmt).

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 -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

How come IPP using different compression code values than standard? e.g. 0x7298 vs 0x0031 for GSM 6.10

Therefore it seems like the sample application, usc_speech_codec, can only decodes the files that were encoded first by itself.

why?

Thanks,