MS ADPCM

Question

Hi

Will Microsoft be releasing a document on the MS ADPCM specification?

Thank you

Answer 1

Hi – There are no plans to release a document on the MS ADPCM specification. This codec is legacy technology (shipped prior to Windows 2000) that is not under active development. If you have additional questions about ADPCM, I’d recommend you refer to these sites for more information:

 

http://ltc.cit.cornell.edu/courses/ee476/FinalProjects/s2006/wc227_rks33/wc227_rks33/index.htm

http://www-mobile.ecs.soton.ac.uk/speech_codecs/standards/adpcm.html

http://en.wikipedia.org/wiki/Pulse-code_modulation

http://www.webopedia.com/TERM/A/ADPCM.html

 

Answer 2

Hi.
I read a document named "Microsoft Multimedia Standards Update", where MS ADPCM specification is introduced.
I followed the document and made an MS ADPCM encoder. Everything was fine except a problem of using extra coefficient pairs.
The document said that adding extra coefficients was possible, however, my encoded file was not able to be played on the Windows Media Player after a no.8 coefficient pair was added and used.  The standard seven coefficient pairs remained the same.
(The chunk size and cbSize were also modified after adding the extra coefficients)

I doubt if the Windows Media Player checks the coefficient number and stops decoding if the coefficient number and values do not match the standard seven coefficient pairs.

Thank you!

Answer 3

Hi Tommy,

We will review your question and get back to you soon.

Regards,
Edgar

Answer 4

The MS ADPCM decoder does not support coefficient sets other than the seven listed in the Windows 3.1 era document, you mention, and will properly reject any content with any other number of coefficient sets. If further information is needed you might try the links posted by Keith above.

Richard Guthrie

Support Escalation Engineer