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Covox ADPCM

March 20th, 2007 by Multimedia Mike

Trixter, who’s interested in even older multimedia formats than I am, has unearthed utilities to compress special ADPCM variants used by the Covox Sound Master. The formats include 2-, 3- and 4-bit ADPCM formats. For anyone interested in trying to reverse engineer the details of these obscure formats (and I know you’re out there), check out this directory at the samples site. It has PCM samples compressed in the various formats along with the DOS-based compression utility used. Also, there is a programming library that has C code to interface to a binary library module that handles the meat of the codec operations.

Happy RE’ing.

Posted in Reverse Engineering | 4 Comments »

4 Responses

  1. mark Says:

    oldskool.org appears to be a broken link.

  2. Trixter Says:

    Yes, that’s because http://www.oldskool.org is the site, not just the domain.

  3. Multimedia Mike Says:

    Fixed, thanks. I thought I tested the www-less address when I posted it.

  4. Kostya Says:

    A quick look shows that this is not ordinary ADPCM, as it has markers inside:
    FF 55 FF AA FF 55 FF AA – header (compression type follows)
    FF 55 55 55 – some marker (block start?)
    FF AA AA AA – EOF

    I’ll look further into it when I have some time (sigh)