Parse ACID loops and/or REX files to extract transient data

Question

I am trying to build an audio sampler that accepts ACID, CAF or REX files and can extract their pitch/tempo information. I've read all over the internet that these files store this information in metadata, but I cannot find a spec anywhere that would help me detect and extract this data as well as extract the underlying audio file. Does anyone know of a working spec for this sort of thing or a reference implementation?

For comparison, Apple publishes their reference for the Core Audio Format on their developer site, but I cannot find a similar document for ACID/REX.

Thanks!

Answer 1

https://www.kvraudio.com/forum/viewtopic.php?t=172636

** The acid chunk goes a little something like this:
**
** 4 bytes          'acid'
** 4 bytes (int)     length of chunk starting at next byte
**
** 4 bytes (int)     type of file:
**        this appears to be a bit mask,however some combinations
**        are probably impossible and/or qualified as "errors"
**
**        0x01 On: One Shot         Off: Loop
**        0x02 On: Root note is Set Off: No root
**        0x04 On: Stretch is On,   Off: Strech is OFF
**        0x08 On: Disk Based       Off: Ram based
**        0x10 On: ??????????       Off: ????????? (Acidizer puts that ON)
**
** 2 bytes (short)      root note
**        if type 0x10 is OFF : [C,C#,(...),B] -> [0x30 to 0x3B]
**        if type 0x10 is ON  : [C,C#,(...),B] -> [0x3C to 0x47]
**         (both types fit on same MIDI pitch albeit different octaves, so who cares)
**
** 2 bytes (short)      ??? always set to 0x8000
** 4 bytes (float)      ??? seems to be always 0
** 4 bytes (int)        number of beats
** 2 bytes (short)      meter denominator   //always 4 in SF/ACID
** 2 bytes (short)      meter numerator     //always 4 in SF/ACID
**                      //are we sure about the order?? usually its num/denom
** 4 bytes (float)      tempo
**