VO-BB - 19 YEARS OLD!

[Sameer]

what software can creat ADPCM, 4 bit mono, 11KHz.....wav or vox files

[Drew]

Adobe Audition has encoding presets for those files.
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[Spacegypsy]

Hi Sameer - Vox Studio telephony software has this to say about ADPCM:

ADPCM stands for Adaptive Differential Pulse Code Modulation. There are various flavors of ADPCM. The algorithm we have implemented in this version is the original algorithm used by Dialogic voice processing hardware. Future versions of Vox Studio will support more flavors of ADPCM required for other telephony hardware.
OKI ADPCM, as used by Dialogic, compresses data recorded at 6.0, 6.053, 8.0 or 8.117 KHz sampling rates. Sound is encoded as a succession of 4-bit nibbles glued together in pairs in an 8-bit stream of data. Each 4-bit nibble represents the difference between the current sampled signal value and the previous value. The compression ratio obtained is relatively modest (12 bits resolution data samples are encoded as 4-bit differentials).
ADPCM coding introduces signal errors and the sound quality is slightly affected, but it remains sufficient for many telephony applications. Naturally, 8 KHz ADPCM sounds MUCH better than 6 KHz ADPCM.
Traditionally, 6 KHz ADPCM is also called 24 KBps (6KHz x 4 bits) and 8 KHz ADPCM is called 32 KBps (8KHz x 4 bits). This is a very confusing way of defining the sound coding algorithm used as, for instance, some other ADPCM algorithms produce 24 KBps which is in fact 3-bit data sampled at 8 KHz!
Not many people know that some cards use 6.0 and 8.0 KHz sampling rates and other (very old cards) use 6.053 and 8.117 KHz rates. Beware when playing back files from one card type onto another. If the files contain voice samples, the chances are nobody will ever notice the slight difference in pitch. However, if the files contain frequency-sensitive material, say DTMF data streams, then the 1.5% difference may in fact cause very severe problems.
Vox Studio has the capability to convert to and from, indexed ADPCM files (".vap" files) as well. These are files that contain more than one voice message per physical file, with a header (at the beginning of the file) that contains pointers to the start of each separate voice message. This technique was introduced mainly to circumvent the problems good old DOS had when too many files were opened simultaneously by a running application.
The Dialogic ADPCM ".wav" format uses the same coding as normal Dialogic files (it can contain sound coded in A-law, Mu-law or ADPCM) but it has a RIFF-standard file header instead of just raw data. One more sample frequency is provided: 11.025 KHz.

Cool Edit (Adboe Audition) has this to say:

Dialogic ADPCM (.VOX)
The Dialogic ADPCM format is commonly found in telephony applications, and has been optimized for low sample rate voice. It will only save mono 16-bit audio, and like other ADPCM formats, it compresses to 4-bits/sample (for a 4:1 ratio). This format has no header, so any file format with the extension .vox will be assumed to be in this format. When opening VOX files, you’ll be prompted for a sample rate unless “Don’t ask for further details” is checked in the Open a Waveform dialog.


Take note of the sample rate of your audio before saving as Dialogic VOX, as you’ll need to enter it upon reopening the file.

DVI/IMA ADPCM (.WAV)
The International Multimedia Association (IMA) flavor of ADPCM compresses 16-bit data to 4-bits/sample (4:1) using a different (faster) method than Microsoft ADPCM, and has different distortion characteristics, which can produce either better or worse results, depending on the sample being compressed. As with Microsoft ADPCM, it’s best to save to this format from 16-bit rather than from 8-bit. This compression scheme can be a good alternative to MPEG; it provides reasonably fast decoding of 4:1 compression, and it degrades sample quality only slightly.


Microsoft ADPCM (.WAV)
The Microsoft ADPCM format consists of 4-bit per channel compressed data, which provides 4:1 compression). Files saved in this format will automatically be expanded to 16-bits when loaded, regardless of their original resolution. For this reason, it’s best to save to this format from a 16-bit waveform rather than 8-bit, as the quality will be much greater.

[Philip Banks]

That's just what I was going to say!!

[Spacegypsy]

Kindred Spirits, Banksey, kindred spirits.