Dear Paul,
G.723 does not exist anymore, it's an empty slot.
Historically, G.721 (the 32 kb/s ADPCM) was published in 1984 and subsequently re-issued in 1988 to fix a problem with data signals. At that year, G.723 was approved with the 24 and 40 kb/s ADPCM extensions to G.721, for use in digital circuit multiplication equipment (DCME). In 1990, it was decided to unify the ADPCM spec into a single text, adding the 16 kb/s ADPCM rate as well; this was done into G.726, which is in force today. As a consequence, the G.721 and G.723 slots were left vacant.
When the LBC group defined the current G.723.1 codec, it was originally targeted to occupy the G.723 empty slot, but after a while it was realized that this would be a bit confusing with the previous G.723, and then it was decided to add the ".1" to it.
So, there is no G.723 - would they have meant G.729?
Best regards, Simao Campos PS: to my knowledge, 5.1 is the latest version of the G.723.1 C code. However, an implementor's guide was published in Santiago describes a problem in G.723.1 Annexes A and B. (see COM 16-R57E)
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From: Paul Long plong@SMITHMICRO.COM Sender: owner-tsg16q13@itu.int To: ITU-SG16@MAILBAG.INTEL.COM Subject: G.723.1 vs. G.723 Date: Wed, 6 Oct 1999 10:29:21 -0500
What is the difference between G.723.1 and G.723? And I don't mean the numerical difference, as in 0.1 :-) Are they the same thing, and people are just being imprecise when they refer to G.723.1 as "G.723?" For SuperOp! scheduling, they were both listed as two of the possible audio codecs, as if they were different. Does anyone truly support G.723 but not G.723.1? If so, I've never come across such an implementation. Also, what is the history of G.723.1? I believe the current version is something called 5.1. Is this correct? Were there some intermediate versions?
Paul Long Smith Micro Software, Inc.