request for APC number

Sakae OKUBO okubo at GITI.OR.JP
Wed Oct 6 12:47:22 EDT 1999

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)

> From: Paul Long <plong at SMITHMICRO.COM>
> Sender: owner-tsg16q13 at
> 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.

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