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+++ b/doc/AMR-study-utils	Fri Apr 21 23:41:56 2023 +0000
@@ -0,0 +1,25 @@
+As of this writing (2023-04), the main emphasis here at Themyscira Wireless is
+on classic FR and EFR codecs, particularly the latter, rather than AMR.
+However, given the close relation between GSM EFR and the highest MR122 mode of
+AMR, we are starting to explore AMR a little too, focusing on the reference C
+implementation and various published test sequences.  Working in this direction,
+we have developed the following AMR study and exploration utilities:
+
+amr-cod-parse	This utility reads the *.cod binary file format used by 3GPP
+		reference code and test sequences for AMR-encoded speech, groks
+		every frame and dumps all recorded parameters in human-readable
+		form.
+
+amr-ietf-parse	A similar AMR parse/dump utility to amr-cod-parse, but reading
+		the more common IETF RFC 4867 *.amr binary file format instead.
+
+amr-cod2ietf	These two utilities convert between 3GPP *.cod and IETF *.amr
+amr-ietf2cod	formats.  amr-cod2ietf converts from *.cod to *.amr;
+		amr-ietf2cod converts in the opposite direction.
+
+Just like ETSI *.cod and *.dec formats for EFR, 3GPP *.cod format for AMR is
+endian-dependent.  Our amr-cod-parse and amr-cod2ietf utilities expect LE byte
+order by default, matching the official test sequences in
+ts_126074v170001p0.zip; they also support BE byte order with -b option.
+However, our amr-ietf2cod utility (rarely needed) emits its cod-format output
+in the local machine's native byte order.