FreeCalypso > hg > gsm-codec-lib
diff doc/AMR-study-utils @ 218:f4f68c652e98
doc: document AMR study utilities
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Fri, 21 Apr 2023 23:41:56 +0000 |
parents | |
children | e26b974f7ba3 |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ 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.