FreeCalypso > hg > gsm-codec-lib
comparison doc/AMR-study-utils @ 218:f4f68c652e98
doc: document AMR study utilities
| author | Mychaela Falconia <falcon@freecalypso.org> |
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| date | Fri, 21 Apr 2023 23:41:56 +0000 |
| parents | |
| children | e26b974f7ba3 |
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| 217:1a7d659a952f | 218:f4f68c652e98 |
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| 1 As of this writing (2023-04), the main emphasis here at Themyscira Wireless is | |
| 2 on classic FR and EFR codecs, particularly the latter, rather than AMR. | |
| 3 However, given the close relation between GSM EFR and the highest MR122 mode of | |
| 4 AMR, we are starting to explore AMR a little too, focusing on the reference C | |
| 5 implementation and various published test sequences. Working in this direction, | |
| 6 we have developed the following AMR study and exploration utilities: | |
| 7 | |
| 8 amr-cod-parse This utility reads the *.cod binary file format used by 3GPP | |
| 9 reference code and test sequences for AMR-encoded speech, groks | |
| 10 every frame and dumps all recorded parameters in human-readable | |
| 11 form. | |
| 12 | |
| 13 amr-ietf-parse A similar AMR parse/dump utility to amr-cod-parse, but reading | |
| 14 the more common IETF RFC 4867 *.amr binary file format instead. | |
| 15 | |
| 16 amr-cod2ietf These two utilities convert between 3GPP *.cod and IETF *.amr | |
| 17 amr-ietf2cod formats. amr-cod2ietf converts from *.cod to *.amr; | |
| 18 amr-ietf2cod converts in the opposite direction. | |
| 19 | |
| 20 Just like ETSI *.cod and *.dec formats for EFR, 3GPP *.cod format for AMR is | |
| 21 endian-dependent. Our amr-cod-parse and amr-cod2ietf utilities expect LE byte | |
| 22 order by default, matching the official test sequences in | |
| 23 ts_126074v170001p0.zip; they also support BE byte order with -b option. | |
| 24 However, our amr-ietf2cod utility (rarely needed) emits its cod-format output | |
| 25 in the local machine's native byte order. |