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comparison doc/Codec-utils @ 157:04936af99fc8

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document gsm[e]fr-{en,de}code-r utilities
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 15 Dec 2022 02:08:55 +0000
parents 30c7bc064218
children a053cf0bac04
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156:3f3674c27840 157:04936af99fc8
33 33
34 gsmefr-decode This utility reads our gsmx format (which must be EFR, not FR1) 34 gsmefr-decode This utility reads our gsmx format (which must be EFR, not FR1)
35 and feeds all frames and BFIs to our EFR decoder. The decoded 35 and feeds all frames and BFIs to our EFR decoder. The decoded
36 output is written as WAV. 36 output is written as WAV.
37 37
38 WAV reading and writing functions used by the above utilities have been lifted 38 The above are original programs that read WAV input for encoding and write WAV
39 out of opencore-amrnb test code. 39 output from decoding. We now also have raw versions that read and write our
40 "robe" (raw big-endian) format instead:
40 41
41 Now that we are starting to encounter use cases that involve more than feeding 42 gsmfr-encode-r Just like gsm[e]fr-encode, but reading "robe" instead of WAV.
42 a PC microphone recording to test encoders and playing decoder output on PC 43 gsmefr-encode-r
43 speakers, many of those other use cases call for using raw format instead of WAV 44
44 for 16-bit linear PCM. While it would be philosophically most proper to add an 45 gsmfr-decode-r Just like gsm[e]fr-decode, but writing "robe" instead of WAV.
45 option to gsm[e]fr-encode and gsm[e]fr-decode utilities to read/write raw PCM 46 gsmefr-decode-r
46 files instead of WAV, doing so would complicate the code too much. As a 47
47 compromise between code simplicity and functionality, we provide lossless 48 Please see PCM-file-formats article for the rationale.
48 conversion utilities - see PCM-file-formats article.