FreeCalypso > hg > gsm-codec-lib

annotate doc/EFR-library-API @ 555:62943a1ad64e

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
doc/FR1-Rx-DTX-detail: grammar fix
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 11 Oct 2024 00:22:47 +0000
parents b07dba7b8a4f
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
463
9208db14b4b9 doc/EFR-library-API: rm reference to old libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents: 161
diff changeset
1 Libgsmefr general usage
9208db14b4b9 doc/EFR-library-API: rm reference to old libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents: 161
diff changeset
2 =======================
9208db14b4b9 doc/EFR-library-API: rm reference to old libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents: 161
diff changeset
3
123
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
4 The external public interface to Themyscira libgsmefr consists of a single
463
9208db14b4b9 doc/EFR-library-API: rm reference to old libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents: 161
diff changeset
5 header file <gsm_efr.h>; it should be installed in some system include
9208db14b4b9 doc/EFR-library-API: rm reference to old libgsm
Mychaela Falconia <falcon@freecalypso.org>
parents: 161
diff changeset
6 directory.
123
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
7
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
8 The dialect of C we chose for libgsmefr is ANSI C (function prototypes), const
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
9 qualifier is used where appropriate, and the interface is defined in terms of
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
10 <stdint.h> types; <gsm_efr.h> includes <stdint.h>.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
11
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
12 State allocation and freeing
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
13 ============================
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
14
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
15 In order to use the EFR encoder, you will need to allocate an encoder state
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
16 structure, and to use the EFR decoder, you will need to allocate a decoder state
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
17 structure. The necessary state allocation functions are:
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
18
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
19 extern struct EFR_encoder_state *EFR_encoder_create(int dtx);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
20 extern struct EFR_decoder_state *EFR_decoder_create(void);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
21
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
22 struct EFR_encoder_state and struct EFR_decoder_state are opaque structures to
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
23 library users: you only get pointers which you remember and pass around, but
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
24 <gsm_efr.h> does not give you full definitions of these structs. As a library
544
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
25 user, you ordinarily don't even need to know the size of these structs, hence
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
26 the necessary malloc() operation happens inside EFR_encoder_create() and
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
27 EFR_decoder_create(). (But see a later section of this document regarding
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
28 alternative memory allocation schemes.) However, each structure is malloc'ed
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
29 as a single chunk, hence when you are done with it, simply call free() to
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
30 relinquish each encoder or decoder state instance.
123
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
31
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
32 EFR_encoder_create() and EFR_decoder_create() functions can fail if the malloc()
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
33 call inside fails, in which case the two libgsmefr functions in question return
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
34 NULL.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
35
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
36 The dtx argument to EFR_encoder_create() is a Boolean flag represented as an
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
37 int; it tells the EFR encoder whether it should operate with DTX enabled (run
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
38 GSM 06.82 VAD and emit SID frames instead of speech frames per GSM 06.81) or DTX
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
39 disabled (skip VAD and always emit speech frames).
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
40
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
41 Using the EFR encoder
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
42 =====================
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
43
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
44 To encode one 20 ms audio frame per EFR, call EFR_encode_frame():
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
45
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
46 extern void EFR_encode_frame(struct EFR_encoder_state *st, const int16_t *pcm,
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
47 uint8_t *frame, int *sp, int *vad);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
48
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
49 You need to provide an encoder state structure allocated earlier with
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
50 EFR_encoder_create(), a block of 160 linear PCM samples, and an output buffer of
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
51 31 bytes (EFR_RTP_FRAME_LEN constant also defined in <gsm_efr.h>) into which the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
52 encoded EFR frame will be written; the frame format is that defined in ETSI TS
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
53 101 318 for EFR in RTP, including the 0xC signature in the upper nibble of the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
54 first byte.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
55
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
56 The last two arguments of type (int *) are optional pointers to extra output
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
57 flags SP and VAD, defined in GSM 06.81 section 5.1.1; either pointer or both of
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
58 them can be NULL if these extra output flags aren't needed. Both of these flags
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
59 are needed in order to test our libgsmefr encoder implementation against
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
60 official ETSI test sequences (GSM 06.54), but they typically aren't needed
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
61 otherwise.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
62
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
63 Using the EFR decoder
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
64 =====================
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
65
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
66 The main interface to our EFR decoder is this function:
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
67
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
68 extern void EFR_decode_frame(struct EFR_decoder_state *st, const uint8_t *frame,
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
69 int bfi, int taf, int16_t *pcm);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
70
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
71 The inputs consist of 244 bits of frame payload (the 4 upper bits of the first
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
72 byte are ignored - there is NO enforcement of 0xC signature in our frame
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
73 decoder) and BFI and TAF flags defined in GSM 06.81 section 6.1.1. Note the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
74 absence of a SID flag argument: EFR_decode_frame() calls our own utility
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
75 function EFR_sid_classify() to determine SID from the frame itself per the rules
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
76 of GSM 06.81 section 6.1.1.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
77
161
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
78 The canonical EFR decoder always expects frame bits input to be present, even
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
79 during BFI condtions! More specifically, if a BFI=1 decoding call comes in when
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
80 the decoder is in comfort noise generation state (after a SID), then all frame
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
81 bits passed along with BFI=1 are ignored as one would naturally expect for
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
82 frames that typically aren't transmitted at all - but if a BFI=1 decoding call
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
83 comes in when the decoder is in regular speech mode, the canonical decoder will
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
84 use the "fixed codebook excitation pulses" part of the erroneous frame (one
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
85 declared to be garbage) as part of its decoding operation! (This part
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
86 constitutes 35 bits per subframe or 140 bits out of 244 per frame.)
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
87
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
88 BFI with no data
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
89 ================
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
90
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
91 Many EFR decoder applications will be faced with a situation where they receive
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
92 a frame gap (no data at all), and they need to run the EFR decoder with BFI=1 -
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
93 but the application doesn't have any frame-bits input. Yet the canonical EFR
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
94 decoder requires *some* erroneous frame bits to be fed to it - so what gives?
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
95 Our initial approach was to feed the decoder all zeros in the place of codec
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
96 parameters - but further analysis reveals that approach to be bad. (To see for
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
97 yourself, study the code in d1035pf.c and think what it will do when the input
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
98 is fixed at all zeros.) Our new approach is to generate pseudorandom bits for
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
99 these pulse parameters, as detailed below.
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
100
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
101 If you find yourself in the situation of needing to feed BFI=1 with no frame
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
102 data bits to the decoder, call the following function in the place of
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
103 EFR_decode_frame():
123
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
104
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
105 extern void EFR_decode_bfi_nodata(struct EFR_decoder_state *st, int taf,
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
106 int16_t *pcm);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
107
161
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
108 This function begins by checking the internal state flag RX_SP_FLAG, indicating
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
109 whether the decoder is in speech or comfort noise generation mode. If
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
110 RX_SP_FLAG is set, indicating speech state, then the main body of the decoder
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
111 will be making use of fixed codebook pulse parameters even for erroneous frames,
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
112 and EFR_decode_bfi_nodata() will invoke a PRNG to fill in pseudorandom bits.
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
113 If RX_SP_FLAG is clear, then the decoder is generating comfort noise following
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
114 reception of a SID, and BFI conditions are fully expected because the
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
115 transmitter is expected to be off. In this case EFR_decode_bfi_nodata() feeds
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
116 all-zeros parameters to the main body of the decoder, as none of them will be
fe5aceaf51e0 doc/EFR-library-API: document new handling of BFI with no data
Mychaela Falconia <falcon@freecalypso.org>
parents: 130
diff changeset
117 used.
123
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
118
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
119 Stateless utility functions
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
120 ===========================
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
121
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
122 All functions in this section are stateless (no encoder state or decoder state
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
123 structure is needed); they merely manipulate bit fields.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
124
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
125 extern void EFR_frame2params(const uint8_t *frame, int16_t *params);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
126
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
127 This function unpacks an EFR codec frame in ETSI TS 101 318 RTP encoding (the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
128 upper nibble of the first byte is NOT checked, i.e., there is NO enforcement of
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
129 0xC signature) into an array of 57 (EFR_NUM_PARAMS) parameter words for the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
130 codec. int16_t signed type is used for the params array (even though all
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
131 parameters are actually unsigned) in order to match the guts of ETSI-based EFR
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
132 codec, and EFR_frame2params() is called internally by EFR_decode_frame().
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
133
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
134 extern void EFR_params2frame(const int16_t *params, uint8_t *frame);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
135
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
136 This function takes an array of 57 (EFR_NUM_PARAMS) EFR codec parameter words
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
137 and packs them into a 31-byte (EFR_RTP_FRAME_LEN) frame in ETSI TS 101 318
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
138 format. The 0xC signature is generated by this function, and every byte of the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
139 output buffer is fully written without regard to any previous content. This
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
140 function is called internally by EFR_encode_frame().
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
141
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
142 extern int EFR_sid_classify(const uint8_t *frame);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
143
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
144 This function analyzes an RTP-encoded EFR frame (the upper nibble of the first
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
145 byte is NOT checked for 0xC signature) for the SID codeword of GSM 06.62 and
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
146 classifies the frame as SID=0, SID=1 or SID=2 per the rules of GSM 06.81
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
147 section 6.1.1.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
148
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
149 extern void EFR_insert_sid_codeword(uint8_t *frame);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
150
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
151 This function inserts the SID codeword of GSM 06.62 into the frame in the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
152 pointed-to buffer; specifically, the 95 bits that make up the SID field are all
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
153 set to 1s, but all other bits remain unchanged. This function is arguably least
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
154 useful to external users of libgsmefr, but it exists because of how the original
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
155 code from ETSI generates SID frames produced by the encoder in DTX mode.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
156
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
157 Parameter-based encoder and decoder functions
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
158 =============================================
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
159
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
160 The EFR_encode_frame() and EFR_decode_frame() functions described earlier in
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
161 this document constitute the most practically useful (intended for actual use)
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
162 interfaces to our EFR encoder and decoder, but they are actually wrappers around
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
163 these parameter-based functions:
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
164
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
165 extern void EFR_encode_params(struct EFR_encoder_state *st, const int16_t *pcm,
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
166 int16_t *params, int *sp, int *vad);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
167
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
168 This function is similar to EFR_encode_frame(), but the output is an array of
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
169 57 (EFR_NUM_PARAMS) codec parameter words rather than a finished frame. The two
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
170 extra output flags are optional (pointers may be NULL) just like with
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
171 EFR_encode_frame(), but there is a catch: if the output frame is a SID (which
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
172 can only happen if DTX is enabled), the bits inside parameter words that would
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
173 correspond to SID codeword bits are NOT set, instead one MUST call
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
174 EFR_insert_sid_codeword() after packing the frame with EFR_params2frame(). The
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
175 wrapper in EFR_encode_frame() does exactly as described, and the overall logic
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
176 follows the original code structure from ETSI.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
177
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
178 extern void EFR_decode_params(struct EFR_decoder_state *st,
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
179 const int16_t *params, int bfi, int sid, int taf,
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
180 int16_t *pcm);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
181
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
182 This function is similar to EFR_decode_frame() with the frame input replaced
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
183 with params array input, but the SID classification per the rules of GSM 06.81
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
184 section 6.1.1 needs to be provided by the caller. The wrapper in
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
185 EFR_decode_frame() calls both EFR_frame2params() and EFR_sid_classify() before
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
186 passing the work to EFR_decode_params().
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
187
545
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
188 Decoder RTP input
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
189 =================
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
190
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
191 If a network element is receiving GSM-EFR input via RTP and needs to feed this
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
192 input to the decoder, the RTP payload handler needs to support both the basic
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
193 RTP format of ETSI TS 101 318 (also RFC 3551) and the extended RTP format of
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
194 TW-TS-001. Depending on the format received, and depending on bit flags in the
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
195 TEH octet in the case of TW-TS-001, the RTP input handler will need to call
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
196 either EFR_decode_frame() or EFR_decode_bfi_nodata() with correct bfi and taf
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
197 arguments. Seeing that this complex logic should be abstracted away from
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
198 applications into the library, we've added the following wrapper function:
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
199
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
200 extern int EFR_decode_rtp(struct EFR_decoder_state *st, const uint8_t *rtp_pl,
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
201 unsigned rtp_pl_len, int16_t *pcm);
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
202
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
203 The semantics and return value of this function are the same as its FRv1
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
204 counterpart gsmfr_fulldec_rtp_in(), documented in FR1-library-API article.
b07dba7b8a4f doc/EFR-library-API: document RTP input wrapper
Mychaela Falconia <falcon@freecalypso.org>
parents: 544
diff changeset
205
123
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
206 State reset functions
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
207 =====================
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
208
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
209 extern void EFR_encoder_reset(struct EFR_encoder_state *st, int dtx);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
210 extern void EFR_decoder_reset(struct EFR_decoder_state *st);
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
211
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
212 These functions reset the state of the encoder or the decoder, respectively;
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
213 the entire state structure is fully initialized to the respective home state
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
214 defined in GSM 06.60 section 8.5 for the encoder or section 8.6 for the decoder.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
215
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
216 EFR_encoder_reset() is called internally by EFR_encoder_create() and by the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
217 encoder itself when it encounters the ETSI-prescribed encoder homing frame;
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
218 EFR_decoder_reset() is called internally by EFR_decoder_create() and by the
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
219 decoder itself when it encounters the ETSI-prescribed decoder homing frame.
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
220 Therefore, there is generally no need for libgsmefr users to call these
92fdb499b5c3 doc/EFR-library-API article written
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
221 functions directly - but they are made public for the sake of completeness.
130
1c529bb31219 doc/EFR-library-API: explain dtx argument to EFR_encoder_reset()
Mychaela Falconia <falcon@freecalypso.org>
parents: 123
diff changeset
222
1c529bb31219 doc/EFR-library-API: explain dtx argument to EFR_encoder_reset()
Mychaela Falconia <falcon@freecalypso.org>
parents: 123
diff changeset
223 If you call EFR_encoder_reset() manually, you can change the DTX enable/disable
1c529bb31219 doc/EFR-library-API: explain dtx argument to EFR_encoder_reset()
Mychaela Falconia <falcon@freecalypso.org>
parents: 123
diff changeset
224 flag from its initial value given to EFR_encoder_create() - the new value of
1c529bb31219 doc/EFR-library-API: explain dtx argument to EFR_encoder_reset()
Mychaela Falconia <falcon@freecalypso.org>
parents: 123
diff changeset
225 this flag passed to EFR_encoder_reset() always takes effect. There is no
1c529bb31219 doc/EFR-library-API: explain dtx argument to EFR_encoder_reset()
Mychaela Falconia <falcon@freecalypso.org>
parents: 123
diff changeset
226 provision for changing this mode within an encoder session without a full reset.
473
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
227
544
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
228 These reset functions may be used to implement an alternative memory allocation
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
229 scheme, if there is a requirement or desire to use something other than plain
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
230 malloc(). To make such alternative schemes possible, the following const
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
231 "variables" are provided beginning with libgsmefr version 1.2.0:
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
232
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
233 extern const unsigned EFR_encoder_state_size;
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
234 extern const unsigned EFR_decoder_state_size;
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
235
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
236 Using this feature, one can replace EFR_encoder_create() and
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
237 EFR_decoder_create() with something like the following (example for
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
238 applications based on Osmocom libraries):
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
239
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
240 struct EFR_encoder_state *enc_state;
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
241 enc_state = talloc_size(ctx, EFR_encoder_state_size);
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
242 if (enc_state)
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
243 EFR_encoder_reset(enc_state, dtx_flag);
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
244
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
245 struct EFR_decoder_state *dec_state;
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
246 dec_state = talloc_size(ctx, EFR_decoder_state_size);
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
247 if (dec_state)
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
248 EFR_decoder_reset(dec_state);
bd32bb1e8dab doc/EFR-library-API: document malloc-alternative provision
Mychaela Falconia <falcon@freecalypso.org>
parents: 473
diff changeset
249
473
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
250 Public const datum: decoder homing frame
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
251 ========================================
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
252
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
253 While the encoder homing frame is the same for all codecs defined by ETSI and
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
254 then later 3GPP, each codec has its own unique decoder homing frame (DHF). A
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
255 public const datum introduced in libgsmefr version 1.1.0 provides the
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
256 RTP-encoded form of the ETSI-prescribed DHF for EFR:
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
257
2d46abdfbe91 libgsmefr version 1.1.0 for DHF addition
Mychaela Falconia <falcon@freecalypso.org>
parents: 463
diff changeset
258 extern const uint8_t EFR_decoder_homing_frame[EFR_RTP_FRAME_LEN];