falconia has submitted this change. ( https://gerrit.osmocom.org/c/libosmocore/+/41256?usp=email )

Change subject: AMR codec: add conversion between s-bits and codec parameters ......................................................................

AMR codec: add conversion between s-bits and codec parameters

At the lowest level of frame information content, before introducing higher layers of RTP or TRAU frame or other encoding, an AMR codec frame (speech or SID) can be represented in 3 fundamental ways:

* 35 to 244 s-bits as defined theoretically in TS 26.090 & 26.092 and used in practice in 2G TRAU frames;

* 39 to 244 d-bits as defined theoretically in TS 26.101 and used in practice in 3G IuUP and in RTP;

* 5 to 57 codec parameters, each fitting into uint16_t, as implemented in 3GPP reference C code (TS 26.073) and assumed by the same spec in its listing of decoder homing frame bit patterns.

libosmocodec previously provided conversion functions between s-bits and d-bits, as well as a table that gives the number of d-bits per mode - but no conversion to or from arrays of codec parameters. Add the latter functionality.

Change-Id: I28eae702204d7f7ff164e17c5e26152a94a12cba --- M include/osmocom/codec/codec.h M src/codec/gsm690.c 2 files changed, 198 insertions(+), 0 deletions(-)

Approvals: laforge: Looks good to me, but someone else must approve fixeria: Looks good to me, approved Jenkins Builder: Verified

diff --git a/include/osmocom/codec/codec.h b/include/osmocom/codec/codec.h index 008eab1..b697cfb 100644 --- a/include/osmocom/codec/codec.h +++ b/include/osmocom/codec/codec.h @@ -90,6 +90,14 @@ } }

+extern const uint8_t osmo_amr_sbits_per_mode[AMR_NO_DATA+1]; +extern const uint8_t osmo_amr_params_per_mode[AMR_NO_DATA+1]; + +int osmo_amr_param_to_sbits(ubit_t *s_bits, const uint16_t *param, + enum osmo_amr_type mode); +int osmo_amr_sbits_to_param(uint16_t *param, const ubit_t *s_bits, + enum osmo_amr_type mode); + /* SID ternary classification per GSM 06.31 & 06.81 section 6.1.1 */ enum osmo_gsm631_sid_class { OSMO_GSM631_SID_CLASS_SPEECH = 0, diff --git a/src/codec/gsm690.c b/src/codec/gsm690.c index 3b2e669..5730718 100644 --- a/src/codec/gsm690.c +++ b/src/codec/gsm690.c @@ -322,6 +322,196 @@ return n_bits; }

+/*! This table provides the number of s-bits (as defined in TS 26.090 and + * TS 26.092, clause 7 in each spec) for every possible speech or SID mode + * in AMR. It differs from gsm690_bitlength[] in the case of SID: there are + * 35 s-bits in the original 2G definition that started out as GSM 06.92, + * captured in this table, whereas 3G-oriented TS 26.101 AMR Core Frame + * definition captured in gsm690_bitlength[] has 39 d-bits for SID instead. + * + * The array is allocated up to AMR_NO_DATA in order to reduce the probability + * of buggy code making an out-of-bounds read access. + */ +const uint8_t osmo_amr_sbits_per_mode[AMR_NO_DATA+1] = { + [AMR_4_75] = 95, + [AMR_5_15] = 103, + [AMR_5_90] = 118, + [AMR_6_70] = 134, + [AMR_7_40] = 148, + [AMR_7_95] = 159, + [AMR_10_2] = 204, + [AMR_12_2] = 244, + [AMR_SID] = 35, +}; + +/*! This table provides the number of distinct codec parameters (groupings + * of s-bits into 16-bit parameter words as implemented in 3GPP reference + * C code and assumed in TS 26.073 definition of decoder homing frames) + * that exist for every possible speech or SID mode in AMR. + * + * The array is allocated up to AMR_NO_DATA in order to reduce the probability + * of buggy code making an out-of-bounds read access. + */ +const uint8_t osmo_amr_params_per_mode[AMR_NO_DATA+1] = { + [AMR_4_75] = 17, + [AMR_5_15] = 19, + [AMR_5_90] = 19, + [AMR_6_70] = 19, + [AMR_7_40] = 19, + [AMR_7_95] = 23, + [AMR_10_2] = 39, + [AMR_12_2] = 57, + [AMR_SID] = 5, +}; + +/* parameter sizes (# of bits), one table per mode */ + +static const uint8_t bit_counts_4_75[17] = { + 8, 8, 7, /* LSP VQ */ + 8, 7, 2, 8, /* 1st subframe */ + 4, 7, 2, /* 2nd subframe */ + 4, 7, 2, 8, /* 3rd subframe */ + 4, 7, 2, /* 4th subframe */ +}; + +static const uint8_t bit_counts_5_15[19] = { + 8, 8, 7, /* LSP VQ */ + 8, 7, 2, 6, /* 1st subframe */ + 4, 7, 2, 6, /* 2nd subframe */ + 4, 7, 2, 6, /* 3rd subframe */ + 4, 7, 2, 6, /* 4th subframe */ +}; + +static const uint8_t bit_counts_5_90[19] = { + 8, 9, 9, /* LSP VQ */ + 8, 9, 2, 6, /* 1st subframe */ + 4, 9, 2, 6, /* 2nd subframe */ + 8, 9, 2, 6, /* 3rd subframe */ + 4, 9, 2, 6, /* 4th subframe */ +}; + +static const uint8_t bit_counts_6_70[19] = { + 8, 9, 9, /* LSP VQ */ + 8, 11, 3, 7, /* 1st subframe */ + 4, 11, 3, 7, /* 2nd subframe */ + 8, 11, 3, 7, /* 3rd subframe */ + 4, 11, 3, 7, /* 4th subframe */ +}; + +static const uint8_t bit_counts_7_40[19] = { + 8, 9, 9, /* LSP VQ */ + 8, 13, 4, 7, /* 1st subframe */ + 5, 13, 4, 7, /* 2nd subframe */ + 8, 13, 4, 7, /* 3rd subframe */ + 5, 13, 4, 7, /* 4th subframe */ +}; + +static const uint8_t bit_counts_7_95[23] = { + 9, 9, 9, /* LSP VQ */ + 8, 13, 4, 4, 5, /* 1st subframe */ + 6, 13, 4, 4, 5, /* 2nd subframe */ + 8, 13, 4, 4, 5, /* 3rd subframe */ + 6, 13, 4, 4, 5, /* 4th subframe */ +}; + +static const uint8_t bit_counts_10_2[39] = { + 8, 9, 9, /* LSP VQ */ + 8, 1, 1, 1, 1, 10, 10, 7, 7, /* 1st subframe */ + 5, 1, 1, 1, 1, 10, 10, 7, 7, /* 2nd subframe */ + 8, 1, 1, 1, 1, 10, 10, 7, 7, /* 3rd subframe */ + 5, 1, 1, 1, 1, 10, 10, 7, 7, /* 4th subframe */ +}; + +static const uint8_t bit_counts_12_2[57] = { + 7, 8, 9, 8, 6, /* LSP VQ */ + 9, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5, /* 1st subframe */ + 6, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5, /* 2nd subframe */ + 9, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5, /* 3rd subframe */ + 6, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5, /* 4th subframe */ +}; + +static const uint8_t bit_counts_sid[5] = { 3, 8, 9, 9, 6 }; + +/* overall table with all parameter sizes for all modes */ +static const uint8_t * const bit_counts_per_mode[AMR_SID + 1] = { + bit_counts_4_75, + bit_counts_5_15, + bit_counts_5_90, + bit_counts_6_70, + bit_counts_7_40, + bit_counts_7_95, + bit_counts_10_2, + bit_counts_12_2, + bit_counts_sid, +}; + +/*! Convert AMR codec frame from parameters to s-bits + * + * \param[out] s_bits Caller-provided array of unpacked bits to be filled + * with s-bits of the converted codec frame. + * \param[in] param Array of AMR codec speech or SID parameters. + * \param[in] mode Speech or SID mode according to which conversion shall + * be performed. + * \returns 0 if successful, or negative if \ref mode is invalid. + */ +int osmo_amr_param_to_sbits(ubit_t *s_bits, const uint16_t *param, + enum osmo_amr_type mode) +{ + if (mode > AMR_SID) + return -EINVAL; + + const uint8_t *table = bit_counts_per_mode[mode]; + unsigned nparam = osmo_amr_params_per_mode[mode]; + unsigned n, p, mask; + ubit_t *b = s_bits; + + for (n = 0; n < nparam; n++) { + p = param[n]; + mask = 1 << (*table++ - 1); + for (; mask; mask >>= 1) { + if (p & mask) + *b++ = 1; + else + *b++ = 0; + } + } + return 0; +} + +/*! Convert AMR codec frame from s-bits to parameters + * + * \param[out] param Caller-provided buffer for array of AMR codec speech + * or SID parameters. + * \param[in] s_bits Unpacked s-bits of the frame to be converted. + * \param[in] mode Speech or SID mode according to which conversion shall + * be performed. + * \returns 0 if successful, or negative if \ref mode is invalid. + */ +int osmo_amr_sbits_to_param(uint16_t *param, const ubit_t *s_bits, + enum osmo_amr_type mode) +{ + if (mode > AMR_SID) + return -EINVAL; + + const ubit_t *bit = s_bits; + const uint8_t *table = bit_counts_per_mode[mode]; + unsigned nparam = osmo_amr_params_per_mode[mode]; + unsigned n, m, acc; + + for (n = 0; n < nparam; n++) { + acc = 0; + for (m = 0; m < *table; m++) { + acc <<= 1; + if (*bit) + acc |= 1; + bit++; + } + param[n] = acc; + table++; + } + return 0; +} + /* See also RFC 4867 §3.6, Table 1, Column "Total speech bits" */ static const uint8_t amr_len_by_ft[16] = { 12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0