freecalypso-docs: Speech-codec-selection annotate

annotate Speech-codec-selection @ 108:e26623146358 default tip

new article DSP-speech-decoder

author	Mychaela Falconia <falcon@freecalypso.org>
date	Tue, 29 Oct 2024 22:11:41 +0000
parents	c28a1518d268
children

rev	line source
98 915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	1 There exist a total of 5 speech TCH modes in classic GSM, outside of exotic
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	2 additions (did anyone ever implement them?) of AMR-WB and TCH-8PSK; these
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	3 classic 5 speech TCH modes are:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	4
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	5 TCH/FS (FRv1 codec)
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	6 TCH/HS (HRv1 codec)
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	7 TCH/EFS (EFR codec)
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	8 TCH/AFS (AMR-FR)
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	9 TCH/AHS (AMR-HR)
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	10
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	11 The selection of TCH type (full-rate or half-rate) and speech version (specific
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	12 codec) assigned to each voice call is always done by the GSM network - the MS
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	13 has no direct control over these decisions. However, the MS tells the network
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	14 which codecs it supports by way of Bearer capability IE (information element)
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	15 in CC (call control) Layer 3 messages, and networks that are designed to support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	16 a wide range of GSM MS technology generations (as opposed to, for example,
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	17 operating with a policy that excludes non-AMR-capable MS) heed these MS-declared
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	18 speech codec capabilities when deciding which codec and TCH type to use.
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	19
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	20 Per the specs, every type-approved GSM MS is required to support FRv1 codec,
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	21 but support for all other speech codecs is optional in any combination.
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	22
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	23 In TI's GSM MS firmware architecture there is a configuration record in the
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	24 Condat PCM layer that tells the protocol stack's CC component which speech
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	25 versions it should list as supported in the Bearer capability IE. This PCM
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	26 configuration record is called EF_MSCAP; normally the firmware runs with its
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	27 compiled-in default for this record, and that default is crafted to match the
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	28 capabilities of Calypso L1. However, if there is a file named /pcm/MSCAP in
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	29 FFS, that FFS file overrides the compiled-in default for EF_MSCAP; this MSCAP
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	30 override mechanism can be used to artificially restrict which codecs the MS
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	31 will declare to the network as supported, thereby influencing the actual codec
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	32 selection by the network.
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	33
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	34 As of 2023-06-05 FreeCalypso Tourmaline firmware offers 3 different methods for
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	35 manipulating the speech version list sent to the network in the Bearer
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	36 capability IE for voice calls:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	37
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	38 * Writing /pcm/MSCAP with fc-fsio;
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	39 * Writing to EF_MSCAP more conveniently with AT%MSCAP;
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	40 * Setting the speech version list directly with AT%SPVER.
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	41
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	42 MSCAP record manipulation
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	43 =========================
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	44
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	45 Writing /pcm/MSCAP with fc-fsio is the oldest method for artificially
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	46 restricting the selection of speech codec for voice calls - this method has been
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	47 available since the earliest FreeCalypso firmware versions. However, this
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	48 method is very inconvenient: the firmware checks FFS for the presence of
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	49 /pcm/MSCAP only once on boot, when the Condat PCM layer is initialized, and
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	50 this file is never re-read afterward. Therefore, if you create or modify or
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	51 delete this file with fc-fsio, your change won't have any effect whatsoever on
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	52 the already-booted firmware session, instead it will only take effect on the
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	53 next firmware boot cycle.
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	54
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	55 The addition of AT%MSCAP private AT command solves this problem: this command
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	56 updates the EF_MSCAP record through the firmware's pcm_WriteFile() API, which
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	57 not only writes to FFS, but also updates the in-RAM copy in the PCM layer which
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	58 takes effect on the next voice call. This command supports both set and query
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	59 forms:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	60
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	61 AT%MSCAP=byte1,byte2,byte3[,byte4,byte5,byte6] -- set form
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	62 AT%MSCAP? -- query form
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	63
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	64 This private AT command is unusual (differs from 3GPP standard commands) in that
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	65 each of the byte arguments is hexadecimal. The hexadecimal form is "raw", i.e.,
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	66 just the two hexadecimal digits without any prefix or suffix. For example, the
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	67 following command restores the standard EF_MSCAP setting for CSD-enabled
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	68 firmware builds on Calypso C035 platfotms with AMR-capable DSP ROM versions:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	69
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	70 AT%MSCAP=B7,C7,00
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	71
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	72 The full EF_MSCAP record consists of 6 bytes, but only the first 3 bytes contain
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	73 defined bits; the last 3 bytes are unused and should be set to 0. The set form
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	74 of AT%MSCAP command requires the first 3 bytes to be fully specified (there is
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	75 no default), but the last 3 unused bytes default to 0 if left unspecified.
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	76
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	77 The first byte of EF_MSCAP indicates supported speech codec versions, and the
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	78 following two bytes specify CSD capabilities. The firmware's compiled-in MSCAP
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	79 standard configurations are:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	80
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	81 Firmware build w/o CSD Firmware build with CSD
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	82 Early Calypso silicon w/o AMR 07,00,00 87,C7,00
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	83 Final Calypso silicon with AMR 37,00,00 B7,C7,00
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	84
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	85 The first byte of EF_MSCAP is called chnMode and has the following bit
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	86 definitions (ASCII art diagrams copied from TI's source comments):
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	87
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	88 _______________________________________________________
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	89 \|8 \|7 \|6 \|5 \|4 \|3 \|2 \|1 \|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	90 \|------\|------\|------\|------\|------\|------\|------\|------\|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	91 \|L1 \|Tm \|afs \|ahs \|spV3 \|efrV2 \|hr \|spV1 \|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	92 -------------------------------------------------------
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	93
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	94 (Note the same bit numbering convention as is used in the GSM 11.11 spec for
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	95 EFs in the SIM file system.)
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	96
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	97 Bit 1: indicates support for FRv1, must always be set
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	98 Bit 2: indicates support for HRv1
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	99 Bit 3: indicates support for EFR
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	100 Bit 4: defined as indicating support for "EFR v3", but there is no such thing
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	101 Bit 5: indicates support for AMR-HR
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	102 Bit 6: indicates support for AMR-FR
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	103 Bit 7: defined as meaning "Test Mobile", not actually used
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	104 Bit 8: defined as meaning "L1 Version", not actually used
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	105
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	106 The second byte is called datCap1 and has the following bit definitions:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	107
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	108 _______________________________________________________
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	109 \|8 \|7 \|6 \|5 \|4 \|3 \|2 \|1 \|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	110 \|------\|------\|------\|------\|------\|------\|------\|------\|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	111 \|14.4 \|tfax \|ntfax \|tsyn \|syn \|asyn \|rlp \|ds \|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	112 -------------------------------------------------------
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	113
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	114 Specific bit meanings per TI's source comments:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	115
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	116 Bit 1: Data support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	117 Bit 2: RLP data (NT Async)
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	118 Bit 3: T Async data support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	119 Bit 4: NT Sync data support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	120 Bit 5: T Sync data support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	121 Bit 6: NT Fax support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	122 Bit 7: T Fax support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	123 Bit 8: Data rate 14.4 support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	124
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	125 The third byte is called datCap2 and has the following bit definitions:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	126
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	127 _______________________________________________________
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	128 \|8 \|7 \|6 \|5 \|4 \|3 \|2 \|1 \|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	129 \|------\|------\|------\|------\|------\|------\|------\|------\|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	130 \|DHR \| \| \|NAS \|TPD \|NTPD \|TP \|NTP \|
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	131 -------------------------------------------------------
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	132
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	133 Specific bit meanings per TI's source comments:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	134
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	135 Bit 1: NT Packet Service
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	136 Bit 2: T Packet Service
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	137 Bit 3: NT PAD Access Service
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	138 Bit 4: T PAD Access Service
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	139 Bit 5: No Alternate Services
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	140 Bit 8: Data Halfrate support
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	141
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	142 Note that Calypso Layer1 as delivered by TI does not support CSD on TCH/H, only
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	143 on TCH/F, and this lack of CSD half-rate support is reflected in the compiled-in
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	144 EF_MSCAP configuration. However, the DSP does have channel mode definitions for
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	145 TCH/H4.8 and TCH/H2.4, suggesting at least partial support for half-rate CSD -
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	146 perhaps this support is incomplete and/or non-functional. ARM L1 support for
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	147 half-rate CSD (called IDS in the code) is very obviously missing, though. But
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	148 on TCH/F our TI-inherited GSM MS solution does support CSD modes from F2.4
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	149 through F14.4 inclusive, with bearer services of transparent async,
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	150 non-transparent RLP and fax.
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	151
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	152 Playing with AT%MSCAP and cleaning up afterward
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	153 -----------------------------------------------
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	154
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	155 The set form of AT%MSCAP command issues a pcm_WriteFile() internal API call,
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	156 and that operation writes /pcm/MSCAP into FFS in addition to updating the record
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	157 inside the PCM layer. Therefore, MSCAP changes made with this command persist
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	158 across firmware boot cycles. There is no way to delete /pcm/MSCAP via AT%MSCAP,
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	159 and thus no way to return to the standard system design state where the active
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	160 MSCAP record depends on the firmware build variant on development boards where
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	161 different fw build configurations are often being run. Therefore, the following
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	162 clean-up procedure is recommended:
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	163
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	164 Step 1: set AT%MSCAP to the standard config for your currently running firmware
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	165 version, usually AT%MSCAP=37,00,00 or AT%MSCAP=B7,C7,00.
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	166
915ff61137ee Speech-codec-selection: document MSCAP Mychaela Falconia <falcon@freecalypso.org> parents: diff changeset	167 Step 2: execute 'rm /pcm/MSCAP' in fc-fsio, deleting the file from FFS.
99 c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	168
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	169 Speech version preference list
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	170 ==============================
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	171
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	172 Whenever a GSM MS supports any additional speech codecs beyond the always-
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	173 required FRv1, it needs to indicate this support to the network in the Bearer
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	174 capability IE. However, the encoding of the relevant bits in this IE indicates
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	175 not only which codecs the MS supports, but also their order of preference.
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	176 Indicating the order of preference between supported codecs is not optional:
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	177 the MS always has to transmit _some_ order-of-preference list toward the
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	178 network. (For GSM MS supporting FRv1 and HRv1 but no others, there is an
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	179 abbreviated version of the Bearer capability IE with octet 3a list omitted, but
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	180 even then the order of preference between the two supported codecs is still
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	181 indicated via the two radio channel requirement bits.)
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	182
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	183 Our current FreeCalypso TCS2/TCS3 hybrid firmware indicates the following order
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	184 of preference to the network, between the 5 potentially supported codecs:
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	185
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	186 AMR-FR > AMR-HR > EFR > FRv1 > HRv1
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	187
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	188 (The '>' character in the above line indicates that the codec on the left is
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	189 preferred over the codec on the right.)
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	190
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	191 The actual Bearer capability IE is constructed by first masking off each of the
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	192 5 possible codecs as supported or not-supported per EF_MSCAP (see previous
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	193 section), but those codecs that remain in the supported set are sent to the
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	194 network in the order of preference following the above diagram.
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	195
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	196 It appears that most GSM networks ignore the speech version preference order
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	197 indicated by the MS, treating the MS-provided speech version list as an
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	198 unordered checklist of supported or non-supported, and impose their own
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	199 preference order set by network policy. Such behavior is implemented in Osmocom
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	200 CNI software, and is also observed on the legacy GSM network of T-Mobile USA as
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	201 of this writing. However, the world as a whole is big, there are many different
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	202 GSM networks in different countries, and I (Mother Mychaela) deem it valuable to
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	203 provide a mechanism whereby FreeCalypso-equipped GSM community members can test
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	204 experimentally how their countries' GSM networks react to different speech
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	205 version lists indicated by the MS, including peculiar preference orders.
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	206
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	207 To facilitate such testing, FreeCalypso Tourmaline firmware provides a private
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	208 debug-oriented AT command controlling the speech version list: AT%SPVER. This
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	209 command takes the following forms:
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	210
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	211 AT%SPVER=0 -- restore standard behavior
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	212 AT%SPVER=1,sv1[,sv2[,sv3[,sv4[,sv5]]]]] -- set custom speech version list
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	213 AT%SPVER? -- query current setting
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	214
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	215 In the second listed form of AT%SPVER command, arguments sv1 through sv5 are
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	216 speech version codes as transmitted over the air in the Bearer capability IE,
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	217 as given in Table 10.5.103/3GPP TS 24.008:
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	218
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	219 0 = FRv1
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	220 1 = HRv1
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	221 2 = EFR
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	222 4 = AMR-FR
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	223 5 = AMR-HR
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	224
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	225 The speech version list sent to the network will be exactly as given in the
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	226 AT%SPVER command, in that order. You can list just one speech version, or all
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	227 5 of them, or any intermediate subset - but FRv1 (sv code 0) must always be
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	228 included, or the AT%SPVER command will be rejected. Some examples:
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	229
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	230 AT%SPVER=1,0 -- declare support for FRv1 only
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	231 AT%SPVER=1,2,0,1 -- declare support for EFR, FRv1 and HRv1 in this order
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	232 AT%SPVER=1,1,0 -- prefer HRv1 over FRv1
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	233
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	234 Unlike AT%MSCAP, the setting made with AT%SPVER is volatile: it is not saved
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	235 anywhere in FFS, and thus does not persist across firmware boot cycles.
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	236
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	237 In order to affect the Bearer capability IE in the Call confirmed message for
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	238 MT calls, the AT%SPVER command needs to be given before the MT Setup message
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	239 arrives from the network. For MO call testing, it is sufficient to set AT%SPVER
c28a1518d268 Speech-codec-selection: document AT%SPVER Mychaela Falconia <falcon@freecalypso.org> parents: 98 diff changeset	240 before dialing the MO call with ATD command.

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