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  • v1.1

    8f2a4948 · Version bump to v1.1 ·
    ## v1.1 (2023-02-21)
    
    Added code to setup Wireguard VPNs using SIP
    - Key material is derived dynamically as part of SIP call signaling
    - Exchange SDP attachments specially structured for Wireguard
    - Passing public key and to-be-implemented PSK derivation method
    - The idea of PSK is to derive it from authentication
    - This would leave the two ends with a unique shared key
    - The code works, but is still relatively simple
  • v1.0

    622555cf · Version bump to v1.0 ·
    Release: v1.0
    ## v1.0 (2022-09-18)
    
    Proper library, proper programs, HDLC assembler in/out, ...
    - Functional HDLC inject/extract, even from/to HDLC assembler
    - No actual HDLC negotiation yet
    - Proper library design: base, codec, hdlc, [back-inih/...]
    - Tooling now concentrated around this design
    - Manual pages for commands, API, and the project as a whole
    - Internet-Draft to level 01, begun on 02
    - Considerations about cryptography
    - Nicely balanced / mirrorred operation of HDLC, unidirectional mode
  • v0.6

    e28a9ec3 · Version bump to v0.6 ·
    Release: v0.6
    Rounding off proof of concept phase, with documented plans
    - The general model is to connect to services via network, devices, ...
    - Addresses and Dynamic Service Negotiation have been documented
    - Default HDLC info fields can go to 256 bytes (negotiate more if needed)
    - The FCS algorithm will be CRC-16/6sub8, HD(6) up to 8 and HD(4) up to 994
    - Documented framework for MRU, MTU, network packet fragmentation, windowing
    - Services that cannot use fragmentation may fall back on streaming data
    - Services that cannot use windowing may send REJ instead of SREJ for order
    - Looked into a large number of services that could make sense
  • v0.5

    34f5f210 · Version bump to v0.5 ·
    Release: v0.5
    ## v0.5 (2022-06-04)
    
    Adding support for 1-bit spaces for exponent 0x40
    - Shift for 0x40 is << 4 _but_ for 0x00 it is << 1
    - So... the lowest bit is not encoded and so we can go up to the fifth
    - There are interactions between pausing (zeroing the LSB) and mangling
    - Fixed a bug or two
  • v0.4

    b27c8887 · Version bump to v0.4 ·
    Release: v0.4
    ## v0.4 (2022-06-03)
    
    Taking care of mangled codes due to A-μ-A translation
    - Such bits carry no data in the lowest bit
    - Switched A-law data bits writing from MSB to LSB direction
    - This is also applied in pauses without data to transmit
    - Added tool/g711mangle.c to mangle as under A-μ-Α translation
    - Transmitted files get received with or without this mangling
    - Added some amateur poetry in sound/*.txt as test payload
    - Wrote some text about building and playing in README.md
    - Suggested md5sum for comparing transmitted/received files
  • v0.3

    39c7bad2 · Version bump to v0.3 ·
    Release: v0.3
    ## v0.3 (2022-05-31)
    
    Reception of HDLC frames from the A-law codec
    - A number of files can be extracted, as though they were HDLC frames
    - Pausing has been simplified by syncing BREAK with the low bit
    - Proper handling of BREAK and FLAG to start and stop HDLC frames
    - Note that nothing has been done yet on HDLC address, command, checksum
    - The data layer is now ready for interaction with the network layer
  • v0.2

    Release: v0.2
    ## v0.2 (2022-05-30)
    
    Transmission of HDLC frames over the A-law codec
    - A number of files are transmitted, as though they were HDLC frames
    - Proper bit stuffing, frames surrounded with FLAG
    - Start new transmissions with BREAK-FLAG to clear the line
    - After the last frame, send FLAG-BREAK to stop expectations of another frame
    - Reuse of FLAG without BREAK through rejuvenation when more data exists
    - When not transmitting, insert "0" in the lowest bit to avoid FLAG in audio
    - Insertion of low "0" allows more optimal pause detection at the receiver
    - Receiver code is not working yet, but output from insertion looks good
  • v0.1

    Release: v0.1
    ## v0.1 (2022-05-29)
    
    Demonstrations of sound modifications to A-law and μ-law transmissions,
    as commonly used in ISDN, the telephony backbone, and the de-factor codec
    in VoIP phones.
    - Made a recording of The Quick Brown Fox... at normal and loud voice levels
    - Inserted random bits in the bits destined to carry data, causing noise
    - The noise level sounds like an old analog line, bearable at both levels
    - The noise level is clearly audible, certainly at the normal voice level
    - Inserted zero in the lowest bits to pause data without flag detection 
    - The influence of these lowest bits is not audible at both levels
    - The data rate at the loud   voice level is 27% of 64 kb/s = 17.280 kb/s
    - The data rate at the normal voice level is 45% of 64 kb/s = 28.800 kb/s
    - The data rate at complete silence level is 50% of 64 kb/s = 32.000 kb/s
    - Note that calls usually consist of half-time speaking (per direction)
    - Note that listeners are not used to silence; codecs send "comfort noise"
    - The experiments give rise to the work on actually inserting data frames