The two environment variables:
WSJT_RX_AUDIO_BUFFER_FRAMES
WSJT_TX_AUDIO_BUFFER_FRAMES
each can be defined to an integer number which will be used as the
suggested audio buffer size for Rx and Tx respectively. Not setting
the variable or setting it to zero or less will cause the default
buffer size to be used, which should be a good choice for most, if not
all, systems.
WSJT_TX_AUDIO_BUFFER_FRAMES takes the following values:
-1 - use Qt/system default
0 - use 200 mS (WSJT-X default)
+ve integer - value is number of frames at 48 kHz
-1 is likely to be a good choice on Windows and may macOS. 0 has
proven to be good on Windows. On Linux 0 may be OK but we need to try
other values.
The value is only a hint, the actual value used along with the period
size (the size of each chunk of samples requested by the system) is
printed in an info level diagnostic message at the start of each
transmission.
Two new environment variables to control special testing behaviour:
* WSJT_TX_BOTH - set to "1" to force transmission on both periods.
* WSJT_REVERSE_DOPPLER - set to "1" to transpose Tx and Rx Doppler
corrections. Use this to test Doppler tracking on a terrestrial
link.
Default selection is the loop-back interface. Users who require
interoperation between WSJT-X instances cooperating applications
running on different hosts should select a suitable network interface
and carefully choose a multicast group address, and TTL, that has
minimal scope covering the necessary network(s). Using 224.0.0.1 is a
reasonable strategy if all hosts are on the same
subnet. Administratively scoped multicast group addresses like those
within 239.255.0.0/16 can cover larger boundaries, but care must be
taken if the local subnet has access to a multicast enabled router.
The IPv4 broadcast address (255.255.255.255) may be used as an
alternative to multicast UDP, but note that WSJT-X will only send
broadcast UDP datagrams on the loop-back interface, so all recipient
applications must be running on the same host system.
The reference UDP Message protocol applications are being extended to
be configurable with a list of interfaces to join a multicast group
address on. By default they will only join on the loop-back interface,
which is also recommended for any applications designed to take part
in the WSJT-X UDP Message Protocol. This allows full user control of
the scope of multicast group membership with a very conservative
default mode that will work with all interoperating applications
running on the same host system.
Joe Taylor
Bill Somerville