prepare 1.73.4

README.md

@@ -13,10 +13,11 @@
 
 -   Support for **service discovery using a Bluetooth LE "beacon"** for both Linux/\*BSD and Windows (as an alternative to Bonjour/Rendezvous DNS-SD
     service discovery). **This can be used on networks that do not allow the user to run a  DNS_SD service.**   The user must run a Bluetooth LE "beacon", (a USB 4.0 or
-    later "dongle" can be used). The beacon is managed by a Python3 script `uxplay-beacon.py`: three implementations of Bleutooth LE advertising are available
-    as loadable modules: BlueZ for Linux only,  winrt for Windows only, and BleuIO
+    later "dongle" can be used). The beacon is managed by a Python3 script `uxplay-beacon.py`: four implementations of Bleutooth LE advertising are available
+    as loadable modules: BlueZ for Linux only,  winrt for Windows only,  BleuIO
     for the BlueIO usb-serial dongle (which has its own BlueTooth-LE stack, independent of that of the
-    host system) that runs on all systems including macOS and *BSD).   The beacon
+    host system) that runs on all systems including macOS and *BSD), and a low-level HCI module (Linux and BSD only) that
+    access the Host Contoller Interface (but users need enhanced privileges to use this). The beacon
     runs independently of UxPlay: while UxPlay is running, it regularly broadcasts a Bluetooth LE ("Low Energy") 46 byte
     legacy-type advertisement  informing nearby iOS/macOS devices of
     the local IPv4 network address of the UxPlay server, and which TCP port to contact UxPlay on.  Instructions
@@ -1559,9 +1560,8 @@ GStreamer inner workings.
 # Bluetooth LE beacon setup
 
 The python>=3.6 script for running a Bluetooth LE Service Discovery beacon is uxplay-beacon.py.
-It provides three possible Bluetooth LE implementations (loaded as modules):  one for Linux systems with D-Bus,
-one for Windows, and one for 
-the [BleuIO (or BleuIO Pro) USB
+It provides four possible Bluetooth LE implementations (loaded as modules):  one for Linux systems with D-Bus,
+one for Windows,  and one for the [BleuIO (or BleuIO Pro) USB
 dongle](https://www.bleuio.com)  with its own on-board Bluetooth-LE Stack that
 does not use the host operating system Bluetooth (the Host sees the device as a USB serial modem).   This is needed for macOS where the
 operating system does not allow users to send  Bluetooth-LE advertisements of the type we require.  If a BleuIO  dongle is
@@ -1569,6 +1569,11 @@ available, the bleuio version of the python script
 can be used on many operating systems including macOS, Windows and Linux, and perhaps *BSD (not tested):
 it requires python library `python3-pyserial` to be installed.
 
+A fourth implementation (module HCI) for Linux or FreeBSD (maybe other BSD's too?)  requires elevated permissions to access the Host
+Controller  Interface.   These are granted by adding users to a new group "hciusers" that are give permission to
+call "`sudo -n hcitool/hciconfig/hccontrol`" without entering a password:  this can be configured by the system admistrator
+using visudo, but has security implications.
+
 On Linux, Bluetooth support (using the offical Linux Bluetooth stack BlueZ) must be installed (on Debian-based systems: `sudo apt install bluez bluez-tools`;
 recent Ubuntu releases provide bluez as a snap package).
 In addition to standard Python3 libraries, you may need to install the gi, dbus, and psutil Python libraries used by
@@ -2007,6 +2012,10 @@ introduced 2017, running tvOS 12.2.1), so it does not seem to matter
 what version UxPlay claims to be.
 
 # Changelog
+1.73.4 2026-03-15 Modularize Bluetooth support for uxplay-beacon.
+Add modules for BLeuIO serial-modem Bluetooth LE device, and HCI
+access (Linux/FreeBSD).   Fix broken -vol option.
+
 1.73 2026-01-25 Render Audio cover-art inside UxPlay with -ca option (no file
 specified). (D-Bus based) option -scrsv <n> to inhibit screensaver while UxPlay
 is running (Linux/*BSD only). Add password support (-pw)  using a displayed