diy_ptz_switch

diy_ptz_switch

For a typical livestream production environment consisting of 2 ptz cameras and one joystick / controller board, most commercial options like the Skaarhoj PTZ Fly are

• expensive
• offering no API
• nearly impossible to automate
• offering no rs485 serial connection support (basically only IP via RJ45)

To fix this, I thought why not connect the ptz cameras via their rs485 to a rs485 <-> usb serial converter to a computer and use a server that selects which ptz camera is sent the current joystick input. It also has a http api that allows seleting the current camera target and ptz commands like save_preset or goto_preset.

See the following ascii diagram for the architecture.

                        +------------------------+
                        |      PTZ Joystick      |
                        |  (Pelco-D via RS-485)  |
                        +------------------------+
                                     |
                                     v
                     +--------------------------------+
                     |  /dev/ttyUSBX (JOYSTICK_PORT)  |
                     |  [async serial reader]         |
                     +--------------------------------+
                                     |
                                     v
                      +------------------------------+
                      |  Python asyncio PTZ Router   |
                      |------------------------------|
                      | - Parse Pelco-D packets      |
                      | - current_target: cam1/cam2  |
                      | - Forward to selected cam    |
                      | - Handle HTTP API requests   |
                      |                              |
                      |   +----------------------+   |
                      |   |     HTTP API         |   |
                      |   |----------------------|   |
                      |   | POST /target/set     |   |
                      |   | GET  /target/get     |   |
                      |   | POST /preset/goto    |   |
                      |   | POST /preset/save    |   |
                      |   | GET  /mode/get       |   |
                      |   | POST /mode/set       |   |
                      |   +----------------------+   |
                      +------------------------------+
                                     |
                +--------------------+------------------+
                |                                       |
                v                                       v
  +----------------------------+         +----------------------------+
  |  /dev/ttyUSBY (CAM1_PORT)  |         |  /dev/ttyUSBZ (CAM2_PORT)  |
  |  [async serial writer]     |         |  [async serial writer]     |
  +----------------------------+         +----------------------------+
                |                                        |
                v                                        v
    +------------------------+              +------------------------+
    |  PTZ Camera 1          |              |   PTZ Camera 2         |
    |  (Pelco-D via RS-485)  |              |  (Pelco-D via RS-485)  |
    +------------------------+              +------------------------+