Here are the classes, structs, unions and interfaces with brief descriptions:

Cmpv_byte_array	(see mpv_node)
Cmpv_event
Cmpv_event_client_message
Cmpv_event_command
Cmpv_event_end_file
Cmpv_event_hook
Cmpv_event_log_message
Cmpv_event_property
Cmpv_event_script_input_dispatch
Cmpv_event_start_file	Since API version 1.108
Cmpv_node	Generic data storage
Cmpv_node_list	(see mpv_node)
Cmpv_opengl_cb_drm_params
Cmpv_opengl_cb_window_pos
Cmpv_opengl_drm_draw_surface_size	For MPV_RENDER_PARAM_DRM_DRAW_SURFACE_SIZE
Cmpv_opengl_drm_params	Deprecated
Cmpv_opengl_drm_params_v2	For MPV_RENDER_PARAM_DRM_DISPLAY_V2
Cmpv_opengl_fbo	For MPV_RENDER_PARAM_OPENGL_FBO
Cmpv_opengl_init_params	For initializing the mpv OpenGL state via MPV_RENDER_PARAM_OPENGL_INIT_PARAMS
Cmpv_render_frame_info	Information about the next video frame that will be rendered
Cmpv_render_param	Used to pass arbitrary parameters to some mpv_render_* functions
Cmpv_stream_cb_info	See mpv_stream_cb_open_ro_fn callback