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Zeal Stream 11/8/2019 - Learning OBS Lua Plugin Development

Erik Guzman
Developer, streamer, Microsoft MVP and Twitch dev contributer. I love to code and share the knowledge. Check me out at https://www.twitch.tv/talk2megooseman
・5 min read

Checkout the stream @ https://www.twitch.tv/codingzeal

Stream Recap

After getting familiar enough with Lua to be able to read code it was now time to take a look at OBS Plugins scripted in Lua. I spent sometime go through a couple of plugins and seeing how they interface with the OBS C methods.

Once I had a good enough idea of how an OBS plugin is made and the various methods I'll need to use, I started my work on doing the Video Gallery. Afterward, I start tackling the configuration menu so that a user can apply settings and select media sources.


Stream Standup

Any interesting tech things this week


Notes

Lua

If you need a cheat sheet Lua

OBS Plugin Scripting

https://obsproject.com/docs/scripting.html

I have two ideas for possible OBS plugins.

Video Gallery Plugin - Right OBS has an image gallery plugin to you can cycle through different images. But you cant do this with videos.

Feature Ideas:

  • Want to be able to select multiple video sources for display
  • Want to have a flag if you want it to loop

    Maybe even have a loop limit

  • Add a timer to just cap how long its displayed

Stream Closed Captioner Plugin - It will take the text streamed from the Stream CC server and add it to the closed captioning audio channel thing

Lua Example Plugin Notes:

countdown.lua

  • Great example of having a configurable plugin. Show how to display the property fields to user input. Handling timers and when a source activated or deactivated.

clock-source.lua

  • This example showcases loading multiple image assets and positioning them in a source on each tick of the video render. Creates a brand new source to select and show.

instant-replay.lua

  • In this example it is loading a video (from replay) into a media source for display. I think this example might be what I need in order to implement the video gallery idea I have.

To send log message:

obs.script_log(obs.LOG_DEBUG, "heyu")

Found an example of going through the editable list here dmadison/OBS-ChatSpam

Shoutouts and Thanks

DoctorArgus, AntiPixelated, LilyHazel for hanging out

Future action items

  • Continue working the Lua script for Video Gallery
    • Finish trying to construct a Lua array from the video selected in the editable list
    • Figure out how to get them to display in the selected media source

Current Code for Reference

Current Work in Progress Code 100% not finished so take it with a grain of salt

    obs           = obslua
    source_name   = ""
    total_seconds = 0

    cur_seconds   = 0
    activated     = false

    loop = true

    videos = {}
    last_video = ""

    hotkey_id     = obs.OBS_INVALID_HOTKEY_ID
    filer_filter = "*.mp4 *.ts *.mov *.flv *.mkv *.avi *.gif *.webm"

    -- Function to set the time text
    function set_time_text()

      if cur_seconds < 1 then
        -- Do something to stop after end is reached
      end

      if media ~= last_video then
        local source = obs.obs_get_source_by_name(source_name)
        if source ~= nil then
          local settings = obs.obs_data_create()
          obs.obs_data_set_string(settings, "text", text)
          obs.obs_source_update(source, settings)
          obs.obs_data_release(settings)
          obs.obs_source_release(source)
        end
      end

      last_video = media
    end

    function timer_callback()
      cur_seconds = cur_seconds - 1
      if cur_seconds < 0 then
        obs.remove_current_callback()
        cur_seconds = 0
      end

      set_time_text()
    end

    function activate(activating)
      if activated == activating then
        return
      end

      activated = activating

      if activating then
        cur_seconds = total_seconds
        set_time_text()
        obs.timer_add(timer_callback, 1000)
      else
        obs.timer_remove(timer_callback)
      end
    end

    -- Called when a source is activated/deactivated
    function activate_signal(cd, activating)
      local source = obs.calldata_source(cd, "source")
      if source ~= nil then
        local name = obs.obs_source_get_name(source)
        if (name == source_name) then
          activate(activating)
        end
      end
    end

    function source_activated(cd)
      activate_signal(cd, true)
    end

    function source_deactivated(cd)
      activate_signal(cd, false)
    end

    function reset(pressed)
      if not pressed then
        return
      end

      activate(false)
      local source = obs.obs_get_source_by_name(source_name)
      if source ~= nil then
        local active = obs.obs_source_active(source)
        obs.obs_source_release(source)
        activate(active)
      end
    end

    function reset_button_clicked(props, p)
      reset(true)
      return false
    end

    ----------------------------------------------------------

    -- A function named script_properties defines the properties that the user
    -- can change for the entire script module itself
    function script_properties()
      local props = obs.obs_properties_create()
      obs.obs_properties_add_int(props, "duration", "Duration (minutes)", 1, 100000, 1)

      -- Crearte Dropdown Selector
      local media_dropdown = obs.obs_properties_add_list(props, "source", "Media Source", obs.OBS_COMBO_TYPE_EDITABLE, obs.OBS_COMBO_FORMAT_STRING)
      local sources = obs.obs_enum_sources()
      if sources ~= nil then
        for _, source in ipairs(sources) do
          source_id = obs.obs_source_get_id(source)
          if source_id == "ffmpeg_source" or source_id == "vlc_source" then
            local name = obs.obs_source_get_name(source)
            obs.obs_property_list_add_string(media_dropdown, name, name)
          end
        end
      end
      obs.source_list_release(sources)

      obs.obs_properties_add_editable_list(props, "video_sources", "Videos for gallery", obs.OBS_EDITABLE_LIST_TYPE_FILES, filer_filter, script_path())
      obs.obs_properties_add_bool(props, "loop_videos", "Loop Gallery")
      -- obs.obs_properties_add_text(props, "stop_text", "Final Text", obs.OBS_TEXT_DEFAULT)
      obs.obs_properties_add_button(props, "reset_button", "Reset", reset_button_clicked)

      return props
    end


    -- A function named script_update will be called when settings are changed
    function script_update(settings)
      obs.script_log(obs.LOG_DEBUG, "Values Set")
      activate(false)

      -- total_seconds = obs.obs_data_get_int(settings, "duration") * 60
      -- stop_text = obs.obs_data_get_string(settings, "stop_text")
      source_name = obs.obs_data_get_string(settings, "source")
      loop = obs.obs_data_get_bool(settings, "loop_videos")

      -- Grab the video from what was set in the editable list
      selected_videos = obs.obs_data_get_array(settings, "video_sources")
      num_videos = obs.obs_data_array_count(selected_videos)

      -- Loop through the array so that we construct a Lua version
      for i = 1, num_videos do
            video_obj = obs.obs_data_array_item(selected_videos, i)
        videos[i] = obs.obs_data_get_string(video_obj, "value")
      end

      -- Dont forget to garbage collect
      obs.obs_data_array_release(selected_videos)
      reset(true)
    end

    -- A function named script_defaults will be called to set the default settings
    function script_defaults(settings)
      obs.obs_data_set_default_int(settings, "duration", 5)
      obs.obs_data_set_default_bool(settings, "loop_videos", true)
      -- obs.obs_data_set_default_string(settings, "stop_text", "Starting soon (tm)")
    end

    -- A function named script_save will be called when the script is saved
    --
    -- NOTE: This function is usually used for saving extra data (such as in this
    -- case, a hotkey's save data).  Settings set via the properties are saved
    -- automatically.
    function script_save(settings)
    end

    -- A function named script_description returns the description shown to
    -- the user
    function script_description()
      return "Create a video gallery and have full control how its displayed."
    end

    -- a function named script_load will be called on startup
    function script_load(settings)
      -- Connect hotkey and activation/deactivation signal callbacks
      --
      -- NOTE: These particular script callbacks do not necessarily have to
      -- be disconnected, as callbacks will automatically destroy themselves
      -- if the script is unloaded.  So there's no real need to manually
      -- disconnect callbacks that are intended to last until the script is
      -- unloaded.
      local sh = obs.obs_get_signal_handler()
      obs.signal_handler_connect(sh, "source_activate", source_activated)
      obs.signal_handler_connect(sh, "source_deactivate", source_deactivated)
    end

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