Dynamic caption of Camatsia is an easy and AI-based way that convert speech to text and generate animated caption for the video. But there is no way to edit wrong or not-detected parts of speech. So I figured out that one can edit the json-like Camtasia saved project file using notepad or notepad++.

this is the code of auto-generated caption (keyframes of a test caption “this is a text”):

... {
          "range" : [0, 2819071],
          "type" : 2,
          "editRate" : 44100,
          "trackRect" : [0, 0, 0, 0],
          "sampleRate" : 44100,
          "bitDepth" : 16,
          "numChannels" : 2,
          "integratedLUFS" : -11.382925129554,
          "peakLevel" : 1.18406045436859,
          "metaData" : "videoname.mp4;",
          "transcriptionSet" : true,
          "parameters" : {
            "transcription" : {
              "type" : "string",
              "keyframes" : [
                {
                  "endTime" : 259308000,
                  "time" : 259308000,
                  "value" : "this",
                  "duration" : 0
                },
                {
                  "endTime" : 301644000,
                  "time" : 301644000,
                  "value" : "is",
                  "duration" : 0
                },
                {
                  "endTime" : 386316000,
                  "time" : 386316000,
                  "value" : "a",
                  "duration" : 0
                },
                {
                  "endTime" : 555660000,
                  "time" : 555660000,
                  "value" : "text",
                  "duration" : 0
                },  ...
              ]
            }
          }
        }
      ],
      "metadata" : {
        "timeAdded" : "20240909T025035.025180"
      }
    }
  ], ...

To add a custom keyframe, I need to know what these timestamp-like numbers are. (“endtime” and “time”). Are you familiar with this?