Camtasia file formats

What the scripts read and write, as observed in Camtasia 2025 for Mac.

Project bundle

A .cmproj directory holding project.tscproj (JSON), bookmarks.plist, docPrefs (property lists), and media/, originals/, recordings/. While a project is open, Camtasia keeps a ~project.tscproj beside it.

• Time is in ticks at the project's editRate. Frame snapping is tick in skills/screencast-editor/scripts/camtasia_model.py.
• Tracks live at timeline.sceneTrack.scenes[0].csml.tracks, with display names in timeline.trackAttributes. Each clip has start, duration (timeline ticks), mediaStart, mediaDuration (source ticks), and scalar (speed as an exact fraction such as "57/47", or 1).
• A screen + camera recording opens as track 0 ScreenVMFile and track 1 UnifiedMedia (camera video plus mic audio).
• Position is translation0/translation1 in canvas pixels, center-relative, y up. scale0/scale1 are relative to source pixels: 0.5 fits a 3840x2160 source to a 1080-high canvas.
• An animated parameter is {"type": "double", "defaultValue", "interp": "eioe", "keyframes": [{"time", "endTime", "duration", "value"}]} with times relative to the clip, plus animationTracks.visual entries {"endTime", "duration"}.
• The rounded inset is the native RoundCorners effect followed by an alpha-aware Border (type 1); AI noise removal is the audio effect VSTEffect-DFN3NoiseRemoval. Definitions: skills/screencast-editor/scripts/camtasia-effects.json.

Dynamic captions

• Recognition is stored once, on the source: sourceBin[].sourceTracks[type 2] .parameters.transcription.keyframes, one {"time", "value"} per word in source ticks. %GAP marks the start of a pause; the first keyframe is a %GAP at 0.
• The caption itself is a Callout clip on its own track whose def.modifier is dynamicCaption. Box size is def.width/def.height, position the clip's translation0/translation1, and text size both def.font.size and the fontSize entry of def.textAttributes.
• def.dynamic-caption-new-paragraph-for-each-sentence starts a caption block at each sentence, so punctuation in the words changes the blocks.

Recording (.trec)

An MP4 with three streams: the TSCC2 screen, the H.264 camera, and AAC mic. The pointer is not drawn into the screen stream. A top-level TSCM atom (64-bit size) holds records: <u32 count> "DATA" <u64 length> <16-byte GUID> <payload>, with the length spanning the record from the count field.

• GUID 2b7b6af2-7a1f-11e2-83d0-0017f200be7f (raw bytes as listed) is the pointer path: <u32 version> <u32 16> then <f64 seconds> <i32 x> <i32 y> samples in global points.
• GUID 2b7b6af6-... is the capture rectangle: <u32 version> <u32 24> then <f64> <i32 x> <i32 y> <i32 width> <i32 height>.