Converting CMTime to Timecode

[latenitefilms]

Sorry, this is a dumb newbie question...

What's the best way to convert CMTime into a timecode string.

For example, if I have the current playhead time, and the frame duration in CMTime, how can I convert this into HH:MM:SS:FF?

[orchetect]

First construct a TimecodeFrameRate instance from the frame duration.

let frameDuration = CMTime(value: 1, timescale: 25)
let tcFrameRate = TimecodeFrameRate(frameDuration: frameDuration)

Then construct a Timecode instance from the playhead position.

If the play position is also a CMTime, and assuming the video starts at 00:00:00:00, you can do this:

let playheadPosition = CMTime( /* ... */ )
let tc = try Timecode(.cmTime(playheadPosition), at: tcFrameRate)

If the play position is a different time format, such as floating-point elapsed seconds, you can use a different time value type. It supports quite a few formats.

let playheadPosition: TimeInterval = 12.45
let tc = try Timecode(.realTime(seconds: playheadPosition), at: tcFrameRate)

To get the timecode string, with or without subframes:

let string = tc.stringValue() // "00:00:00:00"
let string = tc.stringValue(format: [.showSubFrames]) // "00:00:00:00.00"

[latenitefilms]

Legend, thanks for the fast reply! I'm FINALLY trying out TimelineKit for the first time - it's really cool!

Also, thanks for the updated/extended answer - you updated whilst I was replying!

For anyone who stumbles across this, I stupidly missed the most helpful part of the documentation here.

[orchetect]

No sweat - there is a slight learning curve, and the API is little bit unconventional. But it's distilled in the form that it is now through years of woodshedding in day-to-day use, and covering a myriad of edge cases and contingencies. We spared no expense. 😉

[orchetect]

Side note: TimecodeKit primarily uses its own analogue to CMTime called Fraction and they are 100% interchangeable/convertible with each other by accessing properties on each respectively. Eventually Fraction may be phased out in favor of just using CMTime but there were a few logistical reasons to implement a custom type - the least of which was to try and mitigate the need to import/rely on CoreMedia if it's not needed.

On the note of rational time values - FCPXML time strings can be used and generated as well.

// from FCPXML
guard let frameDuration = Fraction(fcpxmlString: "1/25s") else { /* ... */ }
let tcFrameRate = TimecodeFrameRate(frameDuration: frameDuration)

// to FCPXML
let tc = try Timecode(.string("01:00:12:05"), at: .fps25)
let string = tc
    .rationalValue // Fraction instance
    .fcpxmlStringValue // "18061/5s"

[latenitefilms]

Legend, thanks again!

Next up... I'm going to try and import DAWFileKit to really make things interesting!