Skip to content

[fix] drop-frame timecode emits illegal values at minute boundaries #139

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
xianjianlf2 wants to merge 1 commit into
base: main
Choose a base branch
from
Open

[fix] drop-frame timecode emits illegal values at minute boundaries #139

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 4 additions & 2 deletions Sources/PalmierPro/Export/XMLExporter.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -66,8 +66,10 @@ enum XMLExporter {
var f = frame
if dropFrame {
let drop = Int((Double(fps) * 0.066666).rounded()) // 2 @ 30, 4 @ 60
let d = f / (fps * 600), m = f % (fps * 600)
f += drop * 9 * d + (m > drop ? drop * ((m - drop) / (fps * 60)) : 0)
// Drop-frame partitions the real (post-drop) count: 17982 per 10 min, 1798 per min at 30.
let per10Min = fps * 600 - drop * 9, perMin = fps * 60 - drop
let d = f / per10Min, m = f % per10Min
f += drop * 9 * d + (m > drop ? drop * ((m - drop) / perMin) : 0)
}
let sep = dropFrame ? ";" : ":"
let ff = f % fps, ss = (f / fps) % 60, mm = (f / (fps * 60)) % 60, hh = f / (fps * 3600)
Expand Down
11 changes: 11 additions & 0 deletions Tests/PalmierProTests/Export/XMLExporterTimecodeTests.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,17 @@ struct XMLExporterTimecodeTests {
#expect(XMLExporter.formatTimecode(frame: 42966, fps: 30, dropFrame: true) == "00;23;53;18")
}

@Test func dropFrameSkipsTwoFramesAtEachNonTenthMinute() {
// The first real frame of minute 1 must read ;02 — frames ;00/;01 are dropped. The raw
// count (fps*60 etc.) would emit an illegal 00;01;00;00 here.
#expect(XMLExporter.formatTimecode(frame: 1800, fps: 30, dropFrame: true) == "00;01;00;02")
#expect(XMLExporter.formatTimecode(frame: 3598, fps: 30, dropFrame: true) == "00;02;00;02")
// Minute 10 keeps all frames, so ;00 is legal there.
#expect(XMLExporter.formatTimecode(frame: 17982, fps: 30, dropFrame: true) == "00;10;00;00")
// 59.94: 4 frames dropped per non-tenth minute (quanta 60 DF).
#expect(XMLExporter.formatTimecode(frame: 3600, fps: 60, dropFrame: true) == "00;01;00;04")
}

@Test func zeroFpsDoesNotCrash() {
#expect(XMLExporter.formatTimecode(frame: 100, fps: 0, dropFrame: false) == "00:00:00:00")
}
Expand Down