Computing offset in clip from filter

[Leo_Sutic]

I thought that it was possible to compute the clip offset in seconds by dividing the offset frame with the frame rate:

function getFrameRate() {
    return producer.getDouble("meta.media.frame_rate_num", getPosition()) / producer.getDouble("meta.media.frame_rate_den", getPosition())
}

function getClipOffset() {
    return filter.in
}

clipOffsetInSeconds = (getClipOffset() / getFrameRate())

However, I get slightly different results every now and then, and I suspect this has to do with the 29.97fps drop-frame. That is, every now and then there is a frame missing or inserted. Anyone knows how to either tell Shotcut to ignore drop frames on 29.97fps video (just treat it as a sequence of frames, ignore timecode), or how to reliably get the offset?

[Leo_Sutic]

Ok, now I’m suspecting that Shotcut doesn’t store float filter parameters with greater precision than three decimals, and that it was this that caused the issue.

Note to self: don’t use double values to lookup entries in a map.

[Austin]

I’m a little fuzzy on which offset you’re trying to get. A clip’s offset from the beginning of the timeline? Or a filter’s offset from the beginning of a clip when filter trimming is applied?

If wanting the timeline offset, then querying producer could be misleading because a clip’s frame rate may not be the same as the timeline’s frame rate (profile.num/den).

[Leo_Sutic]

I want the offset in seconds from the start of the source clip to the start of the filter.

Like, I place a clip (sample.avi) on the timeline starting at 0:00;0, then I split it at 0:10;0 (timeline at 10 seconds), giving me clip A and clip B. I want something that gives me zero seconds for clip A, and 10 seconds for clip B, so that I can figure out that two seconds into clip B is 12 seconds into sample.avi.