select_every

select_every(
  input: Clip,
  #{
    cycle: Int,
    offsets: Int | Array<Int>,
  }
)

Builds a new clip by keeping selected frame offsets from every fixed-size cycle of one input clip. Offsets are zero-indexed within each cycle, preserve the written order, and may repeat; repeated offsets duplicate the corresponding source frame in the output.

The input must be one fixed-format planar Gray, YUV, or planar RGB clip with a finite frame count and a positive constant frame rate. cycle must be greater than or equal to 2. offsets must be one integer or a non-empty integer array where every entry is greater than or equal to 0 and less than cycle. The output frame rate is scaled by offsets.len() / cycle; scalar offsets counts as one kept frame per cycle. In a partial final cycle, offsets beyond the input frame count are ignored.

Examples

# Return even numbered frames, starting with 0.
output = source("input.mkv").std.select_every(#{ cycle: 2, offsets: 0 })

# Return odd numbered frames, starting with 1.
output = source("input.mkv").std.select_every(#{ cycle: 2, offsets: 1 })

# Fixed pattern 1-in-5 decimation, removing the first frame in every cycle.
output = source("input.mkv").std.select_every(#{ cycle: 5, offsets: [1, 2, 3, 4] })

# Duplicate every fourth frame.
output = source("input.mkv").std.select_every(#{ cycle: 4, offsets: [0, 1, 2, 3, 3] })

Input

One fixed-format planar Gray, YUV, or planar RGB clip with a finite frame count and a positive constant frame rate.

Output

A clip with the same format and resolution, containing the selected source frames in cycle/offset order and using a frame rate scaled by offsets.len() / cycle.

Options

• cycle (Int) – Number of source frames in each selection cycle; must be at least 2.
• offsets (Int | Array<Int>) – Zero-indexed frame offsets to keep from each cycle; duplicate entries duplicate frames.