Trims leading buffers so all input pads start at a common synchronization point.

When H264 pads are present, synchronization is anchored on H264 keyframe cut points. The aligner chooses the earliest H264 cut point for which all non-H264 pads have already started (first_ts <= cut_point). If this is not satisfied, it advances to the next H264 cut point and retries.

Without H264 pads, synchronization falls back to the latest first cuttable timestamp among all pads.

For %Membrane.Text{} pads, if the selected cut point lands inside a subtitle cue (buffer.pts < cut_point < buffer.metadata.to), the first forwarded cue is clipped to start exactly at the cut point instead of being dropped.

H264 pads can only be trimmed at keyframe boundaries and require parser metadata (%Membrane.H264{alignment: :au, nalu_in_metadata?: true}).

Element options

Passed via struct Membrane.HLS.TrimAlign.t/0

• max_leading_trim

  Membrane.Time.t()

  Default value: 3000000000
  Maximum amount of leading content that can be trimmed from a single pad.

• max_queued_buffers

  pos_integer()

  Default value: 2000
  Maximum number of buffers allowed in a single pad queue before alignment is established.

Pads

:input

Accepted formats:

_any

Pad options:

• cut_strategy

  cut_strategy()

  Default value: :any
  Defines where trimming can cut:
  • :any - cut at any buffer boundary
  • :h264_keyframe - cut only on H264 keyframe AUs

:output

Accepted formats:

_any