Extract Left Eye from 3D Video with FFmpeg stereo3d

This guide explains how to extract a single 2D left-eye perspective from a stereoscopic 3D video using FFmpeg. By utilizing the built-in stereo3d video filter, you can convert common stereoscopic layouts—such as Side-by-Side (SBS) or Top-and-Bottom (TAB)—into a standard monoscopic video focused exclusively on the left eye.

Basic Syntax

The stereo3d filter requires two primary parameters: the input format (in) and the output format (out).

ffmpeg -i input.mp4 -vf "stereo3d=in_format:out_format" -c:a copy output.mp4

To extract only the left eye, the output format is always specified as ml (mono left).

Identifying Your Input Format

Before running the command, identify how the stereoscopic 3D is arranged in your source file:

  • Side-by-Side Half (half-SBS): sbs2l (Left eye left, right eye right, horizontal resolution halved)
  • Side-by-Side Full (full-SBS): sbsl (Left eye left, right eye right, full resolution)
  • Top-and-Bottom Half (half-TAB / Over-Under): tb2l (Left eye top, right eye bottom, vertical resolution halved)
  • Top-and-Bottom Full (full-TAB): tbl (Left eye top, right eye bottom, full resolution)

Commands by Layout

1. Extract from Half Side-by-Side (Half-SBS)

Half-SBS is the most common format for 3D digital releases. The filter will extract the left half and stretch the horizontal aspect ratio back to standard 16:9 automatically.

ffmpeg -i input_3d.mp4 -vf "stereo3d=sbs2l:ml" -c:v libx264 -crf 18 -c:a copy output_left.mp4

2. Extract from Full Side-by-Side (Full-SBS)

If the video contains two full-width frames side-by-side:

ffmpeg -i input_3d.mp4 -vf "stereo3d=sbsl:ml" -c:v libx264 -crf 18 -c:a copy output_left.mp4

3. Extract from Half Top-and-Bottom (Half-TAB)

Half-TAB splits the screen vertically. The filter isolates the top frame and restores the vertical aspect ratio.

ffmpeg -i input_3d.mp4 -vf "stereo3d=tb2l:ml" -c:v libx264 -crf 18 -c:a copy output_left.mp4

4. Extract from Full Top-and-Bottom (Full-TAB)

If the video contains two full-height frames stacked vertically:

ffmpeg -i input_3d.mp4 -vf "stereo3d=tbl:ml" -c:v libx264 -crf 18 -c:a copy output_left.mp4

Parameter Breakdown

  • -i input_3d.mp4: Specifies the input source video.
  • -vf "stereo3d=...:ml": Applies the video filter, mapping the specified stereoscopic input to mono left (ml).
  • -c:v libx264: Re-encodes the video stream using the H.264 video codec.
  • -crf 18: Sets a visually lossless constant rate factor (lower values mean higher quality; 17–23 is standard).
  • -c:a copy: Copies the audio stream directly without re-encoding to save time and prevent quality loss.