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FFmpeg Anamorphic Crop Calculator

Calculate proper crop dimensions for anamorphic video (720×540) with 4:3 aspect ratio and 8/9 vertical squeeze adjustment.

Note: This tool is specifically designed for 720×540 anamorphic video. The image you upload must be exactly 720×540 pixels.

Drop image or click to browse

720×540 pixels required

Image size: ×

Crop width:

Crop height: = crop width × 3/4

Adjusted height: = crop height × 8/9

Adjusted Y offset: = Y offset × 8/9

About

What is this?

This is a specialized calculator for cropping anamorphic video content. Anamorphic video uses non-square pixels, which means the stored dimensions differ from the display dimensions. This tool helps you calculate the correct crop parameters while accounting for the pixel aspect ratio.

How to use:

  1. Extract a frame from your 720×540 anamorphic video
  2. Load the frame using the "Image file" input
  3. Enter your desired crop width
  4. Adjust X and Y offsets to position the crop region
  5. The calculator will show you the proper crop filter with aspect ratio adjustments applied
  6. Copy the generated filter and use it in your FFmpeg command

Background:

Anamorphic video (particularly in NTSC DV format) is stored at 720×480 or 720×540 pixels but displays at 4:3 (640×480) or 16:9 (854×480) depending on the pixel aspect ratio. When cropping this content, you need to account for the vertical squeeze factor.

This tool uses an 8/9 vertical squeeze adjustment, which is appropriate for 4:3 DV content. The crop height is calculated as width × 3/4 to maintain a 4:3 aspect ratio, then multiplied by 8/9 to account for the anamorphic encoding.

The "likely full filter" output includes bwdif deinterlacing (common for DV footage), the crop filter with adjustments, scaling back to 720×540, and setting the pixel aspect ratio to square (1:1) with setsar=1.