Resize & aspect

• “No aspect ratio correction” selected: Stretched or shrinked to the specified size.
• “Keep original aspect ratio” selected: Stretched or shrinked until either width or height touch the specified size using the original aspect ratio. Black borders are added, if necessary.
• Manually configured: Stretched or shrinked until either width or height touch the specified size using the specified aspect ratio. Black borders are added, if necessary.

• Height is calculated automatically to keep original aspect ratio.
• “No aspect ratio correction” and “Keep original aspect ratio” give the same result.
• Manually configured: You can specify aspect ratio manually.

• Height is calculated based on width. (Let's call it a box here.)
• “No aspect ratio correction” selected: Stretched to fill the box.
• “Keep original aspect ratio” selected: Stretched or shrinked until either width or height touch the box using the original aspect ratio. Black borders are added, if necessary.
• Manually configured: Stretched or shrinked until either width or height touch the box using the specified aspect ratio. Black borders are added, if necessary.

• Both width and height are expanded to the next multiple of the specified value. For example, if you specify 100, 320×160 becomes 400×200. You may want to use this mode when ffdshow connects to a filter which does not work with width or height of non-multiple of 16.
• “Keep original aspect ratio” and “Manual” work in this mode too.

• Both horizontal and vertical sizes are stretched using the specified magnification ratio.

• The output resolution will match your video card's resolution. Recommended if you have a flat panel display and a multi-core CPU.

• If checked (by default), resize to the size taking into account pixel aspect ratio (SAR), and fix output SAR 1:1.
• If unchecked, output SAR equals input SAR and the video renderer (or any downstream filter) handles it.

Following situation: You have a projector with 1280×720 resolution and you want to play a DVD whose pixel aspect ratio (SAR) changes during playback. How to configure ffdshow's resize options properly?

• “Specify horizontal and vertical size” → “1280×720”.
• Select “Keep original aspect ratio”.
• Make sure “Process pixel aspect ratio internally” is checked.
• If you are using Media Player Classic, uncheck “View” → “Video Frame” → “Keep Aspect Ratio”.