Copy vs Re-encode: When to Use Which

Choosing between Copy and Re-encode determines speed, file size, and compatibility. This guide helps you decide quickly.

What “Copy” means

Copy keeps the original streams without re-encoding.

Pros

• Fastest option
• No quality loss
• Lowest CPU and memory usage

Cons

• Output keeps original codec limitations
• If the source codec is incompatible with the target container, it may fail

What “Re-encode” means

Re-encode decodes and compresses streams again using the selected codec.

Pros

• Best compatibility for target devices
• Lets you change resolution, bitrate, or codec
• Can reduce file size when using efficient codecs

Cons

• Slower and more CPU-intensive
• Quality can degrade if settings are too aggressive

Quick decision guide

• Need speed and no quality loss? Choose Copy.
• Need maximum compatibility? Choose Re-encode.
• Merging for web playback? Use H.264 + AAC.

Recommended defaults in AVMergePro

• Video codec: Copy (fastest)
• Audio codec: Copy (or AAC for MP4)
• Use Re-encode only when a device fails to play the file

Common issues and fixes

• Output won’t play: Re-encode with H.264 (video) and AAC (audio).
• File too large: Re-encode with a higher CRF value (e.g., 24–28).
• Processing too slow: Switch back to Copy mode.