H.264 vs H.265 + AAC vs Opus

Codec choices decide file size, playback compatibility, and processing speed. This guide helps you pick the right combination.

Video codecs

H.264 (most compatible)

• Best for phones, TVs, and older devices
• Fastest to encode and decode
• Larger file size compared to H.265

H.265/HEVC (smaller files)

• Better compression, smaller size
• Slower to encode
• Not supported by all devices or browsers

Audio codecs

AAC (widest support)

• Best for MP4 containers
• Works on most devices
• Balanced quality and size

Opus (best quality per size)

• Excellent quality at smaller bitrates
• Best in WebM containers
• Not ideal for older devices

Quick picks

• Maximum compatibility: H.264 + AAC in MP4
• Smaller files: H.265 + AAC in MP4
• Web-first: VP9/AV1 + Opus in WebM

Recommended defaults in AVMergePro

• MP4 + H.264 + AAC for most users
• Use H.265 only when you know the target device supports it