: Do not put x265 in the "Must Contain" box unless you want to strictly block all x264 releases. Using "Preferred" allows Sonarr to grab an x264 version immediately and then "upgrade" to x265 later when it becomes available.

For more precise control, consider creating multiple custom formats:

: Similar to Tdarr but with a simpler interface, focused on making your library direct-play compatible with Plex, Jellyfin, or Emby.

: For the same bitrate, x265 generally provides a better quality picture than x264. This improvement in quality makes for a more enjoyable viewing experience, especially on high-definition displays.

Set the to 0 (this ensures Sonarr will still download x264 files if no x265 version is available, rather than ignoring the episode entirely). Click Save . Step 3: Handle the Upgrade Threshold (Optional)

Go to the Series tab, select the shows you want to upgrade, and click Interactive Search or Search Monitored to let Sonarr find the more efficient versions.

If you want to replace all your existing x264 library with x265 versions:

Basic tagging fails because uploaders are inconsistent. Some release groups tag HEVC , others tag x265 , and some use H.265 . Worse, fake uploaders tag x265 on low-bitrate garbage.

In the same Profile menu, look at the section. Set the Upgrade Until Score to 100 .

If you already have a large library of x264 content and want to migrate to x265, Sonarr alone isn't the right tool for the job. Sonarr is designed for content, not re-encoding it.

Ensure the checkbox is enabled if you want Sonarr to replace existing x264 files with x265 versions when they appear in your indexers' feeds.

Almost all 4K (UHD) content is encoded in HEVC; preferring it ensures you get the best modern encodes. Automation: