x265 truly shines at content. The standard for 4K releases is x265, as x264 struggles to efficiently handle the massive data of 4K resolution.

x265 requires significantly more processing power to decode.

| Device | x265 Playback Support | Transcoding Need? | | :--- | :--- | :--- | | | Perfect (10-bit, 4K, HDR) | No | | Apple TV 4K (Infuse) | Perfect | No | | Fire Stick 4K Max | Great | No | | iPhone / iPad (Recent) | Great (via native player) | No | | Roku Ultra (2022+) | Good | Rarely | | Your Web Browser (Chrome/Safari) | None | Yes (Server must transcode) | | Old Roku / Smart TV (2017-) | None | Yes |

Given the advantages of the x265 codec, particularly its superior compression efficiency and ability to handle high-resolution videos, configuring Sonarr to prefer x265 can offer several benefits:

The scoring system works as follows:

Before diving into the settings, it is important to understand why this shift matters for your home server.

x265 is an open-source implementation of the High Efficiency Video Coding (HEVC) standard, also known as H.265. Released in 2013 as the successor to x264 (H.264), HEVC was designed to double the data compression ratio while maintaining the same level of video quality. In practical terms, x265 requires roughly for the same video quality. For media server operators, this translates directly into significant storage savings and reduced network usage.

Mastering the "Sonarr Prefer x265" Setup: Optimize Storage Without Sacrificing Quality

Here is a major pitfall. Some uploaders take an x264 source and re-encode it to x265 at an extremely low bitrate to save space. The result is a blocky, artifact-ridden mess.