Video codecs: HEVC, AV1, VP9, H.264 and more

A codec is the method used to compress the picture or the sound in a video file. AIX Player carries its own decoders for the codecs in everyday use and for many older ones, so a file plays without a codec pack and without anything being installed elsewhere in Windows. This page lists them, and explains where your graphics hardware helps.

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Windows 11 & 10 · x64 and Arm64 · Updated 28 October 2026

Codec or file type?

The extension (.mkv, .mp4, .avi) names the container, the box. The codec is how each track inside it was compressed. Two MP4 files can hold different codecs, which is why one plays and the other does not. The video formats page lists the 81 file types AIX Player opens; this page is about what is inside them.

Video codecs decoded in the app

• Today’s video: H.264 (AVC), HEVC (H.265), AV1 and VP9, including 4K and 10-bit video.
• Web video: VP8 and Theora.
• Discs and broadcast: MPEG-1, MPEG-2 and VC-1.
• Older PC and phone video: MPEG-4 Part 2 (DivX and Xvid), H.263, WMV 1, 2 and 3, RealVideo, Cinepak, Sorenson Video 3 and Flash video.
• Editing and camera formats: ProRes and DNxHD.

Audio codecs

AAC, MP3, AC-3 and E-AC-3, FLAC, ALAC, Opus, Vorbis, WMA 2 and WMA Pro, Cook, and the other surround and lossless soundtracks of Blu-ray and DVD copies. Sound is decoded in the app: supported surround outputs can receive multichannel audio, while stereo outputs receive a downmix.

Subtitle formats

Text tracks such as SRT, ASS/SSA and VTT, picture-based tracks from discs (PGS from Blu-ray, VobSub from DVD, and DVB) and closed captions all decode. Teletext subtitles are not supported. The subtitle formats guide covers the differences.

Where your graphics hardware helps

Hardware decode is on by default. The setting is Settings → Video → Hardware decode: “Use the GPU to decode video, or fall back to the CPU.” AIX can use supported graphics decoding and fall back to software; playback still depends on the file and PC. Which codecs a chip supports depends on its generation and its driver, which is why a driver update can matter. Hardware acceleration explains more.

If the picture turns green, pink or blocky, test the graphics path: see the green or pink picture guide. When AIX Player converts video for a TV, NVIDIA, Intel and AMD graphics can do the conversion; on Qualcomm Snapdragon PCs only the H.264 encoding is done in hardware, and the other stages use the processor.

Which codec is my video?

Open the file’s details in AIX Player. The library’s File info lists available video codec, resolution, bitrate and audio-track count, among other details.

Do I need a codec pack?

Not for AIX Player. Its decoders are part of the app, so there is nothing to download and nothing system-wide to install. If another app shows an error, the “unsupported codec” guide explains what the message means.

Codecs on your TV

When you cast to a TV, the TV’s own decoders decide what it can play directly. Most TV families AIX Player supports play H.264 and HEVC, and many also play VP9 or AV1, depending on the model. When a TV cannot play part of a file, AIX Player converts that part while it streams.