GPU routes per vendor and system

The front tries the GPU first and our own CPU code second, for every decode and every encode, and every fallback says why in a plain reason an app can show. Nothing extra is installed or linked: libva is loaded at run time on Linux, VideoToolbox is part of macOS and Media Foundation part of Windows, so a binary starts on a machine without them and decodes on the CPU there.

Route	System	Decode	Encode	Tested on
VA-API, AMD (Mesa radeonsi)	Linux	H.264, H.265, VP9	H.264, H.265; overlays composed on the card	AMD Radeon RX 9060 XT (RDNA 4), before every release
VA-API, Intel (iHD)	Linux	H.264, H.265, VP9	H.264, H.265	Built, untested on Intel hardware
VideoToolbox	macOS	H.264, H.265	H.264, H.265	GitHub’s Apple Silicon runners on every push: decode bit-exact with ffmpeg, encodes decoded back
NVENC	Linux, Windows	—	H.264, H.265	Built and unit-tested, untested on NVIDIA hardware
Media Foundation	Windows	H.264, H.265	—	Built and unit-tested, untested on GPU hardware

The CPU codecs run and are tested on every push on Linux x86-64 and arm64, Windows x86-64 and macOS on Apple Silicon, with AVX2 kernels on x86-64 and NEON or portable paths on arm64.

See what this machine has

gpu::available() lists every codec, direction and backend found:

use pito_codecs::gpu;

println!("{:?}", gpu::available());

On Linux with an AMD card:

[(H264, Decode, VaApi), (H264, Encode, VaApi), (Hevc, Decode, VaApi), (Hevc, Encode, VaApi), (Vp9, Decode, VaApi)]

pcod decode names the route it took, such as GPU (VA-API, radeonsi), and the library guide shows how an app asks the same.

Speed on VA-API

GPU decode and encode through VA-API run 1.1× to 1.3× faster than ffmpeg’s at the same settings, and a transcode keeps every frame on the card from decode to encode.

Limits worth knowing

• VA-API H.264 and HEVC refuse pictures smaller than 352x240 with an error, since smaller ones faulted AMD’s video engine; decode and encode such small pictures on the CPU route.
• H.265 encodes on the GPU only. Without a GPU HEVC encoder, an HEVC encode falls back to H.264 on the GPU, then on the CPU, as Prefs::hevc_encode_fallback says.
• Overlays are composed on the card only with Mesa’s VA-API driver; every other route blends them on the CPU (Overlays and captions).
• On Windows, H.265 decode through Media Foundation needs Microsoft’s HEVC Video Extensions.