input
How frames in pixelFormat reach the encoder. pixelFormat is an FFmpeg pixel format: yuv420p for 8 bit 4:2:0, p010le for 10 bit 4:2:0, yuv444p for full chroma. VAAPI encoders take frames that are uploaded to the GPU by filters, Quick Sync, AMF and Media Foundation take 8 bit 4:2:0 frames as NV12.