As part of the ongoing enablement of AMD’s next generation RDNA 3 GPUs, the company has released a series of patches for Linux that reveal details about the company’s upcoming video engines, the Video Codec Next version 4.x. For now, VCN 4.x supports decoding of virtually all modern codecs, but for some reason AV1 encoding is not supported.
AMD’s VCN 4.0 engine appears to support H.264/MPEG 4 AVC, H.265, VP9, AV1, and JPEG decoding, but only H.264 and H.265 encoding. For now, VCN does not appear to support AV1 encoding as well as H.266/VVC (versatile video coding) decoding/encoding. While VVC is a next-generation codec that will be required maybe in 2023 or 2024 (when appropriate content becomes available), AV1 is a current generation codec with expanding usage, and there are users that would like to have it now for encoding or transcoding video.
Intel’s Arc Alchemist GPUs fully support AV1 decoding and encoding, the only chips to do so at present. But RDNA 3 won’t arrive until later this year, so if AMD’s VCN 4.x indeed does not support AV1 encoding, it means that a competing GPU will have an edge over AMD’s upcoming graphics processors. We expect Nvidia may also support AV1 encoding with it’s upcoming Ada architecture, though that remains as yet unconfirmed.
AMD’s current-generation GPUs based on the RDNA 2 architecture use the company’s VCN 3.0, VCN 3.1, and VCN 3.1.2 video decoding blocks. By contrast, next-generation RDNA 3 graphics processors (at least the so-called SoC21, which is believed to be Navi 31) will feature the next-generation VCN 4.0 engine, according to a new Linux patch posted by AMD and discovered by @Kepler_L2.
Speaking of VCN 4.0, even the current VCN 3.x engine fully supports H.264/MPEG4 AVC, H.265, VP9, AV1, and JPEG decoding as well as H.264 and H.265 encoding, so it remains to be seen what VCN 4.0 adds to the list. A natural guess would be higher supported resolutions, color depths/formats, and/or efficiency improvements, but we would anticipate some additional feature set changes as well.
Meanwhile, it should be kept in mind that not all GPU features get enabled ahead of launch, especially in Linux due to various legal and technical reasons. Therefore, it is possible that AV1 encoding will be supported by AMD’s VCN 4.0 hardware, but for now it’s not supported by the Linux software hooks.