Hi Nicolas, On Wed, 26 Jun 2024 13:46:03 -0400, Nicolas Dufresne wrote: >Just to clarify, since you are right that it won't work well with GStreamer. It >does work with multiple decoders (it exposes them all), it is simply that it >will randomly pick one when decoding, and it may not pick the best one. I have tested rkvdec2 and vpu121 with gstreamer 1.24.2 on rk356x to decode a 4K video, and gstreamer always fall with error: "v4l2slh264dec0: Failed to configure H264 decoder". I guess that's because 1080p vpu is at fdea0000 which is always initialized earlier than rkvdec2 at fdf80200, so gstreamer will always choose the 1080p decoder. >In the long term, I'd like to stop having to do "like downstream" and expose >them all. I believe the fix is fairly straightforward in GStreamer. We need to >expose in the generated element the width/height ranges, and for H.264 the >supported profiles and level. With that, we at least won't randomly fail at >decoding 4K, and it should be good enough. Not only gstreamer, chromium also has similar issue. Chromium will only check video resolution globally before starting to use one decoder: if there is a 4K decoder detected before, it will mark 4K resolution as supported. But when decoding videos, it will choose the first decoder supporting profile like H264. So chromium may use a 1080p decoder to decode a 4K video. Chromium's code about v4l2 is complicated for me. I may create a bug about it. But chrome os doesn't support devices with multi v4l2 decoders like rockchip's socs, I don't know if they have the motion to fix it quickly. >For RK3588, which is a new SoC, its not a problem to upstream something that >does not work with existing userspace. It would only be a regression if we where >to enable VDPU121 on RK3399, as now updating linux would cause bugs with >existing userspace. There is an old soc just like RK3399: RK3328, which also has a 1080p hantro h264 decoder and a 4K rkvdec h264 decoder. I guess less people care about its mainline decoding with gstreamer/chromium so it still has 1080p decoder enabled. >For users, it would be best if we get this sorted out in GStreamer by the time >we have a second decoder. Note that I have some vacation coming up this month, >so there might be extra delays. Yet, its logical to merge this (the "worst" >decoder) first, since then randomly picking a better one won't be a regression. Happy vacation days! I will also take a look at chromium's code to see if I can fix it. Best regards, Jianfeng
