Dmabufs allow buffers to be shared between kernel subsystems. For V4L2, once you have allocated buffers you can call VIDIOC_EXPBUF to get an associated dmabuf handle (it's a file descriptor that you can mmap and do a few other manipulations on). https://www.linuxtv.org/downloads/v4l-...
[1:ml1] [INF] [ENC] ffmpeg_avcodec_log: driver 'exynos-gsc' on card 'exynos-gsc gscaler' [1:ml1] [INF] [ENC] ffmpeg_avcodec_log: v4l2 capture format not supported [1:ml1] [INF] [ENC] ffmpeg_avcodec_log: probing device /dev/video20 [1:ml1] [INF] [ENC] ffmpeg_avcodec_log: ...