Gentoo's Bugzilla –
Attachment 530780 Details for
Bug 655442media-video/mplayer-1.3.0-r5 with media-video/ffmpeg-4.0 - libmpcodecs/vd_ffmpeg.c:197:34: error: 'AV_PIX_FMT_XVMC_MPEG2_IDCT' undeclared (first use in this function); did you mean 'AV_PIX_FMT_VAAPI_IDCT'?