https://github.com/qt/qtmultimedia/commit/65b11b9f976
--- a/src/plugins/multimedia/ffmpeg/qffmpegcodecstorage.cpp
+++ b/src/plugins/multimedia/ffmpeg/qffmpegcodecstorage.cpp
@@ -101,3 +101,5 @@
         { AV_CODEC_CAP_SMALL_LAST_FRAME, "SMALL_LAST_FRAME" },
+#ifdef AV_CODEC_CAP_SUBFRAMES
         { AV_CODEC_CAP_SUBFRAMES, "SUBFRAMES" },
+#endif
         { AV_CODEC_CAP_EXPERIMENTAL, "EXPERIMENTAL" },