av_log: readd ffmpeg library runtime version mismatch warning

It just happens far too often.

1 files changed, 13 insertions, 1 deletions

diff --git a/common/av_log.c b/common/av_log.c
index bfd9a836e8..804972889f 100644
--- a/common/av_log.c
+++ b/common/av_log.c
@@ -207,17 +207,29 @@ void print_libav_versions(struct mp_log *log, int v)
 
     mp_msg(log, v, "%s library versions:\n", LIB_PREFIX);
 
+    bool mismatch = false;
     for (int n = 0; n < MP_ARRAY_SIZE(libs); n++) {
         const struct lib *l = &libs[n];
         mp_msg(log, v, "   %-15s %d.%d.%d", l->name, V(l->buildv));
-        if (l->buildv != l->runv)
+        if (l->buildv != l->runv) {
             mp_msg(log, v, " (runtime %d.%d.%d)", V(l->runv));
+            mismatch = true;
+        }
         mp_msg(log, v, "\n");
     }
 
 #if HAVE_AV_VERSION_INFO
     mp_msg(log, v, "%s version: %s\n", LIB_PREFIX, av_version_info());
 #endif
+
+    if (mismatch) {
+        // Using mismatched libraries can be legitimate, but even then it's
+        // a bad idea. We don't acknowledge its usefulness and stability.
+        mp_warn(log, "Warning: mpv was compiled against a different version of "
+                "%s than the shared\nlibrary it is linked against. This is "
+                "most likely a broken build\nand misbehavior and crashes are "
+                "to be expected.\n", LIB_PREFIX);
+    }
 }
 
 #undef V