avformat/mov.: Make the process of uuid-xmp atom faster.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/mov.c

@@ -4776,7 +4776,7 @@ static int mov_read_uuid(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     } else if (!memcmp(uuid, uuid_xmp, sizeof(uuid))) {
         uint8_t *buffer;
         size_t len = atom.size - sizeof(uuid);
-
+        if (c->export_xmp) {
             buffer = av_mallocz(len + 1);
             if (!buffer) {
                 return AVERROR(ENOMEM);
@@ -4789,11 +4789,15 @@ static int mov_read_uuid(MOVContext *c, AVIOContext *pb, MOVAtom atom)
                 av_free(buffer);
                 return AVERROR_INVALIDDATA;
             }
-        if (c->export_xmp) {
             buffer[len] = '\0';
             av_dict_set(&c->fc->metadata, "xmp", buffer, 0);
-        }
             av_free(buffer);
+        } else {
+            // skip all uuid atom, which makes it fast for long uuid-xmp file
+            ret = avio_skip(pb, len);
+            if (ret < 0)
+                return ret;
+        }
     } else if (!memcmp(uuid, uuid_spherical, sizeof(uuid))) {
         size_t len = atom.size - sizeof(uuid);
         ret = mov_parse_uuid_spherical(sc, pb, len);