lavf/movenc: mark mov/mp4 as supporting VFR

libavformat/movenc.c

@@ -8421,11 +8421,11 @@ const FFOutputFormat ff_mov_muxer = {
     .write_packet      = mov_write_packet,
     .write_trailer     = mov_write_trailer,
     .deinit            = mov_free,
+    .p.flags           = AVFMT_GLOBALHEADER | AVFMT_TS_NEGATIVE | AVFMT_VARIABLE_FPS
 #if FF_API_ALLOW_FLUSH
-    .p.flags           = AVFMT_GLOBALHEADER | AVFMT_ALLOW_FLUSH | AVFMT_TS_NEGATIVE,
-#else
-    .p.flags           = AVFMT_GLOBALHEADER | AVFMT_TS_NEGATIVE,
+                       | AVFMT_ALLOW_FLUSH
 #endif
+                         ,
     .p.codec_tag       = (const AVCodecTag* const []){
         ff_codec_movvideo_tags, ff_codec_movaudio_tags, ff_codec_movsubtitle_tags, 0
     },
@@ -8473,11 +8473,11 @@ const FFOutputFormat ff_mp4_muxer = {
     .write_packet      = mov_write_packet,
     .write_trailer     = mov_write_trailer,
     .deinit            = mov_free,
+    .p.flags           = AVFMT_GLOBALHEADER | AVFMT_TS_NEGATIVE | AVFMT_VARIABLE_FPS
 #if FF_API_ALLOW_FLUSH
-    .p.flags           = AVFMT_GLOBALHEADER | AVFMT_ALLOW_FLUSH | AVFMT_TS_NEGATIVE,
-#else
-    .p.flags           = AVFMT_GLOBALHEADER | AVFMT_TS_NEGATIVE,
+                       | AVFMT_ALLOW_FLUSH
 #endif
+                         ,
     .p.codec_tag       = mp4_codec_tags_list,
     .check_bitstream   = mov_check_bitstream,
     .p.priv_class      = &mov_isobmff_muxer_class,