diff --git a/libavformat/adp.c b/libavformat/adp.c
index c5feac4fa5..08a4225e46 100644
--- a/libavformat/adp.c
+++ b/libavformat/adp.c
@@ -26,14 +26,21 @@
 
 static int adp_probe(AVProbeData *p)
 {
-    int i;
+    int i, changes = 0;
+    char last = 0;
 
     if (p->buf_size < 32)
         return 0;
 
-    for (i = 0; i < p->buf_size - 3; i+=32)
+    for (i = 0; i < p->buf_size - 3; i+=32) {
         if (p->buf[i] != p->buf[i+2] || p->buf[i+1] != p->buf[i+3])
             return 0;
+        if (p->buf[i] != last)
+            changes++;
+        last = p->buf[i];
+    }
+    if (changes <= 1)
+        return 0;
 
     return p->buf_size < 260 ? 1 : AVPROBE_SCORE_MAX / 4;
 }
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 92ce5341e6..7315417ca2 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -3885,7 +3885,8 @@ static int mov_write_header(AVFormatContext *s)
             }else{
                 track->sample_size = (av_get_bits_per_sample(st->codec->codec_id) >> 3) * st->codec->channels;
             }
-            if (st->codec->codec_id == AV_CODEC_ID_ILBC) {
+            if (st->codec->codec_id == AV_CODEC_ID_ILBC ||
+                st->codec->codec_id == AV_CODEC_ID_ADPCM_IMA_QT) {
                 track->audio_vbr = 1;
             }
             if (track->mode != MODE_MOV &&