avformat/vivo: Favor setting fps from explicit fractions

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

libavformat/vivo.c

@@ -121,7 +121,7 @@ static int vivo_get_packet_header(AVFormatContext *s)
 static int vivo_read_header(AVFormatContext *s)
 {
     VivoContext *vivo = s->priv_data;
-    AVRational fps = { 1, 25};
+    AVRational fps = { 0 };
     AVStream *ast, *vst;
     unsigned char *line, *line_end, *key, *value;
     long value_int;
@@ -212,13 +212,16 @@ static int vivo_read_header(AVFormatContext *s)
                     return AVERROR_INVALIDDATA;
 
                 value_used = 1;
-                fps = av_inv_q(av_d2q(d, 10000));
+                if (!fps.num && !fps.den)
+                    fps = av_inv_q(av_d2q(d, 10000));
             }
 
             if (!value_used)
                 av_dict_set(&s->metadata, key, value, 0);
         }
     }
+    if (!fps.num || !fps.den)
+        fps = (AVRational){ 1, 25 };
 
     avpriv_set_pts_info(ast, 64, 1, ast->codecpar->sample_rate);
     avpriv_set_pts_info(vst, 64, fps.num, fps.den);