@@ -797,8 +797,7 @@ static int configure_input_video_filter(FilterGraph *fg, InputFilter *ifilter,

     AVFilterContext *first_filter = in->filter_ctx;

     AVFilter *filter = avfilter_get_by_name("buffer");

     InputStream *ist = ifilter->ist;

-    AVRational tb = ist->framerate.num ? (AVRational){ist->framerate.den,

-                                                      ist->framerate.num} :

+    AVRational tb = ist->framerate.num ? av_inv_q(ist->framerate) :

                                          ist->st->time_base;

     AVRational sar;

     char args[255], name[255];

@@ -2197,8 +2196,7 @@ static int output_packet(InputStream *ist, const AVPacket *pkt)

             if (avpkt.duration)

                 ist->next_dts += av_rescale_q(avpkt.duration, ist->st->time_base, AV_TIME_BASE_Q);

             else if (ist->st->avg_frame_rate.num)

-                ist->next_dts += av_rescale_q(1, (AVRational){ist->st->avg_frame_rate.den,

-                                                              ist->st->avg_frame_rate.num},

+                ist->next_dts += av_rescale_q(1, av_inv_q(ist->st->avg_frame_rate),

                                               AV_TIME_BASE_Q);

             else if (ist->st->codec->time_base.num != 0) {

                 int ticks      = ist->st->parser ? ist->st->parser->repeat_pict + 1 :

@@ -115,6 +115,17 @@ AVRational av_add_q(AVRational b, AVRational c) av_const;

 AVRational av_sub_q(AVRational b, AVRational c) av_const;

 /**

+ * Invert a rational.

+ * @param q value

+ * @return 1 / q

+ */

+static av_always_inline AVRational av_inv_q(AVRational q)

+{

+    AVRational r = { q.den, q.num };

+    return r;

+}

+

+/**

  * Convert a double precision floating point number to a rational.

  * inf is expressed as {1,0} or {-1,0} depending on the sign.

  *