ffmpeg/avformat: factor av_guess_frame_rate() out

This will be used in ffplay
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/APIchanges

@@ -15,6 +15,9 @@ libavutil:     2012-10-22
 
 API changes, most recent first:
 
+2013-03-29 - xxxxxxx - lavf 55.1.100 - avformat.h
+  Add av_guess_frame_rate()
+
 2013-03-20 - xxxxxxx - lavu 52.22.100 - opt.h
   Add AV_OPT_TYPE_DURATION value to AVOptionType enum.
 

ffmpeg_filter.c

@@ -542,22 +542,15 @@ static int configure_input_video_filter(FilterGraph *fg, InputFilter *ifilter,
     InputStream *ist = ifilter->ist;
     AVRational tb = ist->framerate.num ? av_inv_q(ist->framerate) :
                                          ist->st->time_base;
-    AVRational fr = ist->framerate.num ? ist->framerate :
-                                         ist->st->r_frame_rate;
+    AVRational fr = ist->framerate;
     AVRational sar;
     AVBPrint args;
     char name[255];
     int pad_idx = in->pad_idx;
     int ret;
 
-    if (!ist->framerate.num && ist->st->codec->ticks_per_frame>1) {
-        AVRational codec_fr = av_inv_q(ist->st->codec->time_base);
-        AVRational   avg_fr = ist->st->avg_frame_rate;
-        codec_fr.den *= ist->st->codec->ticks_per_frame;
-        if (   codec_fr.num>0 && codec_fr.den>0 && av_q2d(codec_fr) < av_q2d(fr)*0.7
-            && fabs(1.0 - av_q2d(av_div_q(avg_fr, fr)))>0.1)
-            fr = codec_fr;
-    }
+    if (!fr.num)
+        fr = av_guess_frame_rate(input_files[ist->file_index]->ctx, ist->st, NULL);
 
     if (ist->st->codec->codec_type == AVMEDIA_TYPE_SUBTITLE) {
         ret = sub2video_prepare(ist);

libavformat/avformat.h

@@ -2107,6 +2107,16 @@ const struct AVCodecTag *avformat_get_riff_audio_tags(void);
  */
 AVRational av_guess_sample_aspect_ratio(AVFormatContext *format, AVStream *stream, AVFrame *frame);
 
+/**
+ * Guess the frame rate, based on both the container and codec information.
+ *
+ * @param ctx the format context which the stream is part of
+ * @param stream the stream which the frame is part of
+ * @param frame the frame for which the frame rate should be determined, may be NULL
+ * @return the guessed (valid) frame rate, 0/1 if no idea
+ */
+AVRational av_guess_frame_rate(AVFormatContext *ctx, AVStream *stream, AVFrame *frame);
+
 /**
  * Check if the stream st contained in s is matched by the stream specifier
  * spec.

libavformat/utils.c

@@ -4278,6 +4278,22 @@ AVRational av_guess_sample_aspect_ratio(AVFormatContext *format, AVStream *strea
         return frame_sample_aspect_ratio;
 }
 
+AVRational av_guess_frame_rate(AVFormatContext *format, AVStream *st, AVFrame *frame)
+{
+    AVRational fr = st->r_frame_rate;
+
+    if (st->codec->ticks_per_frame > 1) {
+        AVRational codec_fr = av_inv_q(st->codec->time_base);
+        AVRational   avg_fr = st->avg_frame_rate;
+        codec_fr.den *= st->codec->ticks_per_frame;
+        if (   codec_fr.num > 0 && codec_fr.den > 0 && av_q2d(codec_fr) < av_q2d(fr)*0.7
+            && fabs(1.0 - av_q2d(av_div_q(avg_fr, fr))) > 0.1)
+            fr = codec_fr;
+    }
+
+    return fr;
+}
+
 int avformat_match_stream_specifier(AVFormatContext *s, AVStream *st,
                                     const char *spec)
 {

libavformat/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFORMAT_VERSION_MAJOR 55
-#define LIBAVFORMAT_VERSION_MINOR  0
+#define LIBAVFORMAT_VERSION_MINOR  1
 #define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \