[FFmpeg-cvslog] mux/nut: factorize ff_choose_timebase() out of nut

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Wed Oct  3 21:34:43 2012 +0200| [de707bc8bdfff92a1905169ba6054034d464dbb5] | committer: Michael Niedermayer

mux/nut: factorize ff_choose_timebase() out of nut

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=de707bc8bdfff92a1905169ba6054034d464dbb5
---

 libavformat/internal.h |    8 ++++++++
 libavformat/mux.c      |   19 +++++++++++++++++++
 libavformat/nutenc.c   |    6 +-----
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/libavformat/internal.h b/libavformat/internal.h
index 402e155..2689b2f 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -354,5 +354,13 @@ void ff_compute_frame_duration(int *pnum, int *pden, AVStream *st,
 
 int ff_get_audio_frame_size(AVCodecContext *enc, int size, int mux);
 
+/**
+ * Chooses a timebase for muxing the specified stream.
+ *
+ * The choosen timebase allows sample accurate timestamps based
+ * on the framerate or sample rate for audio streams. It also is
+ * at least as precisse as 1/min_precission would be.
+ */
+AVRational ff_choose_timebase(AVFormatContext *s, AVStream *st, int min_precission);
 
 #endif /* AVFORMAT_INTERNAL_H */
diff --git a/libavformat/mux.c b/libavformat/mux.c
index debc6a1..cd5481f 100644
--- a/libavformat/mux.c
+++ b/libavformat/mux.c
@@ -103,6 +103,25 @@ static void frac_add(AVFrac *f, int64_t incr)
     f->num = num;
 }
 
+AVRational ff_choose_timebase(AVFormatContext *s, AVStream *st, int min_precission)
+{
+    AVRational q;
+    int j;
+
+    if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
+        q = (AVRational){1, st->codec->sample_rate};
+    } else {
+        q = st->codec->time_base;
+    }
+    for (j=2; j<2000; j+= 1+(j>2))
+        while (q.den / q.num < min_precission && q.num % j == 0)
+            q.num /= j;
+    while (q.den / q.num < min_precission && q.den < (1<<24))
+        q.den <<= 1;
+
+    return q;
+}
+
 int avformat_alloc_output_context2(AVFormatContext **avctx, AVOutputFormat *oformat,
                                    const char *format, const char *filename)
 {
diff --git a/libavformat/nutenc.c b/libavformat/nutenc.c
index 1402634..ccd6cb1 100644
--- a/libavformat/nutenc.c
+++ b/libavformat/nutenc.c
@@ -676,11 +676,7 @@ static int nut_write_header(AVFormatContext *s){
         if(st->codec->codec_type == AVMEDIA_TYPE_AUDIO && st->codec->sample_rate) {
             time_base = (AVRational){1, st->codec->sample_rate};
         } else {
-            for (j=2; j<2000; j+= 1+(j>2))
-                while (time_base.den / time_base.num < 48000 && time_base.num % j == 0)
-                    time_base.num /= j;
-            while (time_base.den / time_base.num < 48000 && time_base.den < (1<<24))
-                time_base.den <<= 1;
+            time_base = ff_choose_timebase(s, st, 48000);
         }
 
         avpriv_set_pts_info(st, 64, time_base.num, time_base.den);