Move everything into a separate futatabi/ subdir, for the upcoming merge with Futatabi.

[nageru] / nageru / timebase.h

diff --git a/nageru/timebase.h b/nageru/timebase.h
new file mode 100644 (file)
index 0000000..dbc4402
--- /dev/null
+++ b/nageru/timebase.h
@@ -0,0 +1,25 @@
+#ifndef _TIMEBASE_H
+#define _TIMEBASE_H 1
+
+// Common timebase that allows us to represent one frame exactly in all the
+// relevant frame rates:
+//
+//   Timebase:                1/120000
+//   Frame at 50fps:       2400/120000
+//   Frame at 60fps:       2000/120000
+//   Frame at 59.94fps:    2002/120000
+//   Frame at 23.976fps:   5005/120000
+//
+// If we also wanted to represent one sample at 48000 Hz, we'd need
+// to go to 300000. Also supporting one sample at 44100 Hz would mean
+// going to 44100000; probably a bit excessive.
+#define TIMEBASE 120000
+
+// Some muxes, like MP4 (or at least avformat's implementation of it),
+// are not too fond of values above 2^31. At timebase 120000, that's only
+// about five hours or so, so we define a coarser timebase that doesn't
+// get 59.94 precisely (so there will be a marginal amount of pts jitter),
+// but can do at least 50 and 60 precisely, and months of streaming.
+#define COARSE_TIMEBASE 300
+
+#endif  // !defined(_TIMEBASE_H)