#include <iomanip>
#include <iostream>
#include <fstream>
+#include <climits>
#ifdef DVDOMATIC_POSIX
#include <execinfo.h>
#include <cxxabi.h>
#include "dcp_content_type.h"
#include "filter.h"
#include "sound_processor.h"
+#include "config.h"
using namespace std;
using namespace boost;
+using libdcp::Size;
thread::id ui_thread;
return s.str ();
}
-/** @param fps Arbitrary frames-per-second value.
- * @return DCPFrameRate for this frames-per-second.
- */
-DCPFrameRate
-dcp_frame_rate (float fps)
+static bool about_equal (float a, float b)
+{
+ /* A film of F seconds at f FPS will be Ff frames;
+ Consider some delta FPS d, so if we run the same
+ film at (f + d) FPS it will last F(f + d) seconds.
+
+ Hence the difference in length over the length of the film will
+ be F(f + d) - Ff frames
+ = Ff + Fd - Ff frames
+ = Fd frames
+ = Fd/f seconds
+
+ So if we accept a difference of 1 frame, ie 1/f seconds, we can
+ say that
+
+ 1/f = Fd/f
+ ie 1 = Fd
+ ie d = 1/F
+
+ So for a 3hr film, ie F = 3 * 60 * 60 = 10800, the acceptable
+ FPS error is 1/F ~= 0.0001 ~= 10-e4
+ */
+
+ return (fabs (a - b) < 1e-4);
+}
+
+class FrameRateCandidate
{
- DCPFrameRate dfr;
+public:
+ FrameRateCandidate (float source_, int dcp_)
+ : source (source_)
+ , dcp (dcp_)
+ {}
- dfr.run_fast = (fps != rint (fps));
- dfr.frames_per_second = rint (fps);
- dfr.skip = 1;
+ bool skip () const {
+ return !about_equal (source, dcp) && source > dcp;
+ }
+
+ bool repeat () const {
+ return !about_equal (source, dcp) && source < dcp;
+ }
+
+ float source;
+ int dcp;
+};
+
+/** @param fps Arbitrary source frames-per-second value */
+/** XXX: this could be slow-ish */
+DCPFrameRate::DCPFrameRate (float source_fps)
+{
+ list<int> const allowed_dcp_frame_rates = Config::instance()->allowed_dcp_frame_rates ();
+
+ /* Work out what rates we could manage, including those achieved by using skip / repeat. */
+ list<FrameRateCandidate> candidates;
+
+ /* Start with the ones without skip / repeat so they will get matched in preference to skipped/repeated ones */
+ for (list<int>::const_iterator i = allowed_dcp_frame_rates.begin(); i != allowed_dcp_frame_rates.end(); ++i) {
+ candidates.push_back (FrameRateCandidate (*i, *i));
+ }
+
+ /* Then the skip/repeat ones */
+ for (list<int>::const_iterator i = allowed_dcp_frame_rates.begin(); i != allowed_dcp_frame_rates.end(); ++i) {
+ candidates.push_back (FrameRateCandidate (float (*i) / 2, *i));
+ candidates.push_back (FrameRateCandidate (float (*i) * 2, *i));
+ }
+
+ /* Pick the best one, bailing early if we hit an exact match */
+ float error = numeric_limits<float>::max ();
+ boost::optional<FrameRateCandidate> best;
+ list<FrameRateCandidate>::iterator i = candidates.begin();
+ while (i != candidates.end()) {
+
+ if (about_equal (i->source, source_fps)) {
+ best = *i;
+ break;
+ }
+
+ float const e = fabs (i->source - source_fps);
+ if (e < error) {
+ error = e;
+ best = *i;
+ }
+
+ ++i;
+ }
- /* XXX: somewhat arbitrary */
- if (fps == 50) {
- dfr.frames_per_second = 25;
- dfr.skip = 2;
+ if (!best) {
+ throw EncodeError ("cannot find a suitable DCP frame rate for this source");
}
- return dfr;
+ frames_per_second = best->dcp;
+ skip = best->skip ();
+ repeat = best->repeat ();
+ change_speed = !about_equal (source_fps * factor(), frames_per_second);
}
/** @param An arbitrary sampling rate.