-class FrameRateCandidate
-{
-public:
- FrameRateCandidate (float source_, int dcp_)
- : source (source_)
- , dcp (dcp_)
- {}
-
- 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;
- }
-
- if (!best) {
- throw EncodeError ("cannot find a suitable DCP frame rate for this source");
- }
-
- 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.
- * @return The appropriate DCP-approved sampling rate (48kHz or 96kHz).